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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Noopy on May 10, 2020, 09:43:28 pm

Title: Transistors - die pictures
Post by: Noopy on May 10, 2020, 09:43:28 pm
How about a transistor-die-picture-topic?  :)

I have collected some here:

https://www.richis-lab.de/Transistoren.htm (https://www.richis-lab.de/Transistoren.htm)


And I just have to show you this one:

(https://www.richis-lab.de/images/Transistoren/02x09.gif)

You see the breakdown of the KD501-base-emitter-junction with increasing current.  8) ;D


(https://www.richis-lab.de/images/Transistoren/02x07.jpg)

Does anybody know why Tesla integrated this step at the edge of the die?
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 10, 2020, 10:01:19 pm
The BE breakdown video is great ?

I'm working on a PHD where this effect plays a role. May I use your video in my thesis ?

Just speculating, is this a MESA part ?
Title: Re: Transistors - die pictures
Post by: Noopy on May 11, 2020, 03:10:13 am
The BE breakdown video is great ?

I'm working on a PHD where this effect plays a role. May I use your video in my thesis ?

Thanks!
Of course you can use it in your PHD.
If you need something special (higher resolution, different angle,...) just tell me.


Just speculating, is this a MESA part ?

Sounds reasonable!  :-+
Title: Re: Transistors - die pictures
Post by: Miyuki on May 11, 2020, 09:31:49 am
Just speculating, is this a MESA part ?

Sounds reasonable!  :-+

Looks exactly as on book drawings
[attachimg=1]
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 11, 2020, 03:14:55 pm
... just a question - is the 2N2222A also emitting light in BE breakdown ?

 regards
  Wolfgang
Title: Re: Transistors - die pictures
Post by: exe on May 11, 2020, 03:28:34 pm
Is it possible to check tip3055 and tip2955 from onsemi and st? I'm willing to sponsor this. They are in plastic enclosure, to-264 or to-247.
Title: Re: Transistors - die pictures
Post by: Noopy on May 11, 2020, 03:53:05 pm
... just a question - is the 2N2222A also emitting light in BE breakdown ?

 regards
  Wolfgang

I´m pretty sure every bipolar transistor has the same glowing.
I want to do this again with a smaller transistor. Let´s see what I have on my bench.

...I have taken new pictures of the BE-breakdown will upload them today…


Is it possible to check tip3055 and tip2955 from onsemi and st? I'm willing to sponsor this. They are in plastic enclosure, to-264 or to-247.

In principle that´s no problem:

(https://www.richis-lab.de/images/decap-ofen/22.jpg)
https://www.richis-lab.de/decap-ofen.htm (https://www.richis-lab.de/decap-ofen.htm)
 ;D

My success rate is something around 95%. Only very few package fail in decapping but there are some.
And it takes some days. After all it´s only a hobby.  :-/O
If that´s ok for you feel free to send me the parts.  :-+
Title: Re: Transistors - die pictures
Post by: Noopy on May 11, 2020, 07:37:50 pm
I have uploaded a new row of pictures including the current values:
https://www.richis-lab.de/Bipolar02.htm (https://www.richis-lab.de/Bipolar02.htm)

One interesting effect is the positive temperature coefficient of the breakdown voltage (Z-diode with Vbr=10V). If you connect a voltage at B-E that is just high enough to let it break down and then increase the current the B-E-junction suddenly gets non conductive again. => Physics! :-+ ;D
Title: Re: Transistors - die pictures
Post by: mawyatt on May 12, 2020, 02:46:49 pm
I have uploaded a new row of pictures including the current values:
https://www.richis-lab.de/Bipolar02.htm (https://www.richis-lab.de/Bipolar02.htm)

One interesting effect is the positive temperature coefficient of the breakdown voltage (Z-diode with Vbr=10V). If you connect a voltage at B-E that is just high enough to let it break down and then increase the current the B-E-junction suddenly gets non conductive again. => Physics! :-+ ;D

Very interesting results with the optical output from the reversed breakdown EB junction!! 8) Also like the method you've developed to de-encapsulate ICs based upon "burning" off the epoxy, very clever :-+

An interesting effect on some bipolar transistors when used with EB junction reversed biased in this type behavior where the plot of voltage vs. current has a region of negative slope when entering breakdown, or dV/dI is negative, thus negative resistance. This is the type of behavior of a avalanche or tunnel diode.

One can build a simple "relaxation oscillator" by using a large (~100K) resistor to supply a higher than breakdown voltage (usually >10 volts) to the Emitter junction of an NPN transistor. The base is ground and collector open (also try a connect to collector ground and leave the base open), a capacitor (10nF) shunting the EB junction to ground. With a scope you can observe a sawtooth relaxation waveform across the EB junction as you adjust the supply voltage. This waveform is caused by the charging of the capacitor with the RC time constant, then a rapid discharge as the junction enters the negative resistance region, then a repeat of this cycle.

The late Jim Williams (brilliant analog engineer, RIP) discussed at the ISSCC awhile back (I had a brief private discussion with him) how he designed a cheap voltage reference using a small NPN transistor with the EB junction operated in breakdown which produces a positive TC, then the base was left open and the collector grounded. This would forward bias the base to collector diode would produce the negative TC compensating the positive TC of the reversed breakdown of the EB junction. This went into production only to find that the composite transistor based reference was oscillating using the decoupling capacitor and resistor bias!!

Best,
Title: Re: Transistors - die pictures
Post by: Noopy on May 12, 2020, 04:47:28 pm
Very interesting results with the optical output from the reversed breakdown EB junction!! 8)

I did this also with the famous LTZ1000 to identify where the different junctions are:

(https://richis-lab.de/images/REF01/01_11.jpg)
(https://richis-lab.de/images/REF01/01_12.jpg)

https://richis-lab.de/REF03.htm (https://richis-lab.de/REF03.htm)


Also like the method you've developed to de-encapsulate ICs based upon "burning" off the epoxy, very clever :-+

It´s a simple and much less dangerous way than working with ultra special solvents or hot concentrated acids. It works quite well and very fast!  :-+


An interesting effect on some bipolar transistors when used with EB junction reversed biased in this type behavior where the plot of voltage vs. current has a region of negative slope when entering breakdown, or dV/dI is negative, thus negative resistance. This is the type of behavior of a avalanche or tunnel diode.
...

I think I have heard of that somewhere...  :-+


The late Jim Williams (brilliant analog engineer, RIP) discussed at the ISSCC awhile back (I had a brief private discussion with him) how he designed a cheap voltage reference using a small NPN transistor with the EB junction operated in breakdown which produces a positive TC, then the base was left open and the collector grounded. This would forward bias the base to collector diode would produce the negative TC compensative the positive TC of the reversed breakdown of the EB junction. This went into production only to find that the composite transistor based reference was oscillating using the decoupling capacitor and resistor bias!!

Best,

You had a private discussion with Jim Williams? Very cool!  8)
Title: Re: Transistors - die pictures
Post by: Noopy on May 12, 2020, 05:28:07 pm
Today I have a Germanium-Transistor for you, a Philips AU301:

https://www.richis-lab.de/Bipolar03.htm (https://www.richis-lab.de/Bipolar03.htm)


(https://www.richis-lab.de/images/transistoren/03x04.jpg)


It´s an alloy transistor. The combination of power and alloy transistor leads to an interesting design...
Title: Re: Transistors - die pictures
Post by: Noopy on May 12, 2020, 08:43:38 pm
I have uploaded a new row of pictures including the current values:
https://www.richis-lab.de/Bipolar02.htm (https://www.richis-lab.de/Bipolar02.htm)

Now with animated GIF:

(https://www.richis-lab.de/images/Transistoren/02x12.gif)

 8) ;D 8)
Title: Re: Transistors - die pictures
Post by: exe on May 12, 2020, 09:41:40 pm
There are spots that light up first. Are those the hot spots responsible for secondary breakdown?
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 12, 2020, 09:49:21 pm
No. Secondary breakdown occurs at the BC junction, not at BE.
Title: Re: Transistors - die pictures
Post by: mawyatt on May 13, 2020, 03:00:02 am

You had a private discussion with Jim Williams? Very cool!  8)

Yes, we talked briefly over coffee at the ISSCC in 2011 (Feb) and Jim passed away a few months later  :(

 Also had the pleasure of meeting and discussing things with Larry Nagle (Berkeley SPICE Author) at the ISSCC, a colleague worked with Larry at Bell Labs. Didn't make the ISSCC this year though, too risky.

BTW what current did you run thru the LTZ1000 to see the optical output? Would really like to get an LTZ1000, but they've become very expensive lately :-\

Best,
Title: Re: Transistors - die pictures
Post by: Noopy on May 13, 2020, 03:19:42 am
BTW what current did you run thru the LTZ1000 to see the optical output? Would really like to get an LTZ1000, but they've become very expensive lately :-\

I believe it was something around 10mA or 20mA back in the day.
The LTZ1000 was a noisy one a voltnut donated to me.
...I have a AD1139 on the bench…  8)
Title: Re: Transistors - die pictures
Post by: Noopy on May 13, 2020, 07:43:04 pm
... just a question - is the 2N2222A also emitting light in BE breakdown ?

Coincidentally I had a 2N2222A in my inbox.  ;D


(https://www.richis-lab.de/images/transistoren/04x05.jpg)

As expected the BE-junction glows too.


I then killed the 2N2222A and made a short video.  >:D

(https://www.richis-lab.de/images/transistoren/04x09.png)


You can identify the route of destruction:

(https://www.richis-lab.de/images/transistoren/04x09.jpg)

My Interpretation:
1) First breakdown destruction of the BE-junction.
2) Base-Electrode melts and cuts the current.
3) Second destruction of the BE-junction.
4) Base-metal melts further to the bondpad.
5) Last connection is disrupted with a bright arc.
Interesting...  :popcorn:


More pictures here:

https://www.richis-lab.de/Bipolar04.htm (https://www.richis-lab.de/Bipolar04.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 13, 2020, 10:54:33 pm
... just a question - is the 2N2222A also emitting light in BE breakdown ?

Coincidentally I had a 2N2222A in my inbox.  ;D


(https://www.richis-lab.de/images/transistoren/04x05.jpg)

As expected the BE-junction glows too.


I then killed the 2N2222A and made a short video.  >:D

(https://www.richis-lab.de/images/transistoren/04x09.png)


You can identify the route of destruction:

(https://www.richis-lab.de/images/transistoren/04x09.jpg)

My Interpretation:
1) First breakdown destruction of the BE-junction.
2) Base-Electrode melts and cuts the current.
3) Second destruction of the BE-junction.
4) Base-metal melts further to the bondpad.
5) Last connection is disrupted with a bright arc.
Interesting...  :popcorn:


More pictures here:

https://www.richis-lab.de/Bipolar04.htm (https://www.richis-lab.de/Bipolar04.htm)

 :popcorn:

Rich, just awesome, just what I need ! Thanks a lot !

Some questions:
- the video shows a very fast current increase. Did you run this with a current source ? Or is just the video too fast ?
- In my transistors, I see a noise curve very explainable by your KD503 video. First, only a few hotspots light up,
then more and more, until the whole area is bright. So noise *falls* with rising current. The 2N2222 seems to start almost immediately. Why ?
The Zener range is the same (> 7V), so it must be an avalanche mechanism.
- Do you want noise plots ? In case the 2N2222A behaves the same, they could be of interest.

Thanks again ! If you dont mind, I really want to give you an honourable mention in a paper I'm writing.
Title: Re: Transistors - die pictures
Post by: Noopy on May 14, 2020, 03:39:53 am
- the video shows a very fast current increase. Did you run this with a current source ? Or is just the video too fast ?

The bench supply is the weak spot of my lab.  :-X
I used a very cheap supply for this experiment. In the video I just cranked up the current limit to overload the 2N2222. I assume the current jumped up to something around 200mA, didn´t check that.
In the meantime I have some HP-supplies but I still have to integrate them into my bench...


- In my transistors, I see a noise curve very explainable by your KD503 video. First, only a few hotspots light up,
then more and more, until the whole area is bright. So noise *falls* with rising current. The 2N2222 seems to start almost immediately. Why ?
The Zener range is the same (> 7V), so it must be an avalanche mechanism.

Why? My supply!  ;D
It´s a pain in the ass to adjust the current limit around 10mA. The supply doesn´t even show smaller currents than 10mA. I had to meassure the current with my bench meter.
In the KD503 10mA is low enough to get the small little hotspots. In the 2N2222 with 10mA the current density is already high enough to light it up almost completely.
I have uploaded a new picture showing the glowing with lower current:

(https://www.richis-lab.de/images/Transistoren/04x11.jpg)

You can see the light is not uniform. With smaller currents I´m sure it would look like the KD501.

I observed the same effect with the 2N3055:
To get a uniform light in the big old ones you need a lot of current. They get pretty hot. In the newer small dies some ten mA are enough to get a nice light all over the place.


- Do you want noise plots ? In case the 2N2222A behaves the same, they could be of interest.

Of course! That would be very interesting!


Thanks again ! If you dont mind, I really want to give you an honourable mention in a paper I'm writing.

It would be an honour!  8)

Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 14, 2020, 03:47:54 am
I wonder if the glow pattern varies with charge state on the surface passivation (which is likely silica glass).  This would be hard to test; perhaps exposed metal surfaces could be insulated with an insulating film, then a conductive liquid (e.g. salt water) applied to control the surface electric field?  (Might need hundreds of volts, since the insulation will be so thick at this point.)

Tim
Title: Re: Transistors - die pictures
Post by: RoGeorge on May 14, 2020, 07:36:35 am
Why nobody put a photodiode inside to protect expensive power transistors?
Title: Re: Transistors - die pictures
Post by: Noopy on May 14, 2020, 09:23:56 am
I wonder if the glow pattern varies with charge state on the surface passivation (which is likely silica glass).  This would be hard to test; perhaps exposed metal surfaces could be insulated with an insulating film, then a conductive liquid (e.g. salt water) applied to control the surface electric field?  (Might need hundreds of volts, since the insulation will be so thick at this point.)

Tim

Possible but hard to test...  :-//


Why nobody put a photodiode inside to protect expensive power transistors?

In my view in real applications transistors rarely die because of base-emitter-breakdown.
Secondly you must be able to do something against the base-emitter-breakdown. Often base-emitter-breakdown occurs due to a bad design or a failure in an other circuit. It´s hard to compensate these things...
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 14, 2020, 10:46:30 am
Why nobody put a photodiode inside to protect expensive power transistors?

... its not a real world problem for power parts. Any useful design prevents this, e.g. by an antiparallel diode at the base. Furthermore, you need quite some current to kill those parts.
The problem is more with small transistors, where a BE breakdown even with small currents and for short times only degrades gain at low currents permanently.
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 14, 2020, 10:53:38 am
Hi Rich,

if you have no reliable constant current source you could try a normal power supply in constant voltage mode with a series resistor (or a pot) and a good multimeter in current mode. That should work.

Next week I could try to run this on a Keysight B2962 SMU.

Measured noise plot for 100uA, 1mA and 10mA is attached.

Best regards
  Wolfgang
Title: Re: Transistors - die pictures
Post by: Noopy on May 14, 2020, 11:44:31 am
Hi Wolfgang,

I just have to power up my HP6627A. That should be sufficient. But it has binding posts on the back so I need some kind of a connection panel first.

The bench supply I use at the moment is ok (with a Fluke 45) but it´s definitely no SMU to specify semiconducter properties.  :-/O

Thanks for the noise plots! Quite interesting!

Best regards,

Richard
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 14, 2020, 02:01:57 pm
Why nobody put a photodiode inside to protect expensive power transistors?

But they did!  C-B junction generates a small photocurrent; Widlar famously employed this trick to generate a few mV / uA negative say for biasing a single-supply op-amp's output so that it can go all the way through and below zero. :)

Tim
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 14, 2020, 02:19:26 pm
... Widlar used the trick to protect *power* transistors ?

I heard the story but never seen a practical Op amp that uses the effect. Curious !
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 14, 2020, 04:40:07 pm
Not to protect, of course, just that it's possible in a sense to build such a circuit around a normal device.  Obviously if you're using C-B as a photodiode, you can't very well also use it for delivering power to a load. ;D

Interesting consequence: when C-B is reverse biased (as normal) and E-B is avalanched, the same photocurrent flows C-B, which means C leakage increases.  Need low leakage?  Clamp that base voltage, say with a diode, or a zener/TVS with rating somewhat below Vebo.  Simple enough. :)

Tim
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 14, 2020, 06:43:35 pm
... tried this with a 2N2222A. When you set VCE=5V and then you let BE break down, collector current does not move.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 14, 2020, 07:54:33 pm
What magnitude?  Ic should be at least ~nA to start with; I would guess uA is reasonable to expect here?

If it doesn't actually go up, that's quite interesting.  Do you measure any negative voltage when it's open?

Tim
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 14, 2020, 07:59:50 pm
Keysight B2962 SMU starting with 10nA, IIRC.
Maybe you need more collector voltage than the 5V I had ?

IIRC, I did not measure anything negative, but I can recheck next week when I'm back in the lab.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 15, 2020, 04:36:42 am
Hmm. Offhand, here's a... 2N2102, nice TO-39 can.  Setup:
9.76V supply
100 ohm series resistor to E
B = GND
C = open

E measures 7.54V (rising slowly as it warms up).
C measures -380mV, also rising slowly (i.e. towards zero) as it warms up.
C shorted, I measure -4uA.  Hey, not bad!

Presumably, leakage shorts out the photocurrent (or free charge current, whichever it is, I forget exactly) as it heats up, so the efficiency of this mode drops quickly, much as solar panels do.

With a 10k pullup from +9.76V to C, I measure 9.71V... or more precisely a drop of 38.8mV.  So, 3.88uA, consistent with the shorted measurement; seemingly less, but it's only a 5% resistor.

Collector current drops to -0.01mV (over 10k) when the emitter is open-circuited.  (Meter is fluctuating between -0.02mV and 0.00 when shorted.  This is the Hi-Z range, no loading on the circuit.  Not that it would matter out of 10k.)

With a 1M pullup, it still measures +/- 0.01mV.  Dang, this must be a nice transistor.  (Brand name Central Semi, yay?)

With a 10M pullup and a 22nF bypass cap in parallel with the resistor (just in case there's rectification here?), it's reading 0.14mV, a whopping -- 14pA?  Fuck me, that's damn good for a BJT, especially this size?

And, with the transistor removed from circuit, it's 11mV drop.  So, plus or minus a lot of leakage through the breadboard, or the meter itself.  (Meter with just the 10M and no ground or supply connection reads -0.07mV.)

Gosh... I slide my be-socked foot across the wood floor and the measurement goes nuts... :-DD  (Meter is just a BM235.)

Whelp... I'm sure you'll have much more noticeable results with a big fat power transistor, especially a sloppy one like 2N3055 (depending on age of the specimen..), or at higher voltages (9V is a far cry from the 120V rating of the 2N2102).

Tim
Title: Re: Transistors - die pictures
Post by: jaromir on May 15, 2020, 09:55:40 am
Regarding the glow of reverse biased PN junction of transistors or zeners, you state here https://www.richis-lab.de/REF03.htm (https://www.richis-lab.de/REF03.htm)
Quote
Während die Z-Diode leitet arbeitet sie zumindest zum Teil im Lawinendurchbruch. Wie bei den Versuchen mit den 2N3055-Transistoren ist dabei im Bereich der Sperrschicht ein Leuchten zu erkennen. Rekombinieren Ladungsträger in einem Siliziumhalbleiter, so emittieren sie üblicherweise kein Licht im sichbaren Bereich. Bei einem Lawinendurchbruch erfolgen allerdings relativ unkontrollierte Ionisierungen im Kristallgitter, die unter anderem auch sichtbares Licht erzeugen.
My German is rather poor, so I used google translator
Quote
While the Zener diode is conducting, it works at least in part in the avalanche breakdown. As in the experiments with the 2N3055 transistors, a glow can be seen in the area of the junction. If charge carriers recombine in a silicon semiconductor, they usually do not emit light in the visible range. In the event of an avalanche breakdown, however, relatively uncontrolled ionizations occur in the crystal lattice, which among other things also generate visible light.

I'm not sure whether this was debated here, but indeed the principle behind the glow is a bit peculiar one. I found relevant part of a book "Handbook of Silicon Photonics" here
https://books.google.sk/books?id=6zjNBQAAQBAJ&pg=PA347&lpg=PA347#v=onepage&q&f=false (https://books.google.sk/books?id=6zjNBQAAQBAJ&pg=PA347&lpg=PA347#v=onepage&q&f=false)
In a case the link above becomes dead, attached is excerpt with relevant part.
Title: Re: Transistors - die pictures
Post by: David Hess on May 15, 2020, 10:37:52 am
What magnitude?  Ic should be at least ~nA to start with; I would guess uA is reasonable to expect here?

10s of microamps is feasible with small signal devices.  a 4N25 used as a photovoltaic source is 10 times more efficient.
Title: Re: Transistors - die pictures
Post by: Noopy on May 15, 2020, 09:46:49 pm
I'm not sure whether this was debated here, but indeed the principle behind the glow is a bit peculiar one. I found relevant part of a book "Handbook of Silicon Photonics" here
https://books.google.sk/books?id=6zjNBQAAQBAJ&pg=PA347&lpg=PA347#v=onepage&q&f=false (https://books.google.sk/books?id=6zjNBQAAQBAJ&pg=PA347&lpg=PA347#v=onepage&q&f=false)
In a case the link above becomes dead, attached is excerpt with relevant part.

Very interesting!  :-+

I´m not sure if I understood the text 100%:
With a STM they were able to put a light in a silicon wafer. But they needed an energy of at least 3,2V.
In my view that is no "normal recombination", is it?
My understanding is that higher energies (=>avalanche) are necessary to get a glowing pn-junction. Normal recombination (normal conducting diode) can only generate heat, no light.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on May 16, 2020, 12:04:50 am
Yes, something like that.  High voltages also generally throw around charge carriers, and this can be used to inject charge through insulating barriers.  Which are just semiconductors with higher band gap than the base material, hence non-conductive at room temperature, or even elevated temperature.  But given charges with sufficient energy (or high enough temperature, same thing), well, they'll merrily grab a conduction band state and pass through.

Hence EEPROM and Flash, which is programmed by dumping a relatively high voltage through the channel, spraying some charge into the floating gate.  (Though I happen to forget how and why it's also electrically erasable.)  I suppose presumably you could see an extremely small amount of light emitted from such a chip as it's being erased or written, though as we're talking very small transistors and microamperes at best, probably not much.

And then yeah, they talk about, what, nanocrystals I suppose?  The band structure, rather than being an effectively-continuous band in a bulk material, it takes on recognizable discrete levels (effectively as many allowed levels as there are atoms along a given axis, I think?), and evidently some of these levels happen to not only correspond to lower visible wavelengths (red) but emissive states as well.

There's also something about implanting dyes or phosphors or other semiconductors (as nanodots) in silicon, that act as direct bandgap recombination centers, so there's just some free charges in the silicon that happens to diffuses over to these sites and emit light.

IIRC, something like that is what gives us modern high efficiency green LEDs, which are InGaN, normally a blue substrate (and still sporting the 3.0V drop you'd expect from it) but made to emit green instead.  These LEDs are recognizable not only from their much brighter output, but a... very slightly cyan-ier rather than yellower/lime-greenier hue?  Made a board some years ago that had a mixture of both on it for status LEDs, wasn't the most consistent appearance... :D

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on May 16, 2020, 10:00:06 pm
Today I can show you a very cheap TO3-transistor, a 3DD15D:

https://www.richis-lab.de/Bipolar05.htm (https://www.richis-lab.de/Bipolar05.htm)


(https://www.richis-lab.de/images/Transistoren/05x04.jpg)

As I said: cheap…
Anyway the datasheet seems to contain some truth: Ptot=50W, Rth=2°C/W


(https://www.richis-lab.de/images/Transistoren/05x09.jpg)
(https://www.richis-lab.de/images/Transistoren/05x08.jpg)

But I´m not sure how they built this transistor. There are more areas than I would have suspected (red and blue)…  :-//
Title: Re: Transistors - die pictures
Post by: Jay_Diddy_B on May 17, 2020, 12:44:14 am
Hi,

If you have access to a metal lathe, you need to build this:

(https://www.eevblog.com/forum/repair/warning-fake-mj16012-transistors-on-ebay/?action=dlattach;attach=261701;image)

(https://www.eevblog.com/forum/repair/warning-fake-mj16012-transistors-on-ebay/?action=dlattach;attach=261703;image)

It puts the T03 can on the axis of the lathe and you can turn the top off.

(https://www.eevblog.com/forum/repair/warning-fake-mj16012-transistors-on-ebay/?action=dlattach;attach=261678;image)

Regards,
Jay_Diddy_B
Title: Re: Transistors - die pictures
Post by: Noopy on May 17, 2020, 07:38:10 am
If you have access to a metal lathe, you need to build this:
...

A good idea!  :-+
Unfortunatelly I have no access to a metal workshop...
Title: Re: Transistors - die pictures
Post by: Wolfgang on May 17, 2020, 10:02:36 am
I have one ! I will try this out. :)
Title: Re: Transistors - die pictures
Post by: Noopy on May 17, 2020, 08:08:02 pm
Finally a diode is half a transistor?  ;D

Today I have an old BAV45 for you:

https://richis-lab.de/Diode01.htm (https://richis-lab.de/Diode01.htm)


Not extremely interesting:

(https://richis-lab.de/images/Dioden/01x04.jpg)

Title: Re: Transistors - die pictures
Post by: Noopy on May 23, 2020, 10:17:15 pm
Today I have the breakdown of a SS109 for you:

https://www.richis-lab.de/Bipolar01.htm (https://www.richis-lab.de/Bipolar01.htm)


(https://www.richis-lab.de/images/Transistoren/01x05.jpg)
(https://www.richis-lab.de/images/Transistoren/01x06.jpg)
(https://www.richis-lab.de/images/Transistoren/01x07.jpg)
(https://www.richis-lab.de/images/Transistoren/01x08.jpg)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: RoGeorge on May 24, 2020, 01:15:44 am
Wow!   :-+

Is that ring of light visible to the eye, or is it infra red visible only by the camera?
Title: Re: Transistors - die pictures
Post by: Noopy on May 24, 2020, 07:11:24 am
The light is visible to the naked eye. It's dim and small but you can see it. :)
Usually silicon pn-junctions don't emit visible light but in avalanche breakdown the electrons are lifted to some higher energy levels.
Title: Re: Transistors - die pictures
Post by: Noopy on May 31, 2020, 08:15:16 pm
Today I have a Siemens ASY25 for you, it´s an old small signal alloy transistor:

(https://www.richis-lab.de/images/transistoren/06x01.jpg)

(https://www.richis-lab.de/images/transistoren/06x05.jpg)

 :wtf:
I assume they use this orange slurry to transfer heat from the transistor to the housing.


(https://www.richis-lab.de/images/transistoren/06x06.jpg)

(https://www.richis-lab.de/images/transistoren/06x09.jpg)

Germanium, yeah!  ;D


More Pictures on my website:

https://www.richis-lab.de/Bipolar06.htm (https://www.richis-lab.de/Bipolar06.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: RoGeorge on May 31, 2020, 10:50:08 pm
It's interesting that thermal paste is orange.  Is that orange because with time it developed rust inside?

When I was a kid I opened a few Romanian Ge transistors (AC180, AC181, EFT323, ASZ15, etc.) in order to turn them into photo-diodes (or photo-transistors).  Also we use to never throw away the broken high power transistors.  Those were usually filled with thermal paste, and we use to harvest the thermal paste and use it later on radiators.

Big or small, all the transistors I opened have had milky white thermal paste.

Since we are talking about die pics, recently bumped into a small power Ge that I opened during the 70's or 80's, in order to build an "Electronic Eye" from a book.  Back then the image sensor chips were not yet invented, so the so called "electronic eye" circuit was in fact just a light detector with a relay.   :)


[attachimg=1]
From left to right, the EBC of a PNP Ge transistor (EFT323 or AC180?).  E wire to junction EB was cut after opening the transistor


[attachimg=2]
View from the emitter side, E wire to the middle blob was cut, on the most left of the picture is the B wire


[attachimg=3]
View from the collector side, still shiny but heavily contaminated and with big residual reverse ICB, the DMM for the BC junction shows 1.3V when reverse polarized, and about 0.13V when direct polarized.

It has been staying in open air for decades, now rusty and with an almost dead BC junction, but it still is sensitive to light.  Stubborn!  ;D
Title: Re: Transistors - die pictures
Post by: Noopy on June 01, 2020, 06:59:41 am
I didn't find any rust and the orange colour was very uniform. In my view the paste was orange from the start. Perhaps Siemens had a different thermal paste? But I agree with you, orange isn't normal. :)

Thank you for the pictures and the story behind!
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on June 01, 2020, 03:42:18 pm
I would assume it's condensation, polymerization or decomposition.  Perhaps it used to be an oil or resin.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on June 01, 2020, 08:42:19 pm
Today I proudly present a BUX22:

(https://richis-lab.de/images/transistoren/07x01.jpg)

(https://richis-lab.de/images/transistoren/07x03.jpg)

But  :wtf:  is it a fake?

(https://richis-lab.de/images/transistoren/07x04.jpg)

No, it´s an old BUX22!  :wtf: :wtf: :wtf:
Why should anyone put a new cap on an old BUX22?
Perhaps ST did some requalification and sold old parts as new?

(https://richis-lab.de/images/transistoren/07x06.jpg)

300V breakdown voltage
50A peak current
8A base current
 8)

But really interesting is this one:

(https://richis-lab.de/images/transistoren/07x17.jpg)

The BUX22 has some defects at which the glowing of avalanche breakdown occurs first.
The defects are big enough to identify that the glowing occurs next to the defect not exactly at the defect itself. That´s important for interpreting the glowing in the LTZ1000, discussed here:

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg3086013/#msg3086013 (https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg3086013/#msg3086013)


Whole story and much more pictures here:

https://richis-lab.de/Bipolar07.htm (https://richis-lab.de/Bipolar07.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on June 01, 2020, 08:52:54 pm
@Wolfgang: I guess these pictures are also useful for your work.

(https://richis-lab.de/images/transistoren/07x11k.jpg)

 :-+ ;)
Title: Re: Transistors - die pictures
Post by: graybeard on June 03, 2020, 07:13:10 pm
Great photos!

Undesired recombination at the Si SiO2 interface will produce IR. That IR emission is used to find trouble spots.

Standard recombination in GaxAl1-xAs produces quite a bit of light since the dominant mechanism is optical emission.  The color typically ranges from IR to red depending on the composition.

Light emission due to avalanche  breakdown in GaAs is typically green.
Title: Re: Transistors - die pictures
Post by: Noopy on June 03, 2020, 07:28:45 pm
Thanks!  :-+

SiC glows blue. Looks really nice!  8)
Unfortunately I have no pictures of SiC-semiconductors...
Title: Re: Transistors - die pictures
Post by: Noopy on June 09, 2020, 03:43:32 am

Hi all!


Let´s take a look at a newer BUX22!

(https://richis-lab.de/images/Transistoren/08x01.jpg)

(https://richis-lab.de/images/Transistoren/08x03.jpg)

Well that´s a big heatspreader! It was necessary because the base plate of the package is thinner than the old generation (https://richis-lab.de/Bipolar07.htm (https://richis-lab.de/Bipolar07.htm)).


(https://richis-lab.de/images/Transistoren/08x04.jpg)

You can already see the thickness of the metal layer.
The BUX22 makes use of a perforated emitter. The die has a MESA-structure.


(https://richis-lab.de/images/Transistoren/08x06.jpg)

(https://richis-lab.de/images/Transistoren/08x09.jpg)

And of course second breakdown.  ;D


More pictures here:

https://richis-lab.de/Bipolar08.htm (https://richis-lab.de/Bipolar08.htm)

 :popcorn:

Title: Re: Transistors - die pictures
Post by: exe on June 09, 2020, 02:43:24 pm
I wonder why using two dies? As I see, both dies are in parallel without any balansing resistors. They must be very well matched, and, from the secondary breakdown pic, it looks like they are.

I also noticed a few red spots outside where they shouldn't be. I wonder what's that. Like, the one on the right die near the bottom pad.
Title: Re: Transistors - die pictures
Post by: Noopy on June 09, 2020, 02:49:24 pm
I wonder why using two dies? As I see, both dies are in parallel without any balansing resistors. They must be very well matched, and, from the secondary breakdown pic, it looks like they are.

Two smaller dies result in a better production yield than one big die.
And with two smaller dies you can use the same die but one for a smaller transistor.  :-+


I also noticed a few red spots outside where they shouldn't be. I wonder what's that. Like, the one on the right die near the bottom pad.

These are high iso pictures. There are some noise pixels…  ;D
Title: Re: Transistors - die pictures
Post by: Wolfgang on June 09, 2020, 03:53:05 pm
I wonder why using two dies? As I see, both dies are in parallel without any balansing resistors. They must be very well matched, and, from the secondary breakdown pic, it looks like they are.

I also noticed a few red spots outside where they shouldn't be. I wonder what's that. Like, the one on the right die near the bottom pad.

If a high power die is getting too large, temperature in the center is getting too high compared to the boundary due to limited heat conductance.
Not a problem for a 2N3055, but real for a BUX22.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on June 09, 2020, 04:57:48 pm
Not reeeeally... I've seen single MOSFET and IGBT dies bigger than the inside area of a TO-3.  More likely it was contemporary yields.

Don't know what the largest BJT die is, these days; might not even be one as large, just because there's so little demand for them.

Tim
Title: Re: Transistors - die pictures
Post by: Wolfgang on June 09, 2020, 05:23:28 pm
Not reeeeally... I've seen single MOSFET and IGBT dies bigger than the inside area of a TO-3.  More likely it was contemporary yields.

Don't know what the largest BJT die is, these days; might not even be one as large, just because there's so little demand for them.

Tim

Same problem with MOSFETs. IXYS uses graded threshold voltages to tackle this problem (high threshold in the center) for their linear MOSFETSs.
All others - same story, with hotspotting in linear mode. See NASA, Spirito Effect.
Title: Re: Transistors - die pictures
Post by: SilverSolder on June 09, 2020, 05:36:59 pm
I wonder why using two dies? As I see, both dies are in parallel without any balansing resistors. They must be very well matched, and, from the secondary breakdown pic, it looks like they are.

I also noticed a few red spots outside where they shouldn't be. I wonder what's that. Like, the one on the right die near the bottom pad.

We could drill out the remaining pin hole, and get a cheap matched pair transistor? :)
Title: Re: Transistors - die pictures
Post by: Noopy on June 09, 2020, 05:40:46 pm

We could drill out the remaining pin hole, and get a cheap matched pair transistor? :)


A very good idea!
I think that´s the ideal input stage for a small earphone amp!  ;D ;D ;D
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on June 09, 2020, 05:58:59 pm
Not reeeeally... I've seen single MOSFET and IGBT dies bigger than the inside area of a TO-3.  More likely it was contemporary yields.

Don't know what the largest BJT die is, these days; might not even be one as large, just because there's so little demand for them.

Tim

Same problem with MOSFETs. IXYS uses graded threshold voltages to tackle this problem (high threshold in the center) for their linear MOSFETSs.
All others - same story, with hotspotting in linear mode. See NASA, Spirito Effect.

The "reeeeally" being, most transistors that size are made for switching, so may have awful SOAs.  The power dissipation is there, no contest, just doing it at voltage is harder.

That said, many newer MOSFETs, and even some IGBTs, are specified with DC SOA.  However they've approached it -- graded threshold, tempco hackery, ballasting*, whatever -- it's done the trick.

*Probably not that, because source/emitter degeneration would severely eat into the saturated performance.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on June 11, 2020, 11:56:40 am
(https://www.richis-lab.de/images/Transistoren/07x13.jpg)

Did you know these small emitter contacts are called "wide-emitter narrow-contact"?
These structures make sure the current is evenly distributed. I assume that´s one reason why it was no bigger problem to connect the two dies in parallel.  :-+
Title: Re: Transistors - die pictures
Post by: Wolfgang on June 11, 2020, 12:05:31 pm
Not reeeeally... I've seen single MOSFET and IGBT dies bigger than the inside area of a TO-3.  More likely it was contemporary yields.

Don't know what the largest BJT die is, these days; might not even be one as large, just because there's so little demand for them.

Tim

Same problem with MOSFETs. IXYS uses graded threshold voltages to tackle this problem (high threshold in the center) for their linear MOSFETSs.
All others - same story, with hotspotting in linear mode. See NASA, Spirito Effect.

The "reeeeally" being, most transistors that size are made for switching, so may have awful SOAs.  The power dissipation is there, no contest, just doing it at voltage is harder.

That said, many newer MOSFETs, and even some IGBTs, are specified with DC SOA.  However they've approached it -- graded threshold, tempco hackery, ballasting*, whatever -- it's done the trick.

*Probably not that, because source/emitter degeneration would severely eat into the saturated performance.

Tim

Emitter ballasting is actually used, e.g., in high performance audio and, of course, RF power bipolar. More or less all "wide SOAR" stuff. Saturation voltage is of no concern there, and the drop along these resistors does not need to be large to equalize. Linear MOSFETS use the same trick at the source, among others, their RdsON is not as good as their switching cousins for the same reason.
Title: Re: Transistors - die pictures
Post by: Noopy on June 12, 2020, 08:21:02 pm

Today the last one of the BUX22-trilogy:


(https://richis-lab.de/images/transistoren/09x01.jpg)


(https://richis-lab.de/images/transistoren/09x03.jpg)

Yeah, pretty sure a fake.  :--
How did they cut the heatspreader?  :wtf:


(https://richis-lab.de/images/transistoren/09x05.jpg)

Someone has lost a solder ball.  :palm:


(https://richis-lab.de/images/transistoren/09x11.jpg)

Quite interesting MESA-structure!


(https://richis-lab.de/images/transistoren/09x07.jpg)

And here all three of them.


More pictures here:

https://richis-lab.de/Bipolar09.htm (https://richis-lab.de/Bipolar09.htm)


 :popcorn:
Title: Re: Transistors - die pictures
Post by: duak on June 12, 2020, 09:35:27 pm
I don't believe I've ever seen two dice paralled as in the BUX22 above.  Looking at a data sheet, I don't see anything calling that out.  I expect the dice are matched before packaging.  Any thoughts on the characteristics that make this possible?  I could see that emitter ballasting would help.

I was thinking of other applications for a dual power BJT that have reasonably matched dice with perhaps the bases and emitters brought out separately.  One thing would be simple current mirror with a current range up to a few amps, but the collectors would have to be electrically isolated from each other.
Title: Re: Transistors - die pictures
Post by: Wolfgang on June 12, 2020, 09:47:53 pm
It was common with bipolar RF power parts of the first generation (BLX15, ...)
Its obviously cheaper to have a bigger die when you really command the technology. If you dont,
yield goes substantially down with die size.
Title: Re: Transistors - die pictures
Post by: Noopy on June 13, 2020, 06:03:57 am
I don't believe I've ever seen two dice paralled as in the BUX22 above.  Looking at a data sheet, I don't see anything calling that out.  I expect the dice are matched before packaging.  Any thoughts on the characteristics that make this possible?  I could see that emitter ballasting would help.

I assume this "wide-emitter narrow-contact" technique makes it possible to connect the two dice.
I have heard that the BUX22 can often be seen connected in parallel without ballast resistors. Perhaps the BUX22 is a somewhat special bipolar transistor.  :-/O
Title: Re: Transistors - die pictures
Post by: Noopy on June 14, 2020, 08:47:38 pm
Hi all!

I have started a 2N3055-page:

https://richis-lab.de/2N3055.htm (https://richis-lab.de/2N3055.htm)

Last one is a RCA 2N3055H which should contain a hometaxial transistor.

https://richis-lab.de/2N3055_05.htm (https://richis-lab.de/2N3055_05.htm)


(https://richis-lab.de/images/transistoren/11x01.jpg)

(https://richis-lab.de/images/transistoren/11x03.jpg)

(https://richis-lab.de/images/transistoren/11x12.jpg)

(https://richis-lab.de/images/transistoren/11x07.jpg)

The trench following the emitter electrode contains the base-emitter-junction as the pictures of the avalanche breakdown shows.


(https://richis-lab.de/images/transistoren/11x13.jpg)

But I´m not sure about the plateau following the trench. That has to be the emitter material. But why didn´t they design the base feed line shorter? There is no reason for more resistance in the base circuit. Perhaps the manufacturing process was the reason...  :-//

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on June 15, 2020, 08:37:13 pm
I took some more pictures of a RCA 2N3055:

https://richis-lab.de/2N3055_02.htm (https://richis-lab.de/2N3055_02.htm)

I´m pretty sure you can see the difference between the hometaxial and the epitaxial structure:


(https://richis-lab.de/images/transistoren/11x13.jpg)

2N3055H
Here you can see a trench and some "small hills". With a hometaxial construction you have to etch the emitter away to contact the base material.
The surface is uneven because it´s cut or grinded or whatever (mechanical).


(https://richis-lab.de/images/transistoren/12x05.jpg)

2N3055
The surface is very smooth. The reason behind this is the epitactical growth of silicon that gives a much cleaner surface.


  :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on June 17, 2020, 08:03:44 pm
Today I have a BD522 for you:

https://www.richis-lab.de/FET01.htm (https://www.richis-lab.de/FET01.htm)

(https://www.richis-lab.de/images/Transistoren/10x01.jpg)

(https://www.richis-lab.de/images/Transistoren/10x02.jpg)

(https://www.richis-lab.de/images/Transistoren/10x06.jpg)

(https://www.richis-lab.de/images/Transistoren/10x05.jpg)

It seems the metal layer is slightly shifted…

 :popcorn:
Title: Re: Transistors - die pictures
Post by: SilverSolder on June 18, 2020, 02:45:03 am

The BD522  looks like it's got eyes, LOL!  :D
Title: Re: Transistors - die pictures
Post by: Noopy on June 18, 2020, 06:25:44 am
The BD522  looks like it's got eyes, LOL!  :D

You are right, didn´t see that!  ;D :-+
Title: Re: Transistors - die pictures
Post by: Noopy on June 19, 2020, 05:47:23 pm
Today a new ST TIP3055:

https://richis-lab.de/Bipolar10.htm (https://richis-lab.de/Bipolar10.htm)


(https://richis-lab.de/images/Transistoren/14x01.jpg)

(https://richis-lab.de/images/Transistoren/14x02.jpg)

Unfortunatelly the die didn´t survive in one piece but damage is not too bad.
I had only one try…


(https://richis-lab.de/images/Transistoren/14x03.jpg)

It uses a perforated emitter.  :-+


Thanks to exe for the part!

 :popcorn:
Title: Re: Transistors - die pictures
Post by: SilverSolder on June 19, 2020, 05:54:13 pm

What's the thinking behind a perforated emitter?
Title: Re: Transistors - die pictures
Post by: Noopy on June 19, 2020, 06:01:49 pm
You connect the base over the whole die through perforations of the emitter. That gives you a better current Distribution and that leads to lower saturation voltage and second breakdown appears later.

Here you have more perforated emitter:
https://www.richis-lab.de/2SC2922.htm (https://www.richis-lab.de/2SC2922.htm)
https://www.richis-lab.de/Bipolar08.htm (https://www.richis-lab.de/Bipolar08.htm)
Title: Re: Transistors - die pictures
Post by: Wolfgang on June 19, 2020, 08:30:30 pm
You connect the base over the whole die through perforations of the emitter. That gives you a better current Distribution and that leads to lower saturation voltage and second breakdown appears later.

Here you have more perforated emitter:
https://www.richis-lab.de/2SC2922.htm (https://www.richis-lab.de/2SC2922.htm)
https://www.richis-lab.de/Bipolar08.htm (https://www.richis-lab.de/Bipolar08.htm)

Richie,

do you by accident have an 2N2857 at hand ?
I would be curious about this one.

Regards
   Wolfgang
Title: Re: Transistors - die pictures
Post by: SilverSolder on June 19, 2020, 08:31:59 pm
You connect the base over the whole die through perforations of the emitter. That gives you a better current Distribution and that leads to lower saturation voltage and second breakdown appears later.

Here you have more perforated emitter:
https://www.richis-lab.de/2SC2922.htm (https://www.richis-lab.de/2SC2922.htm)
https://www.richis-lab.de/Bipolar08.htm (https://www.richis-lab.de/Bipolar08.htm)

Thank you @Noopy, those articles taxed my German vocabulary to the limit, aber es ist etwas gut!
Title: Re: Transistors - die pictures
Post by: Noopy on June 19, 2020, 08:43:30 pm
do you by accident have an 2N2857 at hand ?
I would be curious about this one.

Hm... Have to take a look at my huge inbox. Got a lot of transistors the last few weeks.  ;D


Thank you @Noopy, those articles taxed my German vocabulary to the limit, aber es ist etwas gut!

 ;D Sorry for the german text but english would take me twice the time and I have so much more parts here.  :-/O A HF-Power-Transistor (the big one for GSM stations), a 18Bit-DAC, a 7,5A linear Regulator, a huge opamp and a looooot of smaller but also interesting parts.
I hope Google translator can help a bit and you can ask me here whatever you want.  :-+
Title: Re: Transistors - die pictures
Post by: SilverSolder on June 19, 2020, 08:51:37 pm

Not a problem, es macht mir vergnugt to read your articles in German (aided by Google if I get stuck)

 :-+
Title: Re: Transistors - die pictures
Post by: Noopy on June 21, 2020, 08:20:20 pm
Well it´s not transistor but i switches transistors: the gate driver TC4429

https://www.richis-lab.de/TC4429.htm (https://www.richis-lab.de/TC4429.htm)

(https://www.richis-lab.de/images/TC4429/02.jpg)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on June 22, 2020, 07:42:38 pm
Today I have a TIP2955 for you. It´s the complementary transistor to the TIP3055.

https://richis-lab.de/Bipolar11.htm (https://richis-lab.de/Bipolar11.htm)


(https://richis-lab.de/images/transistoren/15x01.jpg)

(https://richis-lab.de/images/transistoren/15x02.jpg)

(https://richis-lab.de/images/transistoren/15x03.jpg)

It looks very similar to the TIP3055 and has exactly the same dimensions.


(https://richis-lab.de/images/transistoren/15x04.jpg)

The perforated emitter looks a bit different. You can see less circles in the "holes" than in the TIP3055. Unfortunatelly I don´t know how exactly the structures are built.  :-//

The TIP2955 came form exe.  :-+
Title: Re: Transistors - die pictures
Post by: exe on June 22, 2020, 07:59:20 pm
Thank you very much, this explains why some complementary pairs have very tight parameter matching (e.g., base capacitance). For some reason I expected NPN devices to be smaller for the same power rating. Either this is simply not true, or manufacturing process is well tuned.
Title: Re: Transistors - die pictures
Post by: Noopy on June 22, 2020, 08:06:57 pm
I have often seen mosfets where the p-type is bigger than the n-type. Last time in the TC4429.
I have often seen schematics where the pnp is doubled to achieve the same specifications than the npn.

But as we can see here it´s also possible to design the complementary transistors very similar.
Perhaps it´s a matter of priorities. Perhaps you can design complementary transistors equal but it´s easier to make the "p-type" bigger...  :-//

 :popcorn:
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on June 23, 2020, 10:20:35 am
NPN and PNP with similar build (i.e., those will be N and P substrate, then P/N, then N/P, epitaxy or diffusion) have similar properties.  PNP is only like 10-20% lower performance, I've forgotten exactly why now but clearly electrons and holes participate in the same way and mobility is a smaller factor in operation.

Want to say base diffusion is the only step in a BJT where mobility really matters, and the base can simply be made thinner if needed.  If that's the case, we might expect to find stronger Early effect; or, it's further compensated by collector doping profile, with subtle effects on breakdown voltage, Ccb(Vcb) and voltage drop, Idunno.

If a process is limited by shitty (usually lateral) PNP, large areas might be needed to compensate for that.

Complementary MOSFETs will always differ by about a factor of two, because mobility is a direct proportion in their performance.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on June 25, 2020, 12:09:00 pm
Today I can show you a TIP2955 built by ON-Semi:

https://richis-lab.de/Bipolar11.htm (https://richis-lab.de/Bipolar11.htm)


(https://richis-lab.de/images/transistoren/16x01.jpg)

(https://richis-lab.de/images/transistoren/16x02.jpg)

The die shows a classical construction. It is bigger (2,53mm*2,53mm) than the die in the ST-TIP2955 (2,42mm*2,15mm). I assume that´s because the classical design is less efficient than the perforated emitter design.


(https://richis-lab.de/images/transistoren/16x04.jpg)

A MESA-structure...  8)


The TIP2955 came form exe.


 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on June 25, 2020, 07:19:14 pm
Very interesting, thank you. My measurements showed that sy parts are a bit better than onsemi parts in terms of frequency response. Perhaps, due to smaller geometry. I think it's a trend, so I expect all ST bjts will be slightly smaller than onsemi.
Title: Re: Transistors - die pictures
Post by: Noopy on June 30, 2020, 08:57:46 pm

Today I have a SMART-Highside-MOSFET for you: VN02H


(https://richis-lab.de/images/Transistoren/13x01.jpg)

(https://richis-lab.de/images/Transistoren/13x02.jpg)

Everything on one die. That´s cool but gives you a clamping voltage of only -4V. There are special variants with -18V but that´s still not very much.


(https://richis-lab.de/images/Transistoren/13x18.jpg)
(picture taken from application note and modified)

Do you know why integrated SMART-Highside-Driver have low clamping voltages?
There is a parasitic bipolar transistor between the power transistor and the barrier around the logic part that is connected to the ground potential. You don´t need very much voltage to break the collector-emitter-line and kill the part.


(https://richis-lab.de/images/Transistoren/13x05.jpg)

The datasheet explains that the overcurrent detection is done with the temperature meassurement (this small satellite) but it seems that there are two small MOSFETs. Theses small MOSFETs can be used to sense the current through the VN02H...


(https://richis-lab.de/images/Transistoren/13x09.jpg)

And I have a dead one.  8)
It switched a short circuit.
The ground bondwire acted as a fuse. You can see a colored spot in the transistor area too.
Perhaps there was a overcurrent damage in the transistor and then the rest of the VN02H failed shorting the supply.  :-//
Perhaps there was somehow a transient overvoltage which killed the control part and then the power Transistor died.  :-//
We will never now for sure.


More Pictures here:
https://richis-lab.de/FET02.htm (https://richis-lab.de/FET02.htm)


 :popcorn:
Title: Re: Transistors - die pictures
Post by: David Hess on July 01, 2020, 02:01:25 am
Do you know why integrated SMART-Highside-Driver have low clamping voltages?
There is a parasitic bipolar transistor between the power transistor and the barrier around the logic part that is connected to the ground potential. You don´t need very much voltage to break the collector-emitter-line and kill the part.

I assume the dielectricly isolated process used for DMOS would be too expensive in both fabrication and area.

Quote
The datasheet explains that the overcurrent detection is done with the temperature meassurement (this small satellite) but it seems that there are two small MOSFETs. Theses small MOSFETs can be used to sense the current through the VN02H...

That is a very common technique for CMOS power devices and 4 pin power MOSFETs which allow monitoring the current.  A few cells of the power MOSFET have a separate drain connection brought out and the ratio of areas determines the fraction of the drain current which is detected.

It also works for bipolar devices.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on July 01, 2020, 02:17:18 am
Wow, surprised they waste so much die area on control logic!

Tim
Title: Re: Transistors - die pictures
Post by: David Hess on July 01, 2020, 02:35:12 am
An LM395 die shot would be interesting and I think I have seen it somewhere.  As I recall, it was very similar to the LM317 and might have been the same die with a different metalization.
Title: Re: Transistors - die pictures
Post by: Noopy on July 01, 2020, 03:12:22 am
Do you know why integrated SMART-Highside-Driver have low clamping voltages?
There is a parasitic bipolar transistor between the power transistor and the barrier around the logic part that is connected to the ground potential. You don´t need very much voltage to break the collector-emitter-line and kill the part.

I assume the dielectricly isolated process used for DMOS would be too expensive in both fabrication and area.

And with dielectric isolation you can´t build the more powerful vertical DMOS, can you?


The datasheet explains that the overcurrent detection is done with the temperature meassurement (this small satellite) but it seems that there are two small MOSFETs. Theses small MOSFETs can be used to sense the current through the VN02H...

That is a very common technique for CMOS power devices and 4 pin power MOSFETs which allow monitoring the current.  A few cells of the power MOSFET have a separate drain connection brought out and the ratio of areas determines the fraction of the drain current which is detected.

I know this kind of current measurement. It just surprised me that the datasheet by contrast explains a temperature based overcurrent detection.  :-//


An LM395 die shot would be interesting and I think I have seen it somewhere.  As I recall, it was very similar to the LM317 and might have been the same die with a different metalization.

I will put the LM395 on my to-do-list.  :-+
Title: Re: Transistors - die pictures
Post by: David Hess on July 02, 2020, 02:50:18 am
Do you know why integrated SMART-Highside-Driver have low clamping voltages?
There is a parasitic bipolar transistor between the power transistor and the barrier around the logic part that is connected to the ground potential. You don´t need very much voltage to break the collector-emitter-line and kill the part.

I assume the dielectricly isolated process used for DMOS would be too expensive in both fabrication and area.

And with dielectric isolation you can´t build the more powerful vertical DMOS, can you?

No, I don't think you can but the lateral power devices can still be very powerful.  Their disadvantage is that they take much more area.  On the other hand, they have much lower capacitance.
Title: Re: Transistors - die pictures
Post by: Noopy on July 02, 2020, 03:36:07 am
Well, you are right.  :-+
Title: Re: Transistors - die pictures
Post by: Noopy on July 05, 2020, 07:31:17 pm

Hi all!


Today I have a BD911 for you. It is quite simliar to the TIP3055 (https://richis-lab.de/Bipolar10.htm (https://richis-lab.de/Bipolar10.htm)). The collector-emitter-voltage and the hfe are a bit higher for the BD911.


(https://richis-lab.de/images/Transistoren/17x01.jpg)

(https://richis-lab.de/images/Transistoren/17x02.jpg)

The die is similar to the die in the TIP3055 but it´s smaller (4,66mm² vs. 5,25mm²) although it has the better specifications.
In my view ST was able to enhance the specificatons of the stackup. Probably the more close meshed perforation improves also the specifications.


(https://richis-lab.de/images/Transistoren/17x03.jpg)

I think they did some potential steering in the corners of the die.


(https://richis-lab.de/images/Transistoren/17x05.jpg)

The perforations are quite small compared to the TIP3055.


https://richis-lab.de/Bipolar12.htm (https://richis-lab.de/Bipolar12.htm)


Part was donated by exe.

 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on July 05, 2020, 08:16:49 pm
Very interesting, the die is smaller, however it looks like the "labyrinth" has more total length. I wonder which one has less parasitic capacitance.

Anyway, which one would be prefered for a linear power supply and why? :)
Title: Re: Transistors - die pictures
Post by: Noopy on July 05, 2020, 08:30:03 pm
My read is that the BD911 has less capacitance.
Less area => Less capacitance.

But perhaps the SOA of the BD911 is smaller. A smaller die is often heavier donated. But that´s only a guess…

Hard to decide which on is better for a linear power supply. BD911 has a higher voltage rating but perhaps TIP3055 has a bigger SOA...  :-//
Title: Re: Transistors - die pictures
Post by: Noopy on July 06, 2020, 07:08:37 pm

Today I have an old TIP3055 built by TI:


(https://www.richis-lab.de/images/Transistoren/18x01.jpg)

(https://www.richis-lab.de/images/Transistoren/18x03.jpg)

The mold compound is very persistent...  :-/O


(https://www.richis-lab.de/images/Transistoren/18x04.jpg)

(https://www.richis-lab.de/images/Transistoren/18x05.jpg)

A classical mesa-design but OnSemi uses it still today for the TIP2955:
https://www.richis-lab.de/Bipolar11.htm (https://www.richis-lab.de/Bipolar11.htm)


You can find the TIP3055 overview here:
https://www.richis-lab.de/Bipolar10.htm (https://www.richis-lab.de/Bipolar10.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: David Hess on July 08, 2020, 12:39:17 am
A classical mesa-design but OnSemi uses it still today for the TIP2955:
https://www.richis-lab.de/Bipolar11.htm (https://www.richis-lab.de/Bipolar11.htm)

I was under the impression that the mesa process was long discontinued, except maybe for premium parts, because it is too expensive due to the time it takes to manufacturer.

Title: Re: Transistors - die pictures
Post by: Noopy on July 08, 2020, 02:31:10 am
A classical mesa-design but OnSemi uses it still today for the TIP2955:
https://www.richis-lab.de/Bipolar11.htm (https://www.richis-lab.de/Bipolar11.htm)

I was under the impression that the mesa process was long discontinued, except maybe for premium parts, because it is too expensive due to the time it takes to manufacturer.

 :-//
Perhaps it´s still cheaper than for example manufacturing a perforated emitter?
Perhaps there is an old production line working at a very reasonable price?
 :-//
Title: Re: Transistors - die pictures
Post by: Noopy on July 12, 2020, 08:03:56 pm
Today I have a very special transistor, the Programmable Unijunction Transistor 2N6027:

(https://www.richis-lab.de/images/Transistoren/21x01.jpg)

(https://www.richis-lab.de/images/Transistoren/21x02.jpg)

The die is very small: 440µm x 440µm.
However for 10µs a peak current of 5A is allowed.

These transistors are still in production.  :-/O
Title: Re: Transistors - die pictures
Post by: RoGeorge on July 12, 2020, 09:19:36 pm
Wanted to ask before and censored myself, but I couldn't stand the itch any more:  What's the green and what's the yellow stuff?  What material is that?
Are those the real colors or are they colored by software?   :-[
Title: Re: Transistors - die pictures
Post by: Noopy on July 12, 2020, 09:31:33 pm
That are not the real colors an they are not colored by software.  ;D

With "normal light" you can only see the metal layer:

(https://www.richis-lab.de/images/howto/L_06a.jpg)

With light coming "from the camera" resonances are forming in the thin layers of the chip. Different thicknesses are creating different colors:

(https://www.richis-lab.de/images/howto/L_06.jpg)

Professional people use reflected-light microscopes. I use light coming from behind the die:

(https://www.richis-lab.de/images/howto/L_05.jpg)

It seems the lens is reflecting enough light to do the job.

 :popcorn:
Title: Re: Transistors - die pictures
Post by: magic on July 12, 2020, 09:57:18 pm
Multiple supposedly professional sources claim it's due to iridescence. Off the top of my head:

https://www.quora.com/Why-are-microprocessor-wafers-so-colorful (https://www.quora.com/Why-are-microprocessor-wafers-so-colorful)
http://www.designinganalogchips.com/ (http://www.designinganalogchips.com/)

It basically means you see the thickness of the surface layer of glass. This thickness varies, because glass accumulates on "finished" areas while new masks are applied and selectively etched to expose other areas to subsequent processing steps.
Title: Re: Transistors - die pictures
Post by: Noopy on July 12, 2020, 10:01:50 pm
I'm no optic expert but in principle that is what I said, resonances in thin layers, isn't it?
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on July 13, 2020, 02:18:07 am
There's kind of three things going on, actually:
- Doping
- Layers
- Patterns

Doped semiconductors actually reflect light differently.  I can't find a reference for it (go figure, searching for basic physics only turns up current high-level articles :palm: ) but it's something about the light's interaction with the carrier type and density, causing a phase or polarization shift, and therefore causing interference with the incident light.  There's an optical hall effect which might be what I'm thinking of, which is also affected by ambient magnetic fields as the name suggests.

Layers of semiconductor, oxide and etc. transmit light at different velocities, and are used in varying thicknesses, leading to simple interference colors.

Patterns, when periodic and finely etched (comparable to the wavelength of light), create diffraction gratings -- light is reflected from each wire in a bus, say, which when evenly spaced, causes interference at different angles -- a rainbow is reflected.  We don't see much of this on small devices (few features to reflect light) or large pitch devices (features are widely spaced), but it's why CDs, EPROMs and etc. are so colorful.

Note that interference depends on angle as well, as a glancing angle travels farther through the material.  So you generally get a play of colors over the surface of e.g. a microprocessor, but the exact rate (spectrum and angles) at which the colors are reflected varies by region.

A microprocessor is a good example, containing all of the above: well, probably not much visible semiconductor unless it's a quite old one, but periodic structures such as mask ROM, register files or caches, and buses, tend to show off all sorts of diffraction patterns, while "random logic" regions are more chaotic and have a noisy or speckled appearance.

Tim
Title: Re: Transistors - die pictures
Post by: magic on July 13, 2020, 07:01:10 am
Patters - true but not a thing at sufficient magnification, like in this thread.
Layers - as I said above, I think it's mostly about the layer of glass on the surface. Light penetration through actual silicon is very low (a few µm at best for red) and many of those structures are "relatively" deep.
Doping - not entirely sure. Anyone volunteers to treat a die to hydrofluoric acid to strip the glass and see if any color remains? Actually, people do such things (and also remove the metal layers which might obscure underlying silicon) and I think they end up needing to treat the die chemically to "stain" the doped areas. Look up "deprocessing" and "delayering".
Title: Re: Transistors - die pictures
Post by: Noopy on July 13, 2020, 07:32:16 am
I definitely won´t work with hydrofloric. That´s some pretty nasty shit.  :scared:

It seems that deeper structures don´t show up in different colors. You can spot them only by the bumps they create at the surface.

(https://www.richis-lab.de/images/wafer/12.jpg)

Here the deep implant, the areas containing active elements and the lateral isolation have all the same color. That´s probably because of the low light penetration. No light no colors. All three structures are quite "deep".
Title: Re: Transistors - die pictures
Post by: magic on July 13, 2020, 09:14:52 am
The bumps which seem to be caused by collector buried layer are easy enough to explain - they are bumps on the surface of silicon itself, not differences in glass thickness, so the color is uniform.

But I'm not sure if the same is true about the bumps on isolation diffusions or what those bumps actually are :-//

Maybe doping does play some role.
Title: Re: Transistors - die pictures
Post by: Noopy on July 13, 2020, 10:22:33 am
Hm...  :-//

The glass has to play a role. In the picture above the metal layer is missing but the vias are already etched. In the areas where the glass is missing you can see no color. Whereas around the vias you can see the color of the underlying layer.
Title: Re: Transistors - die pictures
Post by: Noopy on July 13, 2020, 08:56:47 pm
I have taken some pictures of an old thyristor: ST103

https://www.richis-lab.de/Bipolar13.htm (https://www.richis-lab.de/Bipolar13.htm)


(https://www.richis-lab.de/images/transistoren/20x01.jpg)

(https://www.richis-lab.de/images/transistoren/20x05.jpg)

Looks pretty rude.


(https://www.richis-lab.de/images/transistoren/20x08.jpg)

A rough structure...


(https://www.richis-lab.de/images/transistoren/20x06.jpg)

Rough structures gives you a lot of leackage so they etched some traces to get smooth junction edges.

Title: Re: Transistors - die pictures
Post by: David Hess on July 14, 2020, 01:46:35 pm
Rough structures gives you a lot of leackage so they etched some traces to get smooth junction edges.

Like high voltage diodes, I thought the outer ring structure in thyristors was to prevent high voltage breakdown.
Title: Re: Transistors - die pictures
Post by: Noopy on July 14, 2020, 02:23:25 pm
Rough structures gives you a lot of leackage so they etched some traces to get smooth junction edges.

Like high voltage diodes, I thought the outer ring structure in thyristors was to prevent high voltage breakdown.

I think we are talking about the same mechanism:
The amount of leakage current is depending of the voltage.
More voltage, more leakage, triggering the thyristor...  :-BROKE
Title: Re: Transistors - die pictures
Post by: David Hess on July 14, 2020, 03:17:29 pm
Rough structures gives you a lot of leackage so they etched some traces to get smooth junction edges.

Like high voltage diodes, I thought the outer ring structure in thyristors was to prevent high voltage breakdown.

I think we are talking about the same mechanism:
The amount of leakage current is depending of the voltage.
More voltage, more leakage, triggering the thyristor...  :-BROKE

Time dependent false triggering in a thyristor is suppressed with metalization between the base and emitter of each transistor.  "Sensitive gate" SCRs are sensitive because they lack this.  An external resistor is less effective because of the distributed nature of the spreading resistance; the thyristor could be triggered in an area where there is too much resistance to the gate connection which is a very bad situation.

I was referring to the guard rings applied to semiconductor junctions including diodes and transistors which increase breakdown voltage.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on July 14, 2020, 03:30:40 pm
I don't think he was talking about rate?  Lacking a bit of nuance I think is all.

Namely: semiconductor breakdown is weird around the edges.  Guard rings are used to smooth out the electric field there, making breakdown less likely.  I forget exactly how these work; something about spaced P-N junctions, and maybe field plates too, that happens to do the job.

A fractured and contaminated edge can have all sorts of issues, including errant or intermittent conduction (due to stray charges, surface states and other arcana).  Passivated edges are better (keeps contamination out), but the materials can trap charges, and still transmit ambient electric fields (think random MOSFETs around the edges).

I would guess, for the technology of the day, they did the best with what they had: they probably found that etching the sidewalls, rather than leaving them open on the primary surface, simply gave better results.  The device might not be very tolerant of high voltage or rate stresses (avalanche and pulse operation?), but also maybe it was low enough voltage that it worked out okay.

Similarly, for a long time it used to be that silicon rectifiers were more fragile than some of the alternatives.  I guess that's sometimes still true today...  Avalanche-capable diodes were developed, and the huge energy capacity (relatively speaking) of a TVS diode, or a suitably rated MOSFET for that matter, can (probably?) only be possible this way, by preventing edge breakdown.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on July 14, 2020, 03:54:23 pm
Time dependent false triggering in a thyristor is suppressed with metalization between the base and emitter of each transistor.  "Sensitive gate" SCRs are sensitive because they lack this.  An external resistor is less effective because of the distributed nature of the spreading resistance; the thyristor could be triggered in an area where there is too much resistance to the gate connection which is a very bad situation.

I was referring to the guard rings applied to semiconductor junctions including diodes and transistors which increase breakdown voltage.

Didn't know that. Thanks for this information.

You talk about this ring?

(https://www.richis-lab.de/images/transistoren/20x06.jpg)

In my view that's for smooth edges of then pn junction where rough structures and contamination can lead to leakage...

(https://www.richis-lab.de/images/transistoren/20x09.jpg)

Guard rings are normally built with pn-structures and metal for all I know.


I agree with T3sl4co1l.
"Dirty edges" lead to all kind of negative characteristics.
In this thyristor I assume the biggest problem would be leakage current because worst case it can trigger the thyristor.
Title: Re: Transistors - die pictures
Post by: Noopy on July 15, 2020, 03:02:01 pm

I decapped a RF-Power-Transistor!  8)


(https://www.richis-lab.de/images/transistoren/19x01.jpg)

(https://www.richis-lab.de/images/transistoren/19x04.jpg)

In the package we find very long and thin transistors for best high frequency performance.
The capacitors are important for matching the Input and the output to the rest of the circuit.


(https://www.richis-lab.de/images/transistoren/19x05.jpg)

Nice!  8)


(https://www.richis-lab.de/images/transistoren/19x06.jpg)

(https://www.richis-lab.de/images/transistoren/19x07.jpg)

(https://www.richis-lab.de/images/transistoren/19x13.jpg)

There are some protection structures at both ends of the transistor die, probably zener or supressor.
The small transistors are too complex to identify the elements. Probably they used two metal layers.


(https://www.richis-lab.de/images/transistoren/19x16.jpg)

Hey they damaged the die!  :o But probably no bigger problem.


A lot more pictures on my website:

https://www.richis-lab.de/FET03.htm (https://www.richis-lab.de/FET03.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: RoGeorge on July 15, 2020, 05:01:23 pm
Wow, that's beautiful!    :-+

Datasheet says 2GHz https://www.nxp.com/docs/en/data-sheet/MRF18060A.pdf (https://www.nxp.com/docs/en/data-sheet/MRF18060A.pdf)
It's intriguing to see so many wire bonds inside of a 2GHz part, thinking here about parasitic inductance and stray capacitance.  ???
Title: Re: Transistors - die pictures
Post by: exe on July 15, 2020, 05:51:03 pm
Wow, rf beauty!

It's intriguing to see so many wire bonds inside of a 2GHz part, thinking here about parasitic inductance and stray capacitance.  ???

I thought the same. However, many wires in parallel will actually lower inductance.
Title: Re: Transistors - die pictures
Post by: Noopy on July 15, 2020, 08:12:25 pm
And most important is the impedance matching. To achieve this they even put capacitors in the package! 160pF gives you 0,5 \$\Omega\$ @2GHz but if the impedance matching is ok...  :-+
Title: Re: Transistors - die pictures
Post by: ocw on July 15, 2020, 10:25:34 pm
The MRF18060A pictures reminds me of what a SD2942 looks like "under the hood."  Attached are some pictures of it.

The SD2942 is a 500 watt dissipation 250 MHz MOSFET.  The pictures show one of the two matched MOSFET's in it which are used in a common source push-pull situation.  See:https://www.st.com/resource/en/datasheet/sd2942.pdf (https://www.st.com/resource/en/datasheet/sd2942.pdf)
Title: Re: Transistors - die pictures
Post by: David Hess on July 15, 2020, 11:35:53 pm
I would guess, for the technology of the day, they did the best with what they had: they probably found that etching the sidewalls, rather than leaving them open on the primary surface, simply gave better results.  The device might not be very tolerant of high voltage or rate stresses (avalanche and pulse operation?), but also maybe it was low enough voltage that it worked out okay.

The MESA structure apparently does the same thing as the guard rings which were used later.
Title: Re: Transistors - die pictures
Post by: ocw on July 16, 2020, 02:20:18 am
While significantly lower than the normal operating current and voltage, the attachment shows the excellent match in Id/Vds measurements on the two different halves on a SD2942.  The same measurements between two different MOSFET's shows a poor to no match.
Title: Re: Transistors - die pictures
Post by: magic on July 16, 2020, 05:20:11 am
I see the Vgs/Ids consistency being poor. If we adjust Vgs from 2.2V to 2.1V or 2V, the bottom three transistors have almost identical Vds/Ids behavior :box:
Title: Re: Transistors - die pictures
Post by: ocw on July 16, 2020, 01:18:11 pm
Sorry for the lack of an explanation of the Id/Vds graphs.  They showed six different curves at six different Vgs voltages for two matched MOSFET's located in the same physical package.  The first attachment of this message labels the A and B halves of the one matched MOSFET package.

The second attachment shows similar Id/Vds graphs for one half of two different SD2942 MOSFET packages.  The added 1 - 2 lines are between the two different MOSFET's at the same Vgs.  If they were matched they would be much closer together as they were on the first graph.  The match at the higher Vgs is what is important.

The curves in a matched MOSFET pair is typically close, like that shown.  While a perfect match is uncommon, much more significant mismatches between two different MOSFET packages with the same part number are not unusual.
Title: Re: Transistors - die pictures
Post by: magic on July 16, 2020, 02:47:09 pm
You are right, I didn't understand what was shown on the plot.

I was just nitpicking that you have only demonstrated a mismatch of Id vs Vgs rather than Id vs Vds :)
Frankly, you still are talking about Vgs mismtach.

That being said, we can actually see that one of the different FETs tends to have a sharper knee near zero than the other, regardless of Vgs and Id. So I guess that counts as a true mismatch of their Vds / Ids characteristics. I'm no expert on FETs so no idea what's causing this and if it's normal to see such differences correlated with threshold voltage of individual unit.
Title: Re: Transistors - die pictures
Post by: ocw on July 17, 2020, 09:21:24 pm
magic, you seem more comfortable in reviewing Id/Vgs curves.
The attachment shows the five curves from each of the two halves of one SD2942 almost overlapping as compared to the five curves from half of another SD2942 not coming close to the first ten.
Title: Re: Transistors - die pictures
Post by: magic on July 18, 2020, 04:55:01 am
This is kinda offtopic, but no, really not. It doesn't matter how you show it, it's just a philosophical question:

For a FET in the pentode region, is its Vds/Ids characteristic really anything other than just the drain impedance? If it takes different gate voltages to get the desired drain current on two parts, and then their drain impedance is about the same (high enough it's hardly even seen on those plots) is that really a difference in the Vds/Ids characteristic or just Vgs mismatch? That's all I have ever said, and as you see, I really don't  have that much to say :)

Also, I realize that drain impedance is probably not what you care about as long as it's "high enough", which probably isn't even that very high, as your schematic shows a 700Ω drain load.

If anything, it looks like the mismatched parts have different transconductance too, which might be relevant besides the different Id at given Vgs.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on July 18, 2020, 10:34:27 am
In the pentode region, the MOS equivalent of Early effect, is channel length modulation.  Drain conductance (y_oe) is usually very small indeed.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on July 23, 2020, 10:30:42 am
Today I have a MJL21193 for you (250V/16A/30A):

(https://www.richis-lab.de/images/transistoren/23x01.jpg)

The package has notches to increase the creepage distance.


(https://www.richis-lab.de/images/transistoren/23x02.jpg)

The die is quite big: 3,64mm x 3,54mm


(https://www.richis-lab.de/images/transistoren/23x03.jpg)

It´s a perforated Emitter MESA-Transistor just like the new BUX22 (https://www.richis-lab.de/Bipolar08.htm (https://www.richis-lab.de/Bipolar08.htm))


(https://www.richis-lab.de/images/transistoren/23x04.jpg)

(https://www.richis-lab.de/images/transistoren/23x05.jpg)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on July 23, 2020, 11:35:24 am
I wonder what is the biggest bjt (in terms of die area) ever produced?
Title: Re: Transistors - die pictures
Post by: Noopy on July 23, 2020, 11:47:39 am
I have a halfbridge brick sitting here (KD324510). The dies in there are much bigger. Could be something around factor three. I will take some pictures!  ;D
Title: Re: Transistors - die pictures
Post by: capt bullshot on July 23, 2020, 01:09:35 pm
It's not a BJT anyway, I've seen IGBT dice of 11mm * 16mm and larger. You'd find them in modules like this one:

(http://wunderkis.de/gallery/DSCN0148.orig.jpg)

Also have a few BJT modules, but their potting is pitch black, so one can't see the dice.
Title: Re: Transistors - die pictures
Post by: duak on July 23, 2020, 07:31:36 pm
I have some old BJT six-pack modules for a servo drive.  While looking for information on them I ran across the attached paper on the development of similar devices.  Page 2 shows the pre-potted assembly but without device ID or dimensions.  Assuming the overall dimensions are at least 30 mm x 50 mm the largest dice are maybe 10 mm x 10 mm.  If memory serves, these modules are attached with M4 or M5 screws so these dice could be even larger than that.

This fellow built a 3 phase linear amplifier using similar devices: http://wunderkis.de/pwramp3/index.html (http://wunderkis.de/pwramp3/index.html)

I toyed with the idea of making an electronic load with one of modules I have.  I've used one as a battery simulator to test a 50 A battery charger because it was easier than wiring a bunch of power MOSFETs or BJTs in parallel - I just needed a few zener diodes, resistors and wires with ring terminals.  The module was prone to high frequency oscillation when in the linear region at some currents so it seems that the basic devices are reasonably fast.  I think I read somewhere that these are triple diffused epitaxial to minimize switching losses.

These devices remind me of old IC engines with 5 litre cylinders and a 1000 RPM redline.  If memory serves, these run at about 2 kHz.

Title: Re: Transistors - die pictures
Post by: capt bullshot on July 23, 2020, 08:08:50 pm
This fellow built a 3 phase linear amplifier using similar devices: http://wunderkis.de/pwramp3/index.html (http://wunderkis.de/pwramp3/index.html)
That's me, by the way.


Quote
I toyed with the idea of making an electronic load with one of modules I have. 
I'd recommend against that:
- they "like" to oscillate
- their DC SOA isn't that great, they can die at way lower power levels than their maximum ratings if used in DC linear mode (I had this once or twice in my amplifier trying to use is as a DC current source). With AC output, even at as low frequencies as 50Hz, the SOA gets better.

Title: Re: Transistors - die pictures
Post by: duak on July 23, 2020, 10:11:43 pm
Ah, the capt himself.  Nice job on the driver and the write up is very clear - thank you!

Yes, the DC SOAs on the modules I have are not so good - a Pdmax of 200 W for a devices with a BVCEO of 500 V and an ICMAX of 100 A, clearly optimized for switching.  Their instability was a bit of a surprise as the servo drive they are from had 10 to 30 cm long wires and bus bars all over the place carrying drive signals and switched currents.  However, because it was a PWM, the devices weren't in the linear regime long enough to encounter trouble from oscillation.  After encountering the oscillation and reading the write up, it's back to the old plan.  Too bad, because the module would be simple to mount on a heat sink and wire up.
Title: Re: Transistors - die pictures
Post by: Wolfgang on July 23, 2020, 10:24:48 pm
Ah, the capt himself.  Nice job on the driver and the write up is very clear - thank you!

Yes, the DC SOAs on the modules I have are not so good - a Pdmax of 200 W for a devices with a BVCEO of 500 V and an ICMAX of 100 A, clearly optimized for switching.  Their instability was a bit of a surprise as the servo drive they are from had 10 to 30 cm long wires and bus bars all over the place carrying drive signals and switched currents.  However, because it was a PWM, the devices weren't in the linear regime long enough to encounter trouble from oscillation.  After encountering the oscillation and reading the write up, it's back to the old plan.  Too bad, because the module be simple to mount on a heat sink and wire up.

Try linear mosfets (IXYS). They are made for electronic loads.
Title: Re: Transistors - die pictures
Post by: David Hess on July 24, 2020, 04:06:10 am
Try linear mosfets (IXYS). They are made for electronic loads.

The problem is that unless you need maximum power in fewer packages, bipolar transistors just cost less for a given die area and power dissipation is proportional to die area.  So linear MOSFETs come with a double price premium which might even make lateral MOSFETs price competitive.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on July 24, 2020, 04:53:32 pm
Try linear mosfets (IXYS). They are made for electronic loads.

The problem is that unless you need maximum power in fewer packages, bipolar transistors just cost less for a given die area and power dissipation is proportional to die area.  So linear MOSFETs come with a double price premium which might even make lateral MOSFETs price competitive.

If you can find them...

But all of the above seem to be superseded by SuperJunction types, which regularly give DC SOA curves.  I've tested a few and found them to be accurate.  I'm not sure how they do it -- SJ have higher power density than ever, but they still manage not to runaway.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on July 28, 2020, 05:58:47 pm

Today I have a 2N2857 HF-Transistor for you.
It´s a quite interesting transistor manufactured by Central Semiconductor.


(https://www.richis-lab.de/images/Transistoren/24x01.jpg)

Central Semiconductor builds obsolete transistors. Originally the 2N2857 was built by Motorola.
This 2N2857 has a datecode 1738!  :-+


(https://www.richis-lab.de/images/Transistoren/24x04.jpg)

It has four pins. The housing is isolated.


(https://www.richis-lab.de/images/Transistoren/24x05.jpg)

To isolate the transistor it was package on the collector pin.  :-+ ;D
Thermal resistance is probably a bit higher...


(https://www.richis-lab.de/images/Transistoren/24x06.jpg)

(https://www.richis-lab.de/images/Transistoren/24x07.jpg)

The die is ~350µm*350µm.
There is a second transistor on the die probably to test the die. Interesting... Why didn´t they do the testing with the 2N2857 transistor itself?  :-//


And it glows:

(https://www.richis-lab.de/images/Transistoren/24x10.jpg)

1mA

(https://www.richis-lab.de/images/Transistoren/24x11.jpg)

5mA

 8)

Breakdown voltage is quite low (around -6V) because of high doping for high switching frequency.


More pictures here::

https://www.richis-lab.de/Bipolar16.htm (https://www.richis-lab.de/Bipolar16.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on July 28, 2020, 06:13:42 pm
Please excuse my ignorance, where is the second bjt located? Is it two big pads on the left on the close up shot?
Title: Re: Transistors - die pictures
Post by: Noopy on July 28, 2020, 06:17:14 pm
Please excuse my ignorance, where is the second bjt located? Is it two big pads on the left on the close up shot?

Yes it is. The two bigger pads are base and emitter and the smaller at the bottom corner is the collector.
Looking very carefully you can spot the corners of the emitter area around the emitter pad.
Title: Re: Transistors - die pictures
Post by: RoGeorge on July 28, 2020, 06:26:44 pm
I wouldn't expect it to be that smol!   ;D
Title: Re: Transistors - die pictures
Post by: David Hess on July 28, 2020, 06:56:28 pm
There is a second transistor on the die probably to test the die. Interesting... Why didn´t they do the testing with the 2N2857 transistor itself?  :-//

Could the tests be destructive like base-emitter breakdown voltage?
Title: Re: Transistors - die pictures
Post by: Noopy on July 28, 2020, 07:08:17 pm
There is a second transistor on the die probably to test the die. Interesting... Why didn´t they do the testing with the 2N2857 transistor itself?  :-//

Could the tests be destructive like base-emitter breakdown voltage?

Never heard of such testing but that would explain the second transistor...
Title: Re: Transistors - die pictures
Post by: exe on July 28, 2020, 07:16:00 pm
How do they pick and place such small dies? Or even cut them...

Those metal can packages... I have an urge to buy just for the sake of owning it.

PS I have Russian МП-42 (MP-42) somewhere, an old germanium transistor. I wanted to put it into use, but may be I should crack it open and see what's inside :). Can't find it atm, must be hiding from me....
Title: Re: Transistors - die pictures
Post by: Noopy on July 28, 2020, 07:21:00 pm
How do they pick and place such small dies? Or even cut them...

Those metal can packages... I have an urge to buy just for the sake of owning it.

PS I have Russian МП-42 (MP-42) somewhere, an old germanium transistor. I wanted to put it into use, but may be I should crack it open and see what's inside :). Can't find it atm, must be hiding from me....

And look at these small bond wires you have to place them accurate on the bondpad.
The handling must be pretty tricky.
Fascinating engineering!

The MP-42 is afraid...  ;D
Title: Re: Transistors - die pictures
Post by: David Hess on July 29, 2020, 02:50:03 am
There is a second transistor on the die probably to test the die. Interesting... Why didn´t they do the testing with the 2N2857 transistor itself?  :-//

Could the tests be destructive like base-emitter breakdown voltage?

Never heard of such testing but that would explain the second transistor...

It occurred to me because RF transistors often have a rated base-emitter breakdown voltage of only 3 volts instead of the more common 5 volts.
Title: Re: Transistors - die pictures
Post by: Zoli on July 29, 2020, 04:28:48 am
How do they pick and place such small dies? Or even cut them...

Those metal can packages... I have an urge to buy just for the sake of owning it.

PS I have Russian МП-42 (MP-42) somewhere, an old germanium transistor. I wanted to put it into use, but may be I should crack it open and see what's inside :). Can't find it atm, must be hiding from me....
Back in my times(30+years ago) I've opened quite a few from the MP38-42/P401-3 series; first, they are all Ge transistors; second, all of the structures are visible with the naked eye(die connection:1.00X0.01 mm Al or similar flat); third , don't blame my memory if there's something totally diferent inside; I just try to remember best of my impressions.
Title: Re: Transistors - die pictures
Post by: Noopy on July 29, 2020, 06:02:07 am
Back in my times(30+years ago) I've opened quite a few from the MP38-42/P401-3 series; first, they are all Ge transistors; second, all of the structures are visible with the naked eye(die connection:1.00X0.01 mm Al or similar flat); third , don't blame my memory if there's something totally diferent inside; I just try to remember best of my impressions.

Like this one?
https://www.richis-lab.de/Bipolar06.htm (https://www.richis-lab.de/Bipolar06.htm)
That's more mechanical engineering than electrical engineering.  ;D


Regarding the test-transistor:
Perhaps it was easier to test a transistor with all three terminals on the surface instead of the other transistor with it's collector on the back of the die...

Title: Re: Transistors - die pictures
Post by: magic on July 29, 2020, 06:40:38 am
These two transistors have the same collector ;)
Title: Re: Transistors - die pictures
Post by: Noopy on July 29, 2020, 06:48:27 am
These two transistors have the same collector ;)

That's right... It would have been enough to integrate a second collector pad instead of a whole transistor...  :-//
Title: Re: Transistors - die pictures
Post by: exe on July 29, 2020, 08:53:22 am
My friends, look what I found: P503, MP-16B, MP14-A and 2T803A (the big can) . The first one seems to be one of the first germanium bjt produced in the USSR. Accroding to http://www.155la3.ru/p501.htm, (http://www.155la3.ru/p501.htm,) they were developed in 1958-1959, and were in production for 5-6years. Rumors said they were discontinued due to extremely low yield of 1.8%.

It seems my P503 is not doing well or I'm measuring it wrong: [attach=1] . What should I do with it? Shall I keep it for children, donate somewhere, or open it? :)

PS This one was donated to me in late nighties by an ex-EE engineer among with many other old parts. It was sitting in a storage room until last year when I found it while traveling to my home town. I brought a few Soviet bjts back in hope to put them into use. Not sure how to use them. Build a distortion pedal for the guitar?

PPS I wanted to measure the diode drop, so I used a dmm that has test voltage of 3.2V. From my measurements, the forward voltage is 0.244, the reverse is 2.7, so it seems they broke down. According to datasheets, those germanium transistors are only rated up to 3V of reverse voltage.  Does it mean I killed them all?  :palm:

PPPS the year of production of P503 in question is 1963.
Title: Re: Transistors - die pictures
Post by: Noopy on July 29, 2020, 09:09:56 am
I quite sure you can't kill such a transistor with the diode tester. The current should be low enough.

Perhaps your transistor tester has a problem with the probably higher leakage currents?
Title: Re: Transistors - die pictures
Post by: Noopy on July 30, 2020, 07:17:47 pm
Today I have an older part for you, the 2N1561, a high-frequency-germanium-diffusion-alloy-mesa-transistor.  ;D


(https://www.richis-lab.de/images/Transistoren/25x01.jpg)

Nice packing.  8)


(https://www.richis-lab.de/images/Transistoren/25x02.jpg)

TO-107


(https://www.richis-lab.de/images/Transistoren/25x04.jpg)

Absorbent cotton?  :-//


(https://www.richis-lab.de/images/Transistoren/25x05.jpg)

The die is 0,57mm x 0,67mm.
It seems that the sawing of the dies was a bit of a problem. The edges are a little bit splinted.


(https://www.richis-lab.de/images/Transistoren/25x06.jpg)

I assume they had a p-doped substrate, diffused a n-doped base-layer on top of it and then placed a p-dopant and a n-dopant on top of it. After some baking yout get under the p-dopant an emitter and you can use the rest of the material to contact the emitter. The n-dopant gives you the base-contact.
Then some MESA etching and you get a nice clean (ok a bit shaky  ;D) base-collector-edge.


More pictures here:
https://www.richis-lab.de/Bipolar17.htm (https://www.richis-lab.de/Bipolar17.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on July 30, 2020, 08:52:09 pm
Quite some effort to produce a transistor. No wonders they used to be expensive.
Title: Re: Transistors - die pictures
Post by: Noopy on August 01, 2020, 07:30:22 pm
Today I have again a more simple germanium transistor for you:
ACY38 built by COSEM (France) which merged later with SESCO to SESCOSEM (=>Thomson=>SGS Thomson=>STMicroelectronic)


(https://www.richis-lab.de/images/Transistoren/26x01.jpg)

(https://www.richis-lab.de/images/Transistoren/26x02.jpg)

 :palm:
Paint stripper is good to remove this silicone oil based thermal paste.  :-+


(https://www.richis-lab.de/images/Transistoren/26x04.jpg)

Transistor is covered with some silicone stuff.


(https://www.richis-lab.de/images/Transistoren/26x05.jpg)

Unfortunatelly the wires were pulled of while removing the silicone.
But here you can see an interesting thing. The surface under the indium pill looks like it was machined. Actually that´s quite reasonable. A smooth surface gives you a better junction than a lot of roughness (different base thickness and varying doping).


(https://www.richis-lab.de/images/Transistoren/26x06.jpg)

Emitter...


More pictures here:

https://www.richis-lab.de/Bipolar18.htm (https://www.richis-lab.de/Bipolar18.htm)


 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on August 06, 2020, 09:26:53 pm
Well that´s a really old 2N3055:


(https://www.richis-lab.de/images/transistoren/27x01.jpg)

Who knows Solitron?  ;)


(https://www.richis-lab.de/images/transistoren/27x03.jpg)

Nice! You don´t need a datasheet to connect the transistor.  :-+ ;D


(https://www.richis-lab.de/images/transistoren/27x04.jpg)

(https://www.richis-lab.de/images/transistoren/27x06.jpg)

A classical transistor structure.
The solder is not applied evenly. That doesn´t look very promising.
The emitter connector seems to be dangerously long. It looks like it can short to the base...  :-//


(https://www.richis-lab.de/images/transistoren/27x07.jpg)

(https://www.richis-lab.de/images/transistoren/27x08.jpg)

(https://www.richis-lab.de/images/transistoren/27x09.jpg)

And breakdown light of course!  ;D => -16V / 0,5A


(https://www.richis-lab.de/images/transistoren/27x12.jpg)

It´s probably a hometaxial transistor. The surface (emitter) is partly etched down to connect the base.
You can see that the etched base area is smoother than the emitter area.


More pictures here:

https://www.richis-lab.de/2N3055_06.htm (https://www.richis-lab.de/2N3055_06.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 06, 2020, 11:06:10 pm
Hi Noopy,

nice, but what you see here is not a second breakdown, but the breakdown of the base emitter diode.
Title: Re: Transistors - die pictures
Post by: Noopy on August 07, 2020, 03:07:25 am
Thank you Wolfgang!  :-+

Of course that´s not a second breakdown! I have corrected the text...
I had a long day...  :-//
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 07, 2020, 01:26:07 pm
Hi Noopy,

in fact it would be nice to see a second breakdown, but I guess you need a high-speed camera to get this on film.

Thanks for your good work !
 
  Wolfgang
Title: Re: Transistors - die pictures
Post by: Noopy on August 07, 2020, 01:40:42 pm
I would need a high speed super-macro-camera with enough focal distance to protect the camera. That sounds expensive!  ;D

Thank you for the recognition!  :popcorn:
I still have some interesting parts in stock.  8)

Best regards,

Richard
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on August 07, 2020, 01:45:37 pm
Also 2nd breakdown probably doesn't emit any visible light, so you'd need a high framerate IR camera at that!

Tim
Title: Re: Transistors - die pictures
Post by: magic on August 07, 2020, 01:48:25 pm
That being said, you could still try basic avalanche breakdown of the BC junction. Just need a resistor-limited HV generator.
Title: Re: Transistors - die pictures
Post by: Noopy on August 07, 2020, 01:55:21 pm
Also 2nd breakdown probably doesn't emit any visible light, so you'd need a high framerate IR camera at that!

Tim

I had in mind a second breakdown with high power. Getting that on a film would be pretty impressive even without IR sensitivity.  8)


That being said, you could still try basic avalanche breakdown of the BC junction. Just need a resistor-limited HV generator.

I once tried a breakdown of the BC junction of a transistor with low voltage rating (can´t remember which one). But I wasn´t able to see any light.
Perhaps that´s because most of the BC junction is covered under "a lot" of silicon.  :-//

Unfortunatelly higher breakdown voltages generate more heat so the transistor dies very quickly...  :-\
Title: Re: Transistors - die pictures
Post by: magic on August 07, 2020, 02:02:35 pm
Did you verify that there was current flow?
I tried measuring breakdown voltage of some BC857 once and found it to be over 100V, which was the limit of my generator. Basically, I applied 100V and nothing happened whatsoever.

Perhaps that´s because most of the BC junction is covered under "a lot" of silicon.  :-//
That's possible, although usually the edges of the junction reach the surface.
Title: Re: Transistors - die pictures
Post by: Noopy on August 07, 2020, 02:13:30 pm
Yes I tracked the current. I finally found one that broke down <80V. I think it was a small HF Transistor.

Perhaps I should try it again...  :-/O :D
Title: Re: Transistors - die pictures
Post by: Noopy on August 07, 2020, 08:24:39 pm
With "Perhaps I should try it again..." I wanted to say "I have to do that instantly!"  ;D

I took the 2N2857 with a maximum collector-base-voltage of 30V:

https://www.richis-lab.de/Bipolar16.htm (https://www.richis-lab.de/Bipolar16.htm)


Beginning at 57V(!) the current through the collector-base-junction reaches 10µA.



(https://www.richis-lab.de/images/Transistoren/24x12a.jpg)

=> 50µA
You can see a small glow in the upper right corner of the base rectangle.


(https://www.richis-lab.de/images/Transistoren/24x12b.jpg)

=> 100µA
The lower right corner starts to glow a little.


(https://www.richis-lab.de/images/Transistoren/24x12c.jpg)

=> 250µA
Now we see the corners!  :-+


(https://www.richis-lab.de/images/Transistoren/24x12d.jpg)

=> 500µA
The left corners start to glow.


(https://www.richis-lab.de/images/Transistoren/24x12e.jpg)

=> 1mA
The electrical field is highest in the corners of the rectangle and so the corners are illuminated first.


(https://www.richis-lab.de/images/Transistoren/24x12f.jpg)

=> 2mA


(https://www.richis-lab.de/images/Transistoren/24x12g.jpg)

=> 3mA
Then the right edge is lightening up.


(https://www.richis-lab.de/images/Transistoren/24x12h.jpg)

=> 5mA / 75V
I can´t go any higher. Probably with more power loss (>375mW) the 2N2857 would die anyhow.
It seems the area under the emitter contact is dark. The emitter isn´t connected but perhaps/probably the emitter contact somehow affects the electrical field.  :-//


 :popcorn:
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on August 08, 2020, 12:11:46 am
The emitter most definitely affects things -- C-E has a lower breakdown than C-B, effectively the C-B leakage is multiplied by hFE so runs away at a lower voltage (Vceo vs. Vcbo).  In the transition region between these two extremes, breakdown depends on e.g. B-E resistance; and breakdown can become exceptionally noisy, so much so that it can effectively switch "on" in a fraction of a nanosecond!

(I've observed avalanche switching in every transistor I've tested; the width of the region (in terms of what range of R_BE works reliably) varies, with most epitaxial parts being poor.  2N2369 is the classic, but 2N3904 also seems to do well.  Power transistors don't handle any more current before burning out, perhaps because avalanche only occurs in a small part of the whole junction, and isn't able to propagate over the full width.)

If the glow persists in Vceo or Vces mode, I wonder if it has any physical significance -- sufficient light output could perhaps cause the junction to ionize much sooner, and more broadly, than it would due to carrier diffusion alone!

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on August 08, 2020, 03:53:33 am
If the glow persists in Vceo or Vces mode, I wonder if it has any physical significance -- sufficient light output could perhaps cause the junction to ionize much sooner, and more broadly, than it would due to carrier diffusion alone!

I just did a short test of Vceo.
At ~45V over emitter-collector and ~10mA you can´t see any light.

I would have guessed to see at least some glowing...  :-//
Perhaps the breakdown ist more chaotic and distributed over the whole die... That would be a good explanation for  more noise... Just speculating...

Have to try Vces but no time left right now.
I assume the collector-base-junction will glow in that case but since a lot of current is flowing to the emitter I won´t be able to raise the current high enough to make the glowing visible before the transistor dies.
Title: Re: Transistors - die pictures
Post by: magic on August 08, 2020, 06:11:40 am
Another factor is beta: at 10mA collector current, only some 0.1mA may be flowing by means of breakdown and the rest because of the normal current gain of the transistor.
Title: Re: Transistors - die pictures
Post by: Noopy on August 08, 2020, 02:17:17 pm
Another factor is beta: at 10mA collector current, only some 0.1mA may be flowing by means of breakdown and the rest because of the normal current gain of the transistor.

I quite agree with you!  :-+
Title: Re: Transistors - die pictures
Post by: Noopy on August 12, 2020, 07:38:20 pm
(https://www.richis-lab.de/images/Transistoren/24x13.jpg)


Hm... Somehow I managed to kill the 2N2857...
Unfortunatelly I can´t say what went wrong. I was in a hurry. That´s never a good thing.   :-BROKE :-//
Title: Re: Transistors - die pictures
Post by: magic on August 12, 2020, 07:49:21 pm
Dunno, looks like you shorted out a PSU with that poor thing :P

Reminds me of that time I tried to weld a thermocouple with a laptop brick.
Title: Re: Transistors - die pictures
Post by: exe on August 12, 2020, 08:00:38 pm
May be it's only bound wires are broken. Is it possible to solder new wires to the die?
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on August 12, 2020, 08:43:47 pm
The die is discolored.  That's not just ash on top, that's an obliterated what-used-to-be-a-transistor.

Tim
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 12, 2020, 09:02:23 pm
(https://www.richis-lab.de/images/Transistoren/24x13.jpg)


Hm... Somehow I managed to kill the 2N2857...
Unfortunatelly I can´t say what went wrong. I was in a hurry. That´s never a good thing.   :-BROKE :-//

I guess the poor thing needed some limiting for current and power and did not get any :)
Seriously, these parts are not forgiving at all. When you look how they are mounted (on a pin header)
you can imagine that Rth is very large and heat capacitance is very small, i.e. they blow up in milliseconds.
Remedy: use a SMU and set the limits small enough. Fortunaterly, they are cheap.
Title: Re: Transistors - die pictures
Post by: Noopy on August 12, 2020, 09:21:58 pm
That´s not "medium" it´s more "well done".  ;D

@Wolfgang: SMU and cheap are two words that don´t match.  ;)
I still haven´t set up my HP-supply...  :-\
Title: Re: Transistors - die pictures
Post by: David Hess on August 12, 2020, 09:52:49 pm
Somewhere I have seen a table with bond wire fuse ratings for use in failure analysis.
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 12, 2020, 11:30:11 pm
That´s not "medium" it´s more "well done".  ;D

@Wolfgang: SMU and cheap are two words that don´t match.  ;)
I still haven´t set up my HP-supply...  :-\

Sorry I meant that the transistors are cheap. An SMU is not, and I know that after Keysight got all my money :)
Something affordable you could make is a current limiter circuit (I think there was a Jim Williams app note about an electronic fuse).
Thats not rocket science and will prevent a few kills.
Title: Re: Transistors - die pictures
Post by: Noopy on August 13, 2020, 04:16:42 am
 :-+ :)

Up to now I use a cheap bench supply but it has a current limiter of course.
I should have worked more concentrated. The fault is mine....
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 13, 2020, 09:50:08 am
Using a normal PSU with sensitive semiconductors is a problem even with a current limiter.
The problem is the energy stored in the output cap and the slow response of the limiter.
What you need is a limiter/electronic fuse that is fast and has no big electrolytic at the output side.
Title: Re: Transistors - die pictures
Post by: Noopy on August 13, 2020, 10:15:52 am
Yeah, I agree with that. A SMU would definitely be a nice piece of equipment. :)
Title: Re: Transistors - die pictures
Post by: RoGeorge on August 13, 2020, 12:39:07 pm
I proudly did once a demonstration about my latest tool purchase, a brand new Rigol DP832 power source, and how great it is, and how it can serve as a voltage source, or as a current source, upon wish.

And to prove my point, I set the current to 20mA and confidently hooked up a LED to the wires.   :-+

The LED flashed then instantly died with a violent pop sound, I jumped back, and my friend burst into laughter.  :-DD

Those 20mA were enough to charge a few thousands uF of output capacitors up to 32V, then all the energy rushed into the LED, limited only by the ESR and the wires.  In DP832, the output filtering capacitors are located at the end side, in direct contact with the output terminals.  ;D



Regarding the melted bonding wires, they are terminated in intriguingly round spheres of metal, and also there is a segment attached to each sphere, segment that looks like it was melted too but only at its surface, and somehow kept its initial cylindrical shape and its initial diameter, then the rest of the wire suddenly looks like brand new.

How is that possible?  :o
Title: Re: Transistors - die pictures
Post by: SilverSolder on August 13, 2020, 01:26:20 pm
I proudly did once a demonstration about my latest tool purchase, a brand new Rigol DP832 power source, and how great it is, and how it can serve as a voltage source, or as a current source, upon wish.

And to prove my point, I set the current to 20mA and confidently hooked up a LED to the wires.   :-+

The LED flashed then instantly died with a violent pop sound, I jumped back, and my friend burst into laughter.  :-DD

Those 20mA were enough to charge a few thousands uF of output capacitors up to 32V, then all the energy rushed into the LED, limited only by the ESR and the wires.  In DP832, the output filtering capacitors are located at the end side, in direct contact with the output terminals.  ;D

[...]


That's what happens when you use an instrument that is too new and inexperienced!  :D

(https://www.eevblog.com/forum/projects/transistors-die-pictures/?action=dlattach;attach=1046336;image)
Title: Re: Transistors - die pictures
Post by: Mecanix on August 13, 2020, 03:23:29 pm
Those 20mA were enough to charge a few thousands uF of output capacitors up to 32V, then all the energy rushed into the LED, limited only by the ESR and the wires.  In DP832, the output filtering capacitors are located at the end side, in direct contact with the output terminals.  ;D

Interesting. Mine (DP832) ramps up beautifully, no inrush or spikes whatsoever on all 3CH, smooth as silk and stable. Recently had it calibrated also so add in that now impressive accuracy, its incredible now.
Title: Re: Transistors - die pictures
Post by: Wolfgang on August 13, 2020, 03:51:40 pm
Those 20mA were enough to charge a few thousands uF of output capacitors up to 32V, then all the energy rushed into the LED, limited only by the ESR and the wires.  In DP832, the output filtering capacitors are located at the end side, in direct contact with the output terminals.  ;D

Interesting. Mine (DP832) ramps up beautifully, no inrush or spikes whatsoever on all 3CH, smooth as silk and stable. Recently had it calibrated also so add in that now impressive accuracy, its incredible now.

I have a lot of DP832s, and they perform fine. Three things to take care:

- The startup spike only occurs when the load is *very* light.

- Its not an SMU, so accuracy is what is in the datasheet. Last digit has to taken with a larger grain of salt, as usual

- They do have an output cap, and the energy in this cap gets dumped into your load with no current limit being able to do anything against that.
So, if you set voltage to 30V, current to 10mA and then connect your LED, it could still be dead because of the cap discharge current.
Title: Re: Transistors - die pictures
Post by: RoGeorge on August 13, 2020, 06:47:39 pm
I apologize about telling the offtopic tale with the DP832.  I didn't want to hijack the topic.  Should have kept my mouth shut.  It was not the power source's fault, it was my mistake.  Just let it be.  Please let's get back on topic.

-----------------

Anybody knows more about the 2 spheres formed at the end of the melted bonded wires from the last transistor's pics?  Are they usually so round and alike looking?
Title: Re: Transistors - die pictures
Post by: capt bullshot on August 13, 2020, 09:44:06 pm
If you don't have an SMU, a bunch simple resistors should do the job.
Use the lab supply in voltage mode, roughly calculate the required resistance and put the resistor in series to the DUT. Measure the actural current with your multimeter and adjust the output voltage to set the desired current.
Disadvantage: for covering a larger range of currents, one has to switch resistors.
Your typical old-style curve tracer (e.g. Tek 576) does it this way. Pretty simple and effective. The modern ones have multiple digitally controlled SMUs to achieve the same results.
Title: Re: Transistors - die pictures
Post by: Noopy on August 13, 2020, 09:51:20 pm
Anybody knows more about the 2 spheres formed at the end of the melted bonded wires from the last transistor's pics?  Are they usually so round and alike looking?

Well the surface tension of the liquid metal forms a ball...


If you don't have an SMU, a bunch simple resistors should do the job.
Use the lab supply in voltage mode, roughly calculate the required resistance and put the resistor in series to the DUT. Measure the actural current with your multimeter and adjust the output voltage to set the desired current.
Disadvantage: for covering a larger range of currents, one has to switch resistors.
Your typical old-style curve tracer (e.g. Tek 576) does it this way. Pretty simple and effective. The modern ones have multiple digitally controlled SMUs to achieve the same results.

 :-+
Usually my bench supply is good enough for most applications.
I just have to keep calm while meassuring.
I was in a hurry that´s never good...  :--
Title: Re: Transistors - die pictures
Post by: Noopy on August 19, 2020, 06:53:19 pm
Today I have a MJL21193 for you (250V/16A/30A):

[...]

(https://www.richis-lab.de/images/transistoren/23x02.jpg)

The die is quite big: 3,64mm x 3,54mm


I was wrong with the die size!  :o
In fact the die is 5,48mm x 5,36mm! That´s quite big, 5,5 times the ST TIP3055!  8)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on August 19, 2020, 07:46:45 pm

Today I have a new 2N3055 for you, a Motorola 2N3055:

http://www.richis-lab.de/2N3055_07.htm (http://www.richis-lab.de/2N3055_07.htm)


(http://www.richis-lab.de/images/transistoren/29x01.jpg)

The characteristic old package with the characteristic low, more round cap.


(http://www.richis-lab.de/images/transistoren/29x03.jpg)

I don´t think that round low thing is a heatspreader. Perhaps they needed this small plate to manufacture the transistor.  :-//


(http://www.richis-lab.de/images/transistoren/29x04.jpg)

The design is "quite modern" and uses a mesa structure.


 8)


(http://www.richis-lab.de/images/transistoren/29x07a.jpg)

11V 10mA


(http://www.richis-lab.de/images/transistoren/29x07b.jpg)

20mA


(http://www.richis-lab.de/images/transistoren/29x07c.jpg)

30mA


(http://www.richis-lab.de/images/transistoren/29x07d.jpg)

40mA


(http://www.richis-lab.de/images/transistoren/29x07e.jpg)

50mA


(http://www.richis-lab.de/images/transistoren/29x07f.jpg)

100mA


(http://www.richis-lab.de/images/transistoren/29x07g.jpg)

200mA


(http://www.richis-lab.de/images/transistoren/29x07h.jpg)

300mA

 ;D
Title: Re: Transistors - die pictures
Post by: ocw on August 21, 2020, 10:52:48 pm
After prior pictures of a good SD2942W with more zoom https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3138636/#msg3138636 (https://www.eevblog.com/forum/projects/transistors-die-pictures/msg3138636/#msg3138636) , attached is a picture of the same SD2942W with less zoom along with one damaged by lightning.
[attachimg=2]
Title: Re: Transistors - die pictures
Post by: Jay_Diddy_B on August 22, 2020, 02:53:28 am
Hi,

You need to find a big transistor like this one:

[attachimg=1]
(https://www.eevblog.com/forum/projects/transistors-die-pictures/?action=dlattach;attach=1051410;image)

I have included a TO-3 transistor in the picture for scale.

The BJT is rated at 200A 700V.

I am not ready to open this one up. The silicon will probably be 33 or 38mm in diameter.

Regards,
Jay_Diddy_B
Title: Re: Transistors - die pictures
Post by: Noopy on August 22, 2020, 06:35:06 am
Well that's really a big one! :D
Title: Re: Transistors - die pictures
Post by: Noopy on September 05, 2020, 09:09:57 pm
Today I have a really old 2N3055:

(https://www.richis-lab.de/images/transistoren/30x01.jpg)

(https://www.richis-lab.de/images/transistoren/30x02.jpg)

(https://www.richis-lab.de/images/transistoren/30x05.jpg)

Here you can see the protective coating of the die and the higher emitter since it is a hometaxial transistor.


(https://www.richis-lab.de/images/transistoren/30x06.jpg)


Of course  I did some breakdown pictures. The fabrication process didn´t create very smooth structures. You can see that the breakdown light is quite non uniform even at high currents:


(https://www.richis-lab.de/images/transistoren/30x09a.jpg)

0,1A


(https://www.richis-lab.de/images/transistoren/30x09b.jpg)

0,2A


(https://www.richis-lab.de/images/transistoren/30x09c.jpg)

0,3A


(https://www.richis-lab.de/images/transistoren/30x09d.jpg)

0,4A


(https://www.richis-lab.de/images/transistoren/30x09e.jpg)

0,5A


(https://www.richis-lab.de/images/transistoren/30x09f.jpg)

0,6A


(https://www.richis-lab.de/images/transistoren/30x09g.jpg)

0,7A


(https://www.richis-lab.de/images/transistoren/30x09h.jpg)

0,8A


And there is a small structural flaw:


(https://www.richis-lab.de/images/transistoren/30x10a.jpg)

(https://www.richis-lab.de/images/transistoren/30x10.jpg)


https://www.richis-lab.de/2N3055_08.htm (https://www.richis-lab.de/2N3055_08.htm)


Title: Re: Transistors - die pictures
Post by: SilverSolder on September 06, 2020, 01:04:13 am

Interesting with that old 2N3055, it seems technology has moved on and we are making much "cleaner" devices nowadays?
Title: Re: Transistors - die pictures
Post by: Noopy on September 06, 2020, 07:03:34 am
That is for sure.  :-+
Title: Re: Transistors - die pictures
Post by: Noopy on September 06, 2020, 08:42:09 pm

Finally we can compare the hometaxial RCA 2N3055 with the epitaxial RCA 2N3055:


(https://www.richis-lab.de/images/transistoren/31x01.jpg)

(https://www.richis-lab.de/images/transistoren/31x03.jpg)

(https://www.richis-lab.de/images/transistoren/31x05.jpg)

(https://www.richis-lab.de/images/transistoren/31x06.jpg)

The metal layer has an interesting structure. It seems that RCA had to modify the layer to do some current steering. You can see that while driving the base-emitter-junction in breakdown:


(https://www.richis-lab.de/images/transistoren/31x10.jpg)

There are two very bright areas. There is no small bright point as we have seen with impurities. It´s more a line getting constantly brighter and dimmer. For sure that is a local higher current density.


(https://www.richis-lab.de/images/transistoren/31x07.jpg)

In the bottom left corner of the base contact RCA has integrated two holes in the emitter area to increase the resistance and reduce the current density.


(https://www.richis-lab.de/images/transistoren/31x08.jpg)

In the bottom right corner of the die RCA added even a small electrode connected to the base potential over the silicon.


https://www.richis-lab.de/2N3055_09.htm (https://www.richis-lab.de/2N3055_09.htm)


 :-/O
Title: Re: Transistors - die pictures
Post by: David Hess on September 07, 2020, 04:28:50 am
Interesting with that old 2N3055, it seems technology has moved on and we are making much "cleaner" devices nowadays?

Early processing was incredibly crude by modern standards.  Today you could do better in your garage.
Title: Re: Transistors - die pictures
Post by: magic on September 07, 2020, 09:04:41 am
Maybe almost better ;)

https://hackaday.com/2010/05/13/transistor-fabrication-so-simple-a-child-can-do-it/
Title: Re: Transistors - die pictures
Post by: Noopy on September 07, 2020, 05:47:22 pm

I have taken pictures of a Motorola 2N3055I:


(https://www.richis-lab.de/images/transistoren/32x01.jpg)

(https://www.richis-lab.de/images/transistoren/32x02.jpg)

(https://www.richis-lab.de/images/transistoren/32x03.jpg)


It seems like the Motorola 2N3055I has a bigger die than the Motorola 2N3055 (https://www.richis-lab.de/2N3055_07.htm (https://www.richis-lab.de/2N3055_07.htm)). Perhaps the 2N3055I was a more robust version. Perhaps it´s a different generation of the 2N3055.  :-//
I didn´t find a 2N3055I in the Motorola data books, only a 2N3055A which seems to indicate parts with less ft).  :-//


https://www.richis-lab.de/2N3055_10.htm (https://www.richis-lab.de/2N3055_10.htm)


 :-/O
Title: Re: Transistors - die pictures
Post by: Noopy on September 09, 2020, 09:10:47 pm
Hi all!

More power: Darlington-Halfbridge-Powermodul Powerex KD324510  8)


(https://www.richis-lab.de/images/Transistoren/33x01.jpg)

(https://www.richis-lab.de/images/Transistoren/33x04.jpg)

Ugly silicone potting...  :palm:


(https://www.richis-lab.de/images/Transistoren/33x06.jpg)

After a lot of cleaning...


(https://www.richis-lab.de/images/Transistoren/33x08.jpg)

(https://www.richis-lab.de/images/Transistoren/33x09.jpg)

The die is 16,0mm x 12,0mm. Two of them act as highside and two of them act as lowside.


(https://www.richis-lab.de/images/Transistoren/33x12.jpg)

Guard rings for the high voltage.


(https://www.richis-lab.de/images/Transistoren/33x13.jpg)

The diodes are 5,9mm x 3,9mm.
Constant current: 50A
Peak current: 500A


(https://www.richis-lab.de/images/Transistoren/33x14.jpg)

The diodes are also equipped with guard rings.


https://www.richis-lab.de/Bipolar19.htm (https://www.richis-lab.de/Bipolar19.htm)

 :-/O
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on September 10, 2020, 12:14:49 am
Hm, I wonder what the tradeoff is for metallized guard rings versus not.

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on September 10, 2020, 05:51:48 am
Perhaps that´s necessary because of surface charge effects?  :-//
Title: Re: Transistors - die pictures
Post by: Noopy on September 10, 2020, 08:15:31 pm
Today I have a 2N1613 for you:
https://www.richis-lab.de/Bipolar20.htm (https://www.richis-lab.de/Bipolar20.htm)

The 2N1613 is the first planar transistor worldwide and it´s still produced today.  :clap:


(https://www.richis-lab.de/images/transistoren/34x01.jpg)

This 2N1613 was built by Telefunken.


(https://www.richis-lab.de/images/transistoren/34x03.jpg)

(https://www.richis-lab.de/images/transistoren/34x02.jpg)

A small die (0,7mm x 0,7mm), nothing special...

 :-/O


Now you can find me on patreon: https://www.patreon.com/richis_lab (https://www.patreon.com/richis_lab)
Do you like my pictures?  ;)
Title: Re: Transistors - die pictures
Post by: RoGeorge on September 11, 2020, 07:06:13 am
Is all the yellow inside a gold plating?  It might justify outside, so the terminals won't oxidize, but why would gold plating be used inside the transistor's case?
Title: Re: Transistors - die pictures
Post by: Noopy on September 11, 2020, 07:22:13 am
I assume that´s all gold plating.
I further assume that they used gold platingt to assure a good bonding even if the package is stored open some time before attaching the die and closing the package.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on September 11, 2020, 04:29:28 pm
Might be a combination of bonding and contamination.  If it's bare metal, it's likely to spatter when spot-welded together.  Gold, copper, silver and alloys would be fine as a filler, spot-brazing it as it were.  Maybe just convenience as to putting it everywhere?

If the layer is very thin (as gold tends to be these days), it might not be enough to act as a filler; it might diffuse into the base metal, leaving little or no advantage for bonding purposes.  (It might simply be that a clean and smooth enough interface, with a well controlled welding process, doesn't spatter.  I'm sure this is relevant to later production; I have more than a few TO-39s that are full tin plated, so either would've been bonded like that, or bare and plated afterwards.  Hmm, and at that, most of them are smooth but a few Philips 2N4033 are starting to whisker..!)  If it was a heavier layer of gold, it could serve this way though.

It's interesting that only the base seems to be gold plated, which doesn't really go along great with either theory. :-DD

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on September 15, 2020, 03:22:11 am
I have forgotten to post the ITT 2N3055 here:

https://www.richis-lab.de/2N3055_11.htm (https://www.richis-lab.de/2N3055_11.htm)


(https://www.richis-lab.de/images/transistoren/35x01.jpg)

(https://www.richis-lab.de/images/transistoren/35x03.jpg)

(https://www.richis-lab.de/images/transistoren/35x04.jpg)

(https://www.richis-lab.de/images/transistoren/35x05.jpg)

(https://www.richis-lab.de/images/transistoren/35x06.jpg)

The hometaxial structure is easy to see.  :-+


(https://www.richis-lab.de/images/transistoren/35x08.jpg)

Of course it´s glowing!  8) And the ITT 2N3055 has a high BE breakdown voltage (-18V) as it is typically for hometaxial transistors.


(https://www.richis-lab.de/images/transistoren/35x09.jpg)

The current density is not perfectly uniform because of a lack of solder.

 :-/O
Title: Re: Transistors - die pictures
Post by: RoGeorge on September 15, 2020, 06:43:34 am
Looks like the die of the ITT/2N3055 is not flat!   :o
Is that an optical illusion?  Is it even possible to make undulated chips?
Title: Re: Transistors - die pictures
Post by: Noopy on September 15, 2020, 06:51:31 am
That´s the hometaxial structure.

Where you want to contact the base you have to etch away the emitter diffusion. That gives you some "pretty high" steps on the die.

I have some eplaining pictures here:
http://www.richis-lab.de/2N3055_08.htm (http://www.richis-lab.de/2N3055_08.htm)
(taken from RCA transistor, thyristor & diode manual 1971)
Title: Re: Transistors - die pictures
Post by: Noopy on September 15, 2020, 07:31:54 pm

Recently I ordered a SiC-Cascode for burning it in my ofen...  >:D


(https://richis-lab.de/images/Transistoren/36x01.jpg)

A nice package for applications with higher voltages.
It also has a second source pin for more accurate gate control.


(https://richis-lab.de/images/Transistoren/36x10.jpg)

Manufacturing a SiC-J-FET is easier than a SiC-MOSFET. But for power electronics you usually want normaly off switches. Because of that UnitedSiC is building cascodes with a SiC-J-FET and a Si-MOSFET. With the Si-MOSFET we get the normal switching behaviour. Due to the SiC-J-FET the MOSFET has to carry the full current but only a small voltage.


(https://richis-lab.de/images/Transistoren/36x02.jpg)

In the package we see the two dies. The lower MOSFET-die is still in the epoxy.


(https://richis-lab.de/images/Transistoren/36x03.jpg)

The MOSFET is placed on a ceramic insulator.


(https://richis-lab.de/images/Transistoren/36x04.jpg)

The MOSFET is quite small for this big bondwires!
It was not easy to clean the die and we can´t see very much of the mosfet. It´s clearly a low voltage mosfet because there is no bigger gap between the metal layer and the edge of the die.


(https://richis-lab.de/images/Transistoren/36x06.jpg)

(https://richis-lab.de/images/Transistoren/36x11.jpg)

The SiC-FET-die is also not very spectacular, but...


(https://richis-lab.de/images/Transistoren/36x07.jpg)

(https://richis-lab.de/images/Transistoren/36x09.jpg)

It glows blue when you put current over the gate-drain-junction!  8) 1A in this picture.
The forward voltage is 3,5V which is enough for blue light.


https://richis-lab.de/FET05.htm (https://richis-lab.de/FET05.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on September 15, 2020, 08:27:02 pm
Cool!  GaN FET next? :D

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on September 15, 2020, 08:31:20 pm
GaN is already sheduled!  :-+ ;D ...but it will take some time...
I also should take a closer look at a GaAs transistor...  :-/O
Title: Re: Transistors - die pictures
Post by: exe on September 16, 2020, 09:31:10 am
FERD diode please...
Title: Re: Transistors - die pictures
Post by: Noopy on September 16, 2020, 10:16:54 am
FERD diode please...

I can put it on my list.  :-+
(I still have some of your parts left...  ;))
Title: Re: Transistors - die pictures
Post by: daqq on September 16, 2020, 12:55:00 pm
Awesome photos!

I'd love to see what's inside a Behlke module :)
Title: Re: Transistors - die pictures
Post by: Noopy on September 16, 2020, 01:04:10 pm
Thanks!  :-+ :)

The Behlke module seems a bit too big for my ofen...  ::)
Title: Re: Transistors - die pictures
Post by: exe on September 16, 2020, 06:05:03 pm
I can put it on my list.  :-+

Please do!
Title: Re: Transistors - die pictures
Post by: Noopy on September 17, 2020, 08:55:45 pm
I just did a small update of the ST Microelectronics TIP3055. I added a new (better) die picture:

(https://www.richis-lab.de/images/Transistoren/14x02.jpg)

https://www.richis-lab.de/Bipolar10.htm (https://www.richis-lab.de/Bipolar10.htm)
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on September 17, 2020, 10:17:50 pm
That looks downright good, like, a... MJE15000-something? I already forget what else has the perf emitter... [well, the BUX22 most similarly, but other than that too]

Does that one measure well, particularly in terms of switching speed?  (Have you tried, or got more to test?)

Tim
Title: Re: Transistors - die pictures
Post by: Noopy on September 18, 2020, 03:16:40 am
I have noted which transistor is using a perforated emitter in my overview:
https://www.richis-lab.de/Transistoren.htm (https://www.richis-lab.de/Transistoren.htm)
Sorry, german...  ;)

That is the:
2SC2922 (Sanken) https://www.richis-lab.de/2SC2922.htm (https://www.richis-lab.de/2SC2922.htm)
(The 2SC2922 is especially interesting because the perforation is different. Sanken is splitting the emitter in small areas.)
BD911 (ST) https://www.richis-lab.de/Bipolar12.htm (https://www.richis-lab.de/Bipolar12.htm)
BUX22 new (ST) https://www.richis-lab.de/Bipolar08.htm (https://www.richis-lab.de/Bipolar08.htm)
MJL21193 (ON) https://www.richis-lab.de/Bipolar15.htm (https://www.richis-lab.de/Bipolar15.htm)
TIP2955 (ST) https://www.richis-lab.de/Bipolar11.htm (https://www.richis-lab.de/Bipolar11.htm)
TIP3055 (ST) https://www.richis-lab.de/Bipolar10.htm (https://www.richis-lab.de/Bipolar10.htm)

I didn´t test the switching speed but the TIP3055 is one of a batch that exe gave to me to take pictures. I think he did some measurements.
exe?
Title: Re: Transistors - die pictures
Post by: exe on September 18, 2020, 09:26:59 am
I didn´t test the switching speed but the TIP3055 is one of a batch that exe gave to me to take pictures. I think he did some measurements.
exe?

I did some measurements, not sure how accurate they are. I also cannot find measurements for tip2955, showing tip3055 here. I was choosing a bjt for a power supply. I wanted the fastest one, so I bought ten or twenty different bjts and measured them I simply hooked base to a siggen (ad2), and measured collector or emitter current with 1 Ohm shunt (I forgot which configuration I used for these plots). My figure of merit was frequency at which the phase shift reaches 45 degrees.

Conditions: collector current Ic=2A, Vce ~=1V (plus 2V drop on 1ohm resistor, that's why in filename it says "3V", that's total psu output).

As one may see, the 45 phase shift happens at following frequencies:
tip3055: 47 kHz
2ta1943: ~18kHz
2sd882: 450 kHz (this transistor is much less beefy than prev two, hence the difference)

NB: Increasing Vce often helps, but I wanted to see performance when Vce is 1V and less.
Title: Re: Transistors - die pictures
Post by: T3sl4co1l on September 18, 2020, 02:33:59 pm
Hmm, do you know what h_fe was under that condition?

That should be the cutoff point, where it transitions from flat h_fe (from down to DC) to asymptotic (constant fT) behavior.  Which means fT = h_fe * Fc.

Tim
Title: Re: Transistors - die pictures
Post by: exe on September 18, 2020, 05:09:30 pm
Hmm, do you know what h_fe was under that condition?

That should be the cutoff point, where it transitions from flat h_fe (from down to DC) to asymptotic (constant fT) behavior.  Which means fT = h_fe * Fc.

Tim

Looking at plots, I kind of see it. The top plot is gain in db, and one can see it 20db/decade (very roughly). That is, when frequency increases for 10x, the gain falls by factor of 10. I attach the picture where it's more obvious. For some reason there is raise in gain at the end of slope. May be there is some sort of cross-talk. I also notice that the yellow line (base current) goes down at high frequencies. I don't know if it's a measurement artefact, or it's Miller capacitance, or something, but for some transistors it is quite high. May be I'm overdriving avg on ad2 as it can only supply 10mA. I also use jumper wires, so I expect measurements above 1MHz are inaccurate.


I can repeat measurement in a more controlled environment if one wants. I also ordered a few more transistors to see how they perform: D44H8, D45VH10G, D45H8G, D45H11G,  MJF45H11G, 2SD1060S-1E, KSE44H11, BD911, BD912,  D45H11FP and KSB772YS .
Title: Re: Transistors - die pictures
Post by: Noopy on October 06, 2020, 06:24:56 pm

I have taken a look into different *44H*-transistors.


D44H11

(https://www.richis-lab.de/images/Transistoren/37x01.jpg)

(https://www.richis-lab.de/images/Transistoren/37x02.jpg)

Decapping was a bit hot...  ::)


D44H8

(https://www.richis-lab.de/images/Transistoren/38x01.jpg)

(https://www.richis-lab.de/images/Transistoren/38x02.jpg)

It seems the D44H8 (specified for lower voltages) is the same as the D44H11. Perhaps ST does some binning and the higher quality is specified for higher voltages...


KSE44H11

(https://www.richis-lab.de/images/Transistoren/39x01.jpg)

(https://www.richis-lab.de/images/Transistoren/39x02.jpg)

On Semi (Fairchild) uses a different structure.
Don´t know why they integrated these holes in the metal layer...  :-//


(https://www.richis-lab.de/images/Transistoren/39x03.jpg)

In the KSE44H11 you can´t find a pn junction. I also wasn´t able to show some light in breakdown mode.
With a closer look at the emitter metal contact we find two steps. One is the contact to the emitter area. Perhaps the second step is the pn-junction. But why did ON hide it under the metal?   :-//


https://www.richis-lab.de/Bipolar21.htm (https://www.richis-lab.de/Bipolar21.htm)


The Transistors were donated by exe.  :-/O
Title: Re: Transistors - die pictures
Post by: exe on October 06, 2020, 09:07:24 pm
Niice, although I'm still not sure which one is better :).

Concerning the metal layer over the pn junction, Could it be to spread the heat?
Title: Re: Transistors - die pictures
Post by: Noopy on October 06, 2020, 09:13:54 pm
Concerning the metal layer over the pn junction, Could it be to spread the heat?

In my view that´s unlikely. The metal is only above the boundary of the pn-junction. Most of the junction is underneath the emitter.
Title: Re: Transistors - die pictures
Post by: Noopy on October 19, 2020, 08:05:50 pm

Do you know the 2N3553?


(https://www.richis-lab.de/images/transistoren/40x01.jpg)

RCA first sold this Power-HF-Transistor in 1966.
The 2N3553 combines a ft of 500MHz with a continous collector current of 0,33A (1A peak, 40V).


(https://www.richis-lab.de/images/transistoren/40x03.jpg)

Two bondwires for the emitter and two bondwires for the base. Probably that´s for low inductance and good current distribution.


(https://www.richis-lab.de/images/transistoren/40x04.jpg)

(https://www.richis-lab.de/images/transistoren/40x05.jpg)

The 2N3553 uses a multi emitter structure for low base resistance and fast switching.
RCA had this design patented: US3434019A


(https://www.richis-lab.de/images/transistoren/40x06e.jpg)

Lights on!  8)
Breakdown of the base-emitter-junction occurs at -6,5V (datasheet: -4V).
The light is quite uniform. In normal conduction mode an even current distribution is very important. Otherwise a high current in one transistor could cause thermal runaway.
But there is one transistor (center, left side) in which you can see only a line. There has to be an imperfection.  :-/O


More pictures here:
https://www.richis-lab.de/Bipolar22.htm (https://www.richis-lab.de/Bipolar22.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: Noopy on October 23, 2020, 09:47:35 pm
(https://www.richis-lab.de/images/transistoren/41x01.jpg)

Westinghouse 156-043, that´s an old power ransistor!
(40V 15A)


(https://www.richis-lab.de/images/transistoren/41x03.jpg)

That´s an interesting potting. It seem´s to be clear with some brownish stuff added in the area of the die...  :-//


(https://www.richis-lab.de/images/transistoren/41x04.jpg)

(https://www.richis-lab.de/images/transistoren/41x05.jpg)

A hometaxial transistor.  :-+


(https://www.richis-lab.de/images/transistoren/41x06f.jpg)

Base-Emitter-Breakdown!  ;D (1,5A)
It seems that the structures are quite inhomogeneous. The right side of the die shows almost no light.


More pictures here:
https://www.richis-lab.de/Bipolar23.htm (https://www.richis-lab.de/Bipolar23.htm)

 :-/O
Title: Re: Transistors - die pictures
Post by: exe on October 24, 2020, 09:56:27 am
That's another brand I've never heard of. Looking in up in wikipedia, it seems they were quite big back in the day, until dissolved in other companies.
Title: Re: Transistors - die pictures
Post by: Noopy on October 24, 2020, 10:52:44 am
Westinghouse is known for old big generators, all kind of old power distribution, nuclear reactors and much more.
But till this one I haven´t seen a Westinghouse transistor too.  8)
Title: Re: Transistors - die pictures
Post by: Noopy on October 28, 2020, 01:35:21 pm
Let´s look at a big darlington built in the "Gleichrichterwerk Stahnsdorf": SU510


(https://richis-lab.de/images/transistoren/42x01.jpg)

800V / 30A / 250W


(https://richis-lab.de/images/transistoren/42x03.jpg)

Without screws you can simply slide out the top cover.


(https://richis-lab.de/images/transistoren/42x07.jpg)

Under the black case there is a white silicone similar to "normal" silicone protecting the semiconductors.
On the bottom there is a thin black layer. I assume the black layer just had to hold the case during assembly and applying the white potting.
On top there is a brownish hard potting. Obviously this material protects the silicone since the top of the case is virtually open.


(https://richis-lab.de/images/transistoren/42x09.jpg)

Cutting the metal sheet contacts you can remove the brown part. The silicone potting had to be removed with patience. On thin layers silicone remover can help.


(https://richis-lab.de/images/transistoren/42x11.jpg)

In the package there are four Darlington-Dies and a large freewheeling diode. Two small diodes are connected in parallel to the base emitter junction of the driver transistor for faster switch off.


(https://richis-lab.de/images/transistoren/42x12.jpg)

The small diodes own only small structures at the edges because they don´t have to withstand high voltages.


(https://richis-lab.de/images/transistoren/42x13.jpg)

(https://richis-lab.de/images/transistoren/42x15.jpg)

The darlington transistor die is quite interesting. In the upper area there is the driver transistor. In the lower area there is the power transistor. Between these transistors they etched a trench. I wonder what exactly is the purpose of this trench. It somehow has to isolate the two transistors.
In the middle of the die you can see the resistor connected between base and emitter of the power transistor.


(https://richis-lab.de/images/transistoren/42x18.jpg)

The freewheeling diode has to withstand the full voltage and because of that has etched edges to reduce leakage current.


More pictures here:

https://richis-lab.de/Bipolar24.htm (https://richis-lab.de/Bipolar24.htm)

 :-/O
Title: Re: Transistors - die pictures
Post by: Noopy on November 01, 2020, 06:02:30 pm

(https://www.richis-lab.de/images/Transistoren/43x01.jpg)

I took a closer look into a Westinghouse 1561-0403 (50V/15A). I wanted to see how similar it is to the 156-043 (40V/15A).


(https://www.richis-lab.de/images/transistoren/43x02.jpg)

The 1561-0403 also has this yellow-brown potting but here it is more homogenous.
And Westinghouse used some years after the 156-043 a smaller die although the 1561-0403 can withstand higher voltages. Interesting...


(https://www.richis-lab.de/images/Transistoren/43x05.jpg)

The base-emitter breakdown is also very inhomogenous (1A).


https://www.richis-lab.de/Bipolar25.htm (https://www.richis-lab.de/Bipolar25.htm)

 :-/O
Title: Re: Transistors - die pictures
Post by: Noopy on November 06, 2020, 10:46:10 pm
(https://www.richis-lab.de/images/transistoren/44x01.jpg)

Have you ever heard of Greaves?  :-//


(https://www.richis-lab.de/images/transistoren/44x02.jpg)

We find a small modern die in the package.


(https://www.richis-lab.de/images/transistoren/44x04.jpg)

The transistor is shorted between collector and emitter.


(https://www.richis-lab.de/images/transistoren/44x06.jpg)

But hey, the base-emitter-junction is good enough for some light (1A)!  ;D


https://www.richis-lab.de/2N3055_12.htm (https://www.richis-lab.de/2N3055_12.htm)

 :-/O
Title: Re: Transistors - die pictures
Post by: Noopy on November 17, 2020, 12:53:25 pm
Today I have a IGBT for you: IXYS IXGH48N60C3D1


(https://www.richis-lab.de/images/transistoren/45x01.jpg)

(https://www.richis-lab.de/images/transistoren/45x02.jpg)

Different packages but same internal construction / dies.


(https://www.richis-lab.de/images/transistoren/45x03.jpg)

On the left we see the IGBT. On the right we see the freewheeling diode.


(https://www.richis-lab.de/images/transistoren/45x04.jpg)

(https://www.richis-lab.de/images/transistoren/45x05.jpg)

The IGBT is 7,2mm x 6,1mm


(https://www.richis-lab.de/images/transistoren/45x07.jpg)

Potential steering to manage the high voltage.


(https://www.richis-lab.de/images/transistoren/45x08.jpg)

In the gap between the two metal areas you can spot the traces conducting the gate current under the emitter area.


(https://www.richis-lab.de/images/transistoren/45x10.jpg)

The freewheeling diode is 6,6mm x 4,2mm.


(https://www.richis-lab.de/images/transistoren/45x11.jpg)

Probably there is also potential steering but they have put some black stuff on this area.


https://www.richis-lab.de/Bipolar26.htm (https://www.richis-lab.de/Bipolar26.htm)


By the way I have done some sorting:
Here you can find the bipolar silicon transistors: https://www.richis-lab.de/Transistoren.htm (https://www.richis-lab.de/Transistoren.htm)
Here you can find the bipolar germanium transistors: https://www.richis-lab.de/Transistoren_Ge.htm (https://www.richis-lab.de/Transistoren_Ge.htm)
Here you can find the FETs: https://www.richis-lab.de/Transistoren_FET.htm (https://www.richis-lab.de/Transistoren_FET.htm)

 :popcorn:
Title: Re: Transistors - die pictures
Post by: exe on November 20, 2020, 12:29:52 pm
Wow, those igbt and diode are quite large.
Title: Re: Transistors - die pictures
Post by: Miyuki on November 20, 2020, 12:59:06 pm
Wow, those igbt and diode are quite large.
It must be huge when
IC25 TC = 25°C (Limited by Leads) 75 A

So bond wires are weaker than die itself  >:D
Title: Re: Transistors - die pictures
Post by: Noopy on November 20, 2020, 07:09:25 pm
Wow, those igbt and diode are quite large.
It must be huge when
IC25 TC = 25°C (Limited by Leads) 75 A

So bond wires are weaker than die itself  >:D

Oh yes, current needs silicon area!  :-+ 8)


Let´s take a look at an older transistor again:


(https://www.richis-lab.de/images/Transistoren/46x01.jpg)

Siemens AD148, a Ge-PNP-transistor: 26V, 3,5A, 0,45MHz


(https://www.richis-lab.de/images/Transistoren/46x02.jpg)

I assume this white powder absorbs humidity.


(https://www.richis-lab.de/images/Transistoren/46x04.jpg)

That´s an interesting colour...  :o ;D 8)
Siemens used one plate for base and emitter connection which is cut after production. We have seen that in the Siemens 2N3055 too: https://www.richis-lab.de/2N3055_01.htm (https://www.richis-lab.de/2N3055_01.htm)


(https://www.richis-lab.de/images/Transistoren/46x05.jpg)

(https://www.richis-lab.de/images/Transistoren/46x06.jpg)

Here you can see the ring electrode connecting the Ge-plate acting as base.
The whole transistor is placed on a socket.
On top of the base you can spot a edged pit with some plating. I assume that´s indium to form the emitter.
The emitter is connected with something like tin.


https://www.richis-lab.de/Bipolar27.htm (https://www.richis-lab.de/Bipolar27.htm)


 :-/O
Title: Re: Transistors - die pictures
Post by: SilverSolder on November 20, 2020, 08:27:31 pm

Some of these pictures are quite beautiful and wouldn't look out of place at an art exhibition, LOL!  :D
Title: Re: Transistors - die pictures
Post by: Noopy on November 21, 2020, 06:08:29 am

Some of these pictures are quite beautiful and wouldn't look out of place at an art exhibition, LOL!  :D

Thanks!  8)
Till know I only have a calender: https://www.meinbildkalender.de/richis-lab (https://www.meinbildkalender.de/richis-lab)
Next "merchandise project" is a LTZ1000 coffee pot.  :D
Title: Re: Transistors - die pictures
Post by: floobydust on November 21, 2020, 07:32:32 am
Apparently tin whiskers are a problem with old germanium transistors, causing short circuits.
NASA failure analysis of vintage radio transistors OC170 and AF114: https://nepp.nasa.gov/whisker/anecdote/af114-transistor/2005-Brusse-tin-whiskers-AF114-transistors.pdf (https://nepp.nasa.gov/whisker/anecdote/af114-transistor/2005-Brusse-tin-whiskers-AF114-transistors.pdf)
Title: Re: Transistors - die pictures
Post by: Noopy on November 21, 2020, 08:27:02 am
Thanks for the hint!   :-+
I will take a closer look at the next germanium transistor. Would be nice to take pictures of some whiskers!  :-/O