EEVblog #992 - Olympus BHM Wafer Inspection Microscope

[Zom-B]

I've been using a multi ten-thousand dollar Carl Zeiss metallurgical microscope at work (inspection, photographing and fibbing preparations) and it has 5/10/20/50/100x optics. At 100x you're very close to the wavelength of light, and modern chips with features <500nm get inherently blurry and the only thing that works beyond that is electron microscopy. We almost never use 100x because with 50x you see about the same amount of details, and DOF is better.

The cool thing is, I was assigned to programming the XYZ stage control and camera capture for automated photographing and stitching of entire chips.

Here's a MEMS microphone from an old cellphone:



Pentium II Klamath (350nm process, 1997 (Ehm wow! 20yo)): (Maximum optical detail, DOF animation)

[S13]

those are some nice looking images!
Very interesting to see the MEMS with so much detail.
I own an old Olympus E series microscope, primarily for biological purposes, so ive never been able to view a silicon die up close this nicely.


To Dave: Swapping out the light bulb is probably the best thing you could have done anyway, broken or not. The crappy standard light bulbs are expensive to replace, dont have very accurate color representation and they warm up badly over time. So perhaps your courier did you a favor in this regard
The warming up from the light bulb is especially annoying if you are camera capturing a screen over a longer period of time, for instance when doing time lapses. The slow building heat from the bulb causes the frame of the microscope to warp excessively, making your picture go out of focus over time. When using a LED this problem is virtually eliminated.   

[FloFo]

Hi Dave,

after watching your latest videos on eevblog2, i think the tension adjustment for the coarse focus is set too low (resulting in the focus drift). Additionally, the too low table can be caused by a stage hight locking feature (could have been used by the previous owner to prevent someone crushing a lens into a sample).
How to use/adjust these features is shown on page 15 (or 16 by pdf numbering) of this BHM manual.

If you want to calibrate the magnification, you can get cheap stage micrometers for approx. 10-20 bucks on ebay (or sometimes amazon). Be shure to get one with 0,01mm divisions (there are some with only 0,1mm for stereoscopic microscopes).

Regarding your sloppy table, this seems not normal. Often there is some kind of friction adjustment on the coaxial knobs on the table, but i don't know olympus construction. With a good adjusted table, you can easily adjust samples with a 100 times lens with some practice, while being able to move larger distances quite fast if necessary

[EEVblog]

If you want to calibrate the magnification, you can get cheap stage micrometers for approx. 10-20 bucks on ebay (or sometimes amazon). Be shure to get one with 0,01mm divisions (there are some with only 0,1mm for stereoscopic microscopes).

Done:

[FloFo]

Magnification, not z-Scale
A Stage micrometer is a slide with a micrometer scale (e.g. this one on ebay) wich is used to calibrate the magnification of every lens (espacially with a camera, but sometimes also with eyepices with an integrated scale). The Magnification printed on the lens itself is not exactly but rounded to nominal values, e.g. i have a Zeiss 100x lens which i measured at 103,9x and a 63x measured at 64,1x. Additionally, camera adapters often have magnification (with rounding to nice values) too, and if you use the zoom of your camera, you can only guesstimate your magnification unless you do such a calibration.

[Fungus]

 

[Brumby]

Yeah .... I noticed that too.  That was obscene. (No other word for it.)

I had the same reaction.

[amspire]

I think I will have to add a micrometer to my microscope - looks like a great idea.

I think 0.01mm is enough resolution for my needs, so I am going for one of these:

https://www.aliexpress.com/item/Brand-New-Car-Tyre-Digital-Tread-Brake-Pad-Shoe-Gauge-Depth-Tester-Guage-Black-H7/32803113797.html

Only cost about $5.

I probably have to add a spring to push the tip downwards, but this kind of calliper sensor does usually have an internal digital output (a 24 bit easy-to-decode packet).

[S13]

After seeing the cleaning and servicing video im wondering if the horrible shakiness of the table is caused by the unstable stack of post-it notes between the XY-table and the wafer? Because normally, these olympus microscopes are rock stable thanks to their heavy solid metal frame.

Ideally you want your sample (the wafer) to be pinned down firmly on the XY-table. Please give that a try!

Glass slide preparations, as used for biological samples for example, are pinned down on the XY table by a spring loaded lever, and doing so myself ive never encountered the horrible shakiness that im seeing in the video. 

[FloFo]

Part of the problem ist the "havy" camera at a high point, connected only through the "thin" back of the microscope. I assume the effekt will be much better if you remove the camera and watch it through the eyepiece. This arrangement can work as a nice acoustic antena
I often work with samples just lying losely on the stage (but without PostIts) at magnifications up to 630x (63x times lens, 10 times eyepices) without any problems, using a Zeiss Axioplan on an table with a 20cm granite top (that's overkill, we just happend to have this one left over from something more sensitive). I think the main culprit is the table itself though, a microscope table should be very rigid and heavy (40mm particle board on a steel frame) and the legs should be properly adjusted to prevent wobbling.

Regarding you current source for the LED: good choise to use a linear regulator, with LEDs you can get problems with interference between shutter speed and switching frequencys. If you plan to implement a dimmer, try to avoid PWM for this reason

[jonovid]

the other microscope video by EEVblog #992 (Part 2) - How To Clean & Service A Microscope 


the other Microscope video by David and Dave -audio input . got to love the LED light bodge Job.  it's a hobbyist classic
is to avoid any one off pcb fabrication and just hot glue it. Hot Snot it!   
also IMO
it just goes to show why, a good consumer 3D printing service is useful for that one off 3D printing job.  no everyone needs a 3D printer at home.
 

[bktemp]

Does the LED current source actually work with the LED attached?
A white LED needs 3-3.3V. Using 5V from USB gives 1.5-2V for the current source. 1.25V are lost on the current sense resistor. So we have 0.25-0.75V available for the LM317 to work with.
I doubt it is able to reach the full current with this low voltage available. The datasheet recommends at least 3V input-output differential (most LM317 work fine down to at least 2V at lower currents).
In the video David only measured the current by shorting the output of the current source directly to GND (so with almost no voltage drop instead of the 3V for the LED).
A simple 5.6 ohms 1W resistor would probably be a better and even cheaper solution.

[jonovid]

too late to move EEVblog #992 (Part 2) post, to its own thread.

[mmagin]

A bit of bubblewrap around some equipment and the rest of the box filled with (or not quite) with packing peanuts is my least favorite experience with far too many ebay sellers.  It bums me out even if I'm getting something that's not functional to have it needlessly beat up in shipment.  A couple extra layers of bubble wrap taped around securely and some packing that doesn't migrate around as much as peanuts (like crumpled newsprint paper) isn't any more expensive but works so much better.

[mrpackethead]

Any chance you want to do a cleaning of a Mantis.. I'm sure mine is pretty dirty, but i'm not sure how to attack it.

Also, related.. can you take photos of what you can see in a mantis..  I've tryed, but just cant it to work.

[SeanB]

With cleaning glass it really is a case of "it depends" as to what you use. In general most optical glass will have a coating of one or more antireflective or filtering material on the surface, and these can be affected by many things, water included. Bare glass not so much, but those coatings are proprietary per lens manufacturer, and vary a lot. So, best is to start with the things that are least likely to damage, like a clean lint free absolutely dry cloth used to pat the surface ( not a wipe, as this will leave scratches) clean of dust.  then you can use distilled water, using another clean microfibre cloth as a wash. Alcohol ( 20% ethanol in water, also called 40 proof cane spirit, not Vodka or anything else, only the clear tasteless stuff ( Mainstay, Mainstay as a brand here) from a nip bottle still sealed) is the next, as it leaves no film, as the base ethanol is 99.6% ultra pure, and the water for blending is first DI and then RO filtered. This may affect some AR films, so the low alcohol content is good.

Do not use any stronger solvents, as many AR films are organic acids that dissolve or react with them. With many lenses you will also need to do the most horrid thing you can think of, and dismantle the lens out of the housing, so that you can take the lens and use a very destructive cleaning on it to kill fungus that has colonised the AR coating and is using it as food. With that your only choice is to strip the layer off, or kill the fungus with either bleach or peroxide, which can further damage the film. When doing the fungal kill, take the housing ( remove all the glass and other parts) and put the aluminium parts in a glass high temperature container, and boil on a stove to kill the spores in the pores of the metal. Plastic you have to chance the peroxide, and with compound lenses you also have a risk of the optical epoxy that glues them together being attacked, so you will need to contact the manufacturer as to which one they used, and if you can buy a lens off them if available. Otherwise you will have to dissolve the epoxy, split the lenses and clean them ( AR coating is pretty much going to be toast here) in strong solvents like MEK, and use some optically clear UV cure resin to put the kit back together. Will never be the same, but better to have at least clear glass as opposed to a growing fungal film that eats the other lenses.

[German_EE]

OK, David's first video:

8/10 for presentation skills, you're obviously treading in the steps of the master 

5/10 for editing technique. The constant editing especially at the beginning was really annoying and at one point we saw four edits in six seconds. That's way too much.

Having said that, David is a lot better in front of a camera than I will ever be and this is a great start. Well done!

[richnormand]

I have a similar setup Reichert microscope.
What I find very useful to examine wafers and ICs is two high quality polarisers.

One is inserted at the light source (you seem to have a place to insert filters as shown in the video).
The other one is in the light return path from the sample. Either one should be rotatable.
Close to 90 degrees it will greatly enhance any defect and change in surface contact.

[smashIt]

Just a few tipps from a fellow olympus-owner:

If you need any documentation for your microscope take a look at http://alanwood.net/photography/olympus/microscopes.html
He has collected a ton of manuals and even service-manuals.

Regarding a plan objective (and the "Plan" realy makes a difference at low magnifications)
There is one up on ebay at the moment:
http://www.ebay.at/itm/201931201422?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Alternatively you can convert your microscope to the current UIS2-system.
All you need is a little piece of aluminium (see attached picture).
With this you can mount UIS components onto your microscope.
But you have to stay in one system (all UIS or all 160mm).

[etelmo]

Did you regrease your microscope after you cleaned it?

Given the magnification some lash and play is to be expected (and vibration will be easily noticed) however it would be exacerbated if all of the old grease was removed in cleaning and none was reapplied. I don't know what product would be specified by Olympus however a tiny amount of NyoGel 774H (heavy) or 774VH (very heavy) on the rack would probably help, it's a pretty generic damping grease.

If someone knows the correct grease (does it need an extra heavy grade? or perhaps this type is designed for none at all?) it would be interesting to find out.