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Decapping and Chip-Documentation - Howto

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Noopy:
10x should almost be enough for my 60D. But with a little more I can be sure that the magnification factor isn't the bottleneck.


Pictures with 100mm<=>10mm(r) show a similar "quality" than pictures with "distance"<=>10mm(r).

The resolution of the 100mm<=>10mm(r) seems to be a little better

BUT I have problems with the overall sharpness of the pictures. I have to do some more tests to check if it's a alignment problem or a lens problem or a handling problem.
The lower magnification makes it more difficult to find the focus.

magic:
If one or two opposite sides are out of focus - that's alignment.
If all sides are soft but the center is sharp - that's the lenses not working very well together.

I have seen a mix of both effects on my PowerShot with webcam lens. Mostly the former, because small size and a rather amateur construction made it very difficult to align everything.

I used AF to fine-tune focus after it was roughly adjusted by tweaking distance.

magic:
If anyone ever wondered what a SO8 package looks like inside, I found some old pictures from my experiments with blueskull's acid + saltpeter formula.

I'm not sure if I was supposed to make a saturated solution of saltpeter in acid or mix a saturated solution of saltpeter in water with acid; maybe the latter would have eliminated crystallization of salts on the chip and sped up the process, but dunno about corrosion OTOH.

Anyway, the junk covering the die on the first picture is just some salt from the process, nothing that came from the factory ;)
The next two pictures were taken after cleanup and some mechanical separation.

Noopy:


I have bought Armour Etch!  :scared: :scared: :scared:
I wanted to strip the metal layers of a ADR1000 and because of that I had to remove the SiO2. Unfortunately you need HF to remove SiO2 and HF is scary as shit. It´s corrosive, it´s toxic, in lower concentrations you don´t recognise it on your skin but it travels very fast in deeper regions of your body. Some gloves are no protection. => You don´t want to mess around with HF.
Armour Etch is a paste with ammonium bifluoride that generates HF. That´s also dangerous but you don´t have to handle large quantities of HF.






Here you see the die before etching. There are two metal layers.




Some Armour Etch on the die.  :-/O




After 6 minutes of HF you can spot some changes at the sides of the upper metal lanes.




5 minutes of 18% HCL dissolves the upper metal layer completely and removes a lot of the lower metal layer too. The SiO2 on top of the lower metal layer is still intact but the HCL takes it´s way through the SiO2 corridors. In the inner circle there is a small part of the metal left.
Where the upper metal layer is dissolved you can see the leftovers of the SiO2. Where the lower metal layer is dissolved you can see the SiO2 corridors.




6 more minutes of HF dissolves the SiO2 on top of the lower metal layer / the empty corridors. The metal leftover is still intact because the HF doesn´t dissolve the metal (Al).
The dark particles look like leftovers of the SiO2.




5 more minutes of HCL remove the metal completely.
There is still a non transparent yellowish layer where the lower metal was. HCL can´t dissolve the yellow layer. I assume that is a SiAl-complex.








More HF and you get rid of the yellow layer and the dark particles.
Unfortunately on this die the layers don´t show the nice colors we have seen with other dies. Nevertheless you can spot the different areas and conclude how the areas interact with each other.
Now you can do some analysis: https://www.eevblog.com/forum/metrology/lowest-drift-lowest-noise-voltage-reference/msg3733504/#msg3733504








before and after the treatment  8)


https://www.richis-lab.de/Howto_Decap_HF.htm

 :-/O

magic:
Looks good.

At one point I tried NaOH solution (less toxic and attacks both glass and aluminium) but it was unusably slow. Boiling should help because everybody says that hot NaOH eats laboratory glassware, but I didn't try.
NaOH is fairly effective against aluminium spills from overheating (a matter of minutes).


--- Quote from: Noopy on October 07, 2021, 08:30:21 am ---Unfortunately on this die the layers don´t show the nice colors we have seen with other dies.

--- End quote ---
Yep, because it was the glass :)

There are some tricks to stain doped areas, but it looks like nasty stuff.
https://siliconpr0n.org/wiki/doku.php?id=delayer:wet#staining

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