Decapping and Chip-Documentation - Howto

[Noopy]

Stripping everything is not too hard. And if it should be as clean as possible just keep it longer in HF (Armour Etch). The silicon etch rate of HF is very low.

...that looks like a darkfield picture...
I should try darkfield illumination next time I strip the metal layer. It could be that darkfield is better for completely stripped parts where you usually don´t have any more resonances / colors left.

[iMo]

So he etched off all the metal layers there, not only the top mesh..
My first thought was he etched off only the top mesh..
..got it..

[Noopy]

Well there is no real high resolution picture but to me it looks like he stripped everything like I did that a few times.

As far as I know there is nobody in the hobbyist area who can do a clean delayering from layer to layer.

Ken Shirriff has some nice pictures of different layers of a Pentium CPU (https://www.righto.com/2025/01/pentium-reverse-engineering-bicmos.html). I talked to him. As everybody he is not able to strip one layer after the other over the entire die. He "just" grinded one area. That is possible, sometimes you are lucky and you get the layer you want in this area and sometimes you are less lucky and you get a mixture (of course it also depends on your experience).

[iMo]

..ion etcher.. 

[Noopy]

...would be nice...  ...with some chemicals and the right equipment for them. 

[Noopy]

For reflected light microscopes you usually use special objectives (right). Olympus marks these objectives with an M (“metallurgical”). The more common “biological” objectives (left) are designed to be used with a coverglass. Metallurgical lenses, on the other hand, give you the best pictures without a coverglass. With small numerical apertures, but the influence of the coverglass is negligible. However, there is another important difference between the two lens types. The lenses in metallurgical objectives are usually additionally coated so that they reflect less light. This is very important for coaxial illumination, where the illumination of the object follows the same path as the light reflected from the object.

The two lenses above are broadly comparable. They differ only minimally in terms of their magnification and numerical aperture. Both lenses are the revised U variants.




For comparison, the same black plastic surface was photographed with both lenses. The white balance was fixed, only a small adjustment of the exposure time was made. The images have not been post-processed. The biological lens clearly shows a bright spot in the inner area. The shorter wavelengths are more noticeable. The metallurgical objective, on the other hand, shows no weaknesses.




The weaknesses are not overly noticeable on a detailed picture.




The difference becomes somewhat clearer if the color information of the images is discarded and the contrast is greatly increased.




Due to the different numerical aperture, it is difficult to compare the resolution of the objectives. However, the image quality of the metallurgical objective appears better than one would expect due to the slightly higher numerical aperture.


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

 

[RoGeorge]

This video popped into subscribed videos list, a microscopy technique similar with focus stacking, but for diffraction.  It allows an increase of optical resolution, and also to recover not only the amplitude, but also the phase of light, though the result is a monochrome picture.  Not sure if this will work for through-lens illumination, but adding the link here just for the docs.

Dramatically improve microscope resolution with an LED array and Fourier Ptychography
Applied Science
https://youtube.com/watch?v=9KJLWwbs_cQ