Mastodawn

There are three obvious memory array types on the die, with I think the fourth one hiding near the centre. The largest one is likely to be the programmable memory.

They decided to protect the second-largest one with a security mesh. Note the pattern is a very peculiar one; very much like ST with their own mesh type, this must belong to a particular manufacturer. Most certainly I have seen this one before on several occasions, but there is no concrete evidence to pin this one on Samsung or another company.

Would it not be nice to have an image database where one could annotate images by their features such as this...

One more reason I think this is Samsung is due to the design of their I/O pads. Two examples to compare; certainly not an exact match but similarities abound.

Taking a peek at the sea of gates now, it is not immediately apparent whether it will be possible to image them optically with a resolution high enough to know exactly which gate does what. The two metal layers, counted from the top, are used for global routing, orthogonal to each other. The metal-1 layer is again used for local interconnect to form the cells and distribute power in each row.

One more interesting feature of the die is this. Two blocks of 10x4 on top metal with no visible connections to anything else. It is very tempting to interpret this pattern as binary. What does it mean? I have no idea. I can only make a guess this identifies the design. If anyone has any information on this, please let me know.

All in all, this looks like a good candidate for deprocessing. I hope not to lose this sample like the others, as it's the only one I have at this moment.

Related, there is one more mystery here, which concerns the damage done to the metal layers of this die. Here I can clearly see the intact metal3 in the power distribution routing in the bottom left corner of the snippet, which is bright yellow like elsewhere on the die. This then transitions to green, the abrupt transition typically means the metal there was etched away by something -- probably the remains of whatever I used to decap this. Going up further though, I see green turning into pale yellow colour, very similar to metal2. The other snippet also shows a similar story, with metal3 being removed leaving some green residue, which is also removed afterwards leaving transparent oxide with some junk inside.

I would so, so much like to know a) what is this green lining? some kind of nitride? and b) what reaction caused it to be stripped. This could be so much useful in deprocessing.

With that, I think I will wrap it for this time. Thank you for following along, I hope you enjoyed exploring this creation.

As always, I am happy to accept any donations to #nakeddiefriday whether in samples or in cash to mitigate the supplies costs. Please get in touch if you want to support my work.

I wish you a nice and calm end of the week. See you next Friday!