Bunnie Huang released an interesting post recently which shows a new way to look into chips without the usual hassle of having to remove, dissolve or grind them down.

The concept is really simple. You modify a digital camera, removing the IR filter, then you shine a 1050nm IR light into the chip. Since silicon is transparent to IR light, it seems to bounce up from the board and you can peer directly inside to inspect them.

https://www.bunniestudios.com/blog/?p=6712
https://www.youtube.com/watch?v=kfsVb0pEayU