[Cryptography] Revealing data from RAM using acid and microscopes

[Oscar Pacey]

Dear all, I have heard a rumour that it is possible to reveal the digital secrets contained within memory chips by 'decapitating' them with nitric acid to reveal the conductors and then finding the sneaky electrons with an electron-scanning microscope. The rumour even says such a reading could be achieved on RAM chips. My instincts tell me this isn't possible, volatile ram of course loses all trace of its memory when power is cut, surely?

My research tells me that it is in fact possible to use this technique to read ROM where physical fuses have been intentionally blown in order to modify the circuit permanently. Some ICs designed with a warp and weft grid of conductors programmed by creating touch points between the layers which then act as transistors - and can be viewed using normal (light) microscopes.

The question is, are there ANY physical properties of RAM (DRAM or others) that would make such an attack possible when the RAM is disconnected/no longer powered?

opacey