Secure chips are in permanent risk of attacks.
Physical attacks usually start removing part of the package and
accessing the dice by different means: laser shots, electrical or
electromagnetic probes, etc. Doing this from the backside of
the chip gives some advantages since no metal layers interfere
between the hacker and the signals of interest. The bulk silicon is
thinned from hundreds to some tens of micrometers in order to
improve the performance of the attack. In this paper a backside
polishing detector is presented that is sensitive to the thickness
of the bulk silicon existing below the transistors, a numerical
signature is generated which is related to this. The detector
implements built-in self-surveillance techniques which protect it
from being tampered.Postprint (published version
