On charge sensors for FIB attack detection

Abstract

A new sensor of Focused Ion Beam (FIB) attacks on security sensitive ICs is presented. The function is based on the FIB navigation process mandatory for FIB attacks, which covers a wide chip area, but deposits only a low charge density. Detecting this very low charge with extremely sensitive local charge sensors allows a loose distribution over the IC. The performance requirements of the charge sensors are specified. A new circuit design is presented capable of storing the information about FIB attacks permanently inside the circuit even while the chip remains unpowered. The circuits are realized on silicon level and characterized in depth. The necessary sensitivity is verified.