Contact-to-Silicide Probing Attacks on Integrated Circuits and Countermeasures
Ana Covic, Qihang Shi, Haoting Shen, Domenic J. Forte · 2019
Sensitive data contained and processed in integrated circuits (ICs), such as secret keys and encrypted firmware, can be extracted with focused ion beam (FIB) based probing attacks. Due to the unprotected structure on the backside of the die, the threat of backside probing attacks is particularly grim. In this study, we develop a quantitative model for backside probing attacks and apply it to three latest technology nodes 7, 10 and 14 nm with 3, 5, 8 and 10 FIB aspect ratios. The probed opening is modeled to have shape of conical frustum, which allows FIB beam diameter, in range of 10nm to 33.3nm, to produce the opening with diameter in range of 22nm to 57.3nm. We also propose a novel backside shield design structure with an estimated 16% area overhead that terminates the die operations as a result of probing to prevent malicious data extraction. Proposed backside countermeasure increases the complexity of the attack performed on protected die.