A Physically Unclonable Function with 0% BER Using Soft Oxide Breakdown in 40nm CMOS
Kai-Hsin Chuang, E. Bury, R. Degraeve, B. Kaczer, Dimitri Linien, Ingrid M.R. Verbauwhede · 2018
A physically unclonable function (PUF) utilizing the randomness of soft oxide breakdown (BD) locations in MOSFETs is presented. The so-called soft-BD PUF features a self-limiting mechanism to generate one single soft-BD spot in a pair of MOSFETs; the subsequent BD location is used as the source of entropy to generate a highly stable "0" or "1" bit with an equal probability of 0.5. The soft-BD PUF comprising all the essential periphery circuits are fabricated in a 40nm CMOS process. Experiments show that the PUF has no instability in most of the operating conditions using the proposed readout scheme. The native bit error rate remains zero from VDD=0.8 V to 1.5 V at room temperature and from -20°C to 120°C at nominal VDD=0.9 V. The throughput is shown to be at least 40 Mb/s and the PUF readout consumes only 51.8 fJ/bit. The randomness and uniqueness of the PUF are close to an ideal case, and no spatial correlation was observed.