Nano-electromechanical switch based on a physical unclonable function for highly robust and stable performance in harsh environments

Abstract

A physical unclonable function (PUF) device using a nano-electro mechanical (NEM) switch was demonstrated. The most important feature of the NEM switch based PUF is its use of stiction. Stiction is one of the chronic problems associated with micro- and nano-electro mechanical system (MEMS/NEMS) devices, however, here it was utilized to intentionally implement a PUF for hardware based security. The stiction is caused by capillary and van der Waals forces, producing strong adhesion, which can be utilized to design a highly robust and stable PUF. The probability that stiction will occur on either of two gates in the NEM switch is the same, and consequently the occurrence of the stiction is random and unique, which is critical to its PUF performance. This uniqueness was evaluated by measuring the inter-chip Hamming distance (inter-chip HD) which characterizes how different responses are made when the same challenge is applied. Uni-formity was also evaluated by the proportion of ‘1’ or ‘0’ in the response bit-string. The reliability of the pro-posed PUF device was assessed by stress tests under harsh environments such as high temperature, high dose radiation, and microwaves