Multilevel States of Nano-Electromechanical Switch for a PUF-Based Security Device

A nano-electromechanical (NEM) switch using multilevel states based on the high security physical unclonable function (PUF) is proposed and experimentally demonstrated. Using the asymmetric random stiction of a silicon nanowire (SiNW), the conventional binary state is simply expanded to a quaternary-state encryption key without increasing chip area. The multiple states are determined by the asymmetrically bent direction and stiction of the SiNW. The experimental results show that the fabricated NEM-PUF with multistates retains unique, random, and robust characteristics, while the key capacity is doubled, even with the same array size footprint.