Experimental Characterization of Physical Unclonable Function Based on 1 kb Resistive Random Access Memory Arrays

In this letter, we propose a reliable design of physical unclonable function (PUF) exploiting resistive random access memory (RRAM). Unlike the conventional silicon PUFs based on manufacturing process variation, the randomness of RRAM PUF comes from the stochastic switching mechanism and intrinsic variability of the RRAM devices. RRAM PUF's characteristics, such as uniqueness and reliability, are evaluated on 1 kb HfO₂-based 1-transistor-1-resistor (1T1R) arrays. Our experimental results show that the selection of the reference current significantly affects the uniqueness. More dummy cells to generate the reference can improve the uniqueness of RRAM. The reliability of RRAM PUF is determined by the RRAM data retention. A new design is proposed where the sum of the readout currents of multiple RRAM cells is used for generating one response bit, which statistically minimizes the risk of early lifetime failure. The experimental results show that with eight cells per bit, the retention time is more than 50 h at 150 °C or equivalently 10 years at 69 °C. This experimental work demonstrates that RRAM PUF is a viable technology for hardware security primitive with inter-Hamming distance 49.8% and intra-Hamming distance 0%.