Phase Change Memory for Physical Unclonable Functions

Abstract

Security has become a crucial concern in hardware design due to the growing need for protection in everyday financial transactions and exchanges of private information. Physical unclonable functions (PUFs) utilize the inevitable manufacturing process variations to provide a unique way to verify trusted users. Improvements in attack methods over the years have recently moved the field of PUFs from traditional silicon devices toward emerging nonvolatile resistive switching memories. Due to the intrinsic programming variability in resistive switching memory mechanisms, together with the high endurance of these devices, unpredictable and reconfigurable PUF challenge-response pairs can be achieved for a very large number of times. In the case of phase change memories (PCMs), cell-to-cell and cycle-to-cycle programming variability is the result of the random atomic structures created after the rapid quench from melt during the reset programming and the stochastic distribution and orientation of seed crystals nucleated in an amorphous plug during the set operation. This programming variability, which comes in addition to the process variations present in any technology, is an important advantage of PCM (and other resistive switching memory technologies) for implementations of PUFs and other hardware security primitives. In this chapter, we review some of the work on conventional CMOS-based PUFs, the operation principles of PCM devices, and recent reports on PCM-based PUFs that utilize programming variability.