Investigation of Physically Unclonable Functions Using Flash Memory for Integrated Circuit Authentication

Flash memory devices are investigated to confirm their application as physically unclonable functions (PUFs). Inherent fluctuations in the characteristics of flash memory devices, even with identical fabrication processes, produce different outputs, which are useful for device fingerprints. A difference in programming/erasing efficiency arises from a widely distributed threshold voltage. However, statistical fluctuations in the threshold voltage represent an advantage for PUF applications. The characteristics of PUFs, such as their unclonability, uncontrollability, unpredictability, and robustness, are investigated using fabricated flash memory devices. A simulation study is performed to support the experimental results and to show that the unpredictability is induced by variations in the gate dielectric thickness.