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Total Ionizing Dose Effects on Physical Unclonable Function From NAND Flash Memory

This article demonstrates the total ionizing dose (TID) impact on a NAND flash memory-based physical unclonable function (PUF). We used commercial-off-the-shelf flash memory chips to generate PUF. The flash chip is irradiated with Co-60 gamma rays up to 10 krad(Si). The irradiated chip shows significant accuracy degradation (bit error ~ 12%) of the flash-PUF. We show that TID-induced trapped charges in the oxide alter the intrinsic cell properties causing accuracy degradation of flash-PUF. We propose two independent techniques to improve the PUF accuracy under radiation environment. The first technique relies on electrical annealing which compensates the trapped charges by program stressing. The second technique uses radiation compensation method by adaptive PUF generation process. Our experimental results show that the accuracy degradation can be as low as 1.5% for TID up to 10 krad(Si) with these radiation mitigation techniques.