A Robust Read-Based PUF Generation Method in a 3-D NAND Flash Memory

This article presents a physical unclonable function (PUF) based on the randomness of the source-side doping profile in 3-DnandFlash technology. The proposed PUF utilizes inherent process variations among the common-source-line (CSL) junctions within individualnandcell strings. During the enrollment phase, bits “0” and “1” are extracted with an ideal probability of 0.5 [Hamming weight (HW)] using a filtration method. This PUF sets a new benchmark for flash-based PUFs, featuring a high generation throughput exceeding 2 Gb/s and operating without error correction coding (ECC). It demonstrates nearly ideal randomness and strong uniqueness, with an inter-Hamming distance (inter-HD) of approximately 0.5. Additionally, the PUF exhibits remarkable sustainability, maintaining a bit error rate (BER) of 0% across various conditions, including cross-temperature operations, over 1 million repeated readouts, retention for over 500 h at$85~^{\circ }$C, and reproducibility exceeding 3000 program/erase (P/E) cycles. The extracted PUF values consistently show good randomness, passing all relevant tests in the NIST 800-22 suite.