In-Situ Encrypted NAND FeFET Array for Secure Storage and Compute-in-Memory

In this work, we present a lightweight in-situ encryption/decryption technique for high-density NAND memory, aiming to meet the growing need for data privacy and security in storage and computing applications. Using ferroelectric FET (FeFET) as a technology platform for demonstration, we show that: i) using a XOR-based cipher, the encryption/decryption can be simply mapped to in-situ array operations, where the encrypted cipher texts are stored as complementary threshold voltage (VTH) states of two consecutive FeFETs in a NAND string and decryption can be simply realized through read operations with key-dependent read gate biases; ii) the proposed technique is scalable to multi-level cells (MLC) by encrypting and decrypting bit-by-bit, thereby significantly increasing the encrypted memory density; iii) a unique advantage of applying XOR-based cipher on NAND array is its capability of supporting high-density and secure compute-in-memory (CiM) (e.g., matrix vector multiplication) with encrypted weights, which is beyond the capability of conventional advanced encryption standard (AES) engine; iv) with integrated NAND FeFET array, we have successfully demonstrated encryption and decryption operations of single-level cell (SLC), MLC, and CiM, showing great promise of the technique.