R&D: 3D NAND Based Filtering Cube with High Resolution 2D Query and Tunable Feature Length for Computational SSD

IEEE Xplore has published, in 2024 IEEE International Memory Workshop (IMW) proceedings, an article written by Po-Hao Tseng; Shao-Yu Fang; Yu-Hsuan Lin; Feng-Ming Lee; Jhe-Yi Liao; Yu-Yu Lin; Ming-Hsiu Lee; Kuang-Yeu Hsieh; Keh-Chung Wang; and Chih-Yuan Lu, Macronix International Co., Ltd., Hsinchu, Taiwan, ROC.

Abstract: “A novel 3D filtering cube is proposed in 3D-NAND flash for computational SSD to execute 3D in-memory-search (3D IMS) function at ultra-high search bandwidth. The 3D filtering cube compares 2D data inputs from word lines (WLs) and string-select lines (SSLs) with the database stored in the 3D NAND cubes. Multi-block operation using string select line (SSL) modulation provides tunable search word length for various dataset applications. Two encoding algorithms were developed for approximate and exact-range computing modes, which provide high filtration efficiency up to 99% from SSD to CPU (or GPU). The cube with normal encoding scheme features ultra-high search bandwidth up to ~3.5Tb/sec. A novel reverse encoding scheme was developed for enhancing output resolution with current-mode page buffer design. Reliability concerns including retention, read disturbance, page buffer (PB) design, and data pattern effects were evaluated. The concepts were successfully demonstrated with 5.5-bit word resolution in our 96-layer 3D NAND chip. The 3D filtering cube can facilitate minimal data movement and be a key component in computational SSD and memory-centric AI computing.“