13.2 A 1Tb 4b/Cell 96-Stacked-WL 3D NAND Flash Memory with 30MB/s Program Throughput Using Peripheral Circuit Under Memory Cell Array Technique
Hwang Huh, Wanik Cho, Jinhaeng Lee, Yujong Noh, Yongsoon Park, Sunghwa Ok, Jongwoo Kim, Kayoung Cho, Hyunchul Lee, Geonu Kim, Kangwoo Park, Kwanho Kim, Heejoo Lee, Sooyeol Chai, Chankeun Kwon, Hanna Cho, Chan‐Hui Jeong, Yujin Yang, Jayoon Goo, Jangwon Park · 2020
Ever since a 3b/cell (TLC) NAND Flash memory became the mainstream in nonvolatile memory market, a new demand for a 4b/cell (QLC) NAND flash memory has been emerging for low-cost applications. However, QLC has inherently much longer page program time than TLC because of 16-state programming within a limited program and erase (PE) window, as well as narrower Vthdistributions. The longer page-program time, subsequently, degrades sequential write performance. Thus it is not possible to meet the required sequential-write performance in applications such as mobile devices and solid state drives (SSDs).