Advanced flash memory technology and trends for file storage application

Abstract

This paper describes a high density flash memory technology suitable for file storage application. Requirements for file storage memory are low cost, high-speed programming and erasing, low power consumption and good endurance characteristics. In order to satisfy these requirements, key technologies of self-aligned STI (SA-STI) cell, uniform FN-FN program/erase scheme and multi-level-cell (MLC) technology have been developed. By using SA-STI technology, small cell size of 4F/sup 2/ (F: feature size) can be realized. Reliable tunnel oxide can be also obtained because the floating gate does not overlap the STI corner. As a result, reliable 512 Mbit flash memories with 0.145 um/sup 2/ cell size under 0.175 /spl mu/m design rule have been newly developed based on these technologies, as well as 0.25 /spl mu/m 256 Mbit. Moreover, MLC technology combined with this small cell size of 4F/sup 2/ can reduce bit cost more, and can expand the file storage market in the near future.