New Multiple-Times Programmable CMOS ROM Cell

In-Young CHUNG  Seong Yeol JEONG  Sung Min SEO  Myungjin LEE  Taesu JANG  Seon-Yong CHA  Young June PARK  

IEICE TRANSACTIONS on Electronics   Vol.E95-C    No.6    pp.1098-1103
Publication Date: 2012/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1098
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
CMOS memory,  ROM,  FN stress,  nonvolatile memory,  

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New concept of CMOS nonvolatile memory is presented with demonstration of cell implementations. The memory cell, which is a comparator basically, makes use of comparator offset for storage quantity and the FN stress phenomena for cell programming. We also propose the stress-packet operation which is the relevant programming method to finely control the offset of the memory cell. The memory cell is multiple-time programmable while it is implemented in a standard CMOS process. We fabricated the memory cell arrays of the latch comparator and demonstrated that it is rewritten several times. We also investigated the reliability of cell data retention by monitoring programmed offsets for several months.