Semiconductor nonvolatile memory apparatus and computer system using the same,申请号US20000680936-传众专利搜索

Semiconductor nonvolatile memory apparatus and computer system using the same

申请公布号：US6442070(B1)

申请号：US20000680936

申请日期：2000.10.10

申请公布日期：2002.08.27

申请人：

HITACHI, LTD.

发明人：TANAKA TOSHIHIRO;KATO MASATAKA;TSUCHIYA OSAMU;NISHIMOTO TOSHIAKI

分类号：G11C16/04;G11C16/28;G11C16/34;(IPC1-7):G11C16/06

主分类号：G11C16/04

摘要：A nonvolatile semiconductor memory device is provided which includes a plurality of memory cells each having a floating gate, wherein a threshold level of each memory cell depends on a value of electric charge in said floating gate of said memory cell, and wherein said threshold level of each memory cell is placed at one of a first area and a second area. A controller is also provided which controls to set each threshold voltage of selected ones of said plurality of memory cells, wherein said controller performs a first setting operation and a verifying operation. The first setting operation shifts threshold voltages of the selected ones of said plurality of memory cells in a direction from said first area to said second area. The verifying operation detects erratic memory cells which have threshold voltages which are on a side of said second area which is opposite of a middle area formed between the first area and the second area.