发明名称 |
Method of improving data retention ability of semiconductor memory device, and semiconductor memory device |
摘要 |
This invention is a method of improving a data retention ability of a semiconductor memory device having a plurality of nonvolatile memory cells storing a plurality of memory states. The method includes the steps of: (a) selecting the nonvolatile memory cells in a first memory group each of which accumulates charges higher in level than a first threshold from the plurality of nonvolatile memory cells; (b) extracting the nonvolatile memory cells in a first sub-group each of which accumulates the charges lower in level than a second threshold from the nonvolatile memory cells in the first memory group; and (c) programming the nonvolatile memory cells in the first sub-group until each of the nonvolatile memory cells accumulates the charges higher in level than the second threshold.
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申请公布号 |
US7079421(B2) |
申请公布日期 |
2006.07.18 |
申请号 |
US20040848313 |
申请日期 |
2004.05.19 |
申请人 |
SHARP KABUSHIKI KAISHA |
发明人 |
YAOI YOSHIFUMI;IWATA HIROSHI;SHIBATA AKIHIDE;MORIKAWA YOSHINAO;NAWAKI MASARU |
分类号 |
G11C11/34;G11C16/02;G11C16/10;H01L21/8247;H01L27/10;H01L27/115;H01L29/788;H01L29/792 |
主分类号 |
G11C11/34 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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