| 摘要 |
PROBLEM TO BE SOLVED: To surely select a defective bit of a nonvolatile memory cell caused by COP. SOLUTION: In write-in (electrons injection), write-in voltage is made approximately 1/2 of normal voltage, a write-in time is extended to about 5-30 times, and write-in is performed for the nonvolatile memory cell 4a. In a normal memory cell, electrons injection is not caused by approximately 5V being approximately half of normal write-in voltage, threshold voltage is scarcely raised, while in a nonvolatile semiconductor memory cell 4a having crystal defect 9 in a channel region, electric field concentration is caused in the channel region of the crystal defect 9, electrons are injected to a floating gate FG in a shorter period of time than a normal time by FN tunnel phenomenon, causing the problem that the threshold voltage Vth of the nonvolatile memory cell 4a is raised and write-in is performed. COPYRIGHT: (C)2005,JPO&NCIPI
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