| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To shorten a rewriting time of a nonvolatile semiconductor memory device and to suppress deterioration in reliability of a tunnel insulation film of a nonvolatile memory cell. <P>SOLUTION: Frequency with which rewriting of a memory cell is stored by EW frequency storable sections (15A, 15B). At rewriting of data of a memory cell, rewriting frequency data of a selected memory cell is transferred to a EW frequency sense latch section (22) and latched, and transferred to an EW frequency counter (10). A CPU for control (16) sets conditions of a rewriting pulse based on a updated value of a count value of the EW frequency counter and performs rewriting. At data rewriting, a count value after updating of the EW frequency counter (10) is transferring to the EW frequency sense latch section (22). In parallel to the time of writing data for the memory cell, this updated rewriting frequency data is transferred to the EW frequency storing sections and stored. <P>COPYRIGHT: (C)2003,JPO</p> |
