| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve a data reading stability in a nonvolatile memory. <P>SOLUTION: The semiconductor device includes a plurality of memory cells MC storing data of two bits per one cell; and a first reference cell RC1 and a second reference cell RC2 shared by the plurality of memory cells MC. When program operation for the memory cell MC is performed, program for a program object cell PMC and refresh for a refresh object cell RMC are performed using a threshold of the second reference cell RC2 corresponding to a program state of the memory cell MC to verify. Also, for the second reference cell RC2, program is performed using a first threshold to verify when the program is performed, refresh is performed using a second threshold being lower than the first threshold when refresh is performed. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
