| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To shorten a data write operation time, in a NAND type flash memory adopting a write method which needs two data write operations. <P>SOLUTION: For example, when writing final data at a desired threshold voltage level in a nonvolatile memory cell, first, a preliminary data write operation of writing preliminary data of a temporary level lower than the desired threshold voltage level, is performed. Then, write verify read of the preliminary data write is performed. A WL waiting WTa of the verify read is made shorter than it (WL waiting time WT) of write verify read of the final data. After that, final data write operation of writing final data of the desired threshold voltage level is performed, and write verify read of final data write is performed. A WL waiting time WT at this time is made a time in which a potential is sufficiently stabilized so that difference of voltage levels between the root and the top end of a selected word line is not caused. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
