| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To shorten a period for rewriting data of a nonvolatile semiconductor memory device. <P>SOLUTION: The nonvolatile semiconductor memory device 1 has a storage area in which data can be rewritten for each block, a RAM 4 for evacuating data, and a controller 3. The device 1 includes: a preprogram step for applying a program voltage when a state of each cell in a block 2 is an erasing state; an erasing step for erasing all cells in the block; and a post program step for equalizing a threshold voltage. In the preprogram step, copying to the RAM is performed while determining the state of each cell in the block, and in the post program step, when data after the cells are rewritten is data corresponding to the erasing state, the post program voltage is applied to the cell to equalize the threshold voltage after erasing the cells, and when data after the cells are rewritten is data corresponding to a program state, the program voltage is applied to the cell to put the cell into the program state. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
