| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a selective erasing method for a flash memory. <P>SOLUTION: In the selective erasing method for the flash memory, when the threshold voltage of the memory cell which is connected to an arbitrary word line being erased is lower than a prescribed erasing threshold voltage, no further erasing for the memory cell connected to the word line is performed and the erasing is conducted only for the remaining cells. Then, the selective erasing for each word line is repeatedly conducted until the threshold voltages of the memory cells which are connected to all word lines become lower than the erasing threshold voltage. Thus, no excessive erasing is conducted to the memory cells, erasing threshold voltage scattering is improved, a pre-program or a post program is eliminated by the improved erasing threshold voltage scattering and the amount of electric current required for the erasing is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
