| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve the data retention of a nonvolatile memory element and, in addition, to improve the data retention of a side-wall memory element with respect to two memory function groups. <P>SOLUTION: This method is used for improving the data retention of a conductor storage device. The nonvolatile memory element 1 comprises: a gate electrode 104 formed on a semiconductor layer through a gate insulating film 103; a channel region disposed under the gate electrode 104; and diffusion regions 107a disposed on both sides of the channel region and having conductivity opposite to that of the channel region. The memory element 1 also comprises memory function groups 105a formed on both sides of the gate electrode 104 and having charge holding functions. This method includes steps of: (a) selecting a first memory group, in which charges are accumulated more than a first threshold out of a plurality of memory elements, (b) extracting a first subgroup in which charges are accumulated less than a second threshold, out of the memory elements of the first memory group, and (c) programming a memory element in the first subgroup until charges are accumulated more than the second threshold. Since the programming is executed on the memory element selected by judging the level of charges accumulated in the nonvolatile memory element 1, the data retention of each memory element is improved even when charge leakage occurs. Therefore, a highly reliable semiconductor storage device having satisfactory data retention characteristics is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
