| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device which reads and writes data at a high speed, and eliminates influence on a low threshold voltage which is already set. <P>SOLUTION: The nonvolatile memory device includes: a multi-value data storing memory cell array having multi-value memory cells divided into two groups, the memory cell array being configured to assign a piece of multi-value data to the groups and store the data; a data processing circuit which performs read operation of reading data from the multi-value data storing memory cell array and a program operation of writing data to the multi-value data storing memory cell array; and a control circuit which controls the operation of the data processing circuit. The control circuit controls the program operation by defining the assignment of data corresponding to a threshold voltage distribution of the multi-value memory cells so that a shift of the threshold voltage by the first write operation and a shift of the threshold voltage by the second write operation are equal to each other irrespective of write sequence. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
