Patent ID: 9679646
Date: 2017-06-13
CPC Classifications: G11C

Claim:
1. A method for rewriting a nonvolatile semiconductor storage device with a plurality of memory cells each of which having a plurality of write conditions, the method comprising: acquiring read-out data from at least any one memory cell selected from the nonvolatile memory array; generating concurrently rewrite-bit information indicating that a data rewrite is needed or not for a change pattern of each write condition of the plurality of memory cells based on, in a read-back mode, the read-out data and a prepared write data and, in a verify mode, the read-out data and the rewrite-bit information generated previously; repeating a data rewrite on a first change pattern for memory cells for the first change pattern indicated by the generated rewrite-bit information until completion of the data rewrite of all the memory cells on the first change pattern is confirmed; and after the completion of the data rewrite of the selected memory cell on the first change pattern, repeating a data rewrite on a second change pattern for memory cells for the second change pattern indicated by the generated rewrite-bit information until completion of the data rewrite of all the memory cells on the second change pattern is confirmed.