Non-volatile semiconductor memory device.

摘要

A non-volatile semiconductor memory device has writing part for writing data in a non-volatile memory cell in response to a write pulse, readout part for reading out data stored in the memory cell, and verification part for verifying to ensure that normal writing has been completed by reading data from the memory cell after each writing. The device repeats writings unless a normal writing can be confirmed by the verification part. At this time, the writing part can vary writing time and in a part of a sequence of repeating writing unless a normal writing can be confirmed, it sets writing time longer for the next writing action than that for one writing action. Since this setting is performed according to constant multiplication, constant increment, or constant multiplication of accumulated value, necessary time for obtaining normal data write can be reduced. <IMAGE>