Patent ID: 7301806
Filing Date: 2007-11-27
Classification: G11C

Abstract:
1. A non-volatile semiconductor memory device comprising: an electrically data rewritable non-volatile semiconductor memory cell; and a write circuit configured to write data to the memory cell by supplying a write voltage and a write control voltage to the memory cell to change the write state of the memory cell, the write circuit detecting if the write state of the memory cell has reached a first level or not and, upon detecting that the write state of the memory cell has reached the first level, the write circuit reducing a rate of change of the write state by changing the supply of the write control voltage, and the write circuit further changing the supply of the write control voltage to control the reduced rate of changing the write state and terminating the write operation to the memory cell while the rate of changing the write state is controlled, wherein the write circuit performs a write operation to sequentially increase the write voltage when writing data to the memory cell, the write circuit controls the rate of change of the reduced rate of change of the write state by sequentialiy increasing the write control voltage, and the rate of increase of the write voltage is greater than the rate of increase of the write control voltage.