Semiconductor nonvolatile memory device having reduced switching overhead time on the program mode

摘要

A semiconductor nonvolatile memory device capable of reducing the overhead time of the time required for switching the verify operation and the verify operation itself. In the semiconductor nonvolatile memory device which operates to program the threshold of the memory cells on the basis of a plurality of repetitive operations, the mincing width INCREMENT Vth of the variation of the threshold of the memory cells relative to one operation for changing the threshold (applying the program pulse) is expressed by INCREMENT Vth=Kvthxlog (t2/t1), and the ratio (t2/t1) between the program pulse widths is expressed by (t2/t1)=10E( INCREMENT Vth/Kvth). The pulses in which the difference INCREMENT Vth of the variation of the threshold of the memory cells is made constant, and the pulse width is increased as the repetition number increases are applied to the memory cells, thereby reducing the application number of program pulses.