Mis-transistor-based nonvolatile memory device with verify function

Abstract

A nonvolatile semiconductor memory device includes a first latch to store data, a nonvolatile memory cell including two MIS transistors to store data as an irreversible change of transistor characteristics occurring in one of the two MIS transistors selected in response to the data stored in the first latch, a second latch to store data obtained by sensing a difference in the transistor characteristics between the two MIS transistors, a logic circuit to produce a signal indicative of comparison between the data of the first latch and the data of the second latch, and a control circuit configured to repeat a store operation storing data in the nonvolatile memory cell, a recall operation storing data in the second latch, and a verify operation producing the signal indicative of comparison until the signal indicates that the data of the first latch and the data of the second latch are the same.