Non-volatile semiconductor memory device, method of reading data therefrom, and semiconductor device

Abstract

A control circuit is configured to perform, in a write operation to a memory cell and a verify operation for verifying a threshold voltage of the memory cell, a voltage control to provide the memory cell with threshold voltage distributions. The circuit is configured to apply, in a read operation from the memory cell, to a selected memory cell a read voltage between the lower and upper limits of the threshold voltage distributions, and apply to an unselected memory cell a first read-pass voltage higher than the upper limit of a first threshold voltage distribution that is the maximum distribution of the threshold voltage distributions. The circuit is configured to apply, at least during a verify operation in a first write operation conducted before a second write operation that completes writing to the first threshold voltage distribution, a second read-pass voltage lower than the first read-pass voltage to the unselected memory cell, and apply to the semiconductor layer and the source-line a positive voltage.