Patent ID: 6335882
Filing Date: 2002-01-01
Classification: G11C

Abstract:
A nonvolatile semiconductor device, comprising:a memory cell array having a plurality of memory cells arranged in a matrix, each of said memory cells including a memory cell transistor capable of changing a threshold value in accordance with an applied control potential; a plurality of bit lines arranged corresponding to columns of said memory cell array for transmitting data stored in said memory cell transistors; a plurality of word lines arranged corresponding to rows of said memory cell array for transmitting said control potential and reading potential to said memory cell transistor; a data detection circuit for detecting said stored data read out through said bit line; an internal power supply circuit capable of generating said control potential for an erasing operation on said stored data of said memory cells and variably generating a first potential applied to a selected memory cell and a second potential applied to non-selected memory cells during a reading operation; a selection circuit for selectively supplying a potential generated by said internal power supply circuit to said memory cells; and an internal control circuit controlling an operation of said nonvolatile semiconductor memory device and controlling said selection circuit for selectively applying said control potential to each block to be erased, said block to be erased including said plurality of memory cells connected to a prescribed number of word lines out of said plurality of word lines, and said internal control circuit updating said second potential in such a way that said second potential can render nonconductive said memory cells belonging at least to said block to be erased, and verifying erasing based on the detection result of said data detection circuit by selectively applying said first potential to one of said word lines in said block to be erased and applying the updated second potential to the remaining word lines in said block to be erased.