Patent ID: 6181600
Filing Date: 2001-01-30
Classification: G11C

Abstract:
A nonvolatile semiconductor memory device formed in a single semiconductor substrate, comprising:a plurality of blocks, each comprising at least one word line, a plurality of data lines and a plurality of memory cells,wherein each of said plurality of memory cells in each of said plurality of blocks includes a single transistor having a floating gate and a control gate, andwherein a threshold voltage of said single transistor is changeable to a first threshold voltage corresponding to a first data from a second threshold voltage corresponding to a second data, in a threshold voltage change operation;a selecting unit selecting at least one block of said plurality of said blocks;a counter generating address signals for sequentially selecting lines of at least one group selected from a group of the word lines of said plurality of blocks and a group of said plurality of data lines of at least one of said plurality of blocks;a voltage circuit supplying a control voltage to memory cells in at least one block selected by said selecting unit so as to change threshold voltages of said memory cells in said at least one block in said threshold voltage change operation; anda verify unit verifying a threshold voltage of each of said memory cells supplied with said control voltage based on address signals generated from said counter after said threshold voltage change operation,wherein ones of said memory cells in said at least one block having as the threshold voltages thereof, respectively, said first threshold voltage, corresponding to said first data, upon completion of said threshold voltage change operation, are not supplied with said control voltage after completion of said threshold voltage change operation.