Mitsubishi Denki Kabushiki Kaisha

Minoru Ohkawa

Takeshi Nakayama

Masaaki Mihara

Yoshikazu Miyawaki

Shinichi Kobayashi

Yasushi Terada

Tomoshi Futatsuya

Shinji Kawai

A collective erasure type nonvolatile semiconductor memory device which allows use of redundant structure to word lines is provided. A row address buffer having address converting function simultaneously selects a plurality of physically adjacent word lines from a memory array in programming before erasure. Programming before erasure is effected on the memory cells on the simultaneously selected word lines. Even when physically adjacent word lines are short-circuited between each other, programming high voltage can be transmitted to the defective word lines, as these word lines are selected simultaneously. Therefore, the memory cells on the defective word lines can be programmed before erasure, so that over erasure at the time of collective erasing operation can be prevented. Thus, redundant structure for replacing defecting word lines by spare word lines can be utilized.

Nonvolatile semiconductor memory device with a row redundancy circuit

A source line of a memory array included in a flash memory is set to a 3V potential by a source line circuit, a power supply voltage of 6V is applied to a sense amplifier, and 3V is applied as the ground potential. After the setting of such potential conditions, reading of the memory array is performed. When current flows to the memory cells as a result of reading, it means that the memory cell has been erased. If the current does not flows through the memory cell, erasure pulse is applied again and every memory cell is verified.

Nonvolatile semiconductor memory device and method of erasing stored

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Hyogo-ken, Japan

Minoru Ohkawa