Flash memory device including circuitry for selecting a memory block

Abstract

A nonvolatile semiconductor memory device has a memory block including a string having a string select transistor responsive to a string select line, a ground select transistor responsive to a ground select line, and a plurality of EEPROM cells responsive to a corresponding plurality of word lines, the plurality of EEPROM cells being serially connected between the string select transistor and the ground select transistor. A first block select transistor is coupled to the ground select transistor. A second block select transistor is coupled to the string select transistor. A plurality of third block select transistors is coupled to the plurality of word lines. A voltage control means provides a first voltage to the first block select transistor and a second voltage to the third block select transistors, the first voltage being less than the second voltage during programming. According to the present invention, a voltage difference occurring between the gate and the drain of the first block select transistor is reduced. The result is a significant stress reduction on the first block select transistor.