Nonvolatile semiconductor memory device and erasing method of nonvolatile semiconductor memory device

Abstract

A nonvolatile semiconductor memory device including a first bit line commonly coupling drain sides memory cells; a word line commonly coupling control gates of memory cell transistors; a column decoder coupled to a second bit line; a row decoder coupled to a word line; a first transistor having a source coupled to the first bit line and having a drain electrically coupled to the column decoder via the second bit line; and a first control unit for controlling potential of a gate of the first transistor, the memory cell transistor being formed over a first well, the first transistor being formed over a second well electrically isolated from the first well, a film thickness of a gate insulation film of the first transistor being smaller than that of a gate insulation film of a second transistor formed in the row decoder and coupled to the word line.