NONVOLATILE SEMICONDUCTOR MEMORY DEVICE

摘要

A nonvolatile semiconductor memory device is provided to achieve improvement in read margin and stabilization of a read operation, by reducing an adjacent current through a unit for writing a memory cell adjacent to a reference cell. In a nonvolatile semiconductor memory device adopting a VGA(virtual ground array) scheme where a source and a drain connected in common are used as a bit line among a plurality of nonvolatile memory cells, the nonvolatile memory cell includes a reference cell obtaining reference characteristics of a differential read judgement operation. And adjacent cell is connected to the same word line and shares one of a source and a drain of the reference cell. When the word line is enabled and the reference cell is in a conduction state, an adjacent cell write circuit turns the adjacent cell be into a write state maintaining a non-conduction state.