Nonvolatile semiconductor memory device and method for fabricating the same

Abstract

A nonvolatile semiconductor memory device includes: a gate dielectric made of a multilayer dielectric that is formed on a substrate and discretely accumulates charges; a gate electrode formed on the gate dielectric; a pair of diffusion regions formed in the surface of the substrate with the gate electrode interposed therebetween and serving as a source and a drain; and a channel region existing between the diffusion regions. At least one of regions of the gate dielectric located between the pair of diffusion regions and lateral end parts of the gate electrode opposed to the diffusion regions includes a fixed charge accumulation region in which charges produced by irradiating the gate electrode with ultraviolet light can be accumulated, and at least one said diffusion region located below the fixed charge accumulation region is formed to overlap with the fixed charge accumulation region in plan configuration and extend beyond the fixed charge accumulation region toward the middle of the channel region in plan configuration.