Nonvolatile semiconductor memory device covered with insulating film which is hard for an oxidizing agent to pass therethrough

Abstract

A nonvolatile semiconductor memory device includes comprises: an element isolation region being in contact with a first element region, an insulating film covering a memory cell, a peripheral transistor and the element isolation region, an inter-level insulating film provided on the surface of the insulating film, and a contact hole provided in the inter-level insulating film and the insulating film. The inter-level insulating film contains an insulator different from the insulating film. The contact hole reaches at least one of source and drain diffusion layers of the memory cell and overlaps the element isolation region. The insulating film contains an insulator different from the element isolation region and the insulating film is harder for an oxidizing agent to pass therethrough than a silicon oxide film. A surface of the insulating film is oxidized.