Semiconductor memory device and manufacturing method for semiconductor device

Abstract

The object is simplification of a manufacturing process for nonvolatile memory by reducing additional processes for forming a charge storage structure, and downsizing of nonvolatile memory. The solution is a manufacturing method for semiconductor memory device including a process for forming sequentially a first oxide film, a first nitride filmon a semiconductor substrate, a process for removing the first oxide filmand the first nitride filmin an element isolating regionB, a process for overhanging the first nitride filmover the first oxide filmby removing the edge of the first oxide filmby cleaning or wet etching, a process for forming a first insulating film(element isolating insulating film) so that a lower density parthaving a lower film density than other parts thereof can be formed in the side part of the fist oxide film, a process for exposing the lower density part, a process for forming a hole in the first insulating filmby eroding the lower concentration partusing cleaning or wet etching, and a process for forming charge storage film in the hole.