Nonvolatile semiconductor memory device and method of manufacturing the same

A nonvolatile semiconductor memory device manufacturing method comprising:

• forming a tunnel insulating film on a semiconductor substrate;
• forming a charge storage layer composed of an insulating film on the tunnel insulating film;
• not only selectively etching the charge storage layer and tunnel insulating film between adjacent element forming regions of the substrate but also etching the surface part of the substrate, thereby forming an element isolation trench;
• forming an element isolation insulating film so as to fill up the element isolation trench;
• forming on at least the element isolation insulating film a barrier layer composed of at least one of a silicon nitride film, a silicon oxynitride film, and a silicon oxide film which has a higher density than that of the element isolation insulating film;
• forming on the element isolation insulating film and charge storage layer, a blocking insulating film at the interface with at least the element isolation insulating film so as to sandwich the barrier layer between the element isolation insulating film and the blocking insulating film;
• and
• forming a control gate on the blocking insulating film.

A nonvolatile semiconductor memory device manufacturing method comprising:

• forming a tunnel insulating film on a semiconductor substrate;
• forming a charge storage layer composed of an insulating film on the tunnel insulating film;
• forming a blocking insulating film on the charge storage layer;
• not only selectively etching the blocking insulating film, charge storage layer, and tunnel insulating film between adjacent element forming regions of the substrate but also etching the surface part of the substrate, thereby forming an element isolation trench;
• forming an element isolation insulating film so as to fill up the element isolation trench;
• forming on at least the element isolation insulating film a barrier layer composed of at least one of a silicon nitride film, a silicon oxynitride film, and a silicon oxide film which has a higher density than that of the element isolation insulating film;
• and
• forming on the element isolation insulating film and blocking insulating film, a control gate film at the interface with at least the element isolation insulating film so as to sandwich the barrier layer between the element isolation insulating film and the control gate.