Patent ID: 8008149

Claim:
A method of manufacturing a non-volatile semiconductor memory device, comprising: forming a first insulating film on a semiconductor substrate; forming on said first insulating film a first electrode layer to be turned into a floating gate; forming an element isolation trench extending from said first electrode layer into said semiconductor substrate to define an element forming region in said semiconductor substrate; forming a first buried film and a second buried film sequentially in said element isolation trench in said semiconductor substrate; forming a second insulating film on said first electrode layer and said second buried film; forming on said second insulating film a second electrode layer to be turned into a control gate; selectively removing said second electrode layer to form said control gate crossing said element forming region and said element isolation trench; selectively removing said second insulating film in a region not covered with said control gate; removing said second buried film after selectively removing said second insulating film; and selectively removing said first electrode layer in a region not covered with said control gate to form said floating gate.