Patent ID: 7375018

Claim:
A method of manufacturing a semiconductor device, comprising: preparing a semiconductor substrate on which a first layer constituted of a conductive film, a second layer constituted of an insulating film, and a third layer having etching selectivity from said second layer are sequentially formed; forming a first upper opening in said third layer; forming a first mask insulating film so as to cover an inner wall of said first upper opening; forming a first lower opening in said first layer so as to communicate with said first upper opening, utilizing said first mask insulating film as the mask; forming a first buried insulating film so as to fill said first lower opening; forming a second upper opening by selectively removing said third layer by etching, after said forming of said first buried insulating film; forming a second mask insulating film so as to cover an inner wall of said second upper opening; forming a second lower opening in said first layer so as to communicate with said second upper opening, utilizing said second mask insulating film as the mask; and forming a second buried insulating film so as to fill said second lower opening.