| 摘要 |
A method of fabricating a semiconductor device incorporates the steps of forming in succession a gate insulting film, a polycrystalline silicon film and a first insulating film on a semiconductor substrate surface, and etching a portion of the first insulating film, the polycrystalline silicon film and the gate insulating film to expose the semiconductor substrate. The exposed semiconductor substrate is etched to form a trench. The trench is then buried by depositing a second insulating film and thereafter a third insulating film. The second and third insulating films are then etched with the third insulating film being etched at a higher rate than the second insulating film. The polycrystalline silicon film is used as a stopper to leave behind the second and third insulating films in the trench. A fourth insulating film is deposited, and then etched again using the polycrystalline silicon film as a stopper. The side walls of the trench are thus coated with the fourth insulating film. Lastly, a gate electrode is formed by depositing a conductive film and selectively removing the conductive film and the polycrystalline silicon film.
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