Semiconductor Device and Manufacturing Method of the Same

摘要

A method for manufacturing a semiconductor device having a field-effect transistor, including forming a trench in a semiconductor substrate, forming a first insulating film in the trench, forming an intrinsic polycrystalline silicon film over the first insulating film, and introducing first conductive type impurities into the intrinsic polycrystalline silicon film to form a first conductive film. The first conductive film is etched to form a first gate electrode in the trench. Next, a second insulating film is formed in the trench above the first insulating film and the first gate electrode, and;a first conductivity type doped polycrystalline silicon film, having higher impurity concentration than the first gate electrode is formed over the second insulating film. The doped polycrystalline silicon film, upper part of the trench ton form a second gate electrode.

主权项

1. A method for manufacturing a semiconductor device including a field-effect transistor, comprising steps of:
(a) forming a trench in a semiconductor substrate; (b) forming a first insulating film in the trench; (c) forming an intrinsic polycrystalline silicon film over the first insulating film; (d) introducing impurities of a first conductivity type into the intrinsic polycrystalline silicon film to form a first conductive film; (e) after the step (d), etching the first conductive film so as to provide a portion of the first conductive film in a lower part of the trench, thereby to form a first gate electrode of the field-effect transistor; (f) forming a second insulating film in the trench, wherein the second insulating film is disposed above the first insulating film and the first gate electrode; (g) forming a doped polycrystalline silicon film of the first conductivity type, having higher impurity concentration than the first gate electrode, over the second insulating film; and (h) etching the doped polycrystalline silicon film so as to provide a portion of the doped polycrystalline silicon film in an upper part of the trench, thereby to form a second gate electrode of the field-effect transistor.