Patent ID: 6455378
Filing Date: 2002-09-24
Classification: H01L,Y10S

Abstract:
A manufacturing method of semiconductor device, comprising the steps of:(a) forming a trench in a semiconductor substrate; (b) forming a gate insulator in said trench so that a trench bottom becomes thicker than a trench side face; (c) forming a gate in said trench after forming said gate insulator; (d) implanting impurities for forming a channel region in said semiconductor substrate after forming said gate formation step; and (e) implanting impurities for forming a source region in said semiconductor substrate after forming said gate formation step; wherein said step (a) further comprises the steps of: forming a first insulator on a principal plane of said semiconductor substrate; forming an opening by removing a formation region for said trench from said first insulator; and forming said trench by removing a semiconductor substrate exposed from said opening by using said first insulator as a mask; wherein said method further comprises the step of making said first insulator's opening larger than said trench after said step (a) and before said step (b); and wherein said step (b) further comprises the steps of: forming a second insulator on an inner face of said trench; forming an oxidation-resistant third insulator on a surface of said second insulator; leaving said third insulator on a side face of said trench by etching back said third insulator; selectively forming a thick insulator on a region exposed from said third insulator on said semiconductor substrate by applying oxidation treatment to said semiconductor substrate; removing said third insulator and then removing said second insulator; and forming a gate insulator so that a semiconductor substrate's principal plane portion exposed from said first insulator's opening and said trench bottom become thicker than a trench side face by applying oxidation treatment to said semiconductor substrate after said step of removing said second insulator, and said step (c) further comprises the steps of: depositing a conductor film in said trench and on said semiconductor substrate's principal plane; and forming said gate with a T-shaped cross section by etching back said conductor film.