METHOD OF MANUFACTURING TRENCH GATE TYPE SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To suppress inconvenience such as deterioration of gate breakdown voltage and reliability due to film thinning in an insulator. SOLUTION: A method of manufacturing a trench gate-type semiconductor device where a gate electrode is arranged in a trench part contains a first step of forming the trench part in a semiconductor substrate, a second step of forming a first insulator on a wall face of the trench part, a third step of forming a second insulator to a prescribed depth on an inner side of the first insulator, removing the first insulator to a position deeper than the prescribed depth and forming a depression and a fourth step of forming again the first insulator in a part where the first insulator is removed in the third process. COPYRIGHT: (C)2009,JPO&INPIT