SEMICONDUCTOR DEVICE AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To solve the problem that a channel layer as a MOSFET is not normally formed due to a lower surface of a gate electrode than a diffusion depth of a source region caused by overetching of a polysilicon film in a U-shaped groove when a method for manufacturing a conventional low withstand MOSFET of embedding the gate electrode excepting the polysilicon film only in the groove by etching back by laminating the polysilicon film on the surface of the epitaxial layer formed with the groove when an intermediate pressure or more MOSFET needing widening of a width of the U-shaped groove is manufactured as compared with the low withstand MOSFET. SOLUTION: A method for manufacturing the semiconductor device comprises the steps of embedding and forming the gate electrode 46 in the U-shaped groove 43, and embedding and forming a polysilicon layer 54 in a recess of the electrode 46 via a thin silicon oxide film 53.