PROCESS FOR FABRICATION OF MOS SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a novel process for fabrication of an MOS semiconductor device having a trench gate structure of high reliability. SOLUTION: A gate oxide film 5 is formed after a trench 4 is formed, on which a non-doped polysilicon layer 6 is deposited. A silicon nitride film 7 is deposited over it. A trench bottom and the silicon nitride film on a substrate surface are removed by etching to provide an opening. The exposed polysilicon layer is thermally oxidized so that the gate oxide film at the bottom of the trench is increased in thickness to form a trench gate structure. COPYRIGHT: (C)2007,JPO&INPIT