Renesas Electronics Corporation

Masaki Hama

Yasuaki Kagotoshi

Koichi Arai

Kenichi Hisada

A method for manufacturing a semiconductor device includes carrying out a first heat treatment accompanied by nitration on a first insulating film and a silicon carbide substrate in a first gas atmosphere, after the carrying out of the first heat treatment and after a temperature of the silicon carbide substrate has become 700&#xb0; C. or less, removing the silicon carbide substrate from a processing apparatus and exposing the silicon carbide substrate to air in an atmosphere outside of the processing apparatus, and after the exposing of the silicon carbide substrate to air in the atmosphere, carrying out a second heat treatment on the first insulating film and the silicon carbide substrate in a second gas atmosphere which is an inert gas.

Method for manufacturing semiconductor device

To form a MOSFET over a silicon carbide substrate, when a heat treatment accompanied by nitration is carried out to reduce the interface state density in the vicinity of the boundary between a gate insulating film and a silicon carbide substrate, CV hysteresis occurs due to the relationship between the capacitance and gate voltage of the MOSFET, thereby reducing the reliability of a semiconductor device. To solve the above problem, a heat treatment accompanied by nitration is carried out on the insulating film formed over the silicon carbide substrate (step S). Then, the insulating film is heated in an inert gas atmosphere (step S). Thereafter, a field effect transistor having a gate insulating film which is composed of the insulating film is formed over the silicon carbide substrate.

The present invention makes it possible to improve the accuracy of wet etching and miniaturize a semiconductor device in the case of specifying an active region of a vertical type power MOSFET formed over an SiC substrate by opening an insulating film over the substrate by the wet etching. After a silicon oxide film having a small film thickness and a polysilicon film having a film thickness larger than the silicon oxide film are formed in sequence over an epitaxial layer, the polysilicon film is opened by a dry etching method, successively the silicon oxide film is opened by a wet etching method, and thereby the upper surface of the epitaxial layer in an active region is exposed.

Growing community of inventors

Tokyo, Japan

Masaki Hama