Patent ID: 7993966

Claim:
A method for manufacturing a silicon carbide semiconductor device having a MOS structure comprising steps of: preparing a substrate made of silicon carbide, the substrate having a main surface, which is provided by an (11−20)-plane; forming a channel area on the substrate, wherein the channel area is made of silicon carbide, and provides an electric current path; forming a first impurity area on an upstream side of the electric current path; forming a second impurity area on a downstream side of the electric current path; forming a gate insulating film on a surface of the channel area; forming a gate on the gate insulating film; and heating and cooling the substrate, wherein the channel area provides the electric current path as a channel by controlling a voltage applied to the gate so that an electric current in the electric current path flowing between the first impurity area and the second impurity area is controlled, in the step of heating and cooling the substrate, the substrate is cooled in a wet atmosphere in a temperature range between 800° C. and 900° C. so that a dangling bond of an interface between the gate insulating film and the channel area is terminated by a hydrogen atom or a hydroxyl, the step of heating and cooling the substrate is performed as heat treatment of the step of forming the gate insulating film, the step of heating and cooling the substrate is further performed as an anneal process after the forming of the gate insulating film, the substrate being heated in the wet atmosphere at a temperature range equal to or higher than 800° C.; and the wet atmosphere is maintained in a temperature range equal to or higher than 800° C. after the step of forming the gate insulating film.