Method of manufacturing silicon carbide semiconductor device
An impurity of a first conductivity type is implanted onto a silicon carbide substrate through an opening in a mask layer. First and second films made of first and second materials respectively are formed. It is sensed that etching of the first material is performed during anisotropic etching, and then anisotropic etching is stopped. An impurity of a second conductivity type is implanted onto the silicon carbide substrate through the opening narrowed by the first and second films. Thus, the impurity regions can be formed in an accurately self-aligned manner.
1. A method of manufacturing a silicon carbide semiconductor device, comprising the steps of:
forming a mask layer having an opening on a silicon carbide substrate;
implanting an impurity of a first conductivity type onto said silicon carbide substrate through said opening in said mask layer;
forming a first film made of a first material, which does not substantially contain a metal element, on said silicon carbide substrate to cover said mask layer;
forming a second film made of a second material different from said first material, on said silicon carbide substrate to cover said mask layer and said first film;
performing anisotropic etching for removing a portion of said second film;
sensing an exposed part of said first film during said anisotropic etching;
stopping said anisotropic etching after sensing said first film;
implanting an impurity of a second conductivity type onto said silicon carbide substrate using said second film as a mask after said step of stopping said anisotropic etching; and
removing said mask layer, said first film, and said second film.
2. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said mask layer is made of said second material.
3. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , further comprising, after said step of forming a first film and before said step of forming a second film, the steps of:
forming a third film made of a material different from said first material; and
forming a fourth film made of said first material on said third film.
4. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , further comprising the step of forming an underlying layer on said silicon carbide substrate before said step of forming a mask layer.
5. The method of manufacturing a silicon carbide semiconductor device according to claim 4 , wherein
said underlying layer is made of said first material.
6. The method of manufacturing a silicon carbide semiconductor device according to claim 4 , wherein
said underlying layer is made of a material different from said first material.
7. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said first material does not contain a metal element.
8. The method of manufacturing a silicon carbide semiconductor device according to claim 7 , wherein
said first material is made of any of a silicon-based material and a carbon-based material.