Method for manufacturing silicon carbide semiconductor device

A method for manufacturing a silicon carbide MOSFET, comprising:

• forming a recessed portion in a surface of a first conductivity type substrate in a predetermined pattern, said semiconductor substrate comprising a silicon carbide crystal;
• growing a second conductivity type epitaxial layer on the substrate;
• and
• flattening at least a part of the substrate by removing a surface portion of the substrate including a part of the epitaxial layer grown thereon, so that pn junctions appear on a surface of the substrate, and so that the second conductivity type epitaxial layer is formed into a second conductivity type base region.

A method for manufacturing a CMOS semiconductor device, comprising the steps of:

• covering a portion of a first conductivity type silicon carbide substrate with a mask, and forming a recessed portion to a predetermined depth by etching;
• growing a second conductivity type epitaxial layer on the substrate;
• flattening at least a part of the substrate by removing a surface portion of the substrate including a part of the epitaxial layer grown thereon, so that a pn junction appears on the surface of the substrate, and so that the second conductivity type epitaxial layer is formed into a second conductivity type well region;
• implanting impurities for forming a first conductivity type region in a surface layer of the second conductivity type well region;
• conducting heat treatment to activate the impurities introduced by ion implantation, so as to form a first conductivity type source region and a first conductivity type drain region;
• implanting impurities for forming a second conductivity type region in a flattened surface layer of the first conductivity type silicon carbide substrate,
• conducting heat treatment to activate the impurities introduced by ion implantation, so as to form a second first conductivity type source region and a second conductivity type drain region;
• forming an oxide film on the surface of the substrate by thermal oxidation;
• forming gate electrode layers on the oxide film;
• and
• forming electrodes which are in contact with the first conductivity type source region, first conductivity type drain region, second conductivity type source region, and the second conductivity type drain region.