Super junction silicon carbide semiconductor device and manufacturing method thereof

A method of manufacturing a superjunction silicon carbide semiconductor device, the method comprising:

• as a first process, forming a parallel pn structure on a front surface of a silicon carbide semiconductor substrate of a first conductivity type, the parallel pn structure having a plurality of first columns of the first conductivity type and a plurality of second columns of a second conductivity type, the first columns and the second columns being disposed repeatedly alternating one another in a plane parallel to the front surface;
• as a second process, forming a first semiconductor layer of the second conductivity type at a surface of the parallel pn structure;
• as a third process, selectively forming a plurality of first semiconductor regions of the first conductivity type in a surface layer of the first semiconductor layer;
• as a fourth process, forming a gate insulating film in contact with the first semiconductor layer;
• as a fifth process, forming a gate electrode on a first surface of the gate insulating film, the first surface being opposite to a second surface of the gate insulating film, the second surface being in contact with the first semiconductor layer;
• as a sixth process, forming a first electrode in contact with the first semiconductor layer and the first semiconductor regions;
• and
• as a seventh process, forming a second electrode on a back surface of the silicon carbide semiconductor substrate, wherein
• in the first process, forming an epitaxial layer of the second conductivity type on the front surface of the silicon carbide semiconductor substrate and selectively forming a plurality of semiconductor regions of the first conductivity type by implanting nitrogen ions in the epitaxial layer are repeated a plurality of times, thereby forming the parallel pn structure.