Silicon carbide semiconductor device, inverter circuit using the same, and method for manufacturing silicon carbide semiconductor device

A method for manufacturing a silicon carbide semiconductor device, the silicon carbide semiconductor device having:

• a cell section in which a switching element having a MOS structure is formed;
• and an outer peripheral section surrounding the cell section, in which the cell section includes:
• a substrate of a first conductivity type made of silicon carbide;
• a buffer layer of the first conductivity type formed on the substrate and having an impurity concentration lower than the substrate;
• a low-concentration layer of the first conductivity type formed on the buffer layer and having an impurity concentration lower than the substrate;
• a first deep layer of a second conductivity type formed on the low-concentration layer and having a plurality of linear portions whose longitudinal directions are one direction in a planar direction of the substrate;
• a JFET portion of the first conductivity type disposed on the low-concentration layer and having a linear portion sandwiched between the linear portions of the first deep layer;
• a current diffusion layer of the first conductivity type disposed on the JFET portion and having an impurity concentration higher than the low-concentration layer;
• a second deep layer of the second conductivity type disposed on the first deep layer;
• a base layer of the second conductivity type disposed on the current diffusion layer and the second deep layer;
• an impurity region of the first conductivity type formed in a surface layer portion of the base layer;
• a trench gate structure having a gate insulating film formed on a wall surface of a trench that penetrates the impurity region and the base layer to reach the current diffusion layer, and a gate electrode formed on the gate insulating film;
• a first electrode electrically connected to the impurity region and the base layer;
• and
• a second electrode electrically connected to the substrate, and
• the JFET portion is formed with defect portions,
• the method comprising:
• disposing the low-concentration layer as an epitaxial layer;
• forming the JFET portion by performing ion implantation on a surface layer portion of the low-concentration layer;
• and
• forming the defect portions in the JFET portion by performing the ion implantation.