Silicon carbide semiconductor device and method for manufacturing same

A silicon carbide semiconductor device comprising:

• an inverted semiconductor element including:
• a substrate made of silicon carbide having a first conductivity type or a second conductivity type;
• a drift layer disposed on the substrate and made of silicon carbide having the first conductivity type with an impurity concentration lower than the substrate;
• a base region made of silicon carbide having the second conductivity type and disposed on the drift layer;
• a source region made of silicon carbide having the first conductivity type with a first conductivity type impurity concentration higher than the drift layer and disposed on the base region;
• a plurality of trench gate structures each of which has a gate trench, a gate insulating film and a gate electrode, the gate trench disposed deeper than the base region from a surface of the source region, the gate insulating film covering an inner wall of the gate trench, the gate electrode disposed on the gate insulating film, the trench gate structures aligned in a stripe shape along a single direction corresponding to a longitudinal direction;
• an interlayer insulating film covering the gate electrode and the gate insulating film, and having a contact hole;
• a source electrode in ohmic-contact with the source region through the contact hole;
• and
• a drain electrode disposed at a rear surface of the substrate,
• wherein the source region includes:
• a first source region that has an epitaxial growth layer disposed at the base region;
• and
• a second source region that is in contact with the source electrode, and that has an ion implanted layer having the first conductivity type with the first conductivity type impurity concentration higher than the first source region, and
• wherein a non-doped layer is disposed between the base region and the source region, and has a carrier concentration of 1.0×1016/cm3 and a thickness of 0.05 μm to 0.2 μm.

A method for manufacturing a silicon carbide semiconductor device including an inverted semiconductor element, the method comprising:

• preparing a substrate made of silicon carbide having a first conductivity type or a second conductivity type;
• forming a drift layer disposed on the substrate and made of silicon carbide having the first conductivity type with an impurity concentration lower than the substrate;
• forming a base region made of silicon carbide having the second conductivity type on the drift layer;
• forming a source region made of silicon carbide having the first conductivity type with a first conductivity type impurity concentration higher than the drift layer on the base region, the source region having
• a first source region arranged at the base region, and
• a second source region arranged on the first source region and having an impurity concentration higher than the first source region;
• forming a plurality of trench gate structures by
• forming a plurality of gate trenches deeper than the base region from a surface of the source region and aligned in a stripe shape along a single direction corresponding to a longitudinal direction,
• forming a gate insulating film at an inner surface of each of the gate trenches, and
• forming a gate electrode on the gate insulating film;
• forming a source electrode electrically connected to the base region;
• and
• forming a drain electrode at a rear surface of the substrate,
• wherein, in the forming of the base region, the base region is formed by epitaxial growth, and
• wherein, in the forming of the source region, the first source region is formed by the epitaxial growth at a surface of the base region to have a thickness of 0.2 μm to 0.5 μm and an impurity concentration of 2.0×1016 to 1.0×1017/cm3, and then the second source region is formed by ion implantation of first conductivity type impurities to the first source region to have a thickness of 0.1 μm to 0.2 μm and a second conductivity type impurity concentration of 1.0×1018 to 5.0×1019/cm3.

A method for manufacturing a silicon carbide semiconductor including an inverted semiconductor element, the method comprising:

• preparing a substrate made of silicon carbide having a first conductivity type or a second conductivity type;
• forming a drift layer disposed on the substrate and made of silicon carbide having the first conductivity type with an impurity concentration lower than the substrate;
• forming a base region made of silicon carbide having the second conductivity type on the drift layer;
• forming a non-doped layer having a carrier concentration of 1.0×1016/cm3 and a thickness of 0.05 μm to 0.2 μm on the base region;
• forming a source region made of silicon carbide having the first conductivity type with a first conductivity type impurity concentration higher than the drift layer on the non-doped region, the source region having
• a first source region arranged at the base region, and
• a second source region arranged on the first source region and having an impurity concentration higher than the first source region;
• forming a plurality of trench gate structures by
• forming a plurality of gate trenches deeper than the base region from a surface of the source region and aligned in a stripe shape along a single direction corresponding to a longitudinal direction,
• forming a gate insulating film at an inner surface of each of the gate trenches, and
• forming a gate electrode on the gate insulating film;
• forming a source electrode electrically connected to the base region;
• and
• forming a drain electrode at a rear surface of the substrate,
• wherein, in the forming of the base region, the base region is formed by epitaxial growth, and
• wherein, in the forming of the source region, the first source region is formed by the epitaxial growth, and then the second source region is formed by ion implantation of first conductivity type impurities to the first source region.

A method for manufacturing a silicon carbide semiconductor including an inverted semiconductor element, the method comprising:

• growing epitaxially an n-type silicon carbide layer as a measurement target layer;
• stabilizing a surface electronic state of the n-type silicon carbide layer after growing epitaxially the n-type silicon carbide layer;
• and
• measuring n-type impurity concentration of the n-type silicon carbide layer by measuring a surface potential of the n-type silicon carbide layer after coating an electric charge to charge a surface of the n-type silicon carbide layer, subsequent to stabilizing the surface electronic state of the n-type silicon carbide layer.