Silicon carbide semiconductor substrate, method of manufacturing silicon carbide semiconductor substrate, semiconductor device and method of manufacturing semiconductor device

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

• preparing a silicon carbide substrate of a first conductivity type, the silicon carbide substrate having a central part and a peripheral part surrounding the central part, and being doped with a first impurity that determines the first conductivity type;
• forming a buffer layer of the first conductivity type on a front surface of the central part of the silicon carbide substrate, the buffer layer being doped with the first impurity, of which a concentration is at least 1.0×1018/cm3, and a second impurity different from the first impurity, the buffer layer having a first side and a second side opposite to each other, the second side facing the silicon carbide substrate;
• and
• forming a voltage blocking layer of the first conductivity type on a front surface of the peripheral part of the silicon carbide substrate and on the first side of the buffer layer, the voltage blocking layer being doped with the first impurity, a concentration of which is lower than the concentration of the first impurity in the buffer layer.

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

• preparing a silicon carbide substrate of a first conductivity type, the silicon carbide substrate having a central part and a peripheral part surrounding the central part, and being doped with a first impurity that determines the first conductivity type;
• forming an epitaxial layer of the first conductivity type on a front surface of the silicon carbide substrate, the epitaxial layer being doped with the first impurity, of which a concentration is lower than a concentration of the first impurity in the silicon carbide substrate, the epitaxial layer having a first side and a second side opposite to each other, the second side facing the silicon carbide substrate;
• forming a buffer layer of the first conductivity type in a region of the epitaxial layer corresponding to the central part of the silicon carbide substrate, the buffer layer being doped with the first impurity, of which a concentration is at least 1.0×1018/cm3, and a second impurity different from the first impurity, the buffer layer having a first side and a second side opposite to each other, the second side facing the silicon carbide substrate;
• and
• forming a voltage blocking layer of the first conductivity type on the first side of the epitaxial layer and the first side of the buffer layer, the voltage blocking layer being doped with the first impurity, a concentration of which is lower than the concentration of the first impurity in the buffer layer.