Semiconductor device and manufacturing method of semiconductor device

A semiconductor device comprising:

• a semiconductor substrate having an upper surface and a lower surface, and containing a bulk donor;
• a buffer region of a first conductivity type which is disposed on the lower surface side of the semiconductor substrate and has two or more doping concentration peaks in a depth direction of the semiconductor substrate;
• a high-concentration region of a first conductivity type which is disposed between the buffer region and the upper surface of the semiconductor substrate, and has a donor concentration higher than a bulk donor concentration;
• a lower surface region of a first conductivity type or a second conductivity type which is disposed between the buffer region and the lower surface of the semiconductor substrate and has a doping concentration higher than the high concentration region;
• and
• an impurity chemical concentration peak is provided in the upper surface side of the semiconductor substrate of the high-concentration region, wherein a doping concentration at a position of the impurity chemical concentration peak is less than an impurity chemical concentration of the impurity chemical concentration peak, wherein
• a shallowest doping concentration peak closest to the lower surface of the semiconductor substrate among the doping concentration peaks of the buffer region is a concentration peak of a hydrogen donor having a concentration higher than other doping concentration peaks,
• the high-concentration region is provided from the shallowest doping concentration peak to the impurity chemical concentration peak,
• the high-concentration region includes a uniform region in which a doping concentration is substantially uniform,
• a doping concentration distribution of the uniform region is within a range in which a value of the doping concentration distribution is within ±10% of an average concentration of the doping concentration distribution in a first range in the uniform region, and
• when a length of the high-concentration region in the depth direction is set to ZL and a center between the shallowest doping concentration peak and the impurity chemical concentration peak in the depth direction is set to Z12C, the first range is a section with a length of 0.5ZL including the center Z12C, the length of the first range is set between two points separated by 0.25ZL from the center Z12C between Z1 and Z2, toward the first depth position Z1 side and the second depth position Z2 side, and
• in the high-concentration region, a hydrogen chemical concentration monotonically decreases from the buffer region beyond the impurity chemical concentration peak toward the upper surface.