Semiconductor device and manufacturing method of semiconductor device
Provided is a semiconductor device including: 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 contains a hydrogen donor, and in which a doping concentration distribution in a depth direction of the semiconductor substrate has a single first doping concentration peak; a high-concentration region of a first conductivity type which is disposed between the buffer region and the upper surface of the semiconductor substrate, contains a hydrogen donor, and has a donor concentration higher than a bulk donor concentration; and a lower surface region of a first conductivity type or a second conductivity type which is disposed between the buffer region and a lower surface of the semiconductor substrate, and has a doping concentration higher than the high-concentration region.
1 . 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 contains a hydrogen donor, and in which a doping concentration distribution of the semiconductor substrate in a depth direction has a first doping concentration peak with a first hydrogen chemical concentration peak;
an impurity chemical concentration peak is disposed on an upper surface side of the semiconductor substrate, 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;
a high-concentration region of the first conductivity type including the impurity chemical concentration peak that is located in the upper surface side of the semiconductor substrate in the high-concentration region which is in contact with the first doping concentration peak of the buffer region contains a hydrogen donor, and has a donor concentration higher than a bulk donor concentration; and
a lower surface region of the 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, wherein
at least in a uniform region, a hydrogen chemical concentration monotonically decreases from the buffer region at least up to the impurity chemical concentration peak,
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 Z L and a center between the shallowest doping concentration peak and the impurity chemical concentration peak in the depth direction is set to Z 12C , the first range is a section with a length of 0.5Z L including the center Z 12C , the length of the first range is set between two points separated by 0.25Z L from the center Z 12C between Z 1 and Z 2 , toward the first depth position Z 1 side and the second depth position Z 2 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.
2 . The semiconductor device according to claim 1 , wherein
the first doping concentration peak of the buffer region is a concentration peak of the hydrogen donor.
3 . The semiconductor device according to claim 1 , wherein
the first doping concentration peak of the buffer region is a concentration peak of an N type dopant other than the hydrogen donor.
4 . The semiconductor device according to claim 1 , wherein
the impurity chemical concentration decreases more steeply in an upper tail, in which an impurity chemical concentration decreases from a local maximum of the impurity chemical concentration peak toward the upper surface side, than in a lower tail in which the impurity chemical concentration decreases from the local maximum of the impurity chemical concentration peak toward the lower surface side.
5 . The semiconductor device according to claim 4 , further comprising:
a hydrogen chemical concentration peak which is disposed at a same depth position as the first doping concentration peak of the buffer region; and
a second doping concentration peak which is disposed at a same depth position as the impurity chemical concentration peak, wherein
the impurity chemical concentration peak is a chemical concentration peak of hydrogen,
each concentration peak has a lower tail in which a concentration increases from the lower surface of the semiconductor substrate toward the upper surface, and
a value obtained by normalizing a gradient of the lower tail of the second doping concentration peak with a gradient of the lower tail of the impurity chemical concentration peak is smaller than a value obtained by normalizing a gradient of the lower tail of the first doping concentration peak with a gradient of the lower tail of the hydrogen chemical concentration peak.
6 . The semiconductor device according to claim 1 , wherein
the high-concentration region has a length of 50% or more of a thickness of the semiconductor substrate in the depth direction of the semiconductor substrate.
7 . The semiconductor device according to claim 2 , wherein
the high-concentration region has a length of 50% or more of a thickness of the semiconductor substrate in the depth direction of the semiconductor substrate.
8 . The semiconductor device according to claim 1 , wherein
the high-concentration region has a length of 70 μm or more in the depth direction of the semiconductor substrate.
9 . The semiconductor device according to claim 1 , wherein
the donor concentration of the high-concentration region is two times the bulk donor concentration.
10 . The semiconductor device according to claim 1 , wherein
the donor concentration of the high-concentration region is five times or more of the bulk donor concentration.
11 . The semiconductor device according to claim 1 , wherein
when a rated voltage of the semiconductor device is x(V), the bulk donor concentration (atoms/cm 3 ) is (9.20245×10 12 )/x or more and (4.60123×10 16 )/x or less.
12 . The semiconductor device according to claim 11 , wherein
the bulk donor concentration (atoms/cm 3 ) is (9.20245×10 14 )/x or more and (1.84049×10 16 )/x or less.
13 . The semiconductor device according to claim 11 , wherein
a donor concentration (/cm 3 ) at a center of the semiconductor substrate in the depth direction is (9.20245×10 15 )/x or more and (9.20245×10 16 )/x or less.
14 . The semiconductor device according to claim 1 , further comprising:
an accumulation region which is disposed on the upper surface side of the semiconductor substrate, and has a doping concentration higher than the high-concentration region, wherein
the high-concentration region is provided up to a position in contact with the accumulation region.
15 . The semiconductor device according to claim 1 , wherein:
the high-concentration region includes, between the buffer region and the impurity chemical concentration peak, the uniform region in which a doping concentration is substantially uniform.
16 . The semiconductor device according to claim 1 , wherein:
the doping concentration distribution increases from the uniform region toward the impurity chemical concentration peak while the hydrogen chemical concentration decreases.
17 . The semiconductor device according to claim 1 , wherein
a drift region of the first conductivity-type is disposed between the buffer region and the upper surface, the drift region contains the high concentration region, in which a doping concentration of the drift region is a same as the bulk donor concentration.