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; a high-concentration region of a first conductivity type; and a lower surface region of a first conductivity type or a second conductivity type, 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 the other doping concentration peaks, and a ratio A/B of a peak concentration A of the shallowest doping concentration peak and an average peak concentration B of the other doping concentration peaks is 200 or less.
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 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 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 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.
3 . The semiconductor device according to claim 1 , wherein
the high-concentration region has a length of 50 μm or more in the depth direction.
4 . The semiconductor device according to claim 1 , wherein
a ratio A/B of a peak concentration A of the shallowest doping concentration peak and an average peak concentration B of the other doping concentration peaks is 200 or less.
5 . The semiconductor device according to claim 1 , wherein
the high-concentration region has a length of 80 μm or more from the shallowest doping concentration peak toward the upper surface of the semiconductor substrate.
6 . The semiconductor device according to claim 1 , wherein
the high-concentration region has a length of 40% or more of a thickness of the semiconductor substrate in the depth direction.
7 . The semiconductor device according to claim 4 , wherein
the ratio A/B is 2 or more.
8 . The semiconductor device according to claim 1 , wherein
a ratio C/D of a dose amount C of the shallowest doping concentration peak and a total dose amount D of the other doping concentration peaks is 6 or more and 100 or less.
9 . 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.
10 . The semiconductor device according to claim 1 , wherein
a minimum value of the doping concentration of the high-concentration region is two times or more of the bulk donor concentration.
11 . The semiconductor device according to claim 1 , wherein
doping distribution increases from the uniform region toward the impurity chemical concentration peak while a hydrogen chemical concentration decreases.
12 . The semiconductor device according to claim 1 , wherein
from a depth position of the impurity chemical concentration peak toward the upper surface side, a portion where the doping concentration coincides with the bulk donor concentration is provided.
13 . The semiconductor device according to claim 1 , wherein
the doping concentration distribution of the uniform region is within a range in which a difference between a maximum value and a minimum value of the doping concentration is within 50% of the maximum value of the doping concentration.
14 . 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.