CN-122013293-A - SiC single crystal substrate, method for producing SiC single crystal, and apparatus for producing SiC single crystal

Abstract

The technical problem to be solved by the invention is to realize a high-quality SiC single crystal with small crystal defect density and thermal strain generated in the crystal growth process. A SiC single crystal substrate is used, which has a first main surface and a second main surface located on the opposite side of the first main surface, wherein the first main surface is inclined at an off-angle of 0 DEG to 8 DEG with respect to a {0001} plane. Wherein, in the distribution of phase differences obtained by making incident light having two polarization components orthogonal to each other and having a wavelength of 520nm enter the first main surface and measuring the phase difference between the first outgoing light and the second outgoing light outgoing from the second main surface, the average value of the phase differences is 10nm or less, and the maximum value of the phase differences is 70nm or less.

Inventors

• Nan Yiyan
• Kakenagawa Hiroshi
• TAKAO KENTA
• ABE MAI

Assignees

• 株式会社博迈立铖

Dates

Publication Date

20260512

Application Date

20251104

Priority Date

20241111

Claims (15)

1. 1. A SiC single crystal substrate characterized in that: having a first main face and a second main face located on the opposite side of the first main face, The first main surface is inclined at an off-angle of 0 DEG to 8 DEG inclusive with respect to a {0001} plane, In a distribution of phase differences obtained by making incident light having two polarization components orthogonal to each other and a wavelength of 520nm incident on the first main surface and measuring a phase difference between first outgoing light and second outgoing light outgoing from the second main surface, The average value of the phase difference is 10nm or less, The maximum value of the phase difference is 70nm or less.
2. 2. The SiC single crystal substrate of claim 1, wherein: the maximum value of the phase difference is 50nm or less.
3. 3. The SiC single crystal substrate of claim 1, wherein: The maximum value of the phase difference is 25nm or less.
4. 4. The SiC single crystal substrate of claim 1, wherein: The maximum diameter of the first main surface is 140mm or more.
5. 5. The SiC single crystal substrate of claim 1, wherein: an epitaxial layer for device formation is provided on the first main surface or on the second main surface.
6. 6. The SiC single crystal substrate of claim 1, wherein: and n SiC single crystal substrates form a wafer group, wherein n is more than 12.
7. 7. A method for producing a SiC single crystal, characterized by comprising: comprising (a) a step of bringing the lower surface of a seed crystal substrate into contact with a melt containing Si and C to grow a SiC single crystal, In the step (a), the SiC single crystal is grown under the conditions that an in-plane temperature difference at an interface where the lower surface of the seed crystal substrate contacts the melt is set to 4.0 ℃ or less, and a temperature gradient from an upper surface of the seed crystal substrate located on an opposite side of the lower surface is set to 9 ℃ or more and 25 ℃ or less.
8. 8. An apparatus for producing a SiC single crystal, comprising: a seed crystal holding shaft having a cylindrical portion and capable of holding a seed crystal substrate below the cylindrical portion; a side insulating material disposed within the cylindrical portion, and An upper surface heat insulating material provided in the cylindrical portion, The seed crystal substrate has a lower surface capable of contacting a melt contained in the crucible, and an upper surface located on the opposite side of the lower surface, The melt contains Si and C, The inner diameter of the cylindrical portion is greater than or equal to the diameter of the seed crystal substrate, The side heat insulating material has a length such that a part of the side heat insulating material can be disposed above an upper end of the crucible when the lower surface of the seed crystal substrate is brought into contact with the melt, The upper surface insulating material is disposed at a position spaced above the upper surface of the seed crystal substrate.
9. 9. The apparatus for producing a SiC single crystal according to claim 8, wherein: the side heat insulating material is a member for bringing the in-plane temperature difference of the interface between the lower surface of the seed crystal substrate and the melt into contact with each other to 4.0 ℃ or less, The upper surface heat insulating material is a member for making a temperature gradient upward from the upper surface of the seed crystal substrate be 9 ℃ to 25 ℃ inclusive.
10. 10. The apparatus for producing a SiC single crystal according to claim 8, wherein: The side insulating material is in contact with the upper surface insulating material.
11. 11. The apparatus for producing a SiC single crystal according to claim 8, wherein: The side insulating material is not in contact with the upper surface insulating material.
12. 12. The apparatus for producing a SiC single crystal according to claim 8, wherein: The side insulating material includes a first side insulating material, and a second side insulating material in contact with the first side insulating material.
13. 13. The apparatus for producing a SiC single crystal according to claim 12, wherein: the side insulating material further includes a third side insulating material in contact with the second side insulating material.
14. 14. The apparatus for producing a SiC single crystal according to claim 8, wherein: In the cross section, the upper surface of the side heat insulating material is positioned at a position higher than the upper surface of the crucible.
15. 15. The apparatus for producing a SiC single crystal according to claim 14, wherein: in the cross section, the position of the upper surface of the side heat insulating material coincides with the position of the upper surface of the crucible.

Description

SiC single crystal substrate, method for producing SiC single crystal, and apparatus for producing SiC single crystal Technical Field The present invention relates to a SiC (silicon carbide) single crystal substrate, a method for producing a SiC single crystal, and an apparatus for producing a SiC single crystal, and for example, to a technique for producing a SiC single crystal by a melt method. Background The SiC single crystal has very stable thermal and chemical properties, excellent mechanical strength, radiation resistance, higher dielectric breakdown voltage and thermal conductivity than Si (silicon) single crystal, and excellent physical properties. By using a semiconductor device of SiC single crystal, high power, high frequency, voltage resistance, environmental resistance, and the like which cannot be realized by a semiconductor device using a conventional semiconductor material such as Si single crystal can be realized. Therefore, siC single crystals are expected to be the next-generation semiconductor materials in various fields. Patent document 1 (japanese patent application laid-open No. 2021-4173) discloses evaluation of crystal defects of a compound semiconductor substrate by a photoelastic method. Patent document 2 (japanese patent application laid-open No. 2022-18072) discloses the production of SiC single crystal substrates by a gas phase method. Non-patent document 1 discloses optimizing the growth conditions of a crystal by simulation with respect to SiC single crystal growth by a melt method. The optimization is performed to suppress the generation of polycrystalline SiC called hetero-crystal in the melt. Non-patent document 2 discloses a sublimation recrystallization method as a method for growing SiC single crystals. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2021-4173 Patent document 2 Japanese patent application laid-open No. 2022-18072 Non-patent literature Non-patent document 1:K, kusunoki et al, mater, sci, forum Vol 963 (2018) pp 85-88 Non-patent document 2:H, tsuge et al, mater, sci, forum Vol 740-742 (2013) pp 7-10 Disclosure of Invention Problems to be solved by the invention As described in non-patent document 1, it is known to suppress the generation of hetero crystals by optimizing the crystal growth conditions by simulation. However, optimization of crystal growth conditions by simulation has not been performed at present focusing on reduction of thermal strain of SiC single crystal. In view of the above facts, an object of the present invention is to realize a high-quality SiC single crystal in which thermal strain generated during crystal growth is suppressed and in which crystal defect density is small. Means for solving the problems The SiC single crystal substrate according to one embodiment has a first main surface and a second main surface located on the opposite side of the first main surface, wherein the first main surface is inclined at an off-angle of 0 DEG to 8 DEG with respect to a {0001} plane. Wherein, in a distribution of phase differences obtained by making incident light having two polarization components orthogonal to each other and having a wavelength of 520nm enter the first main surface and measuring a phase difference between first outgoing light and second outgoing light outgoing from the second main surface, an average value of the phase differences is 10nm or less, and a maximum value of the phase differences is 70nm or less. A method for producing a SiC single crystal according to one embodiment includes (a) a step of bringing a lower surface of a seed crystal substrate into contact with a molten phase containing Si (silicon) and C (carbon) to grow the SiC single crystal. In the step (a), the SiC single crystal is grown under the conditions that an in-plane temperature difference at an interface where the lower surface of the seed crystal substrate contacts the melt is set to 4.0 ℃ or less, and a temperature gradient from an upper surface of the seed crystal substrate located on an opposite side of the lower surface is set to 9 ℃ or more and 25 ℃ or less. An apparatus for producing a SiC single crystal according to one embodiment includes a seed crystal holding shaft having a cylindrical portion and capable of holding a seed crystal substrate below the cylindrical portion, a side heat insulating material provided in the cylindrical portion, and an upper surface heat insulating material provided in the cylindrical portion. Wherein the seed crystal substrate has a lower surface capable of contacting with the melt contained in the crucible, and an upper surface located on the opposite side of the lower surface. The melt contains Si and C. The inner diameter of the cylindrical portion is equal to or larger than the diameter of the seed crystal substrate. The side heat insulating material has a length such that a part of the side heat insulating material can be disposed above the upper end of