EP-4741541-A2 - SIC SINGLE CRYSTAL SUBSTRATE, METHOD OF MANUFACTURING SIC SINGLE CRYSTAL, AND APPARATUS OF MANUFACTURING SIC SINGLE CRYSTAL

Abstract

In an SiC single crystal substrate including a first main surface and a second main surface opposite to the first main surface, the SiC single crystal substrate in which the first main surface is a surface that tilts relative to a {0001} plane at an off-cut angle equal to or larger than 0° and equal to or smaller than 8° is used. In a distribution of phase differences obtained by measuring a phase difference between a first emission light and a second emission light emitted from the second main surface by making an incident light with two mutually perpendicular polarization components and a wavelength of 520 nm into the first main surface, an average value of the phase differences is equal to or smaller than 10 nm, and the maximum value of the phase differences is equal to or smaller than 70 nm.

Inventors

• KUSUNOKI, KAZUHIKO
• HASEGAWA, TAKASHI
• TAKAO, KENTA
• ABE, MAI

Assignees

• Proterial, Ltd.

Dates

Publication Date

20260513

Application Date

20251031

Claims (15)

1. An SiC single crystal substrate including a first main surface and a second main surface opposite to the first main surface, wherein the first main surface is a surface that tilts relative to a {0001} plane at an off-cut angle equal to or larger than 0° and equal to or smaller than 8°, in a distribution of phase differences obtained by measuring a phase difference between a first emission light and a second emission light emitted from the second main surface by making an incident light with two mutually perpendicular polarization components and a wavelength of 520 nm into the first main surface, an average value of the phase differences is equal to or smaller than 10 nm, and the maximum value of the phase differences is equal to or smaller than 70 nm.
2. The SiC single crystal substrate according to claim 1, wherein the maximum value of the phase differences is equal to or smaller than 50 nm.
3. The SiC single crystal substrate according to claim 1, wherein the maximum value of the phase differences is equal to or smaller than 25 nm.
4. The SiC single crystal substrate according to claim 1, wherein the maximum diameter of the first main surface is equal to or larger than 140 mm.
5. The SiC single crystal substrate according to claim 1, wherein an epitaxial layer for device formation is provided on the first main surface or the second main surface.
6. The SiC single crystal substrate according to claim 1, wherein the SiC single crystal substrates, the number of which is "n" ("n" is equal to or larger than 12), configure a set of wafers.
7. A method of manufacturing an SiC single crystal, comprising: a step (a) of growing the SiC single crystal by bringing a lower surface of a seed crystal substrate into contact with a solution containing silicon (Si) and carbon (C), wherein in the step (a), the SiC single crystal is grown under a condition that an in-plane temperature difference in a contact interface between the lower surface of the seed crystal substrate and the solution is equal to or smaller than 4.0°C while a temperature gradient upward from an upper surface opposite to the lower surface of the seed crystal substrate is equal to or larger than 9 °C/cm and equal to or smaller than 25 °C/cm.
8. An apparatus of manufacturing SiC single crystal comprising: a seed crystal holding shaft including a cylinder and enabling a seed crystal substrate to be held under the cylinder; a side-surface heat insulating member provided in the cylinder; and an upper-surface heat insulating member provided in the cylinder, wherein the seed crystal substrate has a lower surface enabled to be in contact with a solution housed in a crucible and an upper surface opposite to the lower surface, the solution contains silicon (Si) and carbon (C), an inner diameter of the cylinder is equal to or larger than a diameter of the seed crystal substrate, the side-surface heat insulating member has such a length that a part of the side-surface heat insulating member is enabled to be upper than an upper end of the crucible when the lower surface of the seed crystal substrate is brought into contact with the solution, and the upper-surface heat insulating member is away upward from the upper surface of the seed crystal substrate.
9. The apparatus of manufacturing SiC single crystal according to claim 8, wherein the side-surface heat insulating member is a member having an in-plane temperature difference in a contact interface between the lower surface of the seed crystal substrate and the solution to be equal to or smaller than 4.0°C, and the upper-surface heat insulating member is a member having a temperature distribution in an upward direction from the upper surface of the seed crystal substrate to be equal to or larger than 9 °C/cm and equal to or smaller than 25 ° C/cm.
10. The apparatus of manufacturing SiC single crystal according to claim 8, wherein the side-surface heat insulating member is in contact with the upper-surface heat insulating member.
11. The apparatus of manufacturing SiC single crystal according to claim 8, wherein the side-surface heat insulating member is not in contact with the upper-surface heat insulating member.
12. The apparatus of manufacturing SiC single crystal according to claim 8, wherein the side-surface heat insulating member includes: a first side-surface heat insulating member; and a second side-surface heat insulating member being in contact with the first side-surface heat insulating member.
13. The apparatus of manufacturing SiC single crystal according to claim 12, wherein the side-surface heat insulating member further includes: a third side-surface heat insulating member being in contact with the second side-surface heat insulating member.
14. The apparatus of manufacturing SiC single crystal according to claim 8, wherein in a cross-sectional view, a position of an upper surface of the side-surface heat insulating member is equal to or upper than a position of an upper surface of the crucible.
15. The apparatus of manufacturing SiC single crystal according to claim 14, wherein in a cross-sectional view, the position of the upper surface of the side-surface heat insulating member is equal to the position of the upper surface of the crucible.

Description

CROSS-REFERENCES TO RELATED APPLICATION The disclosure of Japanese Patent Application No. 2024-196631 filed on November 11, 2024, and Japanese Patent Application No. 2025-123872 filed on July 24, 2025, including the specification, drawings and abstract is incorporated herein by reference in its entirety. TECHNICAL FIELD OF THE INVENTION The present invention relates to a silicon carbide (SiC) single crystal substrate, a method of manufacturing SiC single crystal, and an apparatus of manufacturing SiC single crystal, and relates to, for example, a technique of manufacturing SiC single crystal by solution growth method. BACKGROUND OF THE INVENTION The SiC single crystal has excellent physical properties to be very stable thermally and chemically, excellent in mechanical strength, resistant to radiation, and higher in breakdown voltage and heat conductivity than those of silicon (Si) single crystal. A semiconductor device using SiC single crystal can achieve high power, high frequency, high breakdown voltage, environmental tolerance, and the like, which cannot be achieved by a semiconductor device using an existing semiconductor material such as Si single crystal. Thus, SiC single crystal is awaited as a next-generation semiconductor material in various fields. A Patent Document 1 (Japanese Patent Application Laid-open Publication No. 2021-4173) describes that crystal strain of a compound semiconductor substrate is evaluated by a photoelasticity method. A Patent Document 2 (Japanese Patent Application Laid-open Publication No. 2022-18072) describes that an SiC single crystal substrate is manufactured by a vapor phase epitaxy (growth) method. A Non-Patent Document 1 (K. Kusunoki et al., Mater. Sci. Forum Vol. 963 (2018) pp 85 to 88) describes that crystal growth conditions in growth of SiC single crystal by a solution growth method are optimized based on simulation. The optimization is for suppressing formation of polycrystal SiC called miscellaneous crystal in a solution. H. A Non-Patent Document 2 (Tsuge et al, Mater. Sci. Forum Vol. 740 to 742 (2013) pp 7 to 10) describes that a sublimation recrystallization method is used as a method of growing SiC single crystal. SUMMARY OF THE INVENTION As described in the Non-Patent Document 1, it is known that the formation of the miscellaneous crystals is suppressed by the optimization of crystal growth conditions based on simulation. However, crystal growth conditions are not optimized based on simulation aiming at a decrease in thermal strain of SiC single crystal. In consideration of the above circumstances, an objective of the present disclosure is to suppress occurrence of thermal strain during crystal growth, thereby achieving high-quality SiC single crystal with small crystal defect density. An SiC single crystal substrate according to one embodiment is an SiC single crystal substrate including a first main surface and a second main surface opposite to the first main surface, and the first main surface is a surface which tilts relative to a {0001} plane at an off-cut angle equal to or larger than 0° and equal to or smaller than 8°. A distribution of phase differences is obtained by measuring a phase difference between a first emission light and a second emission light emitted from the second main surface by making an incident light with two mutually perpendicular polarization components and a wavelength of 520 nm into the first main surface, and an average value of the phase differences is equal to or smaller than 10 nm while the maximum value of the phase differences is equal to or smaller than 70 nm. A method of manufacturing an SiC single crystal according to one embodiment includes a step (a) of growing the SiC single crystal by bringing a lower surface of a seed crystal substrate into contact with a solution containing silicon (Si) and carbon (C). In the step (a), the SiC single crystal is grown under a condition that an in-plane temperature difference in a contact interface between the lower surface of the seed crystal substrate and the solution is equal to or smaller than 4.0°C while a temperature gradient upward from an upper surface opposite to the lower surface of the seed crystal substrate is equal to or larger than 9 °C/cm and equal to or smaller than 25 °C/cm. An apparatus of manufacturing SiC single crystal according to one embodiment includes: a seed crystal holding shaft including a cylinder and enabling a seed crystal substrate to be held under the cylinder; a side-surface heat insulating member provided in the cylinder; and an upper-surface heat insulating member provided in the cylinder. The seed crystal substrate has a lower surface enabled to be in contact with a solution housed in a crucible, and an upper surface opposite to the lower surface. The solution contains Si and C. An inner diameter of the cylinder is equal to or larger than a diameter of the seed crystal substrate. The side-surface heat insulating member has such a length that a