Evaluation method for bulk silicon carbide single crystals and reference silicon carbide single crystal used in said method
View Patent ↗Provided are a method by which the degrees of the strains of lattices in a plurality of bulk SiC single crystals can be relatively evaluated, and a reference SiC single crystal to be used in the method. Specifically provided are an evaluation method for bulk-shaped silicon carbide single crystals, including: measuring a Raman shift R ref of a reference silicon carbide single crystal to be used as a standard; measuring respective Raman shifts R n of a plurality of bulk-shaped silicon carbide single crystals serving as objects to be evaluated; determining differences between each of the Raman shifts R n and the Raman shift R ref ; and relatively comparing the differences, to thereby relatively evaluate magnitudes of strains of lattices in the plurality of bulk-shaped silicon carbide single crystals serving as objects to be evaluated, and a reference silicon carbide single crystal to be used in the method, having a size of 5 mm square or more and 50 mm square or less and a thickness of 100 μm or more and 2,000 μm or less, having a surface roughness Ra of 1 nm or less, and having a micropipe density of 1.0/cm 2 or less and a dislocation density of 5×10 3 /cm 2 or less.
1. An evaluation method for bulk-shaped silicon carbide single crystals, comprising:
measuring a Raman shift R ref of a reference silicon carbide single crystal to be used as a standard;
measuring respective Raman shifts R n of a plurality of bulk-shaped silicon carbide single crystals serving as objects to be evaluated;
determining differences between each of the Raman shifts R n and the Raman shift R ref ;
relatively comparing the differences,
evaluating the magnitudes of strains of lattices in the plurality of bulk-shaped silicon carbide single crystals serving as objects to be evaluated based upon the compared differences, and
performing treatment for removing an internal stress in the plurality of bulk-shaped silicon carbide single crystals serving as objects to be evaluated that have larger differences between Raman shifts R n and Raman shift R ref .
2. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 , wherein the reference silicon carbide single crystal has a thickness of 100 μm or more and 2,000 μm or less and a surface roughness Ra of 1 nm or less.
3. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 2 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has a micropipe density of 1.0/cm 2 or less and a dislocation density of 5×10 3 /cm 2 or less.
4. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 2 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has a half width of an X-ray rocking curve of 15 arcsec or less.
5. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 2 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has lattice constants falling within the following ranges,
10.05903≤c≤10.05916 (Å)
3.071114≤a≤3.071497 (Å)
2.659663≤m≤2.659994 (Å)
wherein c, a, and m are lattice constants.
6. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 2 , wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal produced by a sublimation recrystallization method.
7. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 2 , wherein the bulk-shaped silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal ingot or a silicon carbide single crystal substrate.
8. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has a micropipe density of 1.0/cm 2 or less and a dislocation density of 5×10 3 /cm 2 or less.
9. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 8 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has lattice constants falling within the following ranges,
10.05903≤c≤10.05916 (Å)
3.071114≤a≤3.071497 (Å)
2.659663≤m≤2.659994 (Å)
wherein c, a, and m are lattice constants.
10. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 8 , wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal produced by a sublimation recrystallization method.
11. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 8 , wherein the bulk-shaped silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal ingot or a silicon carbide single crystal substrate.
12. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has a half width of an X-ray rocking curve of 15 arcsec or less.
13. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 12 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has lattice constants falling within the following ranges,
10.05903≤c≤10.05916 (Å)
3.071114≤a≤3.071497 (Å)
2.659663≤m≤2.659994 (Å)
wherein c, a, and m are lattice constants.
14. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 12 , wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal produced by a sublimation recrystallization method.
15. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 ,
wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each have a polytype of 4H, and
wherein the reference silicon carbide single crystal has lattice constants falling within the following ranges,
10.05903≤c≤10.05916 (Å)
3.071114≤a≤3.071497 (Å)
2.659663≤m≤2.659994 (Å)
wherein c, a, and m are lattice constants.
16. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 15 , wherein the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated each comprise a silicon carbide single crystal produced by a sublimation recrystallization method.
17. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 , further comprising:
producing the reference silicon carbide single crystal and the silicon carbide single crystals serving as objects to be evaluated by a sublimation recrystallization method.
18. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 , further comprising:
producing a silicon carbide single crystal ingot or a silicon carbide single crystal substrate as the bulk-shaped silicon carbide single crystals serving as objects to be evaluated.
19. An evaluation method for bulk-shaped silicon carbide single crystals according to claim 1 , further comprising:
attaching the bulk-shaped silicon carbide single crystals serving as objects to be evaluated onto a supporting pedestal having a horizontal mounting surface before measuring the Raman shifts R n thereof when the bulk-shaped silicon carbide single crystals serving as objects to be evaluated have a thickness of 500 μm or less.