SiC ingot and SiC wafer
A SiC ingot includes a seed crystal and a single crystal grown on the seed crystal, wherein the single crystal has therein a micropipe passing through the single crystal in a growth direction, and when photoluminescence observation is performed on a plurality of wafers cut out from the single crystal in a direction intersecting the growth direction, an S/N ratio of the micropipe in a first wafer cut out of the plurality of wafers, which is closest to the seed crystal, is higher than an S/N ratio of the micropipe in a second wafer cut out from a position further away from the seed crystal than the first wafer.
1 . A SiC ingot, comprising:
a seed crystal; and
a single crystal grown on the seed crystal,
wherein the single crystal has therein one or more micropipes passing through the single crystal in a growth direction, and impurities that are nitrogen, boron, aluminum, titanium, and vanadium, and
when photoluminescence observation is performed on a plurality of wafers cut out from the single crystal in a direction intersecting the growth direction, an S/N ratio of the one or more micropipes in a first wafer cut out of the plurality of wafers, which is closest to the seed crystal, is higher than an S/N ratio of the one or more micropipes in a second wafer cut out from a position further away from the seed crystal than the first wafer,
the S/N ratio of the one or more micropipes in the first wafer is 1.5 or more,
the S/N ratio of the one or more micropipes in the second wafer is 0.75 or less, and
wherein a concentration difference between impurity concentrations in a first region corresponding to the first wafer and impurity concentrations in a second region corresponding to the second wafer, which is 10 mm or more away from the first region in the growth direction, satisfies the following relationships:
impurity concentration difference of titanium: 1×10 16 impurity atoms/cm 3 or more
impurity concentration difference of vanadium: 1×10 14 impurity atoms/cm 3 or more, and
in the single crystal, impurity concentrations on the outermost surface on the terminal side in the growth direction satisfy the following relationships:
impurity concentration of titanium: 1×10 15 impurity atoms/cm 3 or more
impurity concentration of vanadium: 1×10 14 impurity atoms/cm 3 or more
a total impurity concentration of the impurities in the first region is higher than that in the second region, and
the total impurity concentration of the first region is 1×10 14 impurity atoms/cm 3 or more and the total impurity concentration of the second region is 2×10 19 impurity atoms/cm 3 or less.
2 . The SiC ingot according to claim 1 , wherein the closer the wafer is cut from the seed crystal, the higher the S/N ratio of the one or more micropipes in the wafer is.
3 . The SiC ingot according to claim 1 , wherein the closer the wafer is cut from the seed crystal, the higher the total impurity concentration in the wafer is.
4 . The SiC ingot according to claim 1 , wherein a diameter of the single crystal is 150 mm or more.
5 . The SiC ingot according to claim 1 , wherein a diameter of the single crystal is 200 mm or more.
6 . A SiC wafer which is cut out from the SiC ingot according to claim 1 .
7 . The SiC wafer according to claim 6 , wherein the density of the micropipes is 0.003 cm −2 or more and 10 cm −2 or less.
8 . The SiC ingot according to claim 1 ,
wherein the concentration difference between impurity concentrations in the first region and impurity concentrations in the second region satisfies the following relationships:
impurity concentration difference of nitrogen: 1×10 18 impurity atoms/cm 3 or more,
impurity concentration difference of boron: 3×10 16 impurity atoms/cm 3 or more, and
impurity concentration difference of aluminum: 3×10 16 impurity atoms/cm 3 or more, and
in the single crystal, impurity concentrations on the outermost surface on the terminal side in the growth direction satisfy the following relationships:
impurity concentration of nitrogen: 1×10 18 impurity atoms/cm 3 or more,
impurity concentration of boron: 1×10 15 impurity atoms/cm 3 or more, and
impurity concentration of aluminum: 1×10 15 impurity atoms/cm 3 or more.