METHOD FOR MANUFACTURING HEXAGONAL SEMICONDUCTOR PLATE CRYSTAL
A method of efficiently manufacturing a hexagonal semiconductor plate crystal with small warpage is provided. The method of manufacturing a hexagonal semiconductor plate crystal is a method of manufacturing a hexagonal semiconductor plate crystal by cutting a hexagonal semiconductor crystal using a crystal cutting wire, wherein the hexagonal semiconductor crystal is cut by causing the crystal cutting wire to move relative to the hexagonal semiconductor crystal so as to satisfy the conditions of 25°<α≦90° and β=90°±5° where α represents an angle formed by the c axis of the hexagonal semiconductor crystal and the normal line of the crystal face cut out by the wire and β represents an angle formed by a reference axis, which is obtained by perpendicularly projecting the c axis of the hexagonal semiconductor crystal to the crystal face cut out by the wire, and a cutting direction.
1 . A method of manufacturing a hexagonal semiconductor plate crystal by cutting a hexagonal semiconductor crystal using a crystal cutting wire,
wherein the hexagonal semiconductor crystal is cut by causing the crystal cutting wire to move relative to the hexagonal semiconductor crystal so as to satisfy conditions of Expressions (A) and (B):
25°<α≦90° Expression (A); and
β=90°±5° Expression (B)
where α represents an angle formed by a c axis of the hexagonal semiconductor crystal and a normal line of a crystal face cut out by the wire, and β represents an angle formed by a reference axis, which is obtained by perpendicularly projecting the c axis of the hexagonal semiconductor crystal to the crystal face cut out by the wire, and a cutting direction.
2 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein a moving speed of the crystal cutting wire in the cutting direction is equal to or more than 1 mm/h.
3 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein the hexagonal semiconductor plate crystal is cut by causing the crystal cutting wire to move so as to satisfy a condition of Expression (C):
0°≦γ<75° Expression (C)
where γ represents an angle formed by an extending direction of the crystal cutting wire and the reference axis.
4 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein a magnitude of warpage of the plate crystal is equal to or less than 1.0 μm/mm.
5 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein a maximum diameter of the plate crystal is equal to or more than 10 mm.
6 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein the plate crystal is manufactured by cutting two or more faces at a time using a plurality of crystal cutting wires installed in parallel with a specific gap therebetween.
7 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein a face formed by the cutting is ground after the cutting.
8 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein the hexagonal semiconductor crystal is a Group-III nitride semiconductor crystal.
9 . The method of manufacturing a hexagonal semiconductor plate crystal according to claim 1 , wherein the hexagonal semiconductor crystal is a gallium nitride crystal.