Method of producing III-nitride substrate
An ingot 3 of a hexagonal III-nitride crystal is cut using a wire array 21 composed of a wire 22 . On this occasion, the ingot 3 is cut in such a manner that the ingot 3 is sliced with supply of an abrasive fluid while feeding at least one of the ingot 3 and wire 22 in a direction perpendicular to an extending direction B of the wire 22 . During cutting the ingot 3 , the extending direction B of the wire 22 is inclined at 3° or more to the {1-100} plane of the ingot 3.
1. A method of producing a III-nitride substrate by cutting an ingot of a hexagonal III-nitride crystal, using a wire array, comprising:
a step of cutting the ingot with supply of an abrasive fluid, while feeding at least one of the ingot and the wire array in a direction intersecting with an extending direction of a wire in the wire array,
wherein during cutting the ingot, the extending direction of the wire in the wire array is inclined at 3° or more to the {1-100} plane of the ingot.
2. The production method of the III-nitride substrate according to claim 1 , further comprising a step of forming an orientation flat along the (11-20) plane of the ingot in the ingot, prior to the step of cutting the ingot,
wherein during the step of cutting the ingot, an inclination angle of the extending direction relative to the (11-20) plane of the ingot is set at 27° or less.
3. The production method of the III-nitride substrate according to claim 1 , wherein during cutting the ingot, one or more other ingots are arranged in a direction intersecting with the feed direction of the ingot and said other ingots are cut together with the ingot.
4. The production method of the III-nitride substrate according to claim 1 , wherein abrasive grains contained in the abrasive fluid contain at least one material selected from diamond, silicon carbide, boron carbide, alumina, silicon nitride, aluminum nitride, and gallium nitride.
5. The production method of the III-nitride substrate according to claim 1 , wherein a concentration of abrasive grains in the abrasive fluid is set in the range of not less than 40 g nor more than 300 g per liter.
6. The production method of the III-nitride substrate according to claim 1 , wherein an average grain size of abrasive grains contained in the abrasive fluid is set in the range of not less than 1 μm nor more than 15 μm.
7. The production method of the III-nitride substrate according to claim 1 , wherein a feed speed during cutting the ingot is set in the range of not less than 0.4 mm nor more than 2.4 mm per hour.
8. The production method of the III-nitride substrate according to claim 1 , wherein the wire array is comprised of the wire having a diameter of not less than 0.12 mm nor more than 0.2 mm.