Method of manufacturing nitride substrate, and nitride substrate

Abstract

A method of manufacturing a nitride substrate includes the following steps. Firstly, a nitride crystal is grown. Then, the nitride substrate including a front surface is cut from the nitride crystal. In the step of cutting, the nitride substrate is cut such that an off angle formed between an axis orthogonal to the front surface and an m-axis or an a-axis is greater than zero. When the nitride crystal is grown in a c-axis direction, in the step of cutting, the nitride substrate is cut from the nitride crystal along a flat plane which passes through a front surface and a rear surface of the nitride crystal and does not pass through a line segment connecting a center of a radius of curvature of the front surface with a center of a radius of curvature of the rear surface of the nitride crystal.

1 . A method of manufacturing a nitride substrate, comprising the steps of:
 growing a nitride crystal; and   cutting the nitride substrate including a front surface from said nitride crystal,   wherein, in said step of cutting, said nitride substrate is cut such that an off angle formed between an axis orthogonal to said front surface and an m-axis or an a-axis is greater than zero.   
     
     
         2 . The method of manufacturing a nitride substrate according to  claim 1 , wherein, in said step of cutting, said nitride substrate is cut such that said nitride substrate includes said front surface having a first region and a second region surrounding said first region, and said off angle has a minimum value at a first point in said second region. 
     
     
         3 . The method of manufacturing a nitride substrate according to  claim 2 , wherein, in said step of cutting, said nitride substrate is cut such that said second region is within 2 mm from an edge of said nitride substrate. 
     
     
         4 . The method of manufacturing a nitride substrate according to  claim 2 , wherein, in said step of cutting, said nitride substrate is cut such that said off angle has a maximum value at a second point in said second region, and said off angle monotonically decreases from said second point to said first point. 
     
     
         5 . The method of manufacturing a nitride substrate according to  claim 1 , wherein, in said step of cutting, said nitride substrate is cut from said nitride crystal along a flat plane parallel to a flat plane inclined from an a-plane or an m-plane in a c-axis direction. 
     
     
         6 . The method of manufacturing a nitride substrate according to  claim 1 , further comprising the step of performing at least one of polishing and grinding of said front surface of said nitride substrate after said step of cutting. 
     
     
         7 . The method of manufacturing a nitride substrate according to  claim 1 , wherein, in said step of cutting, a plurality of said nitride substrates are cut. 
     
     
         8 . A method of manufacturing a nitride substrate, comprising the steps of:
 growing, in a c-axis direction, a nitride crystal including a front surface and a rear surface opposite to said front surface; and   cutting the nitride substrate from said nitride crystal,   wherein, in said step of cutting, said nitride substrate is cut from said nitride crystal along a flat plane which passes through said front surface and said rear surface of said nitride crystal and does not pass through a line segment connecting a center of a radius of curvature of said front surface with a center of a radius of curvature of said rear surface of said nitride crystal.   
     
     
         9 . The method of manufacturing a nitride substrate according to  claim 8 , wherein, in said step of cutting, said nitride substrate is cut such that said nitride substrate includes a front surface having a first region and a second region surrounding said first region, and an off angle formed between an axis orthogonal to said front surface and an m-axis or an a-axis has a minimum value at a first point in said second region. 
     
     
         10 . The method of manufacturing a nitride substrate according to  claim 9 , wherein, in said step of cutting, said nitride substrate is cut such that said second region is within 2 mm from an edge of said nitride substrate. 
     
     
         11 . The method of manufacturing a nitride substrate according to  claim 9 , wherein, in said step of cutting, said nitride substrate is cut such that said off angle has a maximum value at a second point in said second region, and said off angle monotonically decreases from said second point to said first point. 
     
     
         12 . The method of manufacturing a nitride substrate according to  claim 8 , wherein, in said step of cutting, said nitride substrate is cut from said nitride crystal along said flat plane parallel to a flat plane inclined from an a-plane or an m-plane in the c-axis direction. 
     
     
         13 . The method of manufacturing a nitride substrate according to  claim 8 , further comprising the step of performing at least one of polishing and grinding of a front surface of said nitride substrate after said step of cutting. 
     
     
         14 . The method of manufacturing a nitride substrate according to  claim 8 , wherein, in said step of cutting, a plurality of said nitride substrates are cut. 
     
     
         15 - 19 . (canceled)