Method of Manufacturing III Nitride Crystal, III Nitride Crystal Substrate, and Semiconductor Device

Abstract

Affords III-nitride crystals having a major surface whose variance in crystallographic plane orientation with respect to an {hkil} plane chosen exclusive of the { 0001} form is minimal. A method of manufacturing the III-nitride crystal is one of: conditioning a plurality of crystal plates ( 10 ) in which the deviation in crystallographic plane orientation in any given point on the major face ( 10 m ) of the crystal plates ( 10 ), with respect to an {hkil} plane chosen exclusive of the { 0001} form, is not greater than 0.5′; arranging the plurality of crystal plates ( 10 ) in a manner such that the plane-orientation deviation, with respect to the {hkil} plane, in any given point on the major-face ( 10 m ) collective surface ( 10 a ) of the plurality of crystal plates ( 10 ) will be not greater than 0.5° , and such that at least a portion of the major face ( 10 m ) of the crystal plates ( 10 ) is exposed; and growing second III-nitride crystal ( 20 ) onto the exposed areas of the major faces ( 10 m ) of the plurality of crystal plates ( 10 ).

1 . A III-nitride crystal substrate comprising:
 an undersubstrate constituted by a plurality of first III-nitride crystal plates each defining a major face and adjoining one another so as to form a major-face collective surface, said plates being:
 conditioned to a deviation in crystallographic plane orientation in any given point on the major face of each crystal plate, with respect to an {hkil} plane being a crystallographic plane chosen exclusive of the { 0001 } form, of not greater than 0.5°, and 
 arranged in a manner such that the plane-orientation deviation, with respect to said {hkil} plane, in any given point on the major-face collective surface of the plurality of crystal plates is not greater than 0.5°, and such that at least a portion of the major face of each crystal plate is exposed; and 
   second III-nitride crystal on the major-face collective surface of said undersubstrate, said second III-nitride crystal incorporating and unifying first crystal regions on the exposed areas of the major faces of each crystal plate, and second crystal regions where the first crystal regions merge with each other.   
     
     
         2 . A III-nitride crystal substrate as set forth in  claim 1 , wherein in said plurality of first III-nitride crystal plates constituting said undersubstrate:
 the deviation in crystallographic plane orientation in any given point on the major face of each crystal plate, with respect to an {hkil} plane, is not greater than 0.2°; and   the plane-orientation deviation, with respect to the {hkil} plane, in any given point on the major-face collective surface of said plurality of first III-nitride crystal plates is not greater than 0.2°.   
     
     
         3 . A III-nitride crystal substrate as set forth in  claim 1 , wherein the second III-nitride crystal has a major surface perpendicular to the growth axis of the second III-nitride crystal. 
     
     
         4 . A III-nitride crystal substrate as set forth in  claim 2 , wherein the second III-nitride crystal has a major surface perpendicular to the growth axis of the second III-nitride crystal. 
     
     
         5 . A III-nitride crystal substrate as set forth in  claim 3 , wherein deviation with respect to said {hkil} plane being a crystallographic plane chosen exclusive of the { 0001 } form, in each of points arrayed at a 1-mm pitch within the major surface of the second III-nitride crystal is not greater than 0.6°. 
     
     
         6 . A III-nitride crystal substrate as set forth in  claim 4 , wherein deviation with respect to said {hkil} plane being a crystallographic plane chosen exclusive of the { 0001 } form, in each of points arrayed at a 1-mm pitch within the major surface of the second III-nitride crystal is not greater than 0.6°. 
     
     
         7 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 1 . 
     
     
         8 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 2 . 
     
     
         9 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 3 . 
     
     
         10 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 4 . 
     
     
         11 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 5 . 
     
     
         12 . A semiconductor device built on a III-nitride crystal substrate as set forth in  claim 6 .