Method of manufacturing group III nitride substrate and semiconductor device

Abstract

The present invention provides a method of manufacturing a Group III nitride substrate that has less variations in in-plane carrier concentration and includes crystals grown at a high growth rate. The manufacturing method of the present invention includes: (i) forming a semiconductor layer (a seed layer 12) on a substrate, with the semiconductor layer being formed of a semiconductor expressed by a composition formula of Al u Ga v In 1−u−v N (wherein 0≦u≦1 and 0≦v≦1) and having a (0001) plane present at its surface; (ii) processing the surface of the semiconductor layer so that the surface becomes a plane sloped with respect to the (0001) plane of the semiconductor layer; and (iii) bringing the surface of the semiconductor layer into contact with a melt containing a solvent and at least one Group III element selected from gallium, aluminum, and indium, in an atmosphere containing nitrogen, to make the at least one Group III element and the nitrogen react with each other to grow Group III nitride crystals (GaN single crystals 13) on the semiconductor layer.

1 - 5 . (canceled)  
   
   
       6 . A method of manufacturing a Group III nitride substrate, the method comprising: 
 (i) forming a semiconductor layer on a substrate, the semiconductor layer being formed of a semiconductor expressed by a composition formula of Al u Ga v In 1−u−v N (wherein 0≦u ≦1 and 0≦v≦1) and having a (0001) plane present at its surface;    (ii) processing the surface of the semiconductor layer so that the surface becomes a plane sloped with respect to the (0001) plane of the semiconductor layer; and    (iii) bringing the surface of the semiconductor layer into contact with a melt containing a solvent and at least one Group III element selected from gallium, aluminum, and indium, in an atmosphere containing nitrogen, to make the at least one Group III element and the nitrogen react with each other to grow Group III nitride crystals on the semiconductor layer.    
   
   
       7 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the at least one Group III element is gallium, and the Group III nitride crystals are gallium nitride.  
   
   
       8 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the Group III nitride crystals are grown on the semiconductor layer at a growth rate of at least 20 μm/hr.  
   
   
       9 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the Group III nitride crystals that have grown on the semiconductor layer have variations in in-plane carrier concentration, the variations being within a range of one fifth to five times a carrier concentration mean value.  
   
   
       10 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the atmosphere containing nitrogen is a pressure atmosphere.  
   
   
       11 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the solvent is alkali metal.  
   
   
       12 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the solvent contains alkali metal and alkaline-earth metal.  
   
   
       13 . The method of manufacturing a Group III nitride substrate according to  claim 11 , wherein the alkali metal is at least one selected from a group consisting of sodium, lithium, and potassium.  
   
   
       14 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein in the process (ii), the surface of the semiconductor layer is processed by polishing.  
   
   
       15 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the processes (i) and (ii) are carried out simultaneously.  
   
   
       16 . The method of manufacturing a Group III nitride substrate according to  claim 15 , wherein the processes (i) and (ii) are carried out using temperature gradient provided during crystal growth.  
   
   
       17 . The method of manufacturing a Group III nitride substrate according to  claim 6 , wherein the substrate is made of sapphire.  
   
   
       18 - 19 . (canceled)