Freestanding III-Nitride Single-Crystal Substrate and Method of Manufacturing Semiconductor Device Utilizing the Substrate

Abstract

Freestanding III-nitride single-crystal substrates whose average dislocation density is not greater than 5×10 5 cm −2 and that are fracture resistant, and a method of manufacturing semiconductor devices utilizing such freestanding III-nitride single-crystal substrates are made available. The freestanding III-nitride single-crystal substrate includes one or more high-dislocation-density regions ( 20 h ), and a plurality of low-dislocation-density regions ( 20 k ) in which the dislocation density is lower than that of the high-dislocation-density regions ( 20 h ), wherein the average dislocation density is not greater than 5×10 5 cm −2 . Herein, the ratio of the dislocation density of the high-dislocation-density region(s) ( 20 h ) to the average dislocation density is sufficiently large to check the propagation of cracks in the substrate. And the semiconductor device manufacturing method utilizes the freestanding III-nitride single crystal substrate ( 20 p ).

1 . A freestanding III-nitride single-crystal substrate in which the average dislocation density is not greater than 5×10 5  cm −2 , including:
 one or more high-dislocation-density regions; and   a plurality of low-dislocation-density regions in which the dislocation density is lower than that of said high-dislocation-density regions.   
   
   
       2 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the ratio of the dislocation density of said high-dislocation-density region(s) to said average dislocation density is sufficiently large to check the propagation of cracks in said substrate. 
   
   
       3 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the ratio of the dislocation density of said high dislocation density region(s) to said average dislocation density is 2 or greater. 
   
   
       4 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the dislocation density of said high-dislocation-density region(s) is between 5×10 5  cm −2  and 3×10 6  cm −2 . 
   
   
       5 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the dislocation density of said low-dislocation-density regions is not greater than 1×10 5  cm −2 . 
   
   
       6 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein:
 the substrate has a hexagonal crystal-system structure; and   any chosen {1-100} plane in said substrate intersects said one or more high-dislocation-density regions.   
   
   
       7 . A freestanding III-nitride single-crystal substrate as set forth in  claim 6 , wherein: said one or more high-dislocation-density regions are patterned in a geometry, seen from the major surface of the substrate, that includes any of: striped patterns, polygonally checkered patterns, periodically arrayed islet patterns, or nonrepetitive patterns. 
   
   
       8 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein:
 the surface area of the substrate major surface is 20 cm 2  or greater; and   the substrate thickness is 1000 μm or less.   
   
   
       9 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the substrate is a GaN single-crystal freestanding substrate. 
   
   
       10 . A freestanding III-nitride single-crystal substrate as set forth in  claim 1 , wherein the substrate is formed by HVPE. 
   
   
       11 . A method of manufacturing a semiconductor device utilizing a freestanding III-nitride single-crystal substrate as set forth in  claim 1 .