Method for manufacturing gallium nitride crystal and gallium nitride wafer

Abstract

There is provided a method for fabricating a gallium nitride crystal with low dislocation density, high crystallinity, and resistance to cracking during polishing of sliced pieces by growing the gallium nitride crystal using a gallium nitride substrate including dislocation-concentrated regions or inverted-polarity regions as a seed crystal substrate. Growing a gallium nitride crystal 79 at a growth temperature higher than 1,100° C. and equal to or lower than 1,300° C. so as to bury dislocation-concentrated regions or inverted-polarity regions 17 a reduces dislocations inherited from the dislocation-concentrated regions or inverted regions 17 a , thus preventing new dislocations from occurring over the dislocation-concentrated regions or inverted-polarity regions 17 a . This also increases the crystallinity of the gallium nitride crystal 79 and its resistance to cracking during the polishing.

1 - 78 . (canceled) 
     
     
         79 . A single-crystal gallium nitride wafer manufactured by a method for fabricating a gallium nitride crystal, comprising the steps of:
 preparing a gallium nitride substrate including first regions, a second region, and a primary surface, the first regions comprising single-crystal gallium nitride, the second region comprising single-crystal gallium nitride, a crystal axis of the single-crystal gallium nitride being opposite in orientation to that of the single-crystal gallium nitride in the first regions, the first regions being exposed in the first areas, and the second region being exposed in the second area;   forming recesses in the first areas and a mask over the recesses in the first areas to prepare a seed crystal substrate;   growing a gallium nitride crystal on the seed crystal substrate by liquid-phase deposition or vapor-phase deposition such that voids corresponding to the recesses are formed;   separating the gallium nitride crystal from an integrated piece of the gallium nitride crystal and the seed crystal substrate; and   forming a single-crystal gallium nitride wafer from the separated gallium nitride crystal,   wherein the crystal axis of the single-crystal gallium nitride has the same orientation in any region of the gallium nitride wafer.   
     
     
         80 . A single-crystal gallium nitride wafer manufactured by a method for fabricating a gallium nitride crystal, comprising the steps of:
 preparing a gallium nitride substrate including first regions, a second region, and a primary surface, the first regions comprising single-crystal gallium nitride, the second region comprising single-crystal gallium nitride, a crystal axis of the single-crystal gallium nitride being opposite in orientation to that of the single-crystal gallium nitride in the first regions, the first regions being exposed in the first areas, and the second region being exposed in the second area;   forming recesses in the first areas and a mask over the recesses in the first areas to prepare a seed crystal substrate;   growing a gallium nitride crystal on the seed crystal substrate by vapor-phase deposition at a growth temperature higher than 1,100° C. and equal to or lower than 1,300° C.;   separating the gallium nitride crystal from an integrated piece of the gallium nitride crystal and the seed crystal substrate; and   forming a single-crystal gallium nitride wafer from the separated gallium nitride crystal,   wherein the crystal axis of the single-crystal gallium nitride has the same orientation in any region of the gallium nitride wafer.   
     
     
         81 . The gallium nitride wafer according to  claim 79 , wherein the size of the gallium nitride wafer is 1 cm 2  or more. 
     
     
         82 . The gallium nitride wafer according to  claim 80 , wherein the size of the gallium nitride wafer is 1 cm 2  or more.