Group III nitride semiconductor substrate and manufacturing method thereof

Abstract

A method of manufacturing a group III nitride semiconductor substrate includes the growth step of epitaxially growing a first group III nitride semiconductor layer on an underlying substrate, and the process step of forming a first group III nitride semiconductor substrate by cutting and/or surface-polishing the first group III nitride semiconductor layer. In the growth step, at least one element selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb is added as an impurity element by at least 1×10 17 cm −3 to the first group III nitride semiconductor layer. A group III nitride semiconductor substrate having controlled resistivity and low dislocation density and a manufacturing method thereof can thus be provided.

1 . A group III nitride semiconductor substrate containing at least one element selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb as an impurity element in concentration of at least 1×10 17  cm −3 ; wherein 
 in-plane distribution of the concentration of said impurity element represented as a ratio of a maximum concentration to a minimum concentration of said impurity element in a main surface of the substrate is in a range from at least 1 to at most 3, and    said group III nitride semiconductor substrate has resistivity of at least 1×10 4  Ω·cm and thickness of at least 70 μm.    
   
   
       2 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 average dislocation density is at most 1×10 7  cm −2 , and surface density of a dislocation-concentrated region where dislocation density exceeds 1×10 8  cm −2  is at most 1 cm 2 .    
   
   
       3 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 said group III nitride is GaN.    
   
   
       4 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 said main surface of said group III nitride semiconductor substrate is at an angle in a range from at least −5° to at most 5° with respect to any one of a (0001) surface, a (1-100) surface and a (11-20) surface.    
   
   
       5 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 a half-width of a rocking curve in X-ray diffraction is in a range from at least 10 arcsec to at most 500 arcsec.    
   
   
       6 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 carrier density is at most 1×10 15  cm −3 .    
   
   
       7 . The group III nitride semiconductor substrate according to  claim 1 , wherein 
 absorption coefficient for light having a wavelength of 450 nm is at least 50 cm −1 .    
   
   
       8 . A group IIIi nitride semiconductor substrate containing at least one element selected from the group consisting of O, Si, S, Ge, Se, and Te as an impurity element in concentration of at least 1×10 17  cm −3 ; wherein 
 in-plane distribution of the.concentration of said impurity element represented as a ratio of a maximum concentration to a minimum concentration of said impurity element in a main surface of the substrate is in a range from at least 1 to at most 3, and    said group III nitride semiconductor substrate has resistivity of at most 1 Ω·cm and thickness of at least 70 μm.    
   
   
       9 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 average dislocation density is at most 1×10 7  cm −2 , and surface density of a dislocation-concentrated region where dislocation density exceeds 1×10 8  cm −2  is at most 1 cm −2 .    
   
   
       10 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 said group III nitride is GaN.    
   
   
       11 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 said main surface of said group III nitride semiconductor substrate is at an angle in a range from at least −5° to at most 5° with respect to any one of a (0001) surface, a (1-100) surface and a (11-20) surface.    
   
   
       12 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 a half-width of a rocking curve in X-ray diffraction is in a range from at least 10 arcsec to at most 500 arcsec.    
   
   
       13 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 carrier density is in a range from at least 1×10 17  cm −3  to at most 1×10 20  cm −3 .    
   
   
       14 . The group III nitride semiconductor substrate according to  claim 8 , wherein 
 absorption coefficient for light of a wavelength of 450 nm is at most 10 cm −1 .    
   
   
       15 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a first group III nitride semiconductor layer on an underlying substrate; and    the process step of forming a first group III nitride semiconductor substrate by cutting and/or surface-polishing said first group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb is added as an impurity element by at least 1×10 17  cm −3  to said first group III nitride semiconductor layer.    
   
   
       16 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a second group III nitride semiconductor layer on said first group III nitride semiconductor layer epitaxially grown in the manufacturing method according to  claim 15;  and    the process step of forming a second group III nitride semiconductor substrate by cutting and/or surface-polishing said second group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of O, Si, S, Ge, Se, and Te is added as an impurity element by at least 1×10 17  cm −3  to said second group III nitride semiconductor layer.    
   
   
       17 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a third group III nitride semiconductor layer on said second group III nitride semiconductor substrate formed in the manufacturing method according to  claim 16;  and    the process step of forming a third group III nitride semiconductor substrate by cutting and/or surface-polishing said third group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb is added as an impurity element by at least 1×10 17  cm −3  to said third group III nitride semiconductor layer.    
   
   
       18 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a fourth group III nitride semiconductor layer on said second group III nitride semiconductor substrate formed in the manufacturing method according to  claim 16;  and    the process step of forming a fourth group III nitride semiconductor substrate by cutting and/or surface-polishing said fourth group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of O, Si, S, Ge, Se, and Te is added as an impurity element by at least 1×10 17  cm −3  to said fourth group III nitride semiconductor layer.    
   
   
       19 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 16 , wherein 
 at least one raw material selected from the group consisting of oxygen, water, dichlorosilane, tetrachlorosilane, hydrogen sulfide, germanium chloride, selenium chloride, and tellurium chloride is used as a raw material for said impurity element.    
   
   
       20 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a third group III nitride semiconductor layer on said first group III nitride semiconductor substrate formed in the manufacturing method according to  claim 15;  and    the process step of forming a third group III nitride semiconductor substrate by cutting and/or surface-polishing said third group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb is added as an impurity element by at least 1×10 17  cm −3  to said third group III nitride semiconductor layer.    
   
   
       21 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 20 , wherein 
 at least one raw material selected from the group consisting of methane, magnesium chloride, iron chloride, beryllium chloride, zinc chloride, vanadium chloride, and antimony chloride is used as a raw material for said impurity element.    
   
   
       22 . A method of manufacturing a group III nitride semiconductor substrate, comprising: 
 the growth step of epitaxially growing a fourth group III nitride semiconductor layer on said first group III nitride semiconductor substrate formed in the manufacturing method according to  claim 15;  and    the process step of forming a fourth group III nitride semiconductor substrate by cutting and/or surface-polishing said fourth group III nitride semiconductor layer; wherein    in said growth step, at least one element selected from the group consisting of O, Si, S, Ge, Se, and Te is added as an impurity element by at least 1×10 17  cm −3  to said fourth group III nitride semiconductor layer.    
   
   
       23 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 22 , wherein 
 at least one raw material selected from the group consisting of oxygen, water, dichlorosilane, tetrachlorosilane, hydrogen sulfide, germanium chloride, selenium chloride, and tellurium chloride is used as a raw material for said impurity element.    
   
   
       24 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 15 , wherein 
 any one of a GaAs substrate, a sapphire substrate, an Si substrate, and an SiC substrate is employed as said underlying substrate.    
   
   
       25 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 24 , wherein 
 said growth step is performed after a mask layer having openings is formed on at least a part of said underlying substrate.    
   
   
       26 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 15 , wherein 
 a group III nitride substrate obtained in a facet growth method is employed as said underlying substrate.    
   
   
       27 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 26 , wherein 
 said growth step is performed after a mask layer having openings is formed on at least a part of said underlying substrate.    
   
   
       28 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 15 , wherein 
 a main surface of said underlying substrate is at an angle in a range from at least −5° to at most 5° with respect to any one of a (0001) surface, a (1-100) surface and a (11-20) surface.    
   
   
       29 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 15 , wherein 
 in said growth step, said group III nitride semiconductor layer is grown while a growth surface of said group III nitride semiconductor layer maintains a flat uniform surface.    
   
   
       30 . The method of manufacturing a group III nitride semiconductor substrate according to  claim 15 , wherein 
 at least one raw material selected from the group consisting of methane, magnesium chloride, iron chloride, beryllium chloride, zinc chloride, vanadium chloride, and antimony chloride is used as a raw material for said impurity element.