Semiconductor apparatus, method for growing nitride semiconductor and method for producing semiconductor apparatus

Abstract

A semiconductor apparatus includes a substrate made of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Tl, Zr, Nb and Hf, a semiconductor buffer layer formed on a principal surface of the substrate and made of Al y Ga 1-y N (0<y≦1), and a nitride semiconductor layer which is formed on the semiconductor buffer layer and which includes at least one kind or plural kinds selected from among 13 group elements and As.

1 . A semiconductor apparatus comprising: 
 a substrate made of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Ti, Zr, Nb and Hf;    a semiconductor buffer layer formed on a principal surface of the substrate and made of Al y Ga 1-y N (0<y≦1); and    a nitride semiconductor layer formed on the semiconductor buffer layer, including at least one kind or plural kinds selected from among 13 group elements and As.    
   
   
       2 . A semiconductor apparatus comprising: 
 a substrate made of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Ti, Zr, Nb and Hf;    a semiconductor buffer layer formed on a principal surface of the substrate and made of (AlN) x (GaN) 1-x  (0<x≦1); and    a nitride semiconductor layer formed on the semiconductor buffer layer, including at least one kind or plural kinds selected from among 13 group elements and As.    
   
   
       3 . The semiconductor apparatus of  claim 1 , wherein the substrate is of ZrB 2  or TiB 2 .  
   
   
       4 . The semiconductor apparatus of  claim 2 , wherein the substrate is of ZrB 2  or TiB 2 .  
   
   
       5 . The semiconductor apparatus of  claim 1 , wherein the substrate is a solid solution containing one or a plurality of impurity elements of 5 atom % or less, the one or a plurality of impurity elements being selected from a group consisting of Ti, Cr, Hf, V, Ta and Nb when the substrate is of ZrB 2 , or selected from a group consisting of Zr, Cr, Hf, V, Ta and Nb when the substrate is of TiB 2 .  
   
   
       6 . The semiconductor apparatus of  claim 2 , wherein the substrate is a solid solution containing one or a plurality of impurity elements of 5 atom % or less, the one or a plurality of impurity elements being selected from a group consisting of Ti, Cr, Hf, V, Ta and Nb when the substrate is of ZrB 2 , or selected from a group consisting of Zr, Cr, Hf, V, Ta and Nb when the substrate is of TiB 2 .  
   
   
       7 . The semiconductor apparatus of  claim 1 , wherein the semiconductor buffer layer is AlN.  
   
   
       8 . The semiconductor apparatus of  claim 2 , wherein the semiconductor buffer layer is AlN.  
   
   
       9 . The semiconductor apparatus of  claim 7 , wherein the thickness of the semiconductor buffer layer made of AlN is 10 to 250 nm.  
   
   
       10 . The semiconductor apparatus of  claim 8 , wherein the thickness of the semiconductor buffer layer made of AlN is 10 to 250 nm.  
   
   
       11 . The semiconductor apparatus of  claim 2 , wherein the thickness of the semiconductor buffer layer made of (AlN) x (GaN) 1-x  is within a range of 10 to 100 nm.  
   
   
       12 . The semiconductor apparatus of  claim 2 , wherein x of the semiconductor buffer layer made of (AlN) x (GaN) 1-x  is 0.1≦x≦1.  
   
   
       13 . The semiconductor apparatus of  claim 2 , wherein x of the semiconductor buffer layer made of (AlN) x (GaN) 1-x  is 0.4≦x≦0.6.  
   
   
       14 . The semiconductor apparatus of  claim 1 , wherein an angle θ 1  formed by a normal line of the principal surface of the substrate and a normal line of the (0001) plane of the substrate is 0°≦θ 1 ≦5°.  
   
   
       15 . The semiconductor apparatus of  claim 2 , wherein an angle θ 1  formed by a normal line of the principal surface of the substrate and a normal line of the (0001) plane of the substrate is 0°≦θ 1 ≦5°.  
   
   
       16 . The semiconductor apparatus of  claim 7 , wherein an angle θ 1  formed by a normal line of the principal surface of the substrate and a normal line of the (0001) plane of the substrate is 0°≦O 1 ≦0.55°.  
   
   
       17 . The semiconductor apparatus of  claim 8 , wherein an angle O 1  formed by a normal line of the principal surface of the substrate and a normal line of the (0001) plane of the substrate is 0°≦θ 1 ≦0.55°.  
   
   
       18 . The semiconductor apparatus of  claim 1 , wherein the substrate is eroded and removed by etching.  
   
   
       19 . The semiconductor apparatus of  claim 2 , wherein the substrate is eroded and removed by etching.  
   
   
       20 . A method for growing a nitride semiconductor, comprising: 
 on a substrate of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Ti, Zr, Nb and Hf, growing Al y Ga 1-y N layer (0<y≦1) from vapor phase, and subsequently, growing a nitride semiconductor layer including at least one kind selected from among 13 group elements and As from vapor phase.    
   
   
       21 . A method for growing a nitride semiconductor, comprising: 
 on a substrate of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Ti, Zr, Nb and Hf, growing an (AlN) x (GaN) 1-x  layer (1<x≦1) from vapor phase within a temperature range of more than 400° C. and less than 1100° C. by an MOVPE method, and subsequently, growing a nitride semiconductor layer including at least one kind selected from among 13 group elements and As from vapor phase.    
   
   
       22 . The method of  claim 21 , wherein the thickness of the (AlN) x (GaN) 1-x  layer is within a range of 10 to 100 nm.  
   
   
       23 . A method for growing a nitride semiconductor, comprising: 
 on the (0001) plane of a substrate of a diboride single crystal expressed by a chemical formula XB 2 , in which X includes at least one of Ti, Zr, Nb and Hf, growing an AlN layer from vapor phase so that a deviation angle of a normal line of a surface of the substrate from a direction of the [0001] becomes 0.55 degrees or less, and subsequently, growing a nitride semiconductor layer including at least one kind selected from among 13 group elements and As from vapor phase.    
   
   
       24 . The method of  claim 23 , wherein the thickness of the AlN layer is within a range of 10 to 250 nm.  
   
   
       25 . A method for producing a semiconductor apparatus, comprising: 
 eroding and removing a diboride single crystal substrate of a semiconductor apparatus obtained by the method for growing nitride semiconductor of  claim 21  by etching.    
   
   
       26 . A method for producing a semiconductor apparatus, comprising: 
 eroding and removing a diboride single crystal substrate of a semiconductor apparatus obtained by the method for growing nitride semiconductor of  claim 22  by etching.    
   
   
       27 . A method for producing a semiconductor apparatus, comprising: 
 eroding and removing a diboride single crystal substrate of a semiconductor apparatus obtained by the method for growing nitride semiconductor of  claim 23  by etching.    
   
   
       28 . A method for producing a semiconductor apparatus, comprising: 
 eroding and removing a diboride single crystal substrate of a semiconductor apparatus obtained by the method for growing nitride semiconductor of  claim 24  by etching.    
   
   
       29 . A method for producing a semiconductor apparatus, comprising the steps of: 
 carrying out crystal growth of a nitride semiconductor layer on one principal surface of a single crystal substrate of a hexagonal crystal symmetry having electrical conductivity; and    eroding and removing the single crystal substrate by etching.    
   
   
       30 . The method of  claim 29 , wherein the single crystal substrate is a substrate of a diboride single crystal expressed by XB 2 , in which X includes at least one of Zr and Ti.  
   
   
       31 . The method of  claim 29 , wherein in growing the nitride semiconductor layer from vapor phase, a nitride semiconductor layer grown firstly is an Al x Ga 1-x  layer (0<x≦1).  
   
   
       32 . The method of  claim 29 , wherein a mixed solution of at least nitric acid and hydrofluoric acid is used for the etching.