Semiconductor device and method for manufacturing semiconductor device

Abstract

A semiconductor device of the present invention includes: a III-V nitride semiconductor layer including a channel region in which carriers travel; a concave portion provided in an upper portion of the channel region in the III-V nitride semiconductor layer; and a Schottky electrode consisting of a conductive material forming a Schottky junction with the semiconductor layer, and formed on a semiconductor layer, which spreads over the concave portion and peripheral portions of the concave portion, on the III-V nitride semiconductor layer. A dimension of the concave portion in a depth direction is set so that a portion of the Schottky electrode provided in the concave portion can adjust a quantity of the carriers traveling in the channel region.

1 . A semiconductor device, comprising: 
 a III-V nitride semiconductor layer including a channel region in which carriers travel;    a concave portion provided in an upper portion of said channel region in said III-V nitride semiconductor layer; and    a Schottky electrode consisting of a conductive material forming a Schottky junction with the semiconductor layer, and formed on a semiconductor layer, which spreads over said concave portion and peripheral portions of the concave portion, on said III-V nitride semiconductor layer,    wherein a dimension of said concave portion in a depth direction is set so that a portion of said Schottky electrode provided in said concave portion can adjust a quantity of the carriers traveling in said channel region.    
     
     
         2 . The semiconductor device of  claim 1 , further comprising a film provided between said III-V nitride semiconductor layer and said Schottky electrode so as to open an upper side of said concave portion.  
     
     
         3 . The semiconductor device of  claim 1 , wherein said concave portion is provided so that an opening dimension is smaller from an upper surface side of said III-V nitride semiconductor layer toward a bottom side of said III-V nitride semiconductor layer.  
     
     
         4 . The semiconductor device of  claim 3 , wherein said concave portion is provided so that said opening dimension is linearly changed.  
     
     
         5 . The semiconductor device of  claim 4 , further comprising a film consisting of a crystalline material and provided between said III-V nitride semiconductor layer and said Schottky electrode so as to open an upper side of said concave portion.  
     
     
         6 . The semiconductor device of  claim 3 , wherein said concave portion is provided so that said opening dimension is nonlinearly changed.  
     
     
         7 . The semiconductor device of  claim 6 , further comprising a film consisting of an amorphous material and provided between said III-V nitride semiconductor layer and said Schottky electrode so as to open an upper side of said concave portion.  
     
     
         8 . A method for manufacturing a semiconductor device comprising steps of: 
 sequentially forming a III-V nitride semiconductor layer and a concave portion transfer film on a substrate;    forming a first concave portion in said concave portion transfer film; and    etching said concave portion transfer film by a predetermined depth using etching capable of etching said III-V nitride semiconductor layer and said concave portion transfer film, and thereby forming a second concave portion that has an equivalent shape to a shape of said first concave portion, below said first concave portion in said III-V nitride semiconductor layer.    
     
     
         9 . The method for manufacturing a semiconductor device of  claim 8 , wherein 
 said concave portion transfer film consists of a crystalline material, and    the step of forming said first concave portion includes steps of:    forming a first mask pattern that includes an opening portion in a region in which said first concave portion is formed, on said concave portion transfer film; and    removing a part of said concave portion transfer film which part is exposed to said opening portion of said first mask pattern by a predetermined depth by anisotropic etching.    
     
     
         10 . The method for manufacturing a semiconductor device of  claim 9 , wherein 
 said crystalline material is one of gallium arsenide, silicon, silicon carbide, gallium phosphide, and diamond.    
     
     
         11 . The method for manufacturing a semiconductor device of  claim 9 , wherein 
 said concave portion transfer film contains impurities consisting of a group IV element or a group V element.    
     
     
         12 . The method for manufacturing a semiconductor device of  claim 9 , further comprising a step, after the step of forming said second concave portion, of conducting a heat treatment to said III-V nitride semiconductor layer under conditions of a temperature of 300° C. or more and 1500° C. or less.  
     
     
         13 . The method for manufacturing a semiconductor device of  claim 9 , wherein 
 at the step of forming said second concave portion, an etching depth of the etching on said concave portion transfer film is set so that said concave portion transfer film remains on an upper surface of said III-V nitride semiconductor layer, and    the method further comprises steps of:    forming a second mask pattern that covers said second concave portion and peripheral portions of the second concave portion, on said concave portion transfer film after the step of forming said second concave portion; and    forming a film that covers the peripheral portions of the second concave portion from said concave portion transfer film by etching using said second mask pattern.    
     
     
         14 . The method for manufacturing a semiconductor device of  claim 13 , further comprising a step, between the step of forming said second concave portion and the step of forming said film, of conducting a heat treatment to said III-V nitride semiconductor layer at a temperature of 300° C. or more and 1500° C. or less.  
     
     
         15 . The method for manufacturing a semiconductor device of  claim 13 , wherein 
 said crystalline material that constitutes said concave portion transfer film is one of silicon, silicon carbide, gallium phosphide, and diamond.    
     
     
         16 . The method for manufacturing a semiconductor device of  claim 13 , further comprising a step, after the step of forming said second concave portion, of oxidizing, nitriding, or oxynitriding a surface of said concave portion transfer film.  
     
     
         17 . The method for manufacturing a semiconductor device of  claim 8 , wherein 
 said concave portion transfer film consists of an amorphous material, and    the step of forming said first concave portion includes steps of:    forming a first mask pattern that includes an opening portion in a region in which said first concave portion is formed, on said concave portion transfer film; and    removing a part of said concave portion transfer film which part is exposed to the opening portion of said first mask pattern by a predetermined depth by isotropic etching.    
     
     
         18 . The method for manufacturing a semiconductor device of  claim 17 , wherein 
 said amorphous material is one of amorphous silicon, silicon oxide, silicon nitride, silicon carbide, and a III-V nitride semiconductor.    
     
     
         19 . The method for manufacturing a semiconductor device of  claim 17 , wherein 
 said concave portion transfer film contains impurities consisting of a group IV element or a group V element.    
     
     
         20 . The method for manufacturing a semiconductor device of  claim 17 , wherein 
 at the step of forming said second concave portion, an etching depth of the etching on said concave portion transfer film is set so that said concave portion transfer film remains on an upper surface of said III-V nitride semiconductor layer, and    the method further comprises steps of:    forming a second mask pattern that covers said second concave portion and peripheral portions of the second concave portion, on said concave portion transfer film after the step of forming said second concave portion; and    forming a film that covers the peripheral portions of the second concave portion from said concave portion transfer film by etching using said second mask pattern.    
     
     
         21 . The method for manufacturing a semiconductor device of  claim 20 , further comprising a step, between the step of forming said second concave portion and the step of forming said film, of conducting a heat treatment to said III-V nitride semiconductor layer at a temperature of 300° C. or more and 1500° C. or less.  
     
     
         22 . The method for manufacturing a semiconductor device of  claim 20 , further comprising a step, after the step of forming said second concave portion, of oxidizing, nitriding, or oxynitriding a surface of said concave portion transfer film.  
     
     
         23 . The method for manufacturing a semiconductor device of  claim 8 , wherein 
 said concave portion transfer film consists of a polycrystalline material, and    the step of forming said first concave portion includes steps of:    forming a first mask pattern that includes an opening portion in a region in which said first concave portion is formed, on said concave portion transfer film; and    removing a part of said concave portion transfer film which part is exposed to the opening portion of said first mask pattern by a predetermined depth by isotropic etching.    
     
     
         24 . The method for manufacturing a semiconductor device of  claim 23 , wherein 
 said polycrystalline material is one of gallium arsenide, silicon, silicon carbide, gallium phosphide, diamond, and a III-V nitride semiconductor.    
     
     
         25 . The method for manufacturing a semiconductor device of  claim 23 , wherein 
 said concave portion transfer film contains impurities consisting of a group IV element or a group V element.    
     
     
         26 . The method for manufacturing a semiconductor device of  claim 23 , wherein 
 at the step of forming said second concave portion, an etching depth of the etching on said concave portion transfer film is set so that said concave portion transfer film remains on an upper surface of said III-V nitride semiconductor layer, and    the method further comprises steps of:    forming a second mask pattern that covers said second concave portion and peripheral portions of the second concave portion, on said concave portion transfer film after the step of forming said second concave portion; and    forming a film that covers the peripheral portions of the second concave portion from said concave portion transfer film by etching using said second mask pattern.    
     
     
         27 . The method for manufacturing a semiconductor device of  claim 26 , further comprising a step, between the step of forming said second concave portion and the step of forming said film, of conducting a heat treatment to said III-V nitride semiconductor layer at a temperature of 300° C. or more and 1500° C. or less.  
     
     
         28 . The method for manufacturing a semiconductor device of  claim 26 , further comprising a step, after the step of forming said second concave portion, of oxidizing, nitriding, or oxynitriding a surface of said concave portion transfer film.