Semiconductor device having low interface state density and method for fabricating the same

Abstract

The semiconductor device comprises an intermediate layer formed on a semiconductor substrate 6 , the intermediate layer 12 being formed of an oxide containing a first element which is either of a III group element and a V group element, an insulation film formed on the intermediate layer, the insulation film being formed of an oxide of a second element which is the other of the III group element and the V group element, and an electrode 16 formed on the insulation film. Because the intermediate layer of the oxide containing the first element is formed, even when the gate insulation film is formed of Al 2 O 3 or others, the interface state density can be depressed to be low. Thus, the semiconductor device can have low interface state density and small flat band voltage shift even when Al 2 O 3 , etc. is used as a material of the insulation film.

1 - 14 . (canceled)  
   
   
       15 . A semiconductor device comprising: 
 an insulation film formed on a semiconductor substrate, the insulation film being formed of an oxide of either of a III group element and a V group element;    an intermediate layer formed on the insulation film, the intermediate layer being formed of an oxide containing the other of the III group element and the V group element; and    an electrode formed on the intermediate layer.    
   
   
       16 . A method for fabricating a semiconductor device comprising the steps of: 
 forming an intermediate layer of an oxide containing a first element which is either of a III group element and a V group element on a semiconductor substrate;    forming an insulation film of an oxide of a second element which is the other of the III group element and the V group element on the intermediate layer; and    forming an electrode on the insulation film.    
   
   
       17 . A method for fabricating a semiconductor device according to  claim 16 , wherein 
 in the step of forming an intermediate layer, a first raw material containing the first element and a second raw material containing the second element are used to form the intermediate layer of an oxide containing the first element and the second element; and    in the step of forming an insulation film, the insulation film is formed of the second raw material.    
   
   
       18 . A method for fabricating a semiconductor device according to  claim 16 , further comprising, after the step of forming the insulation film and before the step of forming the electrode, the step of using the first raw material and the second raw material to form another intermediate layer of an oxide containing the first element and the second element.  
   
   
       19 . A method for fabricating a semiconductor device according to  claim 17 , further comprising, after the step of forming the insulation film and before the step of forming the electrode, the step of using the first raw material and the second raw material to form another intermediate layer of an oxide containing the first element and the second element.