Silicon carbide semiconductor device and method for manufacturing the same

Abstract

There is provided a silicon carbide semiconductor device having excellent electrical characteristics such as channel mobility, and a method for manufacturing the same. A semiconductor device includes a substrate made of silicon carbide and having an off-angle of greater than or equal to 50° and less than or equal to 65° with respect to a surface orientation of {0001}, a p-type layer serving as a semiconductor layer, and an oxide film serving as an insulating film. The p-type layer is formed on the substrate and is made of silicon carbide. The oxide film is formed to contact with a surface of the p-type layer. A maximum value of the concentration of nitrogen atoms in a region within 10 nm of an interface between the semiconductor layer and the insulating film (interface between a channel region and the oxide film) is greater than or equal to 1×10 21 cm −3 .

1 .- 30 . (canceled) 
     
     
         31 . A silicon carbide semiconductor device, comprising:
 a substrate made of silicon carbide and having an off-angle of greater than or equal to 50° and less than or equal to 65° with respect to a surface orientation of {0001};   a semiconductor layer formed on said substrate and made of silicon carbide; and   an insulating film formed to contact with a surface of said semiconductor layer,   a maximum value of a total concentration of nitrogen atoms and hydrogen atoms in a region within 10 nm of an interface between said semiconductor layer and said insulating film being greater than or equal to 1×10 21  cm −3 .   
     
     
         32 . The silicon carbide semiconductor device according to  claim 31 , wherein
 an interface state density in an energy level lower than 0.1 eV that of a conduction band is smaller than 1×10 12  cm −2 eV −1 .   
     
     
         33 . The silicon carbide semiconductor device according to  claim 31 , wherein
 said substrate has an off-orientation in a range of less than or equal to ±5° in a <11-20> direction.   
     
     
         34 . The silicon carbide semiconductor device according to  claim 31 , wherein
 said substrate has an off-orientation in a range of less than or equal to ±5° in a <01-10> direction.   
     
     
         35 . The silicon carbide semiconductor device according to  claim 34 , wherein
 a main surface of said substrate has a surface orientation whose off-angle is greater than or equal to −3° and less than or equal to +5° with respect to a surface orientation of {03-38}.   
     
     
         36 . A method for manufacturing a silicon carbide semiconductor device, comprising the steps of:
 preparing a substrate made of silicon carbide and having an off-angle of greater than or equal to 50° and less than or equal to 65° with respect to a surface orientation of {0001};   forming a semiconductor layer on said substrate;   forming an insulating film to contact with a surface of said semiconductor layer; and   adjusting a total concentration of nitrogen atoms and hydrogen atoms in a region within 10 nm of an interface between said semiconductor layer and said insulating film such that a maximum value of said total concentration is greater than or equal to 1×10 21  cm −3 .