Silicon carbide semiconductor device and method of manufacturing thereof

Abstract

A silicon carbide semiconductor device is provided that includes a semiconductor layer made of silicon carbide and having a surface with a trench having a sidewall formed of a crystal plane tilted at an angle in a range of not less than 50° and not more than 65° relative to the {0001} plane, and an insulating film formed to contact the sidewall of the trench. A maximum value of the nitrogen concentration in a region within 10 nm from the interface between the sidewall of the trench and the insulating film is not less than 1×10 21 cm −3 , and the semiconductor device has a channel direction in a range of ±10° relative to the direction orthogonal to the <−2110> direction in the sidewall of the trench. A method of manufacturing the silicon carbide semiconductor device is also provided.

1 - 9 . (canceled) 
     
     
         10 . A method of manufacturing a silicon carbide semiconductor device, comprising the steps of:
 forming an insulating film contacting a semiconductor layer made of silicon carbide; and   adjusting a nitrogen concentration so that a maximum value of the nitrogen concentration in a region within  10  nm from an interface between said semiconductor layer and said insulating film is not less than 1×10 21  cm −3 .   
     
     
         11 . The method of manufacturing a silicon carbide semiconductor device according to  claim 10 , further comprising the step of annealing said semiconductor layer in an atmosphere of an inert gas after said adjusting. 
     
     
         12 . The method of manufacturing a silicon carbide semiconductor device according to  claim 11 , further comprising the step of forming a gate electrode on said insulating film after said annealing. 
     
     
         13 . The method of manufacturing a silicon carbide semiconductor device according to  claim 11 , further comprising the step of forming an electrode to contact said semiconductor layer after said annealing. 
     
     
         14 . The method of manufacturing a silicon carbide semiconductor device according to  claim 13 , wherein said electrode is a source electrode. 
     
     
         15 . The method of manufacturing a silicon carbide semiconductor device according to  claim 11 , wherein said inert gas includes an argon gas. 
     
     
         16 . The method of manufacturing a silicon carbide semiconductor device according to  claim 11 , wherein said annealing is performed at a temperature of approximately 1100° C. 
     
     
         17 . The method of manufacturing a silicon carbide semiconductor device according to  claim 10 , wherein said step of adjusting the nitrogen concentration includes the step of performing a heat treatment in an atmosphere of a gas containing nitrogen, on said semiconductor layer where said insulating film is formed. 
     
     
         18 . The method of manufacturing a silicon carbide semiconductor device according to  claim 10 , further comprising the step of forming a trench having a sidewall, wherein
 said step of forming the insulating film is performed so that said insulating film contacts said sidewall of said trench.