Nitride semiconductor devices and method of their manufacture

Abstract

Affords a manufacturing method enabling nitride-based semiconductor devices containing epitaxial films excelling in flatness and crystallinity to be easily produced, and makes available nitride-based semiconductor devices manufactured by the method. Method of manufacturing nitride semiconductor devices that are formed onto a semiconductor substrate being a compound containing a Group IIIA element for forming compounds with nitrogen, and nitrogen, including steps of heating the semiconductor substrate ( 1 ) to a film-deposition temperature, supplying to the substrate a film-deposition gas containing a source gas for the Group IIIA element and a nitrogen source gas, and epitaxially growing onto the semiconductor substrate a thin film ( 2 ) of a compound containing the Group IIIA element and nitrogen, and being furnished with a step, in advance of the epitaxial growth step, of heating the semiconductor substrate to a pretreating temperature less than the film-deposition temperature, to clean the surface of the semiconductor substrate.

1 . A method of manufacturing nitride-based semiconductor devices formed onto a semiconductor substrate being a compound containing a Group IIIA element for forming compounds with nitrogen, and nitrogen, the nitride semiconductor device manufacturing method comprising: 
 a step of heating the semiconductor substrate to a film-deposition temperature;    a step of supplying to the substrate a film-deposition gas containing a source gas for the Group IIIA element and a nitrogen source gas;    a step of epitaxially growing onto the semiconductor substrate a thin film of a compound containing the Group IIIA element and nitrogen; and    a step, in advance of the epitaxial growth step, of heating the semiconductor substrate to a pretreating temperature less than the film-deposition temperature, to clean the front side of the semiconductor substrate.    
   
   
       2 . A nitride semiconductor device manufacturing method as set forth in  claim 1 , wherein in said semiconductor-substrate cleaning step, a pretreatment gas in which the proportion of Group-IIIA-element source gas has been reduced below what the proportion is in the film-deposition gas for the epitaxial growth step is supplied to the substrate.  
   
   
       3 . A nitride semiconductor device manufacturing method as set forth in  claim 2 , wherein the pretreatment gas does not contain the source gas for the Group IIIA element.  
   
   
       4 . A semiconductor device comprising: 
 a semiconductor substrate formed from a compound containing a Group IIIA element for forming compounds with nitrogen, and nitrogen; and    an epitaxial semiconductor film containing the Group IIIA element and nitrogen, formed onto said semiconductor substrate; wherein    the surface roughness of said semiconductor substrate is 15 nm or less in root-mean-square RMS roughness.    
   
   
       5 . A semiconductor device as set forth in  claim 4 , wherein the root-mean-square roughness of said semiconductor substrate is 5 nm or less.  
   
   
       6 . A semiconductor device as set forth in  claim 4 , wherein the 10-point mean roughness Rz of said epitaxial film is 15 nm or less.  
   
   
       7 . A semiconductor device as set forth in  claim 6 , wherein Rz is 7.5 nm or less.  
   
   
       8 . A semiconductor device as set forth in  claim 4 , wherein the front-side surface of said epitaxial film is free of peaks and valleys of 50 nm to 150 nm height appearing at a pitch of 100 μm to 150 μm.