Semiconductor substrate, seminconductor device, and manufacturing method thereof

Abstract

A semiconductor substrate that suppresses not only auto doping but also warpage can be provided by disposing an oxide film ( 4 ) at a position in a semiconductor substrate ( 1 ), so as to be apart from a main surface ( 1 a ) and a reverse surface ( 1 b ). The oxide film ( 4 ) can be so disposed that it is apart not less than 200 nm from the reverse surface ( 1 b ), and extends throughout the semiconductor substrate ( 1 ) in a thickness of 400 to 1000 nm, by implanting oxygen ion from the reverse surface ( 1 b ), followed by annealing

What is claimed is:  
     
         1 . A semiconductor substrate comprising: 
 first and second surfaces; and    an oxide film apart from said first and second surfaces and extending throughout said semiconductor substrate.    
     
     
         2 . The semiconductor substrate according to  claim 1  wherein the distance between said oxide film and said second surface corresponds to a thickness on the order of 10 −3  of a thickness of said semiconductor substrate.  
     
     
         3 . The semiconductor substrate according to  claim 1  wherein said oxide film has a thickness of 400 to 1000 nm.  
     
     
         4 . The semiconductor substrate according to  claim 2  wherein said oxide film has a thickness of 400 to 1000 nm.  
     
     
         5 . The semiconductor substrate according to  claim 1  further comprising an epitaxial layer disposed on said first surface.  
     
     
         6 . The semiconductor substrate according to  claim 2  further comprising an epitaxial layer disposed on said first surface.  
     
     
         7 . The semiconductor substrate according to  claim 3  further comprising an epitaxial layer disposed on said first surface.  
     
     
         8 . The semiconductor substrate according to  claim 4  further comprising an epitaxial layer disposed on said first surface.  
     
     
         9 . A semiconductor device comprising: 
 a semiconductor substrate having first and second surfaces;    an oxide film apart from said first and second surfaces, and extending throughout said semiconductor substrate;    an epitaxial layer disposed on said first surface; and    a semiconductor element disposed in said epitaxial layer.    
     
     
         10 . The semiconductor device according to  claim 9  wherein the distance between said oxide film and said second surface corresponds to a thickness on the order of 10 −3  of a thickness of said semiconductor substrate.  
     
     
         11 . The semiconductor device according to  claim 9  wherein said oxide film has a thickness of 400 to 1000 nm.  
     
     
         12 . The semiconductor device according to  claim 10  wherein said oxide film has a thickness of 400 to 1000 nm.  
     
     
         13 . A method of manufacturing a semiconductor device comprising the steps of: 
 (a) providing a semiconductor substrate having first and second surfaces; and    (b) forming an oxide film apart from said first and second surfaces and extending throughout said semiconductor substrate.    
     
     
         14 . The method of manufacturing a semiconductor device according to  claim 13  wherein said step (b) includes the steps of: 
 (b-1) introducing oxygen ion into said semiconductor substrate from said second surface; and  
 (b-2) performing heat treatment after said step (b-1).  
 
     
     
         15 . The method of manufacturing a semiconductor device according to  claim 14  further including the step (c), after said step (b), of forming an epitaxial layer on said first surface.  
     
     
         16 . The method of manufacturing a semiconductor device according to  claim 15  further including the step (d) of making a semiconductor element by using said epitaxial layer.