SiC substrate and method of manufacturing the same

Abstract

A method of manufacturing a SiC substrate which has a first principal surface and a second principal surface, includes the step of removing, by a vapor phase etching process, at least a portion of a work-affected layer which is formed by mechanical flattening or cutting on the first principal surface of the SiC substrate.

What is claimed is:  
     
         1 . A method of manufacturing a SiC substrate which has a first principal surface and a second principal surface, comprising the step of removing, by a vapor phase etching process, at least a portion of a work-affected layer which is formed by mechanical flattening or cutting on the first principal surface of the SiC substrate.  
     
     
         2 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the vapor phase etching process is a reactive ion etching process.  
     
     
         3 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the second principal surface is a surface where an element is to be formed.  
     
     
         4 . The method of manufacturing a SiC substrate according to  claim 1 , further comprising the step of mirror polishing the second principal surface.  
     
     
         5 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the SiC substrate has a work-affected layer which is formed by mechanical flattening or cutting, on the second principal surface, and the method further comprises the steps of: 
 removing at least a portion of the work-affected layer of the second principal surface by a vapor phase etching process; and    mirror polishing at least the second principal surface after the steps of removing are performed.    
     
     
         6 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the SiC substrate has a work-affected layer which is formed by mechanical flattening or cutting, on the second principal surface, and the method further comprises the step of removing the work-affected layer of the second principal surface by mechanical polishing and chemical mechanical polishing and mirror finishing the second principal surface.  
     
     
         7 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the first principal surface obtained by the step of removing has a surface roughness of about 10 nm to about 1 μm.  
     
     
         8 . The method of manufacturing a SiC substrate according to  claim 1 , wherein the method further includes a step of cutting the SiC substrate from an ingot of SiC and the first principal surface and second principal surface are formed by the step of cutting.  
     
     
         9 . The method of manufacturing a SiC substrate according to  claim 1 , wherein in the step removing, the SiC substrate is held so as to allow a change in the warp of the SiC substrate.  
     
     
         10 . The method of manufacturing a SiC substrate according to  claim 1 , wherein a gas containing fluorine is used in the vapor phase etching process.  
     
     
         11 . The method of manufacturing a SiC substrate according to  claim 10 , wherein the gas containing fluorine is CF 4  or SF 6 .  
     
     
         12 . The method of manufacturing a SiC substrate according to  claim 10 , wherein in the vapor phase etching process, the work-affected layer is removed at an etching rate in a range of about 0.5 μm/hr to about 20 μm/hr.  
     
     
         13 . The method of manufacturing a SiC substrate according to  claim 10 , wherein the SiC substrate is one of amorphous, a poly crystal and a single crystal.  
     
     
         14 . A SiC substrate manufactured by the manufacturing method specified in  claim 1 .  
     
     
         15 . A SiC substrate comprising two substantially parallel principal surfaces, wherein only one of the two principal surfaces is mirror finished and the warp is not more than about ±50 μm.