Polishing process for producing damage free surfaces on semi-insulating silicon carbide wafers

Abstract

A polishing mixture and related method of polishing a material wafer surface, such as silicon carbide, are disclosed. The polishing mixture comprises; an abrasive and an oxidizer mixed in an acidic solution. Alumina may be used as the abrasive and the polishing mixture may have a pH less than or equal to seven (7).

1 . A process for treating a surface of a material, comprising: 
 polishing the surface using a polishing mixture having a pH of seven (7) or less, wherein the polishing mixture comprises; an abrasive and an oxidizer.    
   
   
       2 . The process of  claim 1 , wherein the surface comprises a scratch and wherein the polishing mixture is non-selective relative to the scratch.  
   
   
       3 . The process of  claim 2 , wherein the abrasive has a hardness less than the material.  
   
   
       4 . The process of  claim 3 , wherein the abrasive comprises at least one of alumina and colloidal alumina.  
   
   
       5 . The process of  claim 2 , wherein the polishing mixture has a pH equal to or less than five (5).  
   
   
       6 . The process of  claim 1 , wherein the material comprises at least one a conducting, insulating, dielectric or semi-conducting material selected from a group of materials consisting essentially of; a metal, an oxide, a glass, an alloy, a carbide, a nitride, diamond, a silicide, a chromide, ferride, a boride, a sulfide, a phosphide, silicon nitride, silicon nitride, aluminum nitride, gallium nitride, alumina-gallium nitride, indium-gallium nitride, Safire, Indium phosphide, boron nitride, silicon, and silica.  
   
   
       7 . The process of  claim 6 , wherein the material comprises silicon carbide terminated in a silicon face, a carbon face, or a non-polar face.  
   
   
       8 . The process of clam  6  wherein the abrasive comprises at least one of alumina, a metal oxide, zirconia, silica, diamond, a carbide, and a nitride.  
   
   
       9 . The process of  claim 8 , wherein the abrasive has a size ranging from between several nanometers to one micron.  
   
   
       10 . The process of  claim 8 , wherein the oxidizer comprises at least one of ozone-treated water, colloidal silica, a hypochlorite, a peroxide, a sulfate, a phosphate, a carbonate, a percarbonate, and an oxide.  
   
   
       11 . A polishing mixture comprising: 
 an abrasive and an oxidizer mixed in an acidic solution having a pH less than or equal to seven (7).    
   
   
       12 . The polishing mixture of  claim 11 , wherein the polishing mixture comprises a non-silica abrasive and has a pH less than or equal to five (5).  
   
   
       13 . The polishing mixture of  claim 11 , wherein the abrasive has a Mohs hardness less than or equal to nine (9).  
   
   
       14 . The polishing mixture of  claim 13 , wherein the abrasive comprises colloidal alumina.  
   
   
       15 . The polishing mixture of  claim 11 , wherein the acidic solution comprises water and an acid.  
   
   
       16 . A process of fabricating a semiconductor device comprising: 
 polishing a surface of a material wafer using a non-selective polishing mixture having a pH of seven (7) or less and comprising an abrasive and an oxidizer; and,    forming at least one of a homo-epitaxial layer, a hetro-epitaxial layer, a dielectric layer, and a conductive layer on the substrate.    
   
   
       17 . The process of  claim 16 , wherein the material comprises silicon carbide and the epitaxial layer comprises a nitride semiconductor layer or a silicon carbide layer.  
   
   
       18 . The process of  claim 16 , wherein the polishing mixture has a pH about five (5) and the abrasive comprises colloidal alumina.  
   
   
       19 . The process of  claim 16 , wherein the material comprises at least one a conducting, insulating, dielectric or semi-conducting material selected from a group of materials consisting essentially of; a metal, an oxide, a glass, an alloy, a carbide, a nitride, diamond, a silicide, a chromide, ferride, a boride, a sulfide, a phosphide, silicon nitride, silicon nitride, aluminum nitride, gallium nitride, alumina-gallium nitride, indium-gallium nitride, Safire, Indium phosphide, boron nitride, silicon, and silica; 
 wherein the abrasive comprises at least one abrasive selected from a group of abrasives consisting essentially of; diamond, an oxide, a metal oxide, a carbide, a nitride, a silicate, and a metal silicate; and,    wherein the oxidizer comprises at least one oxidizer selected from a group of oxidizers consisting essentially of; ozone-treated water, colloidal silica, a hypoclorite, a peroxide, a sulfate, a phosphate, a carbonate, and a percarbonate.    
   
   
       20 . The process of  claim 16 , wherein polishing the surface of the material wafer comprises: 
 polishing the surface of the material wafer using a mechanical polishing process or a chemical-mechanical polishing (CMP) process using diamond or colloidal silica; and thereafter, polishing the surface of the material wafer at a temperature less than 100° C. using the polishing mixture.    
   
   
       21 . The process of  claim 20 , wherein polishing the surface of the material wafer takes place at room temperature.  
   
   
       22 . The process of  claim 16 , further comprising: 
 after polishing the surface of the material wafer, patterning the surface of the wafer, or implanting ions into the surface of the wafer.