Polishing composition and polishing method using the same

Abstract

A polishing composition contains sodium hypochlorite, colloidal silica and water. The effective chlorine concentration in the polishing composition is 0.5 to 2.5%, and the content of colloidal silica in the polishing composition is 1 to 13% by weight. The polishing composition can be preferably used in polishing germanium or silicon-germanium single crystal.

1 . A polishing composition for use in polishing germanium or silicon-germanium single crystal, the polishing composition comprising sodium hypochlorite, colloidal silica and water, wherein the effective chlorine concentration in the polishing composition is 0.5 to 2.5%, and the content of colloidal silica in the polishing composition is 1 to 13% by weight.  
   
   
       2 . The polishing composition according to  claim 1 , wherein the content of colloidal silica in the polishing composition is 3 to 7% by weight.  
   
   
       3 . The polishing composition according to  claim 1 , wherein, when an aqueous dispersion of colloidal silica is prepared using colloidal silica to be contained in the polishing composition so that the content of colloidal silica is 20% by mass, the total content of sodium, aluminum, titanium, iron, nickel and copper in the aqueous dispersion is 100 ppm or less.  
   
   
       4 . The polishing composition according to  claim 1 , wherein colloidal silica in the polishing composition is synthesized by hydrolysis of alkoxysilane.  
   
   
       5 . A method for polishing germanium or silicon-germanium single crystal, the method comprising: 
 preparing a polishing composition including sodium hypochlorite, colloidal silica and water, wherein the effective chlorine concentration in the polishing composition is 0.5 to 2.5%, and the content of colloidal silica in the polishing composition is 1 to 13% by weight; and    using the prepared polishing composition to polish germanium or silicon-germanium single crystal.