Composition and method for polishing polysilicon

Abstract

The invention provides a polishing composition comprising silica, an aminophosphonic acid, a polysaccharide, a tetraalkylammonium salt, a bicarbonate salt, an azole ring, and water, wherein the polishing composition has a pH of about 7 to about 11. The invention further provides a method of polishing a substrate with the polishing composition.

1 . A chemical-mechanical polishing composition consisting essentially of:
 (a) about 0.5 wt. % to about 20 wt. % of silica,   (b) about 0.005 wt % to about 2 wt. % of one or more aminophosphonic acids,   (c) about 0.001 wt. % to about 0.1 wt. % of one or more polysaccharides,   (d) about 0.05 wt. % to about 5 wt. % of one or more tetraalkylammonium salts,   (e) about 0.01 wt. % to about 2 wt. % of a bicarbonate salt,   (f) about 0.005 wt. % to about 2 wt. % of one or more compounds comprising an azole ring,   (g) optionally potassium hydroxide, and   (h) water,   
       wherein the polishing composition has a pH of about 7 to about 11. 
     
     
         2 . The polishing composition of  claim 1 , wherein the silica is wet-process silica. 
     
     
         3 . The polishing composition of  claim 1 , wherein the polishing composition contains about 0.1 wt. % to about 1 wt % of one or more aminophosphonic acids 
     
     
         4 . The polishing composition of  claim 3 , wherein the aminophosphonic acid is selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino tri(methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof. 
     
     
         5 . The polishing composition of  claim 4 , wherein the aminophosphonic acid is amino tri(methylene phosphonic acid). 
     
     
         6 . The polishing composition of  claim 1 , wherein the polysaccharide is hydroxyethylcellulose. 
     
     
         7 . The polishing composition of  claim 6 , wherein the hydroxyethylcellulose has a molecular weight of about 25,000 daltons to about 100,000 daltons. 
     
     
         8 . The polishing composition of  claim 1 , wherein the compound comprising an azole ring is a triazole compound. 
     
     
         9 . The polishing composition of  claim 1 , wherein potassium hydroxide is present in the polishing composition.