Composition for polishing silicon nitride and method of controlling selectivity using same

Abstract

A composition for polishing silicon nitride according to the present invention includes colloidal silica, a polishing aid including a phosphoric acid compound and a sulfuric acid compound. By further including an oxidizing agent, a first selectivity representing the ratio of a polishing speed for a metal layer to a polishing speed for a silicon nitride layer and a second selectivity representing the ratio of a polishing speed for an oxide insulating layer to a polishing speed for a silicon nitride are controlled.

1 . A composition for polishing silicon nitride, comprising:
 1) colloidal silica; and   2) a polishing aid composed of a phosphoric acid compound and a sulfuric acid compound.   
     
     
         2 . The composition for polishing silicon nitride according to  claim 1 , wherein said phosphoric acid compound includes at least one selected from phosphoric acid, pyrophosphoric acid, and polyphosphoric acid. 
     
     
         3 . The composition for polishing silicon nitride according to  claim 1 , of wherein said colloidal silica has an average grain size of 15 nm to 80 nm. 
     
     
         4 . The composition for polishing silicon nitride according to  claim 1 , further comprising an oxidizing agent. 
     
     
         5 . A composition for polishing silicon nitride, comprising:
 1) colloidal silica;   2) a polishing aid composed of a phosphoric acid compound and a sulfuric acid compound; and   3) an oxidizing agent, wherein   a first selectivity and a second selectivity being controllable depending on a content of said oxidizing agent and a pH of said composition for polishing silicon nitride, said first selectivity representing a ratio of a polishing speed for a metal layer to a polishing speed for a silicon nitride layer and said second selectivity representing a ratio of a polishing speed for an oxide insulating layer to a polishing speed for a silicon nitride layer.   
     
     
         6 . A method of controlling a selectivity using the composition for polishing silicon nitride according to  claim 5 , wherein said first selectivity is controlled depending on the content of said oxidizing agent, and
 said second selectivity is controlled depending on the pH of said composition for polishing silicon nitride.   
     
     
         7 . The composition for polishing silicon nitride according to  claim 2 , wherein said colloidal silica has an average grain size of 15 nm to 80 nm. 
     
     
         8 . The composition for polishing silicon nitride according to  claim 2 , further comprising an oxidizing agent. 
     
     
         9 . The composition for polishing silicon nitride according to  claim 3 , further comprising an oxidizing agent. 
     
     
         10 . The composition for polishing silicon nitride according to  claim 7 , further comprising an oxidizing agent.