Polishing composition and polishing method

Abstract

A polishing composition includes more than 0.1% by mass of colloidal silica, and water, and has a pH of 6 or less. The polishing composition has the ability to polish a titanium material at a high stock removal rate. Thus, the polishing composition is suitable for use in applications for polishing a titanium-containing object.

1 . A polishing composition for use in an application for polishing a titanium-containing object, the polishing composition comprising more than 0.1% by mass of colloidal silica, and water, and having a pH of 6 or less.  
   
   
       2 . The polishing composition according to  claim 1 , wherein the average particle size of the colloidal silica is in a range from 1 to 25 nm.  
   
   
       3 . The polishing composition according to  claim 1 , further comprising an oxidizing agent, wherein the object includes an insulator layer having a trench, a titanium barrier layer provided on the insulator layer, and a conductive metal conductor layer provided on the barrier layer, wherein each of the barrier layer and the conductor layer has a portion positioned inside the trench, and a portion positioned outside the trench.  
   
   
       4 . The polishing composition according to  claim 3 , wherein the oxidizing agent is periodic acid.  
   
   
       5 . The polishing composition according to  claim 3 , wherein the content of the oxidizing agent in the polishing composition is in a range from 0.5 to 3.0% by mass.  
   
   
       6 . The polishing composition according to  claim 1 , further comprising fumed oxide-particles.  
   
   
       7 . The polishing composition according to  claim 6 , wherein the fumed oxide-particles comprise fumed silica, fumed alumina, fumed titania, or fumed zirconia.  
   
   
       8 . The polishing composition according to  claim 6 , wherein the average particle size of the fumed oxide-particles is in a range from 15 to 45 nm.  
   
   
       9 . The polishing composition according to  claim 6 , wherein the content of the fumed oxide-particles in the polishing composition is in a range from 0.5 to 10% by mass.  
   
   
       10 . The polishing composition according to  claim 6 , wherein the ratio of weight of the fumed oxide-particles in the polishing composition to the total weight of the colloidal silica and the fumed oxide-particles in the polishing composition is in a range from 77 to 97%.  
   
   
       11 . A polishing method, comprising: 
 preparing a polishing composition including more than 0.1% by mass of colloidal silica, and water, and having a pH of 6 or less; and    polishing a titanium-containing object, by using the prepared polishing composition.