Method of polishing a substrate

Abstract

A method of polishing a substrate by providing a polishing slurry comprising water and silica particles, wherein the average size (by number) of the silica particles is less than 30 nm, providing a polymeric polishing pad substantially free of bound abrasive particles and having a polishing surface comprising a multiplicity of cavities, and polishing the surface of the substrate by contacting the polishing slurry and the polishing pad with the substrate and moving the polishing pad relative to the substrate.

What is claimed is:  
     
         1 . A method of polishing a substrate, which method comprises 
 (a) providing a polishing slurry comprising a liquid carrier and silica particles, wherein the average size of the silica particles is less than 30 nm,    (b) providing a polymeric polishing pad substantially free of bound abrasive particles and having a polishing surface comprising a multiplicity of cavities, and    (c) polishing the surface of the substrate by contacting the polishing slurry and the polishing pad with the substrate and moving the polishing pad relative to the substrate.    
     
     
         2 . The method of  claim 1 , wherein the polishing surface is polyurethane.  
     
     
         3 . The method of  claim 1 , wherein about 90% or more of the abrasive particles (by number) have a particle size less than about 30 nm.  
     
     
         4 . The method of  claim 1 , wherein the silica particles have an average particle size of about 20 nm or less.  
     
     
         5 . The method of  claim 1 , wherein about 90% or more of the abrasive particles (by number) have a particle size of about 20 mn or less.  
     
     
         6 . The method of  claim 1 , wherein the silica particles are condensation-polymerized silica particles.  
     
     
         7 . The method of  claim 1 , wherein the polishing slurry consists essentially of silica particles and water.  
     
     
         8 . The method of  claim 1 , wherein the polishing slurry is basic.  
     
     
         9 . The method of  claim 8 , wherein the polishing slurry has a pH of about 8.5-12.  
     
     
         10 . The method of  claim 1 , wherein the substrate is a semiconductor device.  
     
     
         11 . The method of  claim 1 , wherein the substrate is a dielectric layer of a semiconductor device.  
     
     
         12 . The method of  claim 10 , wherein the polishing pad is not conditioned during the polishing of the semiconductor device.  
     
     
         13 . The method of  claim 12 , wherein the polishing pad is conditioned before and/or after polishing the semiconductor device.  
     
     
         14 . The method of  claim 10 , wherein the semiconductor device comprises device geometries below about 0.25 μm.  
     
     
         15 . The method of  claim 1 , wherein the silica particles communicate with the polishing surface to form an in situ fixed abrasive.  
     
     
         16 . The method of  claim 1 , wherein the silica particles and the pad communicate in a manner consistent with a self-regenerating fixed abrasive article.