Polishing composition and use thereof

Abstract

An acidic aqueous slurry composition comprising silica abrasive particles, an oxidizer, a quaternary ammonium hydroxide; and acid having a maximum pKa of about 2.5; and water is provided along with its use for polishing.

1 . An aqueous slurry composition which comprises: 
 A. about 0.01% by weight to about 50% by weight of abrasive particles;    B. about 0.01% to about 50% by weight of an oxidizer;    C. at least about 500 ppm of a quaternary ammonium hydroxide;    D. an acid having a pKa of about 2.5 or lower in an sufficient amount to provide an acidic pH; and    E. water.    
     
     
         2 . The composition of  claim 1  wherein the amount of the abrasive particles is about 1% to about 20% by weight.  
     
     
         3 . The composition of  claim 1  wherein the amount of the abrasive particles is about 5% to about 15% by weight.  
     
     
         4 . The composition of  claim 1  wherein the abrasive particles comprises silica particles.  
     
     
         5 . The composition of  claim 1  wherein the oxidizer comprises hydrogen peroxide.  
     
     
         6 . The composition of  claim 1  wherein the amount of oxidizer is about 0.05 at % to about 5 wt %.  
     
     
         7 . The composition of  claim 1  wherein the amount of oxidizer is about 0.1 wt, % to about 1 wt. %.  
     
     
         8 . The composition of  claim 1  wherein the quaternary ammonium hydroxide is represented by the formula:  
         [NR 4 R 5 R 6 R 7 ] − OH  
       wherein each of R 4 , R 5 R 6  and R 7  individually is an alkyl group of 1 to 20 carbon atoms.  
     
     
         9 . The composition of  claim 8  wherein the alkyl group contains 1 to 4 carbon atoms.  
     
     
         10 . The composition of  claim 1  wherein the quaternary ammonium hydroxide comprises tetramethyl ammonium hydroxide or tetrabutyl ammonium hydroxide.  
     
     
         11 . The composition of  claim 1  wherein the amount of quaternary ammonium hydroxide is about 1000 ppm or higher.  
     
     
         12 . The composition of  claim 1  wherein the amount of quaternary ammonium hydroxide is about 2500 ppm or higher.  
     
     
         13 . The composition of  claim 1  wherein the acid comprises phosphoric acid.  
     
     
         14 . The composition of  claim 1  wherein the pH is at least about 1.5.  
     
     
         15 . The composition of  claim 1  wherein the pH is about 1.5 to about 5.  
     
     
         16 . The composition of  claim 1  wherein the pH is at least about 2.  
     
     
         17 . The composition of  claim 1  which further comprises a corrosion inhibitor.  
     
     
         18 . The composition of  claim 16  wherein the corrosion inhibitor comprises benzotriazole.  
     
     
         19 . The composition of  claim 1  which further comprises a surface active agent.  
     
     
         20 . A method for polishing a metal which comprises providing on the metal an aqueous slurry composition comprising: 
 A. about 0.1% by weight to about 50% by weight of abrasive particles;    B. about 0.1% to about 50% by weight of an oxidizer;    C. at least about 500 ppm of a quaternary ammonium hydroxide;    D. an acid being a pKa of about 2.5 or lower in amount to provide an acidic pH;    and E. water;    and contacting the metal with a polishing pad.    
     
     
         21 . A process for fabricating semiconductor integrated circuit structure comprising: forming circuits on the surface of a semiconductor wafer by photolithographic process; planarizing the surface by chemical mechanical polishing with the composition of  claim 1 .  
     
     
         22 . The process of  claim 21  wherein the integrated circuit structure comprise a semiconductor substrate; a ferromagnetic metal layer; a metal selected from the group consisting of group 3d and 5d of the periodic table; a layer of copper or aluminum; a barrier layer; and a dielectric layer.