Slurry for use with fixed-abrasive polishing pads in polishing semiconductor device conductive structures that include copper and tungsten

Abstract

A slurry for substantially simultaneously polishing a copper conductive structure of a semiconductor device structure and an adjacent barrier layer. The slurry, which is useful with a fixed-abrasive type polishing pad, is substantially abrasive-free and removes copper at a rate that is substantially the same as or faster than a rate at which it removes a material, such as tungsten, of the barrier layer. The slurry is formulated so as to oxidize copper at substantially the same rate as or at a faster rate than a material of the barrier layer is oxidized. Thus, copper and the barrier layer material have substantially the same oxidation energies in the slurry or the oxidation energy of the barrier layer material in the slurry may be greater than that of copper. Systems and methods for substantially polishing copper conductive structures and adjacent barrier structures on semiconductor device structures are also disclosed.

What is claimed is:  
     
         1 . A slurry for use in polishing a copper structure of a semiconductor device, the slurry being substantially free of abrasives and formulated to substantially concurrently polish copper and a barrier material with the barrier material being removed at substantially the same rate as or at a slower rate than copper is removed.  
     
     
         2 . The slurry of  claim 1 , being formulated for use with a fixed-abrasive polishing pad comprising at least one of aluminum dioxide, titanium dioxide, silicon dioxide, and cerium dioxide.  
     
     
         3 . The slurry of  claim 1 , being formulated to oxidize copper at substantially the same rate as or at a faster rate than said tungsten is oxidized.  
     
     
         4 . The slurry of  claim 1 , wherein, in said slurry, the barrier material and copper have substantially the same oxidation energies.  
     
     
         5 . The slurry of  claim 4 , wherein, in said slurry, the barrier material has an oxidation energy of about 0.25 V more to about 0.20 V less than an oxidation energy of copper in said slurry.  
     
     
         6 . The slurry of  claim 1 , wherein, in said slurry, a rate of removal of the barrier material is up to about ten times slower than a rate of removal of copper.  
     
     
         7 . The slurry of  claim 1 , wherein, in said slurry, a rate of removal of the barrier material is about two to about four times slower than a rate of removal of copper.  
     
     
         8 . The slurry of  claim 1 , wherein said slurry is formulated to remove copper and the barrier material without substantially dissolving the barrier material that underlies remaining portions of copper.  
     
     
         9 . The slurry of  claim 1 , wherein said slurry comprises at least one oxidizer, at least pH control agent, and at least one inhibitor.  
     
     
         10 . The slurry of  claim 9 , wherein said at least one oxidizer comprises at least one of an ammonium compound, a nitrate compound, and an amine compound.  
     
     
         11 . The slurry of  claim 9 , wherein said at least one oxidizer comprises at least one of hydrogen peroxide, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, and ammonia.  
     
     
         12 . The slurry of  claim 9 , wherein said at least one oxidizer comprises about 0.1% to about 20% of the weight of said slurry.  
     
     
         13 . The slurry of  claim 9 , wherein said at least one oxidizer comprises about 0.1% to about 5% of the weight of said slurry.  
     
     
         14 . The slurry of  claim 9 , wherein said at least one pH control agent comprises at least one of potassium hydrogen phthalate, ammonium acetate, ammonium oxalate, ammonium carbamate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, dibasic ammonium citrate, tribasic ammonium citrate, acetic acid, phosphoric acid, and sulfuric acid.  
     
     
         15 . The slurry of  claim 1 , wherein said slurry has a pH of about 2 to about 6.  
     
     
         16 . The slurry of  claim 9 , wherein said at least one inhibitor comprises at least one of an azole, an amine, and a ring compound.  
     
     
         17 . The slurry of  claim 9 , wherein said at least one inhibitor comprises at least one of benzenetriazole (BTA), mercaptobenzothiazole, tolytriazole, methylamine, diethylamine, pyridine, quinoline, dicyclohexamine nitrate, potassium silicate, ammonium borate, ammonium phosphate, and potassium dichromate.  
     
     
         18 . The slurry of  claim 9 , wherein said at least one inhibitor comprises about 0.05% to about 2% of the weight of said slurry.  
     
     
         19 . The slurry of  claim 9 , wherein said at least one inhibitor comprises about 0.05 to about 0.2% of the weight of said slurry.  
     
     
         20 . The slurry of  claim 9 , wherein said slurry further comprises at least one complexing agent comprising at least one of glycine, ammonium citrate, ammonium phosphate, and ammonium acetate.  
     
     
         21 . The slurry of  claim 20 , wherein said at least one complexing agent comprises about 2% to about 15% of the weight of said slurry.  
     
     
         22 . The slurry of  claim 20 , wherein said at least one complexing agent comprises about 3% to about 5% of the weight of said slurry.  
     
     
         23 . The slurry of  claim 9 , wherein said slurry includes: 
 about 0.1% to 20% of said at least one oxidizer, by weight of said slurry; and    about 0.05% to about 2% of said at least one inhibitor, by weight of said slurry.    
     
     
         24 . The slurry of  claim 9 , wherein said slurry includes: 
 about 0.1% to about 5% of said at least one oxidizer, by weight of said slurry; and    about 0.05% to about 0.2% of said at least one inhibitor, by weight of said slurry.    
     
     
         25 . The slurry of  claim 1 , wherein said slurry removes copper at a temperature of about 27° C. or cooler.