Polishing slurries and methods for chemical mechanical polishing

Abstract

Aqueous polishing slurries for chemical-mechanical polishing are effective for polishing copper at high polish rates. The aqueous slurries according to the present invention may include soluble salts of molybdenum dissolved in an oxidizing agent and molybdic acid dissolved in an oxidizing agent. Methods for polishing copper by chemical-mechanical planarization include polishing copper with low pressures using a polishing pad and a aqueous slurries including soluble salts of molybdenum dissolved in an oxidizing agent and molybdic acid dissolved in an oxidizing agent, particles of MoO 3 dissolved in an oxidizing agent, and particles of MoO 2 dissolved in an oxidizing agent.

1 . An aqueous slurry for chemical mechanical planarization of a copper layer on a semiconductor substrate, comprising a soluble salt of molybdenum dissolved in deionized water and an oxidizing agent.  
   
   
       2 . The aqueous slurry of  claim 1 , wherein said soluble salt of molybdenum comprises an ammonium molybdate.  
   
   
       3 . The aqueous slurry of  claim 2 , wherein said ammonium molybdate comprises one or more selected from the group consisting of ammonium dimolybdate, ammonium heptamolybdate, and ammonium octamolybdate.  
   
   
       4 . The aqueous slurry of  claim 1 , wherein said slurry comprises about 0.1% to about 10% by weight of said soluble salt of molybdenum.  
   
   
       5 . The aqueous slurry of  claim 1 , wherein said oxidizing agent comprises one or more selected from the group consisting of hydrogen peroxide, ferric nitrate, potassium iodate, nitric acid, potassium permanganate, potassium persulfate, ammonium persulfate, potassium periodate, and hydroxylamine.  
   
   
       6 . A method for planarizing copper, comprising: 
 providing an aqueous slurry comprising a soluble salt of molybdenum dissolved in deionized water and an oxidizing agent;    introducing the aqueous slurry between the copper and a polishing pad;    applying a pressure between the polishing pad and the copper, said pressure being in a range of about 0.5 psi to about 6 psi; and    moving the polishing pad and the copper relative to one another.    
   
   
       7 . The method of  claim 6 , wherein providing an aqueous slurry comprises dissolving an ammonium molybdate in deionized water.  
   
   
       8 . The method of  claim 7 , wherein dissolving an ammonium molybdate comprises dissolving in deionized water one or more compounds selected from the group consisting of ammonium dimolybdate, ammonium heptamolybdate, and ammonium octamolybdate.  
   
   
       9 . The method of  claim 6 , wherein said pressure is in a range of about 0.5 psi and about 2.0 psi.  
   
   
       10 . The method of  claim 6 , further comprising rinsing the copper with deionized water at a pH of about 5 to about 7 for about five to about fifteen seconds.  
   
   
       11 . A method for polishing copper, comprising: 
 providing a high polish rate slurry comprising a soluble salt of molybdenum dissolved in deionized water and an oxidizing agent;    polishing copper with the high polish rate slurry;    providing a low polish rate slurry comprising said soluble salt of molybdenum dissolved in deionized water, an oxidizing agent, and a corrosion inhibitor; and    additionally polishing the copper with the low polish rate slurry.    
   
   
       12 . The method of  claim 11 , wherein providing a low polish rate slurry comprises changing an amount of the soluable salt of molybdenum that is dissolved in deionized water.  
   
   
       13 . An aqueous slurry comprising a molybdic acid dissolved in an oxidizing agent.  
   
   
       14 . The aqueous slurry of  claim 13 , wherein said molybdic acid comprises one or more selected from the group consisting of: phosphomolybdic acid, phosphotungstomolybdic acid, and vanadiomolybdic acid.  
   
   
       15 . The aqueous slurry of  claim 13 , wherein said slurry comprises about 0.1% to about 10% by weight of said molybdic acid.  
   
   
       16 . The aqueous slurry of  claim 13 , wherein said oxidizing agent comprises one or more selected from the group consisting of hydrogen peroxide, ferric nitrate, potassium iodate, nitric acid, potassium permanganate, potassium persulfate, ammonium persulfate, potassium periodate, and hydroxylamine.  
   
   
       17 . A method for polishing copper, comprising: 
 providing an aqueous slurry comprising molybdic acid dissolved in oxidizing agent;    introducing the aqueous slurry between the copper and a polishing pad;    applying a pressure between the polishing pad and the copper, said pressure being in a range of about 0.5 psi to about 6 psi; and    moving the polishing pad and the copper relative to one another.    
   
   
       18 . The method of  claim 17 , wherein said pressure is in a range of about 0.5 psi and about 2.0 psi.  
   
   
       19 . The method of  claim 17 , wherein providing an aqueous slurry comprises dissolving a phosphomolybdic acid (PMA) in an oxidizing agent.  
   
   
       20 . The method of  claim 17 , further comprising rinsing the copper with de-ionized water at a pH of about 5 to about 7 for about five to about fifteen seconds.  
   
   
       21 . A method for polishing copper, comprising: 
 providing a high polish rate slurry comprising a molybdic acid dissolved in an oxidizing agent;    polishing copper with the high polish rate slurry;    providing a low polish rate slurry comprising said molybdic acid dissolved in an oxidizing agent, and a corrosion inhibitor; and    additionally polishing the copper with the low polish rate slurry.    
   
   
       22 . A method for polishing copper, comprising: 
 providing an aqueous slurry comprising dissolved MoO 3  and an oxidizing agent;    introducing the aqueous slurry between the copper and a polishing pad;    applying a pressure between the polishing pad and the copper, said pressure being in a range of about 0.5 psi and about 6.0 psi; and    moving the polishing pad and the copper relative to one another.    
   
   
       23 . The method of  claim 22 , wherein said pressure is in a range of about 0.5 psi and about 2.0 psi.  
   
   
       24 . A method for polishing copper, comprising: 
 providing an aqueous slurry comprising dissolved MoO 2  and an oxidizing agent;    introducing the aqueous slurry between the copper and a polishing pad;    applying a pressure between the polishing pad and the copper, said pressure being in a range of about 0.5 psi and about 6.0 psi; and    moving the polishing pad and the copper relative to one another.    
   
   
       25 . The method of  claim 24 , wherein said pressure is in a range of about 0.5 psi and about 2.0 psi.