Chemical mechanical polishing slurry and method for using same

Abstract

An aqueous chemical mechanical polishing slurry useful for polishing the polysilicon layer of a semiconductor wafer comprising an aqueous solution of at least one abrasive, and at least one alcoholamine. The slurry preferably has a pH of from about 9.0 to about 10.5 and it includes an optional buffering agent.

What we claim is:  
     
         1 . An aqueous chemical mechanical polishing composition for polishing a substrate containing a metal or silicon layer or thin film, comprising: 
 at least one abrasive; and    at least one alcoholamine.    
     
     
         2 . The aqueous chemical mechanical polishing slurry of  claim 1  wherein the slurry has a polysilicon to insulating layer polishing selectivity greater than about 100.  
     
     
         3 . The aqueous chemical mechanical polishing slurry of  claim 1  having a slurry pH is from about 9 to about 10.5.  
     
     
         4 . The aqueous chemical mechanical polishing slurry of  claim 1  including from about 50 ppm to about 2.0 wt % of at least one alcoholamine.  
     
     
         5 . The aqueous chemical mechanical polishing slurry of  claim 1  wherein the alcoholamine is a tertiary amine.  
     
     
         6 . The aqueous chemical mechanical polishing slurry of  claim 1  wherein the alcoholamine is selected from triethanol amine, dialkylethanol amine, alkyl diethynol amine, and 2-dimethylamino-2-methyl-1-propanol.  
     
     
         7 . The aqueous chemical mechanical polishing slurry of  claim 1  wherein the alcoholamine is 2-dimethylamino-2-methyl-1-propanol.  
     
     
         8 . The aqueous chemical mechanical polishing composition of  claim 1 , wherein the abrasive is a metal oxide.  
     
     
         9 . The aqueous chemical mechanical polishing slurry of  claim 8 , wherein the metal oxide abrasive is at least one compound selected from the group including alumina, titania, zirconia, germania, silica, ceria or chemical mixture of the metal oxides.  
     
     
         10 . The aqueous chemical mechanical polishing slurry of  claim 8 , wherein the abrasive is a physical mixture of the elemental oxides of alumina, titania, zirconia, germania, silica, and ceria  
     
     
         11 . The aqueous chemical mechanical polishing slurry of  claim 8 , wherein the abrasive has a median particle size less than 1000 nm and a mean aggregate diameter less than about 400 nm.  
     
     
         12 . The aqueous chemical mechanical polishing slurry of  claim 1 , wherein the abrasive is present in the range of about 0.5% to 55% solids by weight.  
     
     
         13 . The aqueous chemical mechanical polishing slurry of  claim 1 , wherein the abrasive is from about 0.5 to about 3.0 weight percent fumed silica.  
     
     
         14 . The aqueous chemical mechanical polishing slurry of  claim 1  including at least one buffering agent.  
     
     
         15 . The aqueous chemical mechanical polishing slurry of  claim 1  including a buffering agent selected from carbonate and bicarbonate buffering agents.  
     
     
         16 . The aqueous chemical mechanical composition of  claim 1  including ammonium bicarbonate.  
     
     
         17 . The aqueous chemical mechanical polishing slurry of  claim 1 , including from about 0.01 to about 1.0 weight percent of a buffering agent.  
     
     
         18 . An aqueous chemical mechanical polishing slurry comprising: 
 from about 0.5 to about 15 weight percent fumed silica;    from about 50 ppm to about 2.0 weight percent of at least one tertiary alcoholamine; and    from about 0.01 to about 1.0 weight percent of a buffering agent selected from a carbonate, a bicarbonate, or mixtures thereof, wherein the slurry has a pH of from about 9.0 to about 10.5.    
     
     
         19 . The aqueous chemical mechanical polishing slurry of  claim 18  wherein the tertiary alcoholamine is 2-dimethylamino-2-methyl-t-propanol.  
     
     
         20 . The aqueous chemical mechanical polishing slurry of  claim 18  wherein the buffering agent is ammonium bicarbonate.  
     
     
         21 . The aqueous chemical mechanical polishing slurry of  claim 18  having a polysilicon to PETEOS polishing selectivity of at least 500.  
     
     
         22 . A method for chemical-mechanical polishing of a substrate containing an first insulator layer and at least one second layer selected from at least one conductive or semi-conductive material the method comprising the steps of: 
 a) providing an aqueous chemical mechanical polishing slurry comprising an abrasive and a tertiary amine;    b) applying the slurry to the substrate; and    c) removing at least a portion of the second layer by bringing a polishing pad into contact with the substrate and moving the pad in relation to the substrate.    
     
     
         23 . The aqueous chemical mechanical polishing slurry of  claim 22  wherein the second layer is polysilicon and the slurry has a polysilicon to insulating layer polishing selectivity greater than about 100.  
     
     
         24 . The method of  claim 22 , wherein the second layer is a conductive layer that is selected from tungsten, aluminum, copper, titanium and tantalum.  
     
     
         25 . The method of  claim 22  wherein the second layer is a semi-conductive layer selected from the group consisting of epitaxial silicon and polycrystalline silicon.  
     
     
         26 . The method of  claim 22  wherein the aqueous chemical mechanical polishing slurry includes from about 50 ppm to about 2.0 wt % of at least one alcoholamine.  
     
     
         27 . The method of  claim 22  wherein the aqueous chemical mechanical polishing slurry includes at least one tertiary alcoholamine.  
     
     
         28 . The method of  claim 22  wherein the aqueous chemical mechanical polishing slurry includes an alcoholamine selected from triethanol amine, dialkylethanol amine, alkyl diethanol amine, and 2-dimethylamino-2-methyl-1-propanol.  
     
     
         29 . The method of  claim 22  wherein the alcoholamine is 2-dimethylamino-2-methyl-1-propanol.  
     
     
         30 . The method of  claim 22  wherein the aqueous chemical mechanical polishing composition abrasive is a metal oxide.  
     
     
         31 . The method of  claim 22  wherein the aqueous chemical mechanical polishing slurry abrasive is present in the slurry in an amount ranging from about 0.5% to 55% by weight.  
     
     
         32 . The method of  claim 22  wherein the abrasive used in the aqueous chemical mechanical polishing slurry is from about 0.5 to about 3.0 weight percent fumed silica.  
     
     
         33 . The method of  claim 22  wherein the aqueous chemical mechanical polishing slurry includes at least one buffering agent.  
     
     
         34 . A method for chemical-mechanical polishing of a substrate containing an insulator layer and a polysilicon layer, the method comprising the steps of: 
 a) providing an aqueous chemical mechanical polishing slurry comprising from about 0.5 to about 15 weight percent fumed silica, from about 50 ppm to about 2.0 weight percent 2-dimethylamino-2-methyl-1-propanol, and at least one buffering agent wherein the slurry has a pH of from about 9.0 to about 10.5;    b) applying the slurry to the substrate; and    c) removing at least a portion of the polysilicon layer by bringing a polishing pad into contact with the substrate and moving the pad in relation to the substrate.    
     
     
         35 . The method of  claim 34  wherein the buffering agent used in the aqueous chemical mechanical polishing slurry is from about 0.01 to about 1.0 weight percent ammonium bicarbonate.  
     
     
         36 . The method of  claim 34  wherein the polysilicon to insulating layer polishing selectivity of the slurry is greater than about 100.