Polishing pad and methods of improving pad removal rates and planarization

Abstract

A method of improving a removal rate of a pad includes producing a body of a pad of polyurethane from a mix; and introducing into the mix an additive which decreases an elastic rebound of the pad so as to increase a chemical-mechanical planarization removal rate; and using as the additive a substance which at least contains starch. In another embodiment, in a CMP process that includes removing a barrier and buffing a polyurethane after a bulk copper removal process, a polishing pad is used having a shore D hardness less than 35% and having at least one layer made from a mix composed of at least one of a prepolymer with an isocyanate concentration of between 6.5% and 11.0% to achieve a molal concentration, and a monomer in combination with an addition of isocyanate to achieve the substantially same molal concentration.

1 . An polishing pad comprising:
 a pad, wherein the pad comprises a urethane, a starch, and an isocyanate;   wherein the urethane comprises a base resin;   wherein the starch is configured to both reduce the elastic rebound of the pad and to improve the CMP removal rate of the pad compared to a similar urethane pad that does not include starch; and,   wherein the concentration of the isocyanate is within a range of 6.5% to 11.0% of the urethane in the pad.   
     
     
         2 . The polishing pad of  claim 1 , wherein the Global Planarization Efficiency is 75% to 90%. 
     
     
         3 . A method of improving a removal rate of a polishing pad, at least one layer of which is constructed comprising the steps of producing a body of a pad of polyurethane from a mix; introducing into the mix an additive which decreases an elastic rebound of the pad so as to increase a chemical-mechanical planarization removal rate; and using as the additive a substance which at least contains a starch. 
     
     
         4 . A polishing pad, at least one layer of which is constructed comprising the steps of producing a body of a pad of polyurethane from a mix; and introducing into the mix an additive which decreases an elastic rebound of the pad so as to increase a chemical-mechanical planarization removal rate; and using as the additive a substance which at least contains a starch. 
     
     
         5 . A method as defined in  claim 3 , wherein said using step includes introducing substantially one pound of starch in a 25 pound mix to reduce the elastic rebound of the pad by eight percentage points. 
     
     
         6 . A pad according to  claim 3  wherein said layer comprises at least one of a polyether urethane, a polyester polyurethane, and a polycarbonate. 
     
     
         7 . A pad according to  claim 3  wherein said layer contains abrasive particles selected from any of silica, alumina, ceria, titania, diamond and silicon carbide. 
     
     
         8 . A pad according to  claim 3  wherein said layer comprises at least one of a filler, and a nylon. 
     
     
         9 . A pad according to  claim 3  wherein said layer is absent abrasive particles. 
     
     
         10 . A method of improving planarization of a urethane polishing pad, comprising the steps of combining a base resin; and introducing in the base resin and an isocyanate to form a urethane polishing pad; and selecting a concentration of the isocyanate to be within a range of 6.5% to 11.0% of said base resin to obtain a high planarization property. 
     
     
         11 . The method of  claim 10 , wherein said selecting step includes selecting a concentration of the isocyanate within a range of 6.5 to 8.5%. 
     
     
         12 . The method of  claim 10 , wherein said selecting step includes selecting a concentration of said isocyanate within a range of 8.5% to 11.0%. 
     
     
         13 . The method of  claim 10 , wherein said layer is composed of a polyurethane selected from the group consisting of a polyether polyurethane and polyester polyurethane. 
     
     
         14 . The method of  claim 10 , and further comprising the step of combining a plurality of abrasive particles with said base resin and said isocyanate, wherein said plurality of abrasive particles are selected from the group consisting of silica, alumina, ceria, titania, diamond and silicon carbide. 
     
     
         15 . The method of  claim 10 , wherein said method does not include the step of urethane polishing pad combining abrasive particles with said base resin and said isocyanate. 
     
     
         16 . The method of  claim 10 , further comprising the step of combining a filler with said base resin and said isocyanate. 
     
     
         17 . A urethane polishing pad, comprising at least one layer having a base resin, and isocyanate introduced in the base resin, wherein a concentration of the isocyanate in the base resin is within a range of 6.5% to 11.0%. 
     
     
         18 . The urethane polishing pad as defined in  claim 17 , wherein the concentration of the isocyanate in the base resin is within a range of 6.5% to 8.5%. 
     
     
         19 . The urethane polishing pad of  claim 17 , wherein the concentration of the isocyanate in the base resin is within a range of 8.5% to 11.0%. 
     
     
         20 . The urethane polishing pad of  claim 17 , wherein said at least one layer comprises polyurethane selected from the group consisting of a polyether polyurethane and polyester polyurethane. 
     
     
         21 . The urethane polishing pad of  claim 17 , wherein said at least one layer contains abrasive particles selected from the group consisting of silica, alumina, ceria, titania, diamond, and silicon carbide. 
     
     
         22 . The urethane polishing pad of  claim 17 , wherein at least one layer is absent of abrasive particles. 
     
     
         23 . The urethane polishing pad of  claim 17 , wherein said at least one layer includes a filler. 
     
     
         24 . A method of chemical mechanical polishing of a copper film deposited on a surface of a semiconductor wafer, comprising the steps of:
 removing a bulk copper layer to a barrier;   removing the barrier; and   buffing, wherein said removing the barrier and buffing include using a polyurethane polishing pad having a shore D hardness of less than about 35% and having a layer made of a mix comprising at least one of (i) a prepolymer in combination with an isocyanate concentration of between 6.5% and 11.0% to achieve a molal concentration, and (ii) a monomer in combination with sufficient isocyanate to achieve substantially the same molal concentration as in (i).   
     
     
         25 . The method of  claim 24 , wherein the pad comprises an additive including at least one of a methyl alcohol, water and starch. 
     
     
         26 . The method of  claim 24 , wherein the pad has a thickness between 10 mils and 200 mils. 
     
     
         27 . The method of  claim 26 , wherein the pad has a thickness of between 40 and 100 mils. 
     
     
         28 . The method of  claim 24 , wherein the pad is a single open-layered pad. 
     
     
         29 . The method of  claim 24 , wherein the pad is stacked on and attached to a sub pad. 
     
     
         30 . The method of  claim 24 , wherein said pad includes grooves. 
     
     
         31 . The method of  claim 24 , wherein said pad includes perforations. 
     
     
         32 . The method of  claim 24 , wherein said layer is comprises at least one of a polyether polyurethane and polyester polyurethane. 
     
     
         33 . The method of  claim 24 , further comprising introducing in said layer abrasive particles comprising at least one of silica, alumina, ceria, titania, diamond and silicon carbide. 
     
     
         34 . The method of  claim 24 ; and further comprising introducing a filler into said mix. 
     
     
         35 . A polishing pad for removal of a barrier and buffing after a bulk copper removal to the barrier in a chemical mechanical polishing of a copper film deposited on a surface of a semiconductor wafer, the polishing pad having a shore D hardness of less than 35% and having at least one layer made of a mix comprising at least one of (i) a prepolymer with an isocyanate concentration of between 6.5% and 11.0% to achieve a molal concentration, and (ii) a monomer in combination with sufficient isocyanate to achieve substantially the same molal concentration as in (i). 
     
     
         36 . The pad of  claim 35 , wherein the pad includes an additive comprising at least one of methyl alcohol, water, and starch. 
     
     
         37 . The pad of  claim 36 , wherein the pad is a single open-layered pad. 
     
     
         38 . The pad of  claim 35 , wherein the pad has a thickness between 10 mils and 200 mils. 
     
     
         39 . The pad of  claim 35 , wherein the pad has a thickness of between 40 and 100 mils. 
     
     
         40 . The pad of  claim 35 , wherein the pad is stacked on and attached to a sub pad. 
     
     
         41 . The pad of  claim 35 , wherein said pad includes grooves. 
     
     
         42 . The pad of  claim 35 , wherein said pad includes perforations. 
     
     
         43 . The pad of  claim 35 , wherein said layer comprises at least on of polyether polyurethane and polyester polyurethane. 
     
     
         44 . The pad of  claim 35 , further comprising abrasive particles comprising at least one of silica, alumina, ceria, titania, diamond and silicon carbide. 
     
     
         45 . The pad of  claim 35 ; and further comprising a filler introduced into said mix. 
     
     
         46 . A method of chemical mechanical polishing of a copper film deposited on a surface of a semiconductor wafer, the method comprising:
 removing bulk copper to a barrier;   removing the barrier; and   buffing, and wherein said removing the barrier and buffing include using a polyurethane polishing pad having a shore D hardness of less than 35% and having a layer made from a mix comprising at least one of a prepolymer with an isocyanate concentration of between 6.5% and 8.5% to achieve a molal concentration, and a monomer in combination with sufficient isocyanate to achieve substantially the same molal concentration.