Polyurethane composition for CMP pads and method of manufacturing same

1. A polyurethane chemical mechanical polishing pad derived from a polyether/polyester based prepolymer reaction mixture, comprising:

(a) toluene diisocyanate (TDI)-terminated polytetramethylene ether glycol based prepolymer in an amount of about 60-80 weight percent (wt %) based on the total weight of prepolymer mixture;

(b) toluene diisocyanate (TDI)-terminated ethylene adipate polyester prepolymer in an amount of about 40-20 weight percent (wt %), wherein the weight percent based on the total weight of prepolymer mixture;

(c) an effective amount of surfactant and curative, respectively, and

(d) a foaming agent introduced into the reaction mixture to form said polishing pad, wherein the resulting polishing pad has a density ranging from about 0.6 to about 0.95 g/cc;

wherein the curative is selected from the group consisting of 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline), dimethylthiotoluenediamine, trimethyleneglycol di-p-aminobenzoate, polytetramethyleneoxide di-p-aminobenzoate, polytetramethyleneoxide mono-p-aminobenzoate, polypropyleneoxide di-p-aminobenzoate, polypropyleneoxide mono-p-aminobenzoate, 1,2-bis(2-aminophenylthio)ethane, 4,4′-methylene-bis-aniline, diethyltoluenediamine, 5-tert-butyl-2,4- and 3-tert-butyl-2,6-toluenediamine, 5-tert-amyl-2,4- and 3-tert-amyl-2,6-toluenediamine, chlorotoluenediamine, bis-(alkylthio) aromatic diamines, a mixture of 3,5-bis(methylthio)-2,6-toluenediamine and 3,5-bis(methylthio)-2,4-toluenediamine, a mixture of 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine and combinations thereof.

2. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the prepolymer reaction mixture is about 65-75 wt % TDI-terminated polytetramethylene ether glycol based prepolymer to about 25-35 wt % TDI-terminated ethylene adipate polyester prepolymer.

3. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the prepolymer reaction mixture is about 70 wt % TDI-terminated polytetramethylene ether glycol based prepolymer to about 30 wt % TDI-terminated ethylene adipate polyester prepolymer.

4. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the TDI-terminated ethylene adipate polyester has a molecular weight ranging from about 2500 to 4000 and is based on a reaction of an ethylene adipate polyol with a 1,3-diisocyanato methylbenzene.

5. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the average weight percent of unreacted isocyanate group (NCO) present in the prepolymer mixture ranges from about 6.5% to about 8.5%.

6. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the surfactant is selected from the group of silicone and polysiloxane-polyalkyleneoxide surfactants, in an amount from 0.3 to 5.0 wt % of prepolymers and surfactant.

7. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the effective amount of curative is in a ratio of 0.9 to 1.0 to the prepolymers utilized, wherein the ratio corresponds to a combination of amine and hydroxyl groups relative to an amount of available isocyanate groups.

8. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the pad has a Bashore rebound in the range of about 20% to about 50%.

9. The polyurethane chemical mechanical polishing pad of claim 1 , wherein the pad has a removal rate of a metallic film from a wafer ranging from about 7,400 to about 7,900 Å/min.

10. A method of making a polyurethane chemical mechanical polishing pad derived from a polyether/polyester based prepolymer reaction mixture, comprising:

(a) mixing toluene diisocyanate (TDI)-terminated polyether prepolymer in an amount of about 60-80 weight percent (wt %) with toluene diisocyanate (TDI)-terminated polyester prepolymer in an amount of about 40-20 weight percent (wt %), in the presence of an effective amount of surfactant, wherein the weight percent is based on the total weight of the prepolymers;

(b) frothing the reaction mixture of step (a) by introducing a foaming agent into the reaction mixture; and

(c) polymerizing the frothed reaction mixture in the presence of an effective amount of curative to form a polishing pad having a density ranging from about 0.6 to about 0.95 g/cc, wherein the curative is selected from the group consisting of 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline), dimethylthiotoluenediamine, trimethyleneglycol di-p-aminobenzoate, polytetramethyleneoxide di-p-aminobenzoate, polytetramethyleneoxide mono-p-aminobenzoate, polypropyleneoxide di-p-aminobenzoate, polypropyleneoxide mono-p-aminobenzoate, 1,2-bis(2-aminophenylthio)ethane, 4,4′-methylene-bis-aniline, diethyltoluenediamine, 5-tert-butyl-2,4- and 3-tert-butyl-2,6-toluenediamine, 5-tert-amyl-2,4- and 3-tert-amyl-2,6-toluenediamine, chlorotoluenediamine, bis-(alkylthio) aromatic diamines, a mixture of 3,5-bis(methylthio)-2,6-toluenediamine and 3,5-bis(methylthio)-2,4-toluenediamine, a mixture of 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine and combinations thereof.

11. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the prepolymer reaction mixture is about 65-75 wt % TDI-terminated polytetramethylene ether glycol based prepolymer to about 25-35 wt % TDI-terminated ethylene adipate polyester prepolymer.

12. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the prepolymer reaction mixture is about 70 wt % TDI-terminated polytetramethylene ether glycol based prepolymer to about 30 wt % TDI-terminated ethylene adipate polyester prepolymer.

13. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the TDI-terminated polytetramethylene ether glycol based and TDI-terminated ethylene adipate polyester prepolymers are first mixed with the surfactant in a tank and the foaming agent is added to said tank to form a froth.

14. The method of making a polyurethane chemical mechanical polishing pad of claim 13 , wherein the froth is routed to a mixer tank and the curative is added to said mixer tank.

15. The method of making a polyurethane chemical mechanical polishing pad of claim 14 , wherein a green cured polyurethane foam is dispensed from said mixer tank and further cured.

16. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the prepolymers, surfactant, and foaming, agent are provided in the same tank, and the curative agent is added thereafter to the same tank.

17. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the TDI-terminated polyester is an ethylene adipate polyester having a molecular weight ranging from about 2000 to 4000 and is based on a reaction of an ethylene adipate polydiol with a 1,3-diisocyanato methylbenzene.

18. The method of making a polyurethane chemical mechanical polishing pad of claim 13 , wherein the average weight percent of unreacted isocyanate group (NCO) present in the prepolymer mixture ranges from about 6.5% to about 8.5%.

19. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the surfactant is selected from the group of silicone and polysiloxane-polyalkyleneoxide surfactants, in an amount from 0.3 to 5.0 wt % of prepolymers and surfactant.

20. The method of making a polyurethane chemical mechanical polishing pad of claim 10 , wherein the effective amount of curative is in a ratio of 0.9 to 1.0 to the prepolymers utilized, wherein the ratio corresponds to a combination of amine and hydroxyl groups relative to an amount of available isocyanate groups.

21. A polyurethane chemical mechanical polishing pad polishing pad produced by the method of claim 10 .