Formulations for high porosity chemical mechanical polishing pads with high hardness and CMP pads made therewith
The present invention provides CMP polishing pads or layers having a unfilled Shore D (2 second) hardness of from 57-77 or a filled Shore D (2 second) hardness of from 18-50, made from a two-component reaction mixture of (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of from 18 to 47 wt. %, based on the total solids weight of the aromatic isocyanate component, and (ii) a liquid polyol component including one or more curatives selected from the group of amines defined by Formulas (I) and (II).
1. A chemical mechanical (CMP) polishing pad for polishing a substrate chosen from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate, the polishing pad comprising a polishing layer adapted for polishing the substrate, the polishing layer comprising a thermoset polyurethane foam having roughly spherical hollow cells that are isolated or partially connected forming small isolated clusters, the polyurethane form is a product of an organic solvent free two-component reaction mixture comprising (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of 18 to 47 wt. %, based on the total solids weight of the aromatic isocyanate component, (ii) a liquid polyol component, and (iii) one or more curatives selected from the group of amines having Formulas (I) and (II)
wherein each R 1 and R 2 are independently C 1 -C 6 alkyl, C 1 -C 4 alkyl substituted with one or more C 1 -C 4 alkyl or one or more halogens, —(CR 5 R 6 ) p —S—(CR 5 R 6 ) q — or —(CR 5 R 6 ) p —O—(CR 5 R 6 ) q —; R 3 is C 1 -C 6 alkyl or C 1 -C 4 alkyl substituted with one or more C 1 -C 4 alkyl; each R 4 is independently H or —R 1 —OH; each R 5 and R 6 are independently H or C 1 -C 6 alkyl; each p and q are independently an integer from 1 through 5; and n is in the range of 1 to 4, wherein the reaction mixture comprises 55 to 75 wt. % of hard segment materials, based on the total weight of the reaction mixture, the total amount of the curatives (I) and/or (II) range from 9 to 26.8 wt %, based on the total weight of the reaction mixture, the CMP polishing layer has a unfilled Shore D (2 second) hardness of 57-77 or a filled Shore D (2 second) hardness of 18-50, and densities of 0.43 to 0.78 g/mL.
2. The CMP polishing pad as claimed in claim 1 , wherein the liquid aromatic isocyanate component comprises a linear aromatic isocyanate-terminated urethane prepolymer.
3. The CMP polishing pad as claimed in claim 2 , wherein the one or more curatives are selected from the group of amines having Formula (II).
4. The CMP polishing pad as claimed in claim 3 , wherein n is 2.
5. The CMP polishing pad as claimed in claim 4 , wherein the CMP polishing layer has densities of 0.50 to 0.78 g/mL.
6. The CMP polishing pad as claimed in claim 1 , wherein the one or more curatives are selected from the group of amines having Formula (II).
7. The CMP polishing pad as claimed in claim 6 , wherein n is 2.