Formulations for chemical mechanical polishing pads with high planarization efficiency and CMP pads made therewith
CMP polishing pads or layers made from a polyurethane reaction product of a reaction mixture comprising (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer, and (ii) a liquid polyol component comprising a) one or more polymeric polyols, b) from 12 to 40 wt. %, based on the total weight of the liquid polyol component, of a curative mixture of one or more small chain difunctional polyols having from 2 to 9 carbon atoms, a liquid aromatic diamine, wherein the mole ratio of liquid aromatic diamine to the total moles of small chain difunctional polyols and liquid aromatic diamine ranges from 15:85 to 40:60, wherein, the reaction mixture comprises 48 to 68 wt. % hard segment materials.
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 CMP polishing pad comprising a polishing layer adapted for polishing the substrate, the polishing layer being a polyurethane, the polyurethane is a product of a 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 from 20 to 40 wt. %, based on the total solids weight of the liquid aromatic isocyanate component, and (ii) a liquid polyol component comprising a) one or more polymeric polyols, and b) from 12 to 40 wt. %, based on the total weight of the liquid polyol component, of a curative mixture of one or more small chain difunctional polyols having from 2 to 9 carbon atoms, and a liquid aromatic diamine which is a liquid under ambient conditions, wherein the mole ratio of liquid aromatic diamine to the total moles of small chain difunctional polyols and liquid aromatic diamine ranges from 15:85 to 40:60, the reaction mixture comprises 48 to 68 wt. % of hard segment materials, based on the total weight of the reaction mixture, and, yet still further wherein, the CMP polishing layer has a hardness in the range of from 50 Shore A (15 Second) to 68 Shore D (15 second), and a density of from 0.45 to 0.9 g/mL.
2. The CMP polishing pad as claimed in claim 1 , wherein the (i) liquid aromatic isocyanate component comprises a linear methylene diphenyl diisocyanate (MDI) prepolymer or MDI.
3. The CMP polishing pad as claimed in claim 1 , wherein the (ii) liquid polyol component comprises a) one or more polymeric polyols which is selected from the group consisting of polytetramethylene glycol (PTMEG), polypropylene glycol (PPG), a hexafunctional polyol, and mixtures thereof.
4. The CMP polishing pad as claimed in claim 1 , wherein in the b) curative mixture of the (ii) liquid polyol component, the one or more small chain difunctional polyols having from 2 to 9 carbon atoms is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1, 3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, tripropylene glycol, and mixtures thereof.
5. The CMP polishing pad as claimed in claim 1 , wherein in the b) curative mixture, the liquid aromatic diamine is selected from the group consisting of dimethylthio-toluene diamines, diethyl toluene diamines, tert-butyl toluene diamines, chlorotoluenediamines, N,N′-dialkylaminodiphenylmethane, and mixtures thereof.
6. The CMP polishing pad as claimed in claim 1 , wherein in the b) curative mixture, the mole ratio of liquid aromatic diamine to the total moles of small chain difunctional polyols and liquid aromatic diamine ranges from 23:77 to 35:65.
7. The CMP polishing pad as claimed in claim 1 , wherein reaction mixture comprises from 58 to 63 wt. % of hard segment materials, based on the total weight of the reaction mixture.
8. The CMP polishing pad as claimed in claim 1 , wherein the CMP polishing pad contains no microelements other than those formed by gas, water or CO 2 -amine adduct.
9. A method for making chemical mechanical (CMP) polishing pads having a polishing layer adapted for polishing a substrate comprising providing the two component reaction mixture as claimed in claim 1 , comprising:
providing the two component reaction mixture, including in the ii) liquid polyol component c) water or CO 2 -amine adduct sufficient to create the density of the CMP polishing pad or layer, mixing the (i) liquid aromatic isocyanate component and the (ii) liquid polyol component, and applying the reaction mixture as one component to an open mold surface; curing the reaction mixture at from ambient temperature to 130° C. to form a molded polyurethane reaction product; removing the polyurethane reaction product from the mold; and, then, finally curing at a temperature from 60 to 130° C. for a period of 1 minutes to 18 hours to form the polishing layer.
10. The method as claimed in claim 9 , wherein the mold surface has a male topography that forms a female groove pattern in the top surface of the CMP polishing layer.