SOFT POLISHING PAD FOR POLISHING A SEMICONDUCTOR SUBSTRATE
Soft polishing pads for polishing semiconductor substrates are described. A soft polishing pad includes a molded homogeneous polishing body having a thermoset, closed cell polyurethane material with a hardness approximately in the range of 20 Shore D to 45 Shore D.
1 . A method of fabricating a soft polishing pad for polishing a semiconductor substrate, the method comprising:
mixing a pre-polymer, a primary curative, and a secondary curative different from the primary curative to form a mixture, wherein the primary curative is a diamine compound and the secondary curative is a diol compound; and
curing the mixture to provide a homogeneous polishing body comprising a thermoset, closed cell polyurethane material having a hardness between about 20 Shore D and about 35 Shore D.
2 . The method of claim 1 , wherein the pre-polymer comprises a polyurethane precursor and the primary curative is an aromatic diamine compound.
3 . The method of claim 2 , wherein the polyurethane precursor is an isocyanate and the secondary curative is polytetramethylene glycol.
4 . The method of claim 1 , wherein curing the mixture comprises partially curing in a formation mold to provide a polyurethane material, and further curing in an oven to provide the homogeneous polishing body comprising the thermoset, closed cell polyurethane material.
5 . The method of claim 1 , wherein the homogeneous polishing body comprises a first, grooved surface, and a second, flat surface opposite the first surface.
6 . The method of claim 1 , wherein the mixing further comprises mixing an opacifying lubricant with the pre-polymer, the primary curative, and the secondary curative, and wherein the homogeneous polishing body is opaque.
7 . The method of claim 4 , further comprising:
prior to mixing the pre-polymer and the primary curative and the secondary curative, mixing an aromatic urethane pre-polymer with a curative in a second, separate, formation mold to form a second mixture;
partially curing, in the second formation mold, the second mixture to form a molded gel; and
positioning the molded gel in a designated region of the formation mold, wherein mixing the pre-polymer and the primary curative and the secondary curative to form the mixture comprises forming the mixture at least partially surrounding the molded gel, and wherein curing the mixture to provide the homogeneous polishing body further comprises curing the molded gel to provide a local area transparency (LAT) region disposed in, and covalently bonded with, the homogeneous polishing body.
8 . The method of claim 7 , wherein curing the mixture comprises partially curing, in the formation mold, to provide the polyurethane material and to provide an LAT region precursor, and further curing in the oven to provide the homogeneous polishing body comprising the thermoset, closed cell polyurethane material and to provide the LAT region.
9 . The method of claim 7 , wherein the aromatic urethane pre-polymer comprises polytetramethylene glycol-toluene diisocyanate, and the curative comprises thioether aromatic diamine.
10 . The method of claim 7 , wherein the partial curing of the second mixture is performed solely with thermal energy.
11 . The method of claim 1 , wherein the pre-polymer is polytetramethylene glycol-toluene diisocyanate, the primary curative is a thioether aromatic diamine, and the secondary curative is polyoxytetramethylene glycol.
12 . The method of claim 1 , wherein the mixture further includes a catalyst.
13 . The method of claim 1 , wherein a molar amount of the primary curative is greater than a molar amount of the secondary curative.
14 . A soft polishing pad for polishing a semiconductor substrate, the soft polishing pad comprising:
a homogeneous polishing body comprising a thermoset, closed cell polyurethane material fabricated from polytetramethylene glycol-toluene diisocyanate as a pre-polymer, a thioether aromatic diamine as a primary curative, and polyoxytetramethylene glycol as a secondary curative, the homogeneous polishing body having a hardness between about 20 Shore D and about 35 Shore D.
15 . The soft polishing pad of claim 14 , wherein the homogeneous polishing body comprises a first, grooved surface, and a second, flat surface opposite the first surface.
16 . The soft polishing pad of claim 14 , wherein the homogeneous polishing body comprises an opacifying lubricant.
17 . The soft polishing pad of claim 14 , wherein the polyurethane material fabricated is further fabricated from a catalyst.
18 . The soft polishing pad of claim 14 , wherein the homogeneous polishing body is a molded homogeneous polishing body.
19 . The soft polishing pad of claim 14 , wherein a molar amount of the primary curative is greater than a molar amount of the secondary curative.
20 . A method of fabricating a soft polishing pad for polishing a semiconductor substrate, the method comprising:
mixing, in a formation mold, a pre-polymer, a primary curative, and a secondary curative different from the primary curative to form a mixture, wherein the primary curative is a diamine compound and the secondary curative is a diol compound; and
curing the mixture to provide a molded homogeneous polishing body comprising a thermoset, closed cell polyurethane material having a hardness between about 20 Shore D and about 35 Shore D.
21 . The method of claim 20 , wherein the pre-polymer comprises a polyurethane precursor, the primary curative comprises an aromatic diamine compound, and the secondary curative comprises an ether linkage.
22 . The method of claim 21 , wherein the polyurethane precursor is an isocyanate, the primary curative is an aromatic diamine, and the secondary curative is selected from the group consisting of polytetramethylene glycol, amino-functionalized glycol, and amino-functionalized polyoxopropylene.
23 . The method of claim 20 , wherein the mixing further comprises mixing an opacifying lubricant with the pre-polymer, the primary curative, and the secondary curative, and wherein the molded homogeneous polishing body is opaque.
24 . The method of claim 20 , wherein the pre-polymer is polytetramethylene glycol-toluene diisocyanate, the primary curative is a thioether aromatic diamine, and the secondary curative is polyoxytetramethylene glycol.
25 . The method of claim 20 , wherein the mixture further includes a catalyst.
26 . The soft polishing pad of claim 20 , wherein a molar amount of the primary curative is greater than a molar amount of the secondary curative.
27 . A soft polishing pad for polishing a semiconductor substrate, the soft polishing pad comprising:
a homogeneous polishing body comprising a thermoset, closed cell polyurethane material fabricated from a polyurethane precursor pre-polymer, a primary curative, and a secondary curative different from the primary curative, wherein the primary curative is a diamine compound and the secondary curative is a diol compound, the homogeneous polishing body having a hardness between about 20 Shore D and about 35 Shore D.
28 . The soft polishing pad of claim 27 , wherein the homogeneous polishing body comprises a first, grooved surface, and a second, flat surface opposite the first surface.
29 . The soft polishing pad of claim 27 , wherein the homogeneous polishing body comprises an opacifying lubricant.
30 . The soft polishing pad of claim 27 , wherein the polyurethane material fabricated is further fabricated from a catalyst.
31 . The soft polishing pad of claim 27 , wherein the homogeneous polishing body is a molded homogeneous polishing body.
32 . The soft polishing pad of claim 27 , wherein a molar amount of the primary curative is greater than a molar amount of the secondary curative.