SILICA-BASED SLURRY COMPOSITIONS CONTAINING HIGH MOLECULAR WEIGHT POLYMERS FOR USE IN CMP OF DIELECTRICS
The invention provides a chemical-mechanical polishing composition comprising: (a) about 3.0 wt. % to about 10 wt. % silica abrasive; (b) an anionic polymer having a weight average molecular weight of about 400 kDa to about 7000 kDa; and (c) water, wherein the polishing composition has a viscosity of at least about 1 cPs, a ratio of viscosity (cPs) to wt. % of silica abrasive of about 0.2 cPs/wt. % to about 1.5 cPs/wt. %, and a pH of about 9 to about 12. The invention additional provides a chemical-mechanical polishing composition comprising: (a) about 3.0 wt. % to about 10 wt. % silica abrasive; (b) a nonionicpolymer having a weight average molecular weight of about 300 kDa to about 7000 kDa; and (c) water, wherein the polishing composition has a viscosity of at least about 2 cPs, and a pH of about 9 to about 12. The invention also provides a method of chemically-mechanically polishing a substrate, especially a substrate comprising silicon oxide, silicon nitride, polysilicon, or combinations thereof, using said compositions.
1 . A chemical-mechanical polishing composition comprising:
(a) about 3.0 wt. % to about 10 wt. % silica abrasive;
(b) an anionic polymer having a weight average molecular weight of about 400 kDa to about 7,000 kDa; and
(c) water,
wherein the polishing composition has a viscosity of at least about 1 cPs, a ratio of viscosity (cPs) to wt. % of silica abrasive of about 0.2 cPs/wt. % to about 1.5 cPs/wt. %, and a pH of about 9 to about 12.
2 . The polishing composition of claim 1 , wherein the polishing composition comprises about 3.5 wt. % to about 8 wt. % silica abrasive.
3 . The polishing composition of claim 1 , wherein the polishing composition comprises about 3.5 wt. % to about 5 wt. % silica abrasive.
4 . The polishing composition of claim 1 , wherein the polishing composition has a pH of about 10 to about 12.
5 . The polishing composition of claim 1 , wherein the polishing composition has a viscosity of at least about 2 cPs.
6 . The polishing composition of claim 1 , wherein the polishing composition has a ratio of viscosity (cPs) to wt. % of silica abrasive of about 0.4 cPs/wt. % to about 1.5 cPs/wt. %.
7 . The polishing composition of claim 1 , wherein the polymer has a weight average molecular weight of about 1000 kDa to about 7000 kDa.
8 . The polishing composition of claim 1 , wherein the polymer has a weight average molecular weight of about 2000 kDa to about 4000 kDa.
9 . The polishing composition of claim 1 , wherein the polymer comprises an anionic polymer comprising an anionic monomer comprising a carboxylate group, a phosphonate group, a sulfonate group, or combinations thereof.
10 . The polishing composition of claim 1 , wherein the polymer comprises an anionic polymer comprising an anionic monomer selected from 2-acrylamido-2-methylpropane sulfonic acid, styrene sulfonate, 2-acrylamido-2-methylbutane sulfonic acid, [2-methyl-2-[(1-oxo-2-propenyl)amino]propyl]-phosphonic acid, maleic acid, methacrylic acid, acrylic acid, salts thereof, and combinations thereof.
11 . The polishing composition of claim 1 , wherein the polymer comprises an anionic polymer selected from carboxymethyl cellulose, a hydrophobically modified polyacrylate copolymer, poly-2-acrylamido-2-methylpropane sulfonic acid, polystyrenesulfonate, salts thereof, and combinations thereof.
12 . The polishing composition of claim 1 , wherein the polishing composition comprises about 100 ppm to about 2000 ppm of the polymer.
13 . The polishing composition of claim 1 , wherein the silica abrasive has an average transmission electron microscope (TEM) equivalent diameter of about 60 nm to about 150 nm.
14 . The polishing composition of claim 1 , wherein the silica abrasive has an average transmission electron microscope (TEM) equivalent diameter of about 80 nm to about 120 nm.
15 . The polishing composition of claim 1 , wherein the silica abrasive has an average aspect ratio of at least 1.1.
16 . The polishing composition of claim 1 , wherein the silica abrasive has an average aspect ratio of at least 1.25.
17 . The polishing composition of claim 1 , wherein the silica abrasive has an average Brunauer-Emmet-Teller (BET) surface area of about 20 cm 2 /g to about 60 cm 2 /g.
18 . The polishing composition of claim 1 , wherein the silica abrasive has an average Brunauer-Emmet-Teller (BET) surface area of about 30 cm 2 /g to about 45 cm 2 /g.
19 . A chemical-mechanical polishing composition comprising:
(a) about 3.0 wt. % to about 10 wt. % silica abrasive;
(b) a nonionic polymer having a weight average molecular weight of about 300 kDa to about 7,000 kDa; and
(c) water,
wherein the polishing composition has a viscosity of at least about 1.2 cPs, and a pH of about 9 to about 12.
20 . The polishing composition of claim 19 , wherein the nonionic polymer selected from polyalkylene oxides, polyetheramines, polyethylene oxide/polypropylene oxide copolymers, polyacrylamide, hydrophobically modified polyacrylamide, cellulose, hydrophobically modified cellulose, siloxane polyalkyleneoxide copolymers, hydrophobically modified polyacrylate polymers, polysaccharides, hydrophobically modified polysaccharides, polystyrene, and combinations thereof.
21 . A method of chemically-mechanically polishing a substrate comprising:
(i) providing a substrate,
(ii) providing a polishing pad,
(iii) providing a chemical-mechanical polishing composition comprising:
(a) about 3.0 wt. % to about 10 wt. % silica abrasive;
(b) an anionic polymer having a weight average molecular weight of about 400 kDa to about 7,000 kDa; and
(c) water,
wherein the polishing composition has a viscosity of at least about 1 cPs, a ratio of viscosity (cPs) to wt. % of silica abrasive of about 0.2 cPs/wt. % to about 1.5 cPs/wt. %, and a pH of about 9 to about 12,
(iv) contacting the substrate with the polishing pad and the chemical-mechanical polishing composition, and
(v) moving the polishing pad and the chemical-mechanical polishing composition relative to the substrate to abrade at least a portion of the substrate to polish the substrate.
22 . A method of chemically-mechanically polishing a substrate comprising:
(i) providing a substrate,
(ii) providing a polishing pad,
(iii) providing a chemical-mechanical polishing composition comprising:
(a) about 3.0 wt. % to about 10 wt. % silica abrasive;
(b) a nonionic polymer having a weight average molecular weight of about 300 kDa to about 7,000 kDa; and
(c) water,
wherein the polishing composition has a viscosity of at least about 1.2 cPs, and a pH of about 9 to about 12.