COMPOSITION AND METHOD FOR POLISHING SILICON CARBIDE
The invention provides a chemical-mechanical polishing composition comprising (a) silica particles, (b) a polymer comprising sulfonic acid monomeric units, (c) optionally, a buffering agent, and (d) water, wherein the polishing composition has a pH of about 2 to about 5. The invention further provides a method of chemically-mechanically polishing a substrate with the inventive chemical-mechanical polishing composition. Typically, the substrate comprises silicon carbide and silicon nitride.
1 . A chemical-mechanical polishing composition comprising:
(a) silica particles containing aluminum ions, wherein the aluminum ions are uniformly distributed within the silica particles, and wherein the silica particles have an average particle size of about 40 nm to about 80 nm,
(b) a polymer comprising sulfonic acid monomeric units,
(c) a buffering agent, and
(d) water,
wherein the polishing composition has a pH of about 2 to about 5.
2 . The polishing composition of claim 1 , wherein the silica particles have an average particle size of about 40 nm to about 60 nm.
3 . The polishing composition of claim 1 , wherein the silica particles are substantially spherical.
4 . The polishing composition of claim 1 , wherein the polymer comprising sulfonic acid monomeric units has an average molecular weight of about 75,000 g/mole to about 200,000 g/mole.
5 . The polishing composition of claim 1 , wherein the polymer comprising sulfonic acid monomeric units is selected from polystyrenesulfonic acid, poly(2-acrylamido-2-methyl-1-propanesulfonic acid), and poly(styrenesulfonic acid-co-maleic acid).
6 . The polishing composition of claim 1 , wherein the buffering agent is selected from formic acid, malonic acid, acetic acid, oxalic acid, citric acid, and phosphoric acid.
7 . The polishing composition of claim 1 , wherein the polishing composition further comprises an oxidizing agent.
8 . The polishing composition of claim 7 , wherein the oxidizing agent is hydrogen peroxide.
9 . The polishing composition of claim 1 , wherein the polishing composition does not contain a piperazine compound, a 4-morpholine compound, an amino sulfonic acid compound, a substituted amine compound, a tertiary amine compound, or a bis-amine compound, or salts thereof.