Methods and compositions for polishing silicon-containing substrates
View Patent ↗The invention provides chemical-mechanical polishing (CMP) compositions and methods for polishing a silicon-containing substrate. A method of the invention comprises the steps of contacting a silicon-containing substrate with a polishing pad and an aqueous CMP composition, and causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface of the substrate to abrade at least a portion of the substrate. The CMP composition comprises a ceria abrasive, a polishing additive bearing a functional group with a pK a of about 4 to about 9, a nonionic surfactant with an hydrophilic portion and a lipophilic portion wherein the hydrophilic portion has a number average molecular weight of about 500 g/mol or higher, and an aqueous carrier, wherein the pH of the composition is 7 or less. The method reduces defects on the wafers, particularly local areas of high removal. The method is also useful for polishing dielectric silicon-containing substrates at a high rate relative to semiconductor silicon-containing substrates.
1. A chemical-mechanical polishing (CMP) method for polishing a silicon-containing substrate, the method comprising the steps of:
(a) contacting a surface of a silicon-containing substrate with a polishing pad and a CMP composition comprising;
(i) an aqueous carrier,
(ii) a ceria abrasive,
(iii) a polishing additive bearing a functional group having a pKa of about 4 to about 9, and
(iv) a non ionic surfactant comprising a hydrophilic portion and a lipophilic portion wherein the hydrophilic portion has a number average molecular weight of about 500 g/mol or higher; and wherein the CMP composition has a pH of 7 or less;
(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the substrate to abrade at least a portion of the surface of the substrate, thereby polishing the substrate.
2. The CMP method of claim 1 wherein the hydrophilic portion has a number average molecular weight of 1000 g/mol or higher.
3. The CMP method of claim 1 wherein the polishing additive is a heterocyclic amine.
4. The CMP method of claim 1 wherein the polishing additive is an aminocarboxylic acid.
5. The CMP method of claim 1 wherein the polishing additive is selected from the group consisting of an arylamine, an aliphatic amine, a hydroxamic acid, a cyclic monocarboxylic acid, an unsaturated monocarboxylic acid, a substituted phenol, a sulfonamide, a thiol, salts thereof, and combinations thereof.
6. The CMP method of claim 1 wherein the hydrophilic portion comprises a polyoxyethylene group.
7. The CMP method of claim 1 wherein the surfactant has a hydrophilic-lipophilic balance (HLB) value in the range of about 8 to about 20.
8. The CMP method of claim 1 wherein the surfactant comprises a polyoxyethylene alkylphenyl ether.
9. The CMP method of claim 1 wherein the surfactant comprises a polydimethicone copolymer.
10. The CMP method of claim 1 wherein the surfactant comprises a polyoxyethylene- polyoxypropylene copolymer.
11. The CMP method of claim 1 wherein the pH is about 2 to about 7.
12. The CMP method of claim 1 wherein the surfactant is present in the CMP composition at a concentration in the range of about 5 ppm to about 10,000 ppm.
13. The CMP method of claim 1 wherein the ceria in the CMP composition is present at a concentration of about 0.005 wt. % to about 0.5 wt%.
14. The CMP method of claim 1 wherein the ceria in the CMP composition is present at a concentration of about 0.01 wt. % to about 0.1 wt. %.
15. The method of claim 1 wherein the ceria abrasive has an average primary particle size of between about 10 nm and about 180 nm.
16. The method of claim 1 wherein the ceria abrasive has an average primary particle size of between about 40 nm and about 120 nm.