Compositions for polishing silicon-containing substrates
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 CMP composition having a pH of about 5.5 or less and comprising an aqueous carrier containing a ceria abrasive in a concentration of about 0.005 wt. % to about 0.5 wt. %, wherein the ceria has an average primary particle size of between about 40 nm to about 120 nm, a polishing additive bearing a functional group having a pKa of about 4 to about 9, and a non ionic surfactant comprising a hydrophilic portion and a lipophilic portion wherein the hydrophilic portion has a number average molecular weight of 500 g/mol or higher.
2. The CMP composition of claim 1 wherein the surfactant comprises a polyoxyethylene alkylphenyl ether.
3. The CMP composition of claim 1 wherein the surfactant comprises a polydimethicone copolymer.
4. The CMP composition of claim 1 wherein the surfactant comprises a polyoxyethylene-polyoxypropylene copolymer.