Polishing composition for semiconductor wafers
View Patent ↗An aqueous composition is useful for polishing semiconductor wafers. The composition comprises a nonionic surfactant that suppresses removal rate of silicon carbide-nitride and has a hydrophilic group and a hydrophobic group. The hydrophobic group has a carbon chain length of greater than three. And the nonionic surfactant suppresses silicon carbide-nitride removal rate at least 100 angstroms per minute greater than its decrease in silicon nitride removal rate as measured with a microporous polyurethane polishing pad pressure measured normal to a wafer of 13.8 kPa.
1. A polishing method for removing at least one coating layer from a semiconductor substrate, the semiconductor substrate including silicon nitride, silicon carbide nitride and a dielectric comprising the step of polishing with an aqueous composition, the aqueous composition comprising a nonionic surfactant that suppresses removal rate of silicon carbide-nitride, the nonionic surfactant having a hydrophilic group and a hydrophobic group, the hydrophobic group having a carbon chain length of greater than three, the nonionic surfactant being selected from the group comprising alkanoamide, alkyl polyethylene oxide, alkylphenol polyethylene oxide and a mixture thereof for removing silicon nitride and stopping on a silicon carbide-nitride layer and the nonionic surfactant suppresses silicon carbide-nitride removal rate at least 100 angstroms per minute greater than its decrease in silicon nitride removal rate as measured with a microporous polyurethane polishing pad pressure measured normal to a wafer of 13.8 kPa.
2. The method of claim 1 wherein the nonionic surfactant is selected from the group comprising alkanoamide, alkyl polyethylene oxide, alkylphenol polyethylene oxide, polyoxyethylenated alkyl amine oxide, polyoxyethylenated polyoxypropylene glycols, alkyl polyglucoside, alkyl carboxylic acid esters, polyoxyethylenated mercaptans, alkyl diglyceride, polyoxyethylenated alkanolamine, polyalkoxylated amides, tertiary acetylenic glycols and a mixture thereof.
3. The method of claim 1 wherein the aqueous composition contains 0 to 30 abrasive, 0 to 15 inhibitor for a nonferrous metal, 0 to 25 oxidizer, 0 to 10 tantalum removal agent selected from the group comprising formamidine, formamidine salts, formamidine derivatives, guanidine derivatives, guanidine salts and mixtures thereof and 0.001 to 5 nonionic surfactant.
4. The method of claim 1 wherein the polishing occurs in the presence of a carbon-doped oxide.
5. The method of claim 1 wherein the nonionic surfactant is an alkanoamide and the alkanoamide is an acylation product of alkanolamines from the group comprising monoalkanolamine (MAA), dialkanolamine (DAA), trialkanolamine and a mixture thereof.
6. The method of claim 1 wherein the nonionic surfactant is an alkanolamine selected from the group comprising diethanolamine, monoethanolamine, triethanolamine, diisopropanolamine, monoisopropanolamine, ethanoisopropanolamine and a mixture thereof; and the hydrophobic group has a carbon chain length of at least six carbon atoms.
7. The method of claim 1 wherein the tantalum removal agent is selected from the group comprising guanidine hydrochloride, guanidine sulfate, amino-guanidine hydrochloride, guanidine acetic acid, guanidine carbonate, guanidine nitrate, formanimide, formamidinesulfinic acid and a mixture thereof, and the tantalum removal agent is 0.2 to 6 weight percent.
8. The method of claim 1 including the step of stopping the polishing before removing all of the silicon carbide-nitride layer.
9. The method of claim 1 wherein the polishing stops on a carbon doped oxide layer.
10. The method of claim 1 wherein the aqueous composition has a pH of 7 to 10.