Method to selectively polish silicon carbide films
AssigneeCabot Microelectronics Corporation
InventorsWILLIAM WARD, TIMOTHY JOHNS
Life of this patent
Estimating the term…
Abstract
The present invention provides a method for selectively removing silicon carbide from the surface of a substrate in preference to silicon dioxide. The method comprises abrading a surface of substrate with a polishing composition that comprises a particulate abrasive, at least one acidic buffering agent, and an aqueous carrier.
Claims33
A chemical-mechanical polishing (CMP) method for selectively removing silicon carbide from the surface of substrate in preference to silicon dioxide, the method comprising the steps of:
- (a) contacting a surface of the substrate with a polishing pad and an aqueous CMP composition;
- and
- (b) causing relative motion between the substrate and the polishing pad while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a period of time sufficient to abrade at least a portion of the silicon carbide present in the substrate from the surface;
- wherein the CMP composition contains a particulate silica abrasive present at a concentration in the range of about 0.1 to about 5 percent by weight, and an acidic buffering agent providing a pH in the range of about 2 to about 7, the CMP composition being capable of abrading silicon carbide present on the surface of the substrate at a higher removal rate than the concurrent abrading of silicon dioxide present on the surface of the substrate.
A chemical-mechanical polishing (CMP) method for selectively removing silicon carbide from the surface of a substrate in preference to silicon dioxide, the method comprising the steps of:
- (a) contacting a surface of the substrate with a polishing pad and an aqueous CMP composition;
- and
- (b) causing relative motion between the substrate and the polishing pad while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a period of time sufficient to abrade at least a portion of the silicon carbide present in the substrate from the surface;
- wherein the CMP composition contains about 0.1 to about 1 percent by weight of alumina-doped colloidal silica having a mean particle size in the range of about 40 to about 150 nanometers, and a buffering agent comprising an organic acid, the buffering agent providing a pH in the range of about 2 to about 5;
- the CMP composition being capable of abrading silicon carbide present on the surface of the substrate at a higher removal rate than the concurrent abrading of silicon dioxide present on the surface of the substrate.
A chemical-mechanical polishing (CMP) method of modulating the selectivity for removal of silicon carbide versus silicon dioxide from a substrate surface in a CMP process, the method comprising the steps of:
- (a) polishing a silicon carbide substrate and a silicon dioxide substrate under predetermined polishing conditions with a CMP composition comprising a particulate silica abrasive and an acidic buffering agent;
- (b) determining a silicon carbide-to-silicon dioxide removal rate ratio for the substrates polished in step (a);
- (c) altering a polishing parameter to increase or decrease the silicon carbide-to-silicon dioxide removal rate ratio as desired;
- the polishing parameter to be altered being selected from the group consisting of the pH of the composition, the concentration of the buffering agent in the composition, the concentration of silica in the composition, or a combination of two or more of the foregoing.
Dependencies are inferred from the claim text.