Method of polishing a silicon-containing dielectric

Abstract

The invention is directed to a method of polishing a silicon-containing dielectric layer involving the use of a chemical-mechanical polishing system comprising (a) an inorganic abrasive, (b) a polishing additive, and (c) a liquid carrier, wherein the polishing composition has a pH of about 4 to about 6. The polishing additive comprises a functional group having a pKa of about 4 to about 9 and is selected from the group consisting of arylamines, aminoalcohols, aliphatic amines, heterocyclic amines, hydroxamic acids, aminocarboxylic acids, cyclic monocarboxylic acids, unsaturated monocarboxylic acids, substituted phenols, sulfonamides, thiols, salts thereof, and combinations thereof. The invention is further directed to the chemical-mechanical polishing system, wherein the inorganic abrasive is ceria.

Description

FIELD OF THE INVENTION [0001] This invention pertains to a method of polishing a silicon-containing dielectric substrate. BACKGROUND OF THE INVENTION [0002] Compositions and methods for planarizing or polishing the surface of a substrate are well known in the art. Polishing compositions (also known as polishing slurries) typically contain an abrasive material in an aqueous solution and are applied to a surface by contacting the surface with a polishing pad saturated with the polishing composition. Typical abrasive materials include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. U.S. Pat. No. 5,527,423, for example, describes a method for chemically-mechanically polishing a metal layer by contacting the surface with a polishing slurry comprising high purity fine metal oxide particles in an aqueous medium. The polishing slurry is typically used in conjunction with a polishing pad (e.g., polishing cloth or disk). Suitable polishing pads are described in ...

AI Technical Summary

Benefits of technology

The system achieves improved silicon dioxide removal rates and high selectivity over silicon nitride, with optimized removal rates and reduced defectivity, as demonstrated by examples showing enhanced oxide to nitride selectivity and controlled pH-dependent performance.

Problems solved by technology

Conventional polishing systems and polishing methods typically are not entirely satisfactory at planarizing semiconductor wafers.

In particular, polishing compositions and polishing pads can have less than desirable polishing rates or polishing selectivities, and their use in chemically-mechanically polishing semiconductor surfaces can result in poor surface quality.

The difficulty in creating an effective polishing system for semiconductor wafers stems from the complexity of the semiconductor wafer.

In fact, various problems in semiconductor fabrication can occur if the process steps are not performed on wafer surfaces that are adequately planarized.

Such alkaline polishing compositions, while effective in the removal of silicon dioxide dielectric materials, provide poor selectivity in substrates comprising both silicon dioxide and silicon nitride layers, as in STI substrates.