Copper Polishing Composition for Semiconductor Wiring

The patent changes the chemical parameters of the polishing composition by specifying an anionic surfactant with a particular molecular structure (R1-X1-Y1 where R1 is alkyl/alkylphenyl/alkenyl, X1 is polyoxyethylene/polyoxypropylene/poly(oxyethylene-oxypropylene) with average degree of polymerization 1-10, and Y1 is anionic functional group). This specific parameter change in surfactant structure controls the polishing rate uniformity across the conductor layer surface, preventing dishing while maintaining high stock removal rate.

The patent uses a composite polishing composition containing both anionic surfactant and abrasive grains (silica or colloidal silica). The anionic surfactant forms a protective film on the conductor layer surface that works in conjunction with the abrasive grains to achieve uniform polishing. This composite approach allows the surfactant to control the chemical interaction while the abrasive provides mechanical removal, resolving the contradiction between removal rate and surface uniformity.

The patent optimizes the parameter of surfactant molecular structure by controlling the average degree of polymerization of the polyoxyethylene/polyoxypropylene groups to be 1-10. This parameter change creates an optimal balance where the surfactant provides sufficient protection to prevent excessive removal and dishing, while still allowing adequate polishing rate through controlled affinity between the conductor surface and abrasive grains.

The anionic surfactant acts as an intermediary between the conductor layer and the abrasive grains. It forms a protective film that mediates the interaction, preventing direct excessive contact between abrasive and conductor while still allowing controlled removal. This intermediary layer ensures uniform polishing by distributing the removal action evenly across the surface, preventing dishing.