Polishing Composition for Low-PID Selective Polysilicon CMP

The invention changes the chemical composition parameters of the polishing slurry by incorporating specific organic compounds (tetraalkylammonium salts, carboxylic acids, or their combinations) alongside conventional inorganic additives. This parameter modification enables simultaneous achievement of high selectivity (maintaining stopper film functionality) and reduced PID formation, resolving the technical contradiction between reliability and harmful effects.

The invention uses composite polishing compositions that combine multiple types of additives (inorganic bases like KOH/NaOH, organic compounds like tetraalkylammonium salts or carboxylic acids, and colloidal silica) to achieve synergistic effects. This composite approach allows the slurry to simultaneously provide the chemical etching needed for selectivity and the surface protection needed to reduce PIDs, resolving the contradiction between maintaining stopper film functionality and reducing defects.

The invention modifies the chemical parameters of the polishing slurry by introducing organic compounds (tetraalkylammonium salts with specific alkyl groups, or carboxylic acids with specific carbon chain lengths) in controlled concentrations. These parameter changes enable the slurry to achieve high selectivity for polysilicon removal while simultaneously reducing surface defect formation through the protective effect of the organic additives.

The organic compounds in the polishing slurry act as intermediary substances that mediate between the aggressive inorganic base (which provides selectivity through chemical etching) and the polysilicon surface (which needs protection from excessive etching that causes defects). The organic compounds facilitate controlled material removal while protecting the surface, thereby achieving both high selectivity and reduced surface defects.

The invention employs composite polishing slurry formulations that combine conventional inorganic components (KOH, NaOH, colloidal silica) with organic additives (tetraalkylammonium salts or carboxylic acids). This composite composition maintains the high polishing rate provided by the inorganic base while the organic components suppress PID formation, thereby resolving the contradiction between productivity and harmful effects.

The organic compounds in the polishing slurry provide local protective quality at the polishing interface, creating a protective layer or modifying the local chemical environment where polysilicon removal occurs. This local quality enhancement allows the bulk polishing process to maintain high removal rates while the localized organic modification suppresses PID formation at the critical interface region.