CMP Slurry Copolymer for Silicon Nitride Stopper Selectivity

The patent changes the chemical parameters of the slurry by introducing a copolymer with specific functional groups (carboxyl, hydroxyl, or amine groups) that selectively interact with silicon nitride. This chemical modification allows the slurry to differentiate between the stopper and polishing objects, achieving high selectivity without requiring intensified mechanical action, thus resolving the contradiction between productivity and manufacturing precision.

The copolymer acts as an intermediary substance that mediates the interaction between the slurry and the silicon nitride stopper. The copolymer's functional groups selectively adsorb onto the stopper surface, forming a protective layer that prevents abrasive grains from directly contacting and removing the stopper, while allowing efficient removal of the polishing object. This intermediary mechanism enables simultaneous achievement of high polishing rate and high selectivity.

The patent creates a composite slurry formulation by combining conventional polishing components (abrasive grains, solvents, pH adjusters) with a specifically designed copolymer. This composite approach maintains the ease of manufacture of conventional slurries while adding the adaptability needed for precise stopper polishing control. The copolymer component provides selective interaction with silicon nitride, enabling accurate polishing termination at the stopper interface.

The copolymer component provides multi-functionality: it serves as both a polishing enhancer for metal and insulating materials and a selective protective agent for silicon nitride stoppers. This universal additive allows a single slurry formulation to handle multiple polishing objectives with different requirements, improving adaptability without complicating the overall manufacturing process.