CMP Polishing Liquid Composition for Stopper Rate Suppression

The patent applies parameter changes by modifying the chemical composition parameters of the polishing liquid. Specifically, it adjusts the pH value to 8.0 or higher and controls the concentration ratios of cerium oxide (0.1-10 wt%), silica (1-50 wt%), and alumina (1-50 wt%). These parameter adjustments enable the polishing liquid to achieve high polishing rates for insulating materials while suppressing the polishing rate of polysilicon and amorphous silicon stoppers, thus resolving the technical contradiction between productivity and manufacturing precision.

The patent employs composite materials by creating a multi-component abrasive system combining cerium oxide, silica, and alumina in specific proportions. This composite abrasive composition works synergistically to achieve selective polishing: cerium oxide provides high reactivity with insulating materials, while silica and alumina contribute to controlled abrasion of polysilicon and amorphous silicon. The composite nature of the polishing liquid enables simultaneous optimization of both polishing rate for insulating materials and suppression of stopper removal.

The patent resolves this contradiction through parameter changes, specifically setting the pH value to 8.0 or higher and controlling the concentration ratios of different abrasive materials. This creates a chemical environment where the polishing liquid exhibits high reactivity toward insulating materials (silicon oxide, silicon nitride) while having low reactivity toward polysilicon and amorphous silicon. As a result, the polishing process achieves both deep, fast removal of insulating materials and precise depth control at stopper locations, simultaneously improving manufacturing precision and productivity.

The patent applies local quality by creating a polishing liquid with spatially selective chemical properties. The high pH environment and specific abrasive composition create regions of high reactivity that selectively interact with insulating materials, while being less reactive toward stopper materials. This local differentiation in chemical reactivity allows the polishing process to remove insulating material rapidly in areas where it is present, while automatically stopping at stopper locations, thus achieving both high productivity and precise depth control.