Patent ID: 8822340

Claim:
A method for chemical mechanical polishing of a substrate comprising: (a) contacting a substrate comprising a silicon nitride layer and a silicon oxide layer with a colloidal dispersion, the dispersion comprising: (i) 0.05% to about 10% by weight of an abrasive component and (ii) a water-soluble amphoteric polymer comprising: (aa) at least one part B comprising one or more cationic monomeric units, and (bb) at least one part A comprising one or more anionic monomeric units; wherein the dispersion has a pH of between about 1.5 and about 6; and (b) performing a CMP process on the substrate, wherein polymer is an amphoteric copolymer selected from the group consisting of: (a) a (block A)-(block B) diblock copolymer, wherein the at least one part A is the block A and the at least one part B is the block B; (b) a (block B)-(block A)-(block B) triblock copolymer, wherein the at least one part A is the block A and the at least one part B is the block B; or (c) a (backbone A)-(side chains B) comb copolymer, wherein the at least one part A is the backbone A and the comb copolymer is a plurality of side chains B each bonded to the backbone A at one of their ends.