Process for chemically mechanically polishing substrates containing silicon oxide dielectric films and polysilicon and/or silicon nitride films

A process for chemically mechanically polishing a substrate comprising a silicon oxide dielectric film and a polysilicon film, the process comprising:

• contacting the substrate with an aqueous polishing composition,
• polishing the substrate at a temperature and for a time sufficient to remove the silicon oxide dielectric film and expose a polysilicon nitride film, a silicon nitride film, or both, to obtain a polished substrate;
• and
• removing the polished substrate from contact with the aqueous polishing composition.,
• wherein the aqueous polishing composition comprises:
• abrasive particles which are positively charged when dispersed in an aqueous medium having a pH of from 3 to 9 as evidenced by an electrophoretic mobility;
• at least one water-soluble or water-dispersible polymer selected from the group consisting of a linear alkylene oxide homopolymer, a branched alkylene oxide homopolymer, a linear alkylene oxide copolymer, and a branched alkylene oxide copolymer;
• and
• at least one water-soluble or water-dispersible polymer selected from the group consisting of a linear aliphatic poly(N-vinylamide) homopolymer, a branched aliphatic poly(N-vinylamide) homopolymer, a linear cycloaliphatic poly(N-vinylamide) homopolymer, a branched aliphatic poly(N-vinylamide) homopolymer, a linear aliphatic poly(N-vinylamide) copolymer, a branched aliphatic poly(N-vinylamide) copolymer, a linear cycloaliphatic poly(N-vinylamide) copolymer, a branched aliphatic poly(N-vinylamide) copolymer, a homopolymer of an acrylamide monomer, a copolymer of an acrylamide monomer, and a cationic polymeric flocculant,
• wherein
• the acrylamide has formula I:
• H2C═C(—R)—C(═O)—N(—R1)(—R2) (I), or formula II:
• H2C═C(—R)—C(═O)—R3 (II),
• R is a hydrogen atom, a fluorine atom, a chlorine atom, a nitrile group, or a residue comprising at least one moiety selected from the group consisting of a substituted aliphatic moiety comprising 1 to 6 carbon atoms, an unsubstituted aliphatic moiety comprising 1 to 6 carbon atoms, a substituted cycloaliphatic moiety comprising 3 to 10 carbon atoms, an unsubstituted cycloaliphatic moiety comprising 3 to 10 carbon atoms, a substituted aromatic moiety comprising 6 to 10 carbon atoms, and an unsubstituted aromatic moiety comprising 6 to 10 carbon atoms;
• R1 and R2 are each independently a hydrogen atom or a residue comprising at least one moiety selected from the group consisting of a substituted alipahtic moiety comprising 1 to 20 carbon atoms, an unsubstituted aliphatic moiety comprising 1 to 20 carbon atoms, a substituted cycloaliphatic moiety comprising 3 to 10 carbon atoms, an unsubstituted cycloaliphatic moiety comprising 3 to 10 carbon atoms, a substituted aromatic moiety comprising 6 to 10 carbon atoms., and an unsubstituted aromatic moiety comprising 6 to 10 carbon atoms;
• R3 is a substituted or unsubstituted, saturated heterocyclic ring comprising a nitrogen atom, wherein the heterocyclic ring is linked to a carbon atom of a carbonyl moiety via a covalent carbon nitrogen bond;
• the homopolymers and copolymers have a weight average molecular weight of less than 100,000 Dalton;
• and
• the cationic polymeric flocculant has a weight average molecular weight of less than 100,000 Dalton.