title: Role of poly(diallyldimethylammonium chloride) in selective polishing of polysilicon over silicon dioxide and silicon nitride films.
abstract: A cationic polymer, poly(diallyldimethylammonium chloride), or PDADMAC (MW ≈ 200,000), at a concentration of 250 ppm was used to enhance polysilicon removal rates (RRs) to ∼600 nm/min while simultaneously suppressing both silicon dioxide and silicon nitride RRs to <1 nm/min, both in the absence or in the presence of ceria or silica abrasives during chemical mechanical polishing (CMP). These results suggest that aqueous abrasive-free solutions of PDADMAC are very attractive candidates for several front-end-of-line (FEOL) CMP processes. Possible mechanisms for the enhancement of poly-Si RR and the suppression of oxide and nitride RRs are proposed on the basis of the RRs, contact angle data on poly-Si films, zeta potentials of polishing pads, polysilicon films, silicon nitride particles, and silica and ceria abrasives, thermogravimetric analysis, and UV-vis spectroscopy data.
authors.affiliation: Department of Chemical and Bio-molecular Engineering, and Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699, United States.
authors.forename: Naresh K
authors.initials: NK
authors.lastname: Penta
authors.forename: P R
authors.initials: PR
authors.lastname: Dandu Veera
authors.forename: S V
authors.initials: SV
authors.lastname: Babu