Role of poly(diallyldimethylammonium chloride) in selective polishing of polysilicon over silicon dioxide and silicon nitride films |
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Authors: | Penta Naresh K Dandu Veera P R Babu S V |
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Affiliation: | Department of Chemical and Bio-molecular Engineering, and Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699, United States. |
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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. |
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