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Pore surface grafting of porous low-k dielectrics by selective polymers

Journal Contribution - Journal Article

© 2017 American Vacuum Society. Polymer grafting of pore sidewalls is studied as a protecting agent against processing damage. Polymethyl-methacrylate (PMMA), an improved polystyrene (PS-pro), and a tailored plasma damage management polymer (PDM) are considered as potential candidates. PMMA and PS-pro show nonhomogeneous grafting properties, while PDM coat the pore sidewalls uniformly through the bulk of the porous low-k film. A k ∼ 2.2 porous spin-on glass is used as a vehicle for processing damage study. Approximately one monolayer is grafted on the pore walls, leading to a k-value increase up to Δk ∼ 0.2. Using grafted PDM, the porous low-k chemical stability in 0.5% diluted hydrofluoric acid is significantly improved. Concerning plasma damage, at constant etch depth methyl depletion is decreased, mainly in capacitive coupled plasma discharge showing high polymerizing character, leading to similar damage depth as found for a reference organo-silicate glass 2.7 low-k. However, moisture uptake is not improved, leading to significant drift in the dielectric constant.
Journal: Journal of Vacuum Science and Technology B
ISSN: 2166-2746
Issue: 2
Volume: 35
Number of pages: 11
Publication year:2017