AVS 51st International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThA

Paper PS-ThA3
Deposition and Composition of Polymer Films in Fluorocarbon Plasmas: CW and Pulsed Systems@footnote 1@

Thursday, November 18, 2004, 2:40 pm, Room 213A

Session: Plasma-Surface Interaction
Presenter: K. Rajaraman, University of Illinois at Urbana-Champaign
Authors: K. Rajaraman, University of Illinois at Urbana-Champaign
M.J. Kushner, University of Illinois at Urbana-Champaign
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Fluorocarbon plasma etching is the primary method to obtain selectivity between dielectrics. Optimization of this etching technique becomes more critical as dielectrics thin. To first order, etch rates depend on thickness of the polymer layer, which controls the energy of ions striking the dielectric surface. However, the composition of the polymer determines the rate of deposition and sputtering of the film, as well as the rate of reaction of the polymer with the underlying dielectric. To address this compositional dependence, a surface chemistry model has been developed to resolve the polymer at a mesoscale level by treating CFx sites distinctly. In this manner, the fractional composition of the polymer film on a bond-to-bond basis can be resolved. This surface model was interfaced with a zero-dimensional plasma kinetics model (GLOBAL_KIN) and a 2-dimensional plasma equipment model (HPEM). Simulations were performed using the ICP reactor geometry and conditions from Li et al.@footnote 2@ We will discuss results for film compositions using different fluorocarbon gas chemistries (e.g., M/O@sub 2@/Ar, M = C@sub 2@F@sub 6@, CHF@sub 3@, c-C@sub 4@F@sub 8@). Due to the change in the pathways for generation of major free radicals, the fluorocarbon films formed in the chemistries investigated are qualitatively different, and to some degree reflect the fragmentation pattern of the feedstock gases. Changes in Ar concentration affect the amount of sputtering of the fluorocarbon films, and hence the film thickness. The consequences of pulsing the plasma on the fluorocarbon film structure will also be discussed. @FootnoteText@ @footnote 1@ Work supported by SRC and NSF. @footnote 2@ Li et al., J. Vac. Sci. Technol. A 20, 2052 (2002)