Tunable Conformality of Polymer Coatings on High Aspect Ratio Features

Authors

  • Gozde Ozaydin-Ince,

    1. Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Room 66-466, Cambridge, MA 02149 (USA)
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  • Karen K. Gleason

    Corresponding author
    1. Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Room 66-466, Cambridge, MA 02149 (USA)
    • Department of Chemical Engineering, Massachusetts Institute of Technology 77 Massachusetts Avenue, Room 66-466, Cambridge, MA 02149 (USA).
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  • The authors would like to thank the King Fahd University of Petroleum and Minerals in Dhahran, Saudi Arabia, for funding the research reported in this paper through the Center for Clean Water and Clean Energy at MIT and KFUPM. The authors thank Dr. Ed Gleason of Analog Devices for supplying the substrates.

Abstract

In this work we demonstrate that the concentration of vinyl bonds present in monomers adsorbed onto the surface determines the degree of conformality achieved by polymeric films grown over substrate topology by initiated (i)CVD. For microtrenches of varying aspect ratio, a ballistic model correlates the observed step coverage to a range of sticking coefficients of the initiating radicals, γ, between 0.01 and 0.05. Increasing the surface concentration of the monomer results in higher values of γ. In the deposition regime studied, γ is independent of the concentration of radical initiators. Furthermore, γ is insensitive to substrate temperature if the surface concentration of monomer is fixed. Using this knowledge, conformal coverage on microtrenches is demonstrated from both ethylene glycol diacrylate (EGDA) and neopentyl methacrylate (npMA). Additionally, the conformality permits templating of nanotubes of the mechanically robust and solvent-resistant iCVD-produced p(EGDA) crosslinked polymer.

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