Preparation and characterization of perfluoro-organic thin films on aluminium

Abstract

The purpose of this study was to explore the deposition of low-energy organic films for the prevention of stiction in MEMS (micro electro mechanical systems). Perfluorinated thin films were deposited by the spin coating of fluorocarbon chemicals (FC) and the vapour-phase (VP) adsorption of FC and perfluorodecanoic acid (PFDA) on Al substrates. AFM and contact angle measurements showed poor coverage of the films on aluminium, especially when they were deposited by VP adsorption. The contact angles for water on the spin- and VP-deposited films were similar or higher than on Teflon. The surface energy of FC-and PFDA-coated films was calculated to be lower than that for a Teflon surface. ATR (attenuated total reflectance)-FTIR spectra showed CF2 stretching bands on spin- and VP-deposited films on aluminium. The spin-coated FC films showed good thermal stability at 150 degrees C for 100 h in air. The VP-deposited PFDA and FC films showed degradation as a function of time in an air atmosphere, but not in nitrogen at the same temperature. (C) 1999 Elsevier Science S.A. All rights reserved.