Fourier transform infrared spectroscopy study of thermal annealing behavior of ECR pulsed plasma deposited fluorocarbon thin films from 1,1,2,2-tetrafluoroethane

Fourier transform infrared spectroscopy (FTIR) reveals structural changes i n high and low, and on and off pulsed C2H2F4 ECR plasma deposited films upo n thermal annealing. A significant improvement in thermal stability was ach ieved when the precursor now rate was increased to 50 standard cubic centim eters per minute for high/low pulsing. Evolution of CF3 groups attached to unfluorinated carbons has been identified as a low temperature loss mechani sm in one of these films. Annealing produces shifts in asymmetric vs. symme tric CF2 stretch intensities, as well as initiating of CH stretches. In the 1400-2000 cm(-1) range, a systematic change from carbon-carbon double bond ing structures to carbon-oxygen bonding structures results. These variation s may be due to either additional oxygen absorption after annealing or reac tion between oxygen and fluorocarbon network sites that were previously una vailable due to the steric hindrance. In most films, the thermal stability was dominated by oxygen and hydrogen uptake. The film with the highest oxyg en and hydrogen content after annealing also had the lowest thermal stabili ty. Thus, minimizing both CF3 and susceptibility to oxygen and water uptake by the deposited films would appear to be a valid strategy for increasing film thermal stability. (C) 2000 The Electrochemical Society. S0013-4651(99 )09-020-5. All rights reserved.