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Pulsed plasma‐enhanced chemical vapor deposition from hexafluoropropylene oxide: Film composition study
Author(s) -
Limb Scott J.,
Edell David J.,
Gleason Edward F.,
Gleason Karen K.
Publication year - 1998
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19980222)67:8<1489::aid-app14>3.0.co;2-x
Subject(s) - plasma enhanced chemical vapor deposition , x ray photoelectron spectroscopy , analytical chemistry (journal) , substrate (aquarium) , gas composition , materials science , thin film , sputtering , chemical vapor deposition , plasma , duty cycle , deposition (geology) , pulsed dc , oxide , chemical engineering , chemistry , nanotechnology , sputter deposition , voltage , thermodynamics , electrical engineering , organic chemistry , physics , oceanography , paleontology , quantum mechanics , metallurgy , sediment , geology , engineering , biology
Films deposited using pulsed plasma‐enhanced chemical vapor deposition (PECVD) from hexafluoropropylene oxide (HFPO) were investigated by X‐ray photoelectron spectroscopy (XPS). As compared to continuous rf PECVD, pulsed excitation increases the CF 2 fraction in the film. Film composition was determined as a function of plasma processing conditions including on‐time, off‐time, pressure, flow rate, substrate temperature, electrode spacing, substrate potential, and input power. Varying the on–off pulsing cycle resulted in compositional control of the deposited films. At a low duty cycle [ t on /( t on + t off )], up to 70% CF 2 could be incorporated into the film. The input gas, HFPO, may facilitate greater CF 2 incorporation into the films as this gas thermally decomposes into a difluorocarbene. Both absolute on‐time and off‐time, rather than simply duty cycle, are important parameters for determining film composition. A simple model was developed to describe the experimentally determined variation %CF 2 as a function of substrate temperature and off‐time. This model accounts for changes in film composition due to plasma‐surface modification and differences in gas‐phase chemistry. The model suggests that surface modification by the plasma is the dominant factor only for long on‐times or for low deposition rates. However, the gas‐phase concentration of CF 2 relative to other film‐forming species is typically the controlling factor under conditions which achieve the high %CF 2 in the film. The gas‐phase composition will depend on both abslute on‐time and off‐time, rather than simply on the duty cycle. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1489–1502, 1998