Plasma–surface interaction at atmospheric pressure: A case study of polystyrene etching and surface modification by Ar/O2 plasma jet
- University of Maryland, College Park, MD (United States)
- University of Minnesota, Minneapolis, MN (United States)
In this paper we studied atmospheric pressure plasma-surface interaction (PSI) using a well-characterized radio-frequency (RF) Ar/O2 plasma jet with polystyrene (PS) polymer films in controlled gas environments as a model system. A number of plasma processing parameters, such as treatment distance, environmental gas composition as well as substrate temperature, were investigated by evaluating both the changes of thickness and surface chemical composition of PS after treatment. We found that the polymer average etch rate decayed exponentially with nozzle-surface distance whereas the surface oxygen composition increased to a maximum and then decreased. Both the exponential decay constant and oxidation maximum depended on the composition of gaseous environment which introduced changes in the density of reactive species. We previously reported a linear relationship between measured average etch rates and estimated atomic O flux based on measured gas phase atomic O density. In this work we provided additional insights on the kinetics of surface reaction processes. We measured the substrate temperature dependence of PS etch rate and found that the apparent activation energy (Ea) of the PS etching reaction was in the range of 0.10 – 0.13 eV. Higher values were obtained with greater nozzle-to-surface distance. Furthermore, this relatively low Ea value suggests that additional energetic plasma species might be involved in the etching reactions, which is also consistent with the different behavior of etching and surface oxidation modification reactions at the polymer surface as treatment distance is varied.
- Research Organization:
- Univ. of Maryland, College Park, MD (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); National Science Foundation (NSF)
- Contributing Organization:
- University of Michigan
- Grant/Contract Number:
- SC0001939; PHY-1415353
- OSTI ID:
- 1659739
- Alternate ID(s):
- OSTI ID: 1377951
- Journal Information:
- Journal of Vacuum Science and Technology A, Vol. 35, Issue 5; ISSN 0734-2101
- Publisher:
- American Vacuum Society / AIPCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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