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Title: Effect of water vapor on plasma processing at atmospheric pressure: polymer etching and surface modification by an Ar/H 2O plasma jet

Abstract

In this study, we evaluate the effect of water vapor on the plasma processing of materials using a model system consisting of a well-characterized radio-frequency (RF) plasma jet, controlled gaseous environment, and polystyrene (PS) as target material. We find that the effluent of Ar/H 2O plasma jet is capable of (1) etching polymers with relatively high etch rate and (2) weakly oxidizing the etched polymer surface by forming O containing moieties. When increasing the treatment distance between the polymer and the Ar/H 2O plasma, we find that the polymer etch rate drops exponentially whereas the O elemental composition of the etched surface shows a maximum at intermediate treatment distance. The OH density in the Ar/H 2O jet was measured near the substrate surface by laser induced fluorescence (LIF), and the density change of the OH radicals with treatment distance is found to be consistent with the exponential decrease of polymer etch rate, which indicates that OH may play a dominant role in the polymer etching process. A control experiment of Ar/H 2 plasma shows that the observed fast polymer etching by Ar/H 2O plasma cannot be attributed to H atoms. By correlating the OH flux with the polymer etch rate,more » we estimated the etching reaction coefficient (number of C atoms removed per OH radical from the gas phase) of OH radicals as ~10 -2. The polymer etch rate of Ar/H 2O plasma is enhanced as the substrate temperature is lowered, which can be explained by the enhanced surface adsorption of gas phase species. For the same molecular admixture concentration and plasma power, we find that Ar/H 2O/O 2 plasma has much reduced etching efficiency compared to either Ar/H 2O or Ar/O 2 plasma.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of Maryland, College Park, MD (United States)
  2. Univ. of Minnesota, Minneapolis, MN (United States)
Publication Date:
Research Org.:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1505040
Alternate Identifier(s):
OSTI ID: 1508189
Grant/Contract Number:  
SC0001939
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 37; Journal Issue: 3; Journal ID: ISSN 0734-2101
Publisher:
American Vacuum Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Etching; Surface modification; Atmospheric pressure plasma; cold temperature plasma; Plasma jet; APPJ; Hydroxyl radicals (OH); water plasma; water; polymer

Citation Formats

Luan, Pingshan, Kondeti, V. S. Santosh K., Knoll, Andrew J., Bruggeman, Peter J., and Oehrlein, Gottlieb S. Effect of water vapor on plasma processing at atmospheric pressure: polymer etching and surface modification by an Ar/H2O plasma jet. United States: N. p., 2019. Web. doi:10.1116/1.5092272.
Luan, Pingshan, Kondeti, V. S. Santosh K., Knoll, Andrew J., Bruggeman, Peter J., & Oehrlein, Gottlieb S. Effect of water vapor on plasma processing at atmospheric pressure: polymer etching and surface modification by an Ar/H2O plasma jet. United States. doi:10.1116/1.5092272.
Luan, Pingshan, Kondeti, V. S. Santosh K., Knoll, Andrew J., Bruggeman, Peter J., and Oehrlein, Gottlieb S. Mon . "Effect of water vapor on plasma processing at atmospheric pressure: polymer etching and surface modification by an Ar/H2O plasma jet". United States. doi:10.1116/1.5092272.
@article{osti_1505040,
title = {Effect of water vapor on plasma processing at atmospheric pressure: polymer etching and surface modification by an Ar/H2O plasma jet},
author = {Luan, Pingshan and Kondeti, V. S. Santosh K. and Knoll, Andrew J. and Bruggeman, Peter J. and Oehrlein, Gottlieb S.},
abstractNote = {In this study, we evaluate the effect of water vapor on the plasma processing of materials using a model system consisting of a well-characterized radio-frequency (RF) plasma jet, controlled gaseous environment, and polystyrene (PS) as target material. We find that the effluent of Ar/H2O plasma jet is capable of (1) etching polymers with relatively high etch rate and (2) weakly oxidizing the etched polymer surface by forming O containing moieties. When increasing the treatment distance between the polymer and the Ar/H2O plasma, we find that the polymer etch rate drops exponentially whereas the O elemental composition of the etched surface shows a maximum at intermediate treatment distance. The OH density in the Ar/H2O jet was measured near the substrate surface by laser induced fluorescence (LIF), and the density change of the OH radicals with treatment distance is found to be consistent with the exponential decrease of polymer etch rate, which indicates that OH may play a dominant role in the polymer etching process. A control experiment of Ar/H2 plasma shows that the observed fast polymer etching by Ar/H2O plasma cannot be attributed to H atoms. By correlating the OH flux with the polymer etch rate, we estimated the etching reaction coefficient (number of C atoms removed per OH radical from the gas phase) of OH radicals as ~10-2. The polymer etch rate of Ar/H2O plasma is enhanced as the substrate temperature is lowered, which can be explained by the enhanced surface adsorption of gas phase species. For the same molecular admixture concentration and plasma power, we find that Ar/H2O/O2 plasma has much reduced etching efficiency compared to either Ar/H2O or Ar/O2 plasma.},
doi = {10.1116/1.5092272},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 3,
volume = 37,
place = {United States},
year = {2019},
month = {4}
}

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This content will become publicly available on April 22, 2020
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