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Title: Extraction of negative ions from pulsed electronegative capacitively coupled plasmas

Abstract

Charge buildup during plasma etching of dielectric features can lead to undesirable effects, such as notching, bowing, and twisting. Pulsed plasmas have been suggested as a method to achieve charge-free plasma etching. In particular, electronegative plasmas are attractive as the collapse of the plasma potential during the after-glow period of pulsed capacitively coupled plasmas (CCPs) can allow for extraction of negative ions into the feature. The extraction of negative ions in the after-glow of pulsed CCPs sustained in CF{sub 4} containing gas mixtures is computationally investigated. In this paper, the consequences of pulse frequency and gas chemistry on negative ion flux to the wafer are discussed. A low negative ion flux to the wafer was observed only in the late after-glow period of low pulse frequencies. The negative ion flux was found to significantly increase with the addition of highly electronegative gases (such as thermally attaching Cl{sub 2}) even at a high pulse frequency of 10 kHz. As the production of negative ions during the after-glow diminishes, alternative strategies to enhance the flux were also pursued. The flux of negative ions was found to increase by the addition of a pulsed dc voltage on the top electrode that is 180more » Degree-Sign out-of-phase with the rf pulse.« less

Authors:
; ;  [1]
  1. Applied Materials Inc., 974 E. Arques Avenue, M/S 81312, Sunnyvale, California 94085 (United States)
Publication Date:
OSTI Identifier:
22089371
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 3; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AFTERGLOW; ANIONS; BOWING; CARBON TETRAFLUORIDE; DIELECTRIC MATERIALS; ELECTRONEGATIVITY; ETCHING; EXTRACTION; HIGH-FREQUENCY DISCHARGES; MIXTURES; PLASMA; PLASMA POTENTIAL

Citation Formats

Agarwal, Ankur, Rauf, Shahid, and Collins, Ken. Extraction of negative ions from pulsed electronegative capacitively coupled plasmas. United States: N. p., 2012. Web. doi:10.1063/1.4745877.
Agarwal, Ankur, Rauf, Shahid, & Collins, Ken. Extraction of negative ions from pulsed electronegative capacitively coupled plasmas. United States. https://doi.org/10.1063/1.4745877
Agarwal, Ankur, Rauf, Shahid, and Collins, Ken. 2012. "Extraction of negative ions from pulsed electronegative capacitively coupled plasmas". United States. https://doi.org/10.1063/1.4745877.
@article{osti_22089371,
title = {Extraction of negative ions from pulsed electronegative capacitively coupled plasmas},
author = {Agarwal, Ankur and Rauf, Shahid and Collins, Ken},
abstractNote = {Charge buildup during plasma etching of dielectric features can lead to undesirable effects, such as notching, bowing, and twisting. Pulsed plasmas have been suggested as a method to achieve charge-free plasma etching. In particular, electronegative plasmas are attractive as the collapse of the plasma potential during the after-glow period of pulsed capacitively coupled plasmas (CCPs) can allow for extraction of negative ions into the feature. The extraction of negative ions in the after-glow of pulsed CCPs sustained in CF{sub 4} containing gas mixtures is computationally investigated. In this paper, the consequences of pulse frequency and gas chemistry on negative ion flux to the wafer are discussed. A low negative ion flux to the wafer was observed only in the late after-glow period of low pulse frequencies. The negative ion flux was found to significantly increase with the addition of highly electronegative gases (such as thermally attaching Cl{sub 2}) even at a high pulse frequency of 10 kHz. As the production of negative ions during the after-glow diminishes, alternative strategies to enhance the flux were also pursued. The flux of negative ions was found to increase by the addition of a pulsed dc voltage on the top electrode that is 180 Degree-Sign out-of-phase with the rf pulse.},
doi = {10.1063/1.4745877},
url = {https://www.osti.gov/biblio/22089371}, journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 3,
volume = 112,
place = {United States},
year = {Wed Aug 01 00:00:00 EDT 2012},
month = {Wed Aug 01 00:00:00 EDT 2012}
}