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Title: Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor

Abstract

Gas and surface phase chemistries of CF{sub 4} plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO{sub 2} and Si were measured during plasma processing as functions of the pressure, CF{sub 4} gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF{sub 4}, CF{sub 3}, CF{sub 2}, SiF{sub 4}, and COF{sub 2}, among which CF{sub 4} and SiF{sub 4} were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF{sub 4} and COF{sub 2} was about 2:1 with no bias on the substrate and increased up to {approx}8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF{sub 2} density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF{sub 4} increased. Comparisons between the gas phase data and etch rate results of Si and SiO{submore » 2} indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate.« less

Authors:
; ; ;  [1]
  1. Department of Electrical Engineering, University of Texas at Dallas, Richardson, Texas 75083 (United States)
Publication Date:
OSTI Identifier:
20776939
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 24; Journal Issue: 1; Other Information: DOI: 10.1116/1.2138718; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON TETRAFLUORIDE; CHEMISTRY; COBALT FLUORIDES; DENSITY; ETCHING; FILMS; FLUORINE; FOURIER TRANSFORM SPECTROMETERS; FOURIER TRANSFORMATION; INFRARED SPECTRA; PLASMA; PLASMA DENSITY; QUARTZ; SEMICONDUCTOR MATERIALS; SILICA; SILICON; SILICON OXIDES; SUBSTRATES; SURFACES

Citation Formats

Zhou Baosuo, Joseph, Eric A., Overzet, Lawrence J., and Goeckner, Matthew J. Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor. United States: N. p., 2006. Web. doi:10.1116/1.2138718.
Zhou Baosuo, Joseph, Eric A., Overzet, Lawrence J., & Goeckner, Matthew J. Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor. United States. doi:10.1116/1.2138718.
Zhou Baosuo, Joseph, Eric A., Overzet, Lawrence J., and Goeckner, Matthew J. Sun . "Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor". United States. doi:10.1116/1.2138718.
@article{osti_20776939,
title = {Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor},
author = {Zhou Baosuo and Joseph, Eric A. and Overzet, Lawrence J. and Goeckner, Matthew J.},
abstractNote = {Gas and surface phase chemistries of CF{sub 4} plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO{sub 2} and Si were measured during plasma processing as functions of the pressure, CF{sub 4} gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF{sub 4}, CF{sub 3}, CF{sub 2}, SiF{sub 4}, and COF{sub 2}, among which CF{sub 4} and SiF{sub 4} were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF{sub 4} and COF{sub 2} was about 2:1 with no bias on the substrate and increased up to {approx}8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF{sub 2} density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF{sub 4} increased. Comparisons between the gas phase data and etch rate results of Si and SiO{sub 2} indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate.},
doi = {10.1116/1.2138718},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 1,
volume = 24,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}