Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

doi:10.1116/1.4880800

Title: Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

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Abstract

While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8}more »« less

Authors:

Stephan Thamban, P. L. ^[1]; Goeckner, Matthew J. ^[2]; Overzet, Lawrence J. ^[3]

Department of Mechanical Engineering, University of Texas Dallas, Natural Science and Engineering Laboratory (NSERL), P.O. Box 830688, Richardson, Texas 75083 (United States)
Department of Mathematics, University of Texas Dallas, Natural Science and Engineering Laboratory (NSERL), Rm. 3.408, P.O. Box 830688, Mailstop FO35, Richardson, Texas 75083 (United States)
Department of Electrical Engineering, University of Texas Dallas, Natural Science and Engineering Laboratory (NSERL), Rm. 3.404, P.O. Box 830688, Mailstop RH10, Richardson, Texas 75083 (United States)

Publication Date:: Tue Jul 01 00:00:00 EDT 2014

OSTI Identifier:: 22318068

Resource Type:: Journal Article

Journal Name:: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films

Additional Journal Information:: Journal Volume: 32; Journal Issue: 4; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0734-2101

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; CARBON; CARBON FLUORIDES; DEPOSITION; FILMS; GAS FLOW; LANGMUIR PROBE; PASSIVATION; PLASMA; SILICON; SULFUR FLUORIDES

Citation Formats


                    Bates, Robert L., E-mail: rlb043000@utdallas.edu, Stephan Thamban, P. L., Goeckner, Matthew J., and Overzet, Lawrence J. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures.  United States: N. p., 2014. 
        Web.  doi:10.1116/1.4880800.

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                    Bates, Robert L., E-mail: rlb043000@utdallas.edu, Stephan Thamban, P. L., Goeckner, Matthew J., & Overzet, Lawrence J. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures.  United States.  https://doi.org/10.1116/1.4880800

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                    Bates, Robert L., E-mail: rlb043000@utdallas.edu, Stephan Thamban, P. L., Goeckner, Matthew J., and Overzet, Lawrence J. 2014.  
        "Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures".  United States.  https://doi.org/10.1116/1.4880800.

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@article{osti_22318068,

  title        = {Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures},

  author       = {Bates, Robert L., E-mail: rlb043000@utdallas.edu and Stephan Thamban, P. L. and Goeckner, Matthew J. and Overzet, Lawrence J.},

  abstractNote = {While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.},

  doi          = {10.1116/1.4880800},

  url          = {https://www.osti.gov/biblio/22318068},
  journal      = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},

  issn         = {0734-2101},

  number       = 4,

  volume       = 32,

  place        = {United States},

  year         = {Tue Jul 01 00:00:00 EDT 2014},

  month        = {Tue Jul 01 00:00:00 EDT 2014}

}

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