skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Oxidation threshold in silicon etching at cryogenic temperatures

Abstract

In silicon etching in SF{sub 6}/O{sub 2} plasmas, an oxidation threshold appears when the oxygen content is large enough. A SiO{sub x}F{sub y} passivation layer is formed under such conditions. This threshold is reached at lower oxygen proportions if the substrate is cooled down to cryogenic temperatures. In this article, we present a mass spectrometry study of this oxidation threshold in different experimental conditions (temperature, source rf power, self-bias) on bare silicon wafers. The presence of the threshold is clearly evident in the signals of many ions, for example, SiF{sub 3}{sup +}, F{sup +}, and SOF{sub 2}{sup +}. This helps us to determine the main reactions which can occur in the SF{sub 6}/O{sub 2} plasma in our experimental conditions. This threshold appears for higher oxygen proportions when either the source power or the chuck self-bias is increased. The ion bombardment transfers energy to the surface and makes the film desorb. A model, describing the oxygen coverage as a function of the parameters mentioned above, is proposed to interpret these results. Data presented in this article give another point of view of the cryogenic etching process. They contribute to explain how anisotropic profiles can be achieved at low temperature. Surfaces subjectedmore » to ion bombardment (the bottom of the structures) are below the oxidation threshold while the structures sidewalls, not subjected to ion bombardment, are in passivating regime.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. GREMI-Polytech'Orleans, 14 rue d'Issoudun, BP 6744, 45067 Orleans cedex 2 (France)
Publication Date:
OSTI Identifier:
20777306
Resource Type:
Journal Article
Journal Name:
Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films
Additional Journal Information:
Journal Volume: 24; Journal Issue: 4; Other Information: DOI: 10.1116/1.2210946; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1553-1813
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ETCHING; FILMS; FLUORINE IONS; ION BEAMS; MASS SPECTRA; MASS SPECTROSCOPY; OXIDATION; OXYGEN; PASSIVATION; PLASMA; SEMICONDUCTOR MATERIALS; SILICON; SUBSTRATES; SULFUR FLUORIDES; TEMPERATURE RANGE 0065-0273 K

Citation Formats

Tillocher, T, Dussart, R, Mellhaoui, X, Lefaucheux, P, Maaza, N Mekkakia, Ranson, P, Boufnichel, M, Overzet, L J, STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours cedex 2, and Plasma Applications Laboratory, University of Texas at Dallas, Richardson, Texas 75083-0688. Oxidation threshold in silicon etching at cryogenic temperatures. United States: N. p., 2006. Web. doi:10.1116/1.2210946.
Tillocher, T, Dussart, R, Mellhaoui, X, Lefaucheux, P, Maaza, N Mekkakia, Ranson, P, Boufnichel, M, Overzet, L J, STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours cedex 2, & Plasma Applications Laboratory, University of Texas at Dallas, Richardson, Texas 75083-0688. Oxidation threshold in silicon etching at cryogenic temperatures. United States. https://doi.org/10.1116/1.2210946
Tillocher, T, Dussart, R, Mellhaoui, X, Lefaucheux, P, Maaza, N Mekkakia, Ranson, P, Boufnichel, M, Overzet, L J, STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours cedex 2, and Plasma Applications Laboratory, University of Texas at Dallas, Richardson, Texas 75083-0688. 2006. "Oxidation threshold in silicon etching at cryogenic temperatures". United States. https://doi.org/10.1116/1.2210946.
@article{osti_20777306,
title = {Oxidation threshold in silicon etching at cryogenic temperatures},
author = {Tillocher, T and Dussart, R and Mellhaoui, X and Lefaucheux, P and Maaza, N Mekkakia and Ranson, P and Boufnichel, M and Overzet, L J and STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours cedex 2 and Plasma Applications Laboratory, University of Texas at Dallas, Richardson, Texas 75083-0688},
abstractNote = {In silicon etching in SF{sub 6}/O{sub 2} plasmas, an oxidation threshold appears when the oxygen content is large enough. A SiO{sub x}F{sub y} passivation layer is formed under such conditions. This threshold is reached at lower oxygen proportions if the substrate is cooled down to cryogenic temperatures. In this article, we present a mass spectrometry study of this oxidation threshold in different experimental conditions (temperature, source rf power, self-bias) on bare silicon wafers. The presence of the threshold is clearly evident in the signals of many ions, for example, SiF{sub 3}{sup +}, F{sup +}, and SOF{sub 2}{sup +}. This helps us to determine the main reactions which can occur in the SF{sub 6}/O{sub 2} plasma in our experimental conditions. This threshold appears for higher oxygen proportions when either the source power or the chuck self-bias is increased. The ion bombardment transfers energy to the surface and makes the film desorb. A model, describing the oxygen coverage as a function of the parameters mentioned above, is proposed to interpret these results. Data presented in this article give another point of view of the cryogenic etching process. They contribute to explain how anisotropic profiles can be achieved at low temperature. Surfaces subjected to ion bombardment (the bottom of the structures) are below the oxidation threshold while the structures sidewalls, not subjected to ion bombardment, are in passivating regime.},
doi = {10.1116/1.2210946},
url = {https://www.osti.gov/biblio/20777306}, journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
issn = {1553-1813},
number = 4,
volume = 24,
place = {United States},
year = {Sat Jul 15 00:00:00 EDT 2006},
month = {Sat Jul 15 00:00:00 EDT 2006}
}