Dissociative ionization of silane by electron impact

R. Basner, M. Schmidt, V. Tarnovsky, K. Becker, H. Deutsch

Research output: Contribution to journalArticle

Abstract

We studied the electron impact ionization of silane (SiH4) which is widely used in the plasma deposition of different silicon-containing thin films. Absolute partial cross-sections for the formation of all fragment ions were measured in a high resolution double focusing sector field mass spectrometer with a modified ion extraction stage for electron energies from threshold to 100 eV. No evidence for the formation of stable parent SiH4+ ions was found in agreement with previous experimental investigations. The single positive fragment ion formation is the dominant ionization process. We observed the following product ions: SiH3+, SiH2+, SiH+, Si+, H2+, and H+. The agreement between our measured absolute partial ionization cross-sections and two earlier data sets obtained by different techniques is generally good for the silicon-containing fragment ions taking into account quoted uncertainties of ± 10% to ± 20%, but less satisfactory for the formation of atomic and molecular hydrogen ions which were found to be produced with significant excess kinetic energies, particularly in the case of H+. A comparison of the total SiH4 ionization cross-section derived from the measured partial ionization cross-sections and a calculated cross-section based on the Binary-Encounter-Bethe (BEB) model showed excellent agreement in the energy range above 30 eV.

Original languageEnglish (US)
Pages (from-to)83-93
Number of pages11
JournalInternational Journal of Mass Spectrometry and Ion Processes
Volume171
Issue number1-3
DOIs
StatePublished - Dec 1997

Keywords

  • Cross-sections
  • Electron impact ionization
  • Plasma processing

ASJC Scopus subject areas

  • Spectroscopy

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