Trace impurity analysis in Ta films using glow discharge mass spectrometry: Concentration change of impurities by applying negative substrate bias voltage

Jae Won Lim, Kouji Mimura, Minoru Isshiki

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Glow discharge mass spectrometry (GDMS) was used to analyze a Ta target and Ta films for trace impurities. The Ta films were deposited on Si (100) substrate at substrate bias voltages of 0V and -125V using a non-mass separated ion beam deposition system. Although both Ta films were contaminated by impurities during the deposition, the Ta film deposited at a substrate bias voltage of -125 V showed lower impurity content than the Ta film deposited without the substrate bias voltage, which means that applying a negative bias voltage to the substrate decreased the total concentration of impurities. Furthermore, the concentration change of individual impurities in the Ta film is related to their ionization ratio in the argon discharge plasma. Considering the effect of the ionization potential of an individual impurity on the ionization ratio, purification by applying a negative bias voltage to the substrate results from Penning ionization and an ionization mechanism proposed in this study, as well as from the difference between the kinetic energies of Ta neutral atoms and Ta ions accelerated toward the substrate with/without a negative substrate bias voltage.

Original languageEnglish
Pages (from-to)8267-8272
Number of pages6
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume43
Issue number12
DOIs
Publication statusPublished - 2004 Dec 1

Keywords

  • Glow discharge mass spectrometry
  • Ion beam
  • Ionization potential
  • Substrate bias voltage
  • Tantalum

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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