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Title: Measurements of sputtered neutrals and ions and investigation of their roles on the plasma properties during rf magnetron sputtering of Zn and ZnO targets

Langmuir probe and optical absorption spectroscopy measurements were used to determine the line-integrated electron density, electron temperature, and number density of Ar atoms in metastable {sup 3}P{sub 2} and {sup 3}P{sub 0} levels in a 5 mTorr, rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the average electron energy and density of Ar atoms in {sup 3}P{sub 2} and {sup 3}P{sub 0} excited states were fairly independent of self-bias voltage, the Ar {sup 3}P{sub 2}-to-electron number density ratio decreased by approximately a factor of 5 when going from −115 V to −300 V. This decrease was correlated to an increase by about one order of magnitude of the number density of sputtered Zn atoms determined by absolute actinometry measurements on Zn I using either Ar or Xe as the actinometer gas. These results were also found to be in excellent agreement with the predictions of a global model accounting for Penning ionization of sputtered Zn particles. The importance of the latter reactions was further confirmed by plasma sampling mass spectrometry showing a double peak structure for Zn ions: a low-energy component ascribed to thermalized ions created in the gas phase (by direct electron impact andmore » by Penning ionization) and a high-energy tail due to ions ejected from the target and reaching quasi-collisionlessly the substrate surface.« less
Authors:
;  [1]
  1. Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada)
Publication Date:
OSTI Identifier:
22224104
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 31; Journal Issue: 6; Other Information: (c) 2013 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ADMINISTRATIVE PROCEDURES; ATOMS; ELECTRON DENSITY; ELECTRON TEMPERATURE; ELECTRONS; EXCITED STATES; ION TEMPERATURE; IONIZATION; LANGMUIR PROBE; MAGNETRONS; MASS SPECTRA; MASS SPECTROSCOPY; PLASMA DENSITY; SEMICONDUCTOR MATERIALS; SPUTTERING; THIN FILMS; ZINC IONS; ZINC OXIDES