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Title: Crystalline alumina coatings by reactive ac magnetron sputtering

Abstract

Alumina coatings were deposited on silicon (111 orientation) substrates by reactive ac magnetron sputtering. Film deposition was done using Al targets and three O{sub 2}/Ar gas flow rate ratios at 5 kW power. X-ray diffraction studies showed that films were crystalline and contained several phases of alumina. Secondary ion mass spectroscopy analyses were used to measure O/Al atomic ratio and Ar and H concentrations in the films. Hydrogen content in the coatings depended on the O{sub 2} partial pressure used during sputtering and also on the arrival rate of Al and O species on the substrates and seemed to influence the crystallinity of the coatings.

Authors:
;  [1]
  1. Department of Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States)
Publication Date:
OSTI Identifier:
20979400
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 25; Journal Issue: 2; Other Information: DOI: 10.1116/1.2431353; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM OXIDES; FILMS; GAS FLOW; HYDROGEN; ION MICROPROBE ANALYSIS; MAGNETRONS; MASS SPECTRA; MASS SPECTROSCOPY; PARTIAL PRESSURE; SILICON; SPUTTERING; SUBSTRATES; SURFACE COATING; X-RAY DIFFRACTION

Citation Formats

Khanna, Atul, and Bhat, Deepak G. Crystalline alumina coatings by reactive ac magnetron sputtering. United States: N. p., 2007. Web. doi:10.1116/1.2431353.
Khanna, Atul, & Bhat, Deepak G. Crystalline alumina coatings by reactive ac magnetron sputtering. United States. doi:10.1116/1.2431353.
Khanna, Atul, and Bhat, Deepak G. Thu . "Crystalline alumina coatings by reactive ac magnetron sputtering". United States. doi:10.1116/1.2431353.
@article{osti_20979400,
title = {Crystalline alumina coatings by reactive ac magnetron sputtering},
author = {Khanna, Atul and Bhat, Deepak G.},
abstractNote = {Alumina coatings were deposited on silicon (111 orientation) substrates by reactive ac magnetron sputtering. Film deposition was done using Al targets and three O{sub 2}/Ar gas flow rate ratios at 5 kW power. X-ray diffraction studies showed that films were crystalline and contained several phases of alumina. Secondary ion mass spectroscopy analyses were used to measure O/Al atomic ratio and Ar and H concentrations in the films. Hydrogen content in the coatings depended on the O{sub 2} partial pressure used during sputtering and also on the arrival rate of Al and O species on the substrates and seemed to influence the crystallinity of the coatings.},
doi = {10.1116/1.2431353},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 2,
volume = 25,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Crystalline alumina thin films were deposited on WC-Co substrates using a reactive inverted cylindrical ac magnetron sputtering technique with a chromium oxide prelayer. The interfacial prelayer of chromium oxide was prepared by controlled oxidation of CrN{sub x} and Cr{sub 1-x}Al{sub x}N films deposited previously using the same ac reactive magnetron configured with one Cr and Al target. The oxidation was carried out by annealing CrN{sub x} and Cr{sub 1-x}Al{sub x}N films in air at 973 and 1373 K, respectively. Scanning electron microscopy and energy dispersive x-ray microanalysis were carried out to investigate the thin film surface morphology and composition. Themore » alumina coatings obtained on oxidized CrN{sub x} films (templates) were smooth and consisted primarily of {kappa} and {alpha} phases. The diffraction peaks from the {gamma} phase were not observed in any of the alumina coatings. The morphology and phase composition of the alumina coatings on the oxidized Cr{sub 1-x}Al{sub x}N films (templates) were strongly dependent on the aluminum content in the films.« less
  • No abstract prepared.
  • Cr2O3 thin films were prepared on silicon and glass substrates by mid frequency AC sputtering technique in an Isoflux ICM-10 sputter deposition system consisting of two hollow cylindrical targets of Cr in argon-oxygen plasma and at a discharge power of 5 kW. Thin film samples were deposited on three silicon and one glass substrate. X-ray diffraction studies showed that the coatings were ?-phase Cr2O3. One coating sample grown on a Si substrate was annealed in air up to a maximum temperature of 900 oC. While the heat treatment increased the crystallite size and sharpened the XRD peaks ?-Cr2O3 was thermallymore » stable and did not show any structural transformations. Scanning electron microscopy studies showed differences in the surface morphology of the coatings grown on glass and silicon substrates. Dynamic SIMS measurements performed on one coating deposited on silicon showed that thin films had O/Cr ratio of 1.38. Alumina coatings were deposited on Si substrates by reactive sputtering technique using Cr2O3 coatings as template layers. XRD investigations showed that Cr2O3 template layers improved the crystallinity of alumina coatings grown on top of it and also facilitated the formation of thermodynamically stable alpha-alumina phase.« less
  • A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (F{sub O2}) using the 285 nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35 nm m/min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence onmore » the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5x10{sup -5}) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg/O=48/52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing F{sub O{sub 2}}, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.« less
  • CrO{sub x} thin films were prepared on single crystal silicon (111 orientation) and glass substrates by midfrequency (41 kHz) ac sputtering technique in an Isoflux ICM-10 sputter deposition system consisting of two hollow cylindrical targets of Cr in an argon-oxygen plasma at a discharge power of 5 kW and without any deliberate substrate heating. X-ray diffraction studies showed that the coatings were of hcp rhombohedral {alpha}-phase chromium oxide. CrO{sub x} coating samples were found to grow preferentially towards the (110) crystal orientation of {alpha}-Cr{sub 2}O{sub 3}. Texturing was found to depend on the orientation of the substrates relative to themore » targets and also on the nature of substrates. One coating sample grown on Si substrate was annealed in air up to 1173 K. Whereas heat treatment increased the crystallite size, CrO{sub x} coating was thermally stable and did not show any structural transformations. Scanning electron microscopy studies showed differences in the surface morphology of the coatings grown on glass and silicon substrates. Dynamic secondary ion mass spectrometry measurements performed on one CrO{sub x} coating deposited on silicon showed that the O/Cr ratio in the films was 1.38. Ar and H impurity concentrations were also measured in this coating as a function of film thickness. Alumina coatings were prepared on Si substrates by reactive sputtering technique using CrO{sub x} coating as template layers. X-ray diffraction studies showed that CrO{sub x} template layers improved the crystallinity of alumina coatings grown on top of it and also facilitated the formation of the thermodynamically stable {alpha}-alumina phase.« less