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Title: Aluminide formation in polycrystalline Al/W metal/barrier thin-film bilayers: Reaction paths and kinetics

Abstract

Polycrystalline bcc W layers, 110 nm thick with 011 preferred orientation and an average grain size of 40 nm, were grown on amorphous-SiO{sub 2}/Si(001) substrates by ultrahigh vacuum (UHV) magnetron sputter deposition at T{sub s}=600{degree}C. Al overlayers, 170 nm thick with strong 111 preferred orientation and an average grain size of 120 nm, were then deposited at T{sub s}=100{degree}C without breaking vacuum. Changes in bilayer sheet resistance R{sub s} were monitored continuously as a function of time t{sub a} and temperature T{sub a} during UHV annealing. In addition, area-averaged and local interfacial reaction paths, as well as microstructural changes as a function of annealing conditions, were determined by x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy (TEM), and scanning TEM in which compositional distributions in cross-sectional specimens were obtained by energy-dispersive x-ray analysis using a 1 nm diam probe beam. The two tungsten aluminides which form, WAl{sub 4} and WAl{sub 12}, are nucleated essentially immediately with no measurable induction time. WAl{sub 4} grains, extensively twinned, increase in size during the initial reaction, then stop growing as competitive growth in the diffusion limited regime favors WAl{sub 12}. Information from microstructural and microchemical analyses was used to model the R{sub s}(T{sub a},t{submore » a}) data in order to determine reaction kinetics and activation energies. The results show that WAl{sub 12} growth is limited by W diffusion, with an activation energy of 2.7 eV, to the Al/aluminide interface. {copyright} {ital 1997 American Institute of Physics.}« less

Authors:
; ; ;  [1]
  1. Coordinated Science Laboratory, Materials Research Laboratory, and Department of Materials Science, 1101 West Springfield, University of Illinois, Urbana, Illinois 61801 (United States)
Publication Date:
Research Org.:
Univ. of Illinois at Urbana-Champaign, IL (United States)
OSTI Identifier:
530037
DOE Contract Number:  
AC02-76ER01198
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 82; Journal Issue: 1; Other Information: PBD: Jul 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 40 CHEMISTRY; ALUMINIUM; CHEMICAL REACTIONS; TUNGSTEN; THIN FILMS; POLYCRYSTALS; GRAIN SIZE; SPUTTERING; ELECTRIC CONDUCTIVITY; INTERFACES; ANNEALING; X-RAY DIFFRACTION; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Bergstrom, D B, Petrov, I, Allen, L H, and Greene, J E. Aluminide formation in polycrystalline Al/W metal/barrier thin-film bilayers: Reaction paths and kinetics. United States: N. p., 1997. Web. doi:10.1063/1.365798.
Bergstrom, D B, Petrov, I, Allen, L H, & Greene, J E. Aluminide formation in polycrystalline Al/W metal/barrier thin-film bilayers: Reaction paths and kinetics. United States. https://doi.org/10.1063/1.365798
Bergstrom, D B, Petrov, I, Allen, L H, and Greene, J E. Tue . "Aluminide formation in polycrystalline Al/W metal/barrier thin-film bilayers: Reaction paths and kinetics". United States. https://doi.org/10.1063/1.365798.
@article{osti_530037,
title = {Aluminide formation in polycrystalline Al/W metal/barrier thin-film bilayers: Reaction paths and kinetics},
author = {Bergstrom, D B and Petrov, I and Allen, L H and Greene, J E},
abstractNote = {Polycrystalline bcc W layers, 110 nm thick with 011 preferred orientation and an average grain size of 40 nm, were grown on amorphous-SiO{sub 2}/Si(001) substrates by ultrahigh vacuum (UHV) magnetron sputter deposition at T{sub s}=600{degree}C. Al overlayers, 170 nm thick with strong 111 preferred orientation and an average grain size of 120 nm, were then deposited at T{sub s}=100{degree}C without breaking vacuum. Changes in bilayer sheet resistance R{sub s} were monitored continuously as a function of time t{sub a} and temperature T{sub a} during UHV annealing. In addition, area-averaged and local interfacial reaction paths, as well as microstructural changes as a function of annealing conditions, were determined by x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy (TEM), and scanning TEM in which compositional distributions in cross-sectional specimens were obtained by energy-dispersive x-ray analysis using a 1 nm diam probe beam. The two tungsten aluminides which form, WAl{sub 4} and WAl{sub 12}, are nucleated essentially immediately with no measurable induction time. WAl{sub 4} grains, extensively twinned, increase in size during the initial reaction, then stop growing as competitive growth in the diffusion limited regime favors WAl{sub 12}. Information from microstructural and microchemical analyses was used to model the R{sub s}(T{sub a},t{sub a}) data in order to determine reaction kinetics and activation energies. The results show that WAl{sub 12} growth is limited by W diffusion, with an activation energy of 2.7 eV, to the Al/aluminide interface. {copyright} {ital 1997 American Institute of Physics.}},
doi = {10.1063/1.365798},
url = {https://www.osti.gov/biblio/530037}, journal = {Journal of Applied Physics},
number = 1,
volume = 82,
place = {United States},
year = {1997},
month = {7}
}