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Dependence of the structural and electrical properties of ultrathin cobalt silicide films on formation conditions

Published online by Cambridge University Press:  31 January 2011

Julia M. Phillips
Affiliation:
AT & T Bell Laboratories, Murray Hill, New Jersey 07974
J. L. Batstone
Affiliation:
Department of Materials Science and Engineering, University of Liverpool, Liverpool, L69 3BX, United Kingdom
J. C. Hensel
Affiliation:
AT & T Bell Laboratories, Murray Hill, New Jersey 07974
M. Cerullo
Affiliation:
AT & T Bell Laboratories, Murray Hill, New Jersey 07974
F. C. Unterwald
Affiliation:
AT & T Bell Laboratories, Murray Hill, New Jersey 07974
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Abstract

We have studied the dependence of the electrical and structural properties of ultrathin cobalt silicide films on the annealing temperature and deposited Co thickness. If less than 10 Å of Co is deposited, epitaxial type B CoSi2 forms immediately. As the deposited thickness approaches 10 Å, small amounts of Co2Si are observed. If greater than 10 Å of Co is deposited, epitaxial Co2Si forms at room temperature, which proceeds either via the reaction Co2Si ⇉ CoSi ⇉ CoSi2 or via Co2Si ⇉ CoSi2 during annealing. In these thicker films our results suggest that the formation of type A CoSi2 is correlated with the presence of Co2Si; the presence of CoSi as an intermediate phase is correlated with the occurrence of type B CoSi2. Both film thickness and reaction temperature strongly influence the electrical transport in these films such that very high resistivities are encountered when films either become very thin or are reacted at low temperatures. In the former case the size effect is responsible whereas in the latter the transport properties are dominated by extensive atomic-scale disorder.

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Articles
Copyright
Copyright © Materials Research Society 1989

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References

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