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ZrN Diffusion Barrier in Aluminum Metallization Schemes

Published online by Cambridge University Press:  15 February 2011

L. Krusin-Elbaum
Affiliation:
IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, (U.S.A.)
M. Wittmer
Affiliation:
IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, (U.S.A.)
C.-Y. Ting
Affiliation:
IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, (U.S.A.)
J. J. Cuomo
Affiliation:
IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, (U.S.A.)
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Abstract

We have studied reactively sputtered ZrN, the most thermally stable of the refractory metal nitrides, for its diffusion barrier properties in aluminum metallization schemes with Rutherford backscattering spectroscopy and transmission electron microscopy (TEM). We find this compound to be very effective against aluminum diffusion up to 500 °C, independently of substrate temperature during sputtering. The useful temperature range can be extended by 50 °C with proper preannealing prior to aluminum deposition. The TEM study of the ZrN grain size as a function of annealing temperature revealed that the grain size does not change significantly upon annealing and that the grains are relatively small even at the highest annealing temperatures (about 300 Å at 900 °C). In addition, for annealing temperatures of and below 500 °C large portions of ZrN films were found to be of either amorphous or extremely fine–grain material, thus inhibiting the diffusion along grain boundaries. The presence of Zr3Al4Si5 ternary compound in samples annealed at 600 °C, as determined by X-ray analysis, may suggest that the ZrN barrier fails by decomposition of the film by aluminum.

Type
Research Article
Copyright
Copyright © Materials Research Society 1982

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References

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