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Properties of Sputtered Bilayer WNx/W Diffusion Barriers between Si and Cu

Published online by Cambridge University Press:  17 March 2011

K. D. Leedy ,
M. J. O'Keefe ,
E. J. Dahlgren  and
J. T. Grant
K. D. Leedy
Affiliation:
Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH 45433
M. J. O'Keefe
Affiliation:
University of Missouri-Rolla, Dept. of Metallurgical Engineering, Rolla, MO 65401
E. J. Dahlgren
Affiliation:
University of Missouri-Rolla, Dept. of Metallurgical Engineering, Rolla, MO 65401
J. T. Grant
Affiliation:
Research Institute, University of Dayton, Dayton, OH 45469
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Abstract

Copper interconnect metallizations in next generation integrated circuits will require thin diffusion barrier layers (<20 nm) between the Cu and low-k dielectric which may also function as seed layers for subsequent material depositions. One possible structure entails a multicomponent diffusion barrier with a lower resistivity component, such as W on WNx. In this study, sputtered WNx/W bilayer thin films were investigated as diffusion barriers between Si and Cu. The total thickness of the WNx/W bilayer was fixed at 20 nm while the WNx thickness was varied from 0 to 20 nm. After deposition of the barrier films, a 100 nm thick Cu film was sputtered over the top of the á-W and amorphous WNx bilayer. The as-deposited WNx/W film stress was found to be strongly dependent on the relative amount of WNx and W present and the addition of a Cu overlayer was found to mitigate the stress levels. The WNx/W barriers remained stable after 650°C anneals and exhibited phase transformations to W2N. Microstructural characterization using transmission electron microscopy and x-ray diffraction and chemical analysis by x-ray photoelectron spectroscopy of the films were used to identify the as-deposited and transformed phases.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 714: Symposium – Materials, Technology and Reliability for Advanced Interconnects and Low-k Dielectrics II , 2001 , L4.6.1
Copyright
Copyright © Materials Research Society 2001

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References

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