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Oxygen Diffusion in Tantalum Oxide Metal-Oxide-Metal Capacitor Structures

Published online by Cambridge University Press:  10 February 2011

J. P. Chang
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974
M. L. Steigerwald
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974
R. M. Fleming
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974
R. L. Opila
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974
G. B. Alers
Affiliation:
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974
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Abstract

We have studied structures used in MOM capacitors including Ta2O5/TiN/Ti, Ta2O5/Ti, Ta2O5/TaN/Ti, Ta2O5/WN/Ti, and Ta2O5/M where M = Ta, Pt, W, Al, and Si using X-Ray Photoelectron Spectroscopy. We find that Ti and Al are able to reduce the Ta2O5 to Ta, forming oxides of Ti and Al, respectively. The diffusion barrier TiN hampers the diffusion of oxygen and therefore postpone the reduction of Ta2O5 to higher temperatures. The oxygen migrates from the Ta2O5 layer and through the TIN layer to the Ti layer during the heat treatment. As judged by the temperatures at which the reduction of Ta2O5 occurs, TaN and WN are more effective oxygendiffusion barriers than TiN. Leakage current observed in AI/Ta2O5/TaN/Ta capacitors is one to two orders of magnitude lower than that observed in Al/Ta2O5/TiN/Ti capacitors.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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