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Spectroscopic Ellipsometry of Ta2O5 ON Si

Published online by Cambridge University Press:  10 February 2011

C.A. Richter ,
N.V. Nguyen  and
G.B. Alers
C.A. Richter
Affiliation:
Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8122
N.V. Nguyen
Affiliation:
Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8122
G.B. Alers
Affiliation:
Bell Labs, Lucent Technologies, Inc., Murray Hill, NJ 07974
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Abstract

In this paper, we present the results of spectroscopic ellipsometry (SE) studies of Ta2O5 films on Si. Based on these results, we have experimentally determined an effective method for analyzing SE measurements of Ta2O5. A set of CVD-grown Ta2O5 films on silicon – with thicknesses ranging from below 10 nm to approximately 60 nm thick – was investigated by SE in an effort to improve optical film thickness metrology for Ta2O5. The samples were measured across the spectral range 1.5 eV to 6.0 eV by using a well-characterized, high-accuracy rotating-analyzer-type ellipsometer. We present an analysis method, based upon a Tauc-Lorentz parameterization of the optical properties of Ta2O5, that properly describes the SE data. We also demonstrate how optical properties are affected by the presence of an interlayer at the Si/Ta2O5 interface. Our results show small, but meaningful variations in optical parameters resulting from variations in deposition processes and annealing conditions. This work demonstrates that SE can be used successfully to characterize this category of alternate gate dielectrics.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 567: Symposium R – Ultrathin SiO2 and Higg-K Materials for ULSI Gate Dielectrics , 1999 , 559
Copyright
Copyright © Materials Research Society 1999

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References

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