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Tantalum and Tantalum Nitride as Diffusion Barriers Between Copper and Silicon

Published online by Cambridge University Press:  25 February 2011

Karen Holloway  and
Peter Fryer
Karen Holloway
Affiliation:
T.J. Watson Research Center, Yorktown Heights, NY 10598
Peter Fryer
Affiliation:
T.J. Watson Research Center, Yorktown Heights, NY 10598
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Abstract

We have investigated the effectiveness of thin tantalum layers as diffusion barriers to copper. Fifty nm Ta films were sputtered onto unpatterned single crystal Si wafers and overlaid with 100 nm Cu. Material reactions in these films were followed as a function of annealing temperature by in-situ resistance measurements, and characterized by by Rutherford Backscattering and cross-section TEM. The effect of the incorporation of nitrogen was explored by reactively depositing Ta(5 at.% N) and Ta2N. Pure Ta prevents Cu - silicon interaction to at least 600 °C. At higher temperatures, reaction of the Si substrate with Ta forms a planar TaSi2 layer. Cu rapidly penetrates to the Si substrate, forming Cu silicide precipitates at the TaSi2 - Si interface. A study performed on the Si/Ta(N)/Cu film had very similar results. Ta2N is an even more effective barrier to copper penetration, preventing Cu reaction with the substrate for temperatures up to at least 700 °C.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 181: Symposium B – Advanced Metallizations in Microelectronics , 1990 , 41
Copyright
Copyright © Materials Research Society 1990

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References

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