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Reliability of Tantalum Based Diffusion Barriers between Cu and Si

Published online by Cambridge University Press:  17 March 2011

Tomi Laurila ,
Kejun Zeng ,
A. Seppälä ,
Jyrki Molarius ,
Ilkka Suni  and
Jorma K. Kivilahti
Tomi Laurila
Affiliation:
Lab. of Electronics Production Technology, P.O. Box 3000, FIN-02015 HUT, Finland
Kejun Zeng
Affiliation:
Lab. of Electronics Production Technology, P.O. Box 3000, FIN-02015 HUT, Finland
A. Seppälä
Affiliation:
Accelerator laboratory, P. O. Box 43, FIN-00014 University of Helsinki, Finland
Jyrki Molarius
Affiliation:
VTT Microelectronics, P.O. Box 1101, FIN-02044 VTT, Finland
Ilkka Suni
Affiliation:
VTT Microelectronics, P.O. Box 1101, FIN-02044 VTT, Finland
Jorma K. Kivilahti
Affiliation:
Lab. of Electronics Production Technology, P.O. Box 3000, FIN-02015 HUT, Finland
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Abstract

The reaction mechanisms in the Si|Ta|Cu and Si|TaC|Cu metallization systems are discussed based on the experimental results and the assessed ternary Si-Ta-Cu, Si-Ta-C and Ta-C-Cu phase diagrams. The ternary Si-Ta-N and Ta-N-Cu phase diagrams were also assessed in order to compare the thermodynamic properties of the TaC diffusion barriers to more widely investigated TaNx diffusion barriers. With the help of the sheet resistance measurements, RBS, XRD, SEM, and TEM the Ta barrier layer was observed to fail above 650 °C due to the formation of TaSi2. This was accompanied by the diffusion of Cu through the silicide layer and the resulting formation of Cu3Si precipitates. The stability of the TaC layers was better and the failure was observed above 750 °C due to the formation of Cu3Si and TaSi2. However, interdiffusion of Cu and Si was observed already at lower temperatures due to the presence of pinholes in the TaC layer. This emphasises the importance of the fabrication method and the quality of the TaC layers.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 612: Symposium D – Materials, Technology & Reliability for Advanced Interconnects.. , 2000 , D7.4.1
Copyright
Copyright © Materials Research Society 2000

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