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Interface Stability of Ti(Sil−yGey)2 and Si1−x Gex Alloys

Published online by Cambridge University Press:  15 February 2011

D. B. Aldrich ,
F. M. D'Heurle ,
D. E. Sayers  and
R. J. Nemanich
D. B. Aldrich
Affiliation:
Currently at Texas Instruments, P.O. Box 655012, M/S 461, Dallas, TX 75265 Department of Physics, North Carolina State University, Raleigh, NC 27695-8202
F. M. D'Heurle
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, NY 10598
D. E. Sayers
Affiliation:
Currently at Texas Instruments, P.O. Box 655012, M/S 461, Dallas, TX 75265
R. J. Nemanich
Affiliation:
Currently at Texas Instruments, P.O. Box 655012, M/S 461, Dallas, TX 75265
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Abstract

The stability of C54 Ti(Si1−yGey)2 films in contact with Si1−xGex substrates was investigated. The titanium germanosilicide films were formed from the Ti − Si1−xGex solid phase metallization reaction. It was observed that Ti(Si1−yGey) 2 initially forms with the same germanium content as the Si1−x Gex substrate (i.e., y = x). Following the initial formation of TiM2 (M = Sil−yGey), silicon and germanium from the substrate diffuse into the TiM2 layer, the composition of the TiM2 changes, and Si1−z Gez precipitates form along the TiM2 grain boundaries. The germanium content of the Ti(Sil−y Gey)2 decreases, and the Sil−z Gez precipitates are germanium rich such that y < x < z. This instability of the TiM2 film and the dynamics of the germanium segregation were examined using the Ti-Si-Ge ternary equilibrium diagram. The relevant region of the ternary diagram is the two phase domain limited by a Si-Ge solid solution and a TiSi2 − TiGe2 solid solution. In this study first approximation Ti(Sil−y Gey)2 -to- Sil−xGex tie lines were calculated on the basis of classical thermodynamics. The tie line calculations indicate that for C54 Ti(Sil−yGey)2 to be stable in contact with Sil−xGex, the compositions of the two phases in equilibrium must be such that y < x. The specific compositions of the two phases in equilibrium depend on the temperature and the relative quantities of the two phases. The dynamic processes by which the Ti(Si1−yGey)2/Si1−x. Gex, system progresses from the as-formed state (y = x) to the equilibrium state (y < x) can be predicted using the tie line calculations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 402: Symposium H – Silicide Thin Films-Fabrication, Properties and Applications , 1995 , 21
Copyright
Copyright © Materials Research Society 1996

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