Interface stability of Ti(Si 1-yGe y) 2 and Si 1-xGe x alloys

D. B. Aldrich, F. M. D'Heurle, D. E. Sayers, Robert Nemanich

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The stability of C54 Ti(Si 1-yGe y) 2 films in contact with Si 1-xGe x substrates was investigated. The titanium germanosilicide films were formed from the Ti - Si 1-xGe x solid phase metallization reaction. It was observed that Ti(Si 1-yGe y) 2 initially forms with the same germanium content as the Si 1-xGe x substrate (i.e., y = x). Following the initial formation of TiM 2 (M = Si 1-yGe y), silicon and germanium from the substrate diffuse into the TiM 2 layer, the composition of the TiM 2 changes, and Si 1-zGe z precipitates form along the TiM 2 grain boundaries. The germanium content of the Ti(Si 1-yGe y) 2 decreases, and the Si 1-zGe z precipitates are germanium rich such that y < x < z. This instability of the TiM 2 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 TiSi 2 - TiGe 2 solid solution. In this study first approximation Ti(Si 1-yGe y) 2 -to- Si 1-xGe x tie lines were calculated on the basis of classical thermodynamics. The tie line calculations indicate that for C54 Ti(Si 1-yGe y) 2 to be stable in contact with Si 1-xGe x, 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(Si 1-yGe y) 2/Si 1-xGe x system progresses from the as-formed state (y - x) to the equilibrium state (y < x) can be predicted using the tie line calculations.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
Number of pages6
StatePublished - 1996
Externally publishedYes
EventProceedings of the 1995 MRS Fall Symposium - Boston, MA, USA
Duration: Nov 27 1995Nov 30 1995


OtherProceedings of the 1995 MRS Fall Symposium
CityBoston, MA, USA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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