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Silicide formation with codeposited titanium-tantalum alloys on silicon

Journal Article · · J. Appl. Phys.; (United States)
DOI:https://doi.org/10.1063/1.339678· OSTI ID:6512934

The formation of disilicides of titanium and tantalum from Ti-Ta alloys codeposited on silicon and polycrystalline silicon have been investigated using x-ray diffraction techniques, resistance measurements, and Auger electron spectroscopy. Titanium and tantalum in the Ti-Ta alloy interacted independently with silicon. There was no titanium/tantalum compound formation and no ternary was detected. The growth of each metal silicide was sustained by continuous out-diffusion of silicon into the Ti-Ta alloy film until the metals were consumed in the silicide transformation. This behavior may account for the absence of phase separation and component accumulation. An initial reaction was observed after the 600 /sup 0/C, 30 min anneal. The stable end phases formed at temperatures greater than or equal to800 /sup 0/C are TiSi/sub 2/ and TaSi/sub 2/. High molecular weight intermetallics such as Ta/sub 5/Si/sub 3/ and Ti/sub 5/Si/sub 3/ that are normally not detected in Ta-Si and Ti-Si interaction studies were detected, suggesting a stabilizing effect of the impurities. The sheet resistance of the heat-treated samples is: (a) a strong function of the titanium content of the Ti-Ta alloy (low for Ti-rich alloys); (b) lower on silicon substrates; (c) invariant at temperatures >900 /sup 0/C. The etch rate of the heat-treated samples in buffered hydrofluoric acid increased with increasing titanium content in the film.

Research Organization:
ATandT Bell Laboratories, 600 Mountain Avenue, Murray Hill, New Jersey 07974
OSTI ID:
6512934
Journal Information:
J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 62:4; ISSN JAPIA
Country of Publication:
United States
Language:
English