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Tem Investigation of Co-Si Thin Films on S1-xGex/Si

Published online by Cambridge University Press:  02 July 2020

A. F. Myersa
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD20899
P. T. Goeller
Affiliation:
Materials Science and Engineering Dept., North Carolina State University, Raleigh, NC27695
E. B. Steel
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD20899
B. I. Boyanov
Affiliation:
Physics Dept., North Carolina State University, Raleigh, NC27695
D. E. Sayers
Affiliation:
Physics Dept., North Carolina State University, Raleigh, NC27695
R. J. Nemanich
Affiliation:
Materials Science and Engineering Dept., North Carolina State University, Raleigh, NC27695 Physics Dept., North Carolina State University, Raleigh, NC27695
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Extract

Cobalt disilicide (CoSi2) is an attractive contact material for Si1-xGex devices due to its low resistivity, low Schottky barrier, and good thermal and chemical stability. Previous studies have shown that blanket Co films on Si0.80Ge0.20 react at annealing temperatures of 700 °C to form CoSi, CoSi2 and a Ge-rich Si1-xGex alloy; no Co-Ge phases were found. The Co preferentially reacts with the Si, which can lead to Ge segregation and island formation. To gain a better understanding of cobalt silicide formation, an electron microscopy investigation of Co/Si1-xGex/Si was performed.

Si1-xGex films (x ≤ 0.3) 64 nm to 260-nm thick were grown by molecular beam epitaxy at 550 °C on phosphorus-doped Si <001> substrates. Co films ranging in thickness from 5 nm to 25 nm were electron-beam evaporated (evaporator base pressure < 6.67 x 10-8 Pa) at room temperature on the Si1-xGex films.

Type
Microscopy of Semiconducting and Superconducting Materials
Copyright
Copyright © Microscopy Society of America

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References

References:

1.Tung, R. T. et al., eds., Silicide Thin Films - Fabrication, Properties, and Applications, MRS Symp. Proc. Vol. 402, Pittsburgh Materials Research Society (1996).Google Scholar
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5. The film deposition at NCSU was supported by U. S. Department of Energy grant No. DE-FG05-93ER79236 (D. E. S.) and National Science Foundation grant No. DMR-9633547 (R. J. N.).Google Scholar