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Thickness Effects in the Reaction of Cobalt with Slicon-Germanium Alloys

Published online by Cambridge University Press:  10 February 2011

B. I. Boyanov ,
P. T. Goeller ,
D. E. Sayers  and
R. J. Nemanich
B. I. Boyanov
Affiliation:
Department of Physics and Department of Materials Science, North Carolina State University, Raleigh, NC 27695, boyanov@eos.ncsu.edu
P. T. Goeller
Affiliation:
Department of Physics and Department of Materials Science, North Carolina State University, Raleigh, NC 27695, boyanov@eos.ncsu.edu
D. E. Sayers
Affiliation:
Department of Physics and Department of Materials Science, North Carolina State University, Raleigh, NC 27695, boyanov@eos.ncsu.edu
R. J. Nemanich
Affiliation:
Department of Physics and Department of Materials Science, North Carolina State University, Raleigh, NC 27695, boyanov@eos.ncsu.edu
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Abstract

The thickness dependence of the reaction of cobalt with silicon and epitaxial silicongermanium alloys (SiGe) was studied. Cobalt layers 25 Å and thicker deposited on Si(100) and annealed at 600°C formed CoSi2. When the thickness of the Co film was reduced to 10 Å the Co/Si(100) reaction resulted in a mixture of CoSi and CoSi2 even after annealing for 20 minutes at 800°C. The products of the reaction of Co with (100)-oriented Si1−x Gex after annealing at 800°C depended on the thickness of the Co film and the Ge concentration in the SiGe layer. When the thickness of the Co film was below a critical value, the only phase formed during the Co/SiGe reaction was CoSi. A mixture of CoSi and CoSi2 was observed when the thickness of the Co film exceeded the critical value. The critical thickness for CoSi2 nucleation increased superlinearly with Ge concentration in the range 0≤x≤0.25, and did not depend on the doping of the Si(100) substrate or the strain state of the SiGe film. XRD and EXAFS measurements indicated no measurable incorporation of Ge had occurred in either the CoSi or CoSi2. The amount of CoSi2 formed above the critical thickness increased monotonically with the thickness of the as-deposited Co film. The observed thickness effect was attributed to preferential Co–Si bonding in the reaction zone, and was modeled in terms of the energy cost of Ge segregation, which accompanies the formation of CoSi and CoSi2 during the reaction of Co with SiGe.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 514: Symposium I – Advanced Interconnects & Contact Materials & Processes for… , 1998 , 165
Copyright
Copyright © Materials Research Society 1998

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References

REFERENCES

[1] Tu, K. N., Chu, W. K., and Mayer, J. W., Thin Solid Films, vol.25, pp. 403, 1975.10.1016/0040-6090(75)90058-9Google Scholar
[2] Murarka, S. P., Silicides for VLSI Applications. New York: Academic Press, 1983.Google Scholar
[3] Ridgway, M. C., Elliman, R. G., Hauser, N., and Baribeau, J.-M., Mat. Res. Soc. Symp. Proc., vol.260, pp. 857–861, 1992.Google Scholar
[4] Ying, H., Wang, Z., Aldrich, D. B., Sayers, D. E., and Nemanich, R. J., Mat. Res. Soc. Symp. Proc., vol.320, pp. 335–340, 1994.Google Scholar
[5] Lin, F., Sarcona, G., Hatalis, M. K., Cserhati, A. F., Austin, E., and Greve, D. W., Thin Solid Films, vol.250, pp. 20–25, 1994.Google Scholar
[6] Watson, G. P., Monroe, D., Cheng, J.-Y., Fitzgerald, E. A., Xie, Y.-H., and Vandover, R. B., Mat. Res. Soc. Symp. Proc., vol.320, pp. 323–328, 1994.10.1557/PROC-320-323Google Scholar
[7] Wang, Z., Aldrich, D. B., Chen, Y. L., Sayers, D. E., and Nemanich, R. J., Thin Solid Films, vol.270, pp. 555–560, 1995.Google Scholar
[8] Gltick, M., Schtippen, A., Rösler, M., Heinrich, W., Hersener, J., König, U., Yam, O., Cytermann, C., and Eizenberg, M., Thin Solid Films, vol.270, pp. 549–554, 1995.Google Scholar
[9] van Houtum, H. J. W. and Raaijmakers, I. J. M. M., Mat. Res. Soc. Symp. Proc., vol.54, pp. 38–42, 1986.Google Scholar
[10] Aldrich, D. B., Heck, H. L., Chen, Y. L., Sayers, D. E., and Nemanich, R. J., J. Appl. Phys., vol.78, pp. 4958–4965, 1995.Google Scholar
[11] Jeon, H., Sukow, C. A., Honeycutt, J. W., Humphreys, T. P., Nemanich, R. J., and Rozgonyi, G. A., Mat. Res. Soc. Symp. Proc., vol.181, pp. 559–564, 1990.Google Scholar
[12] Lau, S. S., Mayer, J. W., and Tu, K. N., J. Appl. Phys., vol.49, pp. 4005, 1978.Google Scholar
[13] JCPDS-ICDD PDF-2 Database, 1989.Google Scholar
[14] Wang, Z., Nemanich, R. J., and Sayers, D. E., Physica B, vol.208–568, 1995.Google Scholar
[15] Donaton, R. A., Maex, K., Vantomme, A., Langouche, G., Morciaux, Y., Armour, A. S., and Strum, J. C., Appl. Phys. Lett., vol.70, pp. 1266–1268, 1997.Google Scholar
[16] Bean, J. C., Feldman, L. C., Fiory, A. T., Nakahara, S., and Robinson, I. K., J. Vac. Sci. Technol. A, vol.2, pp. 436, 1984.Google Scholar
[17] Boyanov, B. I., Goeller, P. T., Sayers, D. E., and Nemanich, R. J., J. Appl. Phys. (submitted).Google Scholar
[18] This includes the effect of entropy change that accompanies the CoSi→4CoSi2 transition, which is a significant correction to the enthalpy. See Ref. [17] for details.Google Scholar