Thickness effects in the reaction of cobalt with silicon-germanium alloys

B. I. Boyanov, P. T. Goeller, D. E. Sayers, Robert Nemanich

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

Abstract

The thickness dependence of the reaction of cobalt with silicon and epitaxial silicon-germanium alloys (SiGe) was studied. Cobalt layers 25 angstrom and thicker deposited on Si(100) and annealed at 600°C formed CoSi 2. When the thickness of the Co film was reduced to 10 angstrom the Co/Si(100) reaction resulted in a mixture of CoSi and CoSi 2 even after annealing for 20 minutes at 800°C. The products of the reaction of Co with (100)-oriented Si 1-xGe x 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 CoSi 2 was observed when the thickness of the Co film exceeded the critical value. The critical thickness for CoSi 2 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 CoSi 2. The amount of CoSi 2 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 CoSi 2 during the reaction of Co with SiGe.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMRS
Pages165-170
Number of pages6
Volume514
StatePublished - 1998
Externally publishedYes
EventProceedings of the 1998 MRS Spring Symposium - San Francisco, CA, USA
Duration: Apr 13 1998Apr 16 1998

Other

OtherProceedings of the 1998 MRS Spring Symposium
CitySan Francisco, CA, USA
Period4/13/984/16/98

Fingerprint

Cobalt
Annealing
Silicon
Si-Ge alloys
Nucleation
Doping (additives)
Substrates
Costs

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

Cite this

Boyanov, B. I., Goeller, P. T., Sayers, D. E., & Nemanich, R. (1998). Thickness effects in the reaction of cobalt with silicon-germanium alloys. In Materials Research Society Symposium - Proceedings (Vol. 514, pp. 165-170). MRS.

Thickness effects in the reaction of cobalt with silicon-germanium alloys. / Boyanov, B. I.; Goeller, P. T.; Sayers, D. E.; Nemanich, Robert.

Materials Research Society Symposium - Proceedings. Vol. 514 MRS, 1998. p. 165-170.

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

Boyanov, BI, Goeller, PT, Sayers, DE & Nemanich, R 1998, Thickness effects in the reaction of cobalt with silicon-germanium alloys. in Materials Research Society Symposium - Proceedings. vol. 514, MRS, pp. 165-170, Proceedings of the 1998 MRS Spring Symposium, San Francisco, CA, USA, 4/13/98.
Boyanov BI, Goeller PT, Sayers DE, Nemanich R. Thickness effects in the reaction of cobalt with silicon-germanium alloys. In Materials Research Society Symposium - Proceedings. Vol. 514. MRS. 1998. p. 165-170
Boyanov, B. I. ; Goeller, P. T. ; Sayers, D. E. ; Nemanich, Robert. / Thickness effects in the reaction of cobalt with silicon-germanium alloys. Materials Research Society Symposium - Proceedings. Vol. 514 MRS, 1998. pp. 165-170
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