Structure and stability of cobalt-silicon-germanium thin films

Peter T. Goeller, Boyan I. Boyanov, Dale E. Savers, Robert J. Nemanich

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

The phase formation and stability of CoSi2 on strained epitaxial Si0.80Ge0.20/Si (0 0 1) thin films has been investigated. Silicide films prepared via direct deposition of cobalt (Co/SiGe), and via co-deposition of silicon and cobalt (Co+2Si/SiGe), were compared. EXAFS, XRD, and sheet-resistance measurements indicated that co-deposited Co+2Si films annealed at 400-700°C exhibit the expected low-resistivity CoSi2 structure but were susceptible to roughening, pinhole formation, and agglomeration. In contrast, the Co/SiGe structure formed CoSi2 only after annealing at 700°C and suicide formation was accompanied by Ge segregation in the contact region. In situ RHEED experiments indicated that growth of CoSi2 co-deposited on SiGe at 400-500°C results in immediate island formation. Template methods, which are often used to enhance the quality of co-deposited Co+2Si/Si structures, did not lead to two-dimensional growth in the Co+2Si/SiGe system. In situ EXAFS measurements of 2 A Co films deposited on SiGe substrates and annealed at 450°C suggested that the failure to achieve two-dimensional growth may be due to preferential bonding of Co to Si atoms at the interface, which prevents the formation of a continuous CoSi2 template.

Original languageEnglish (US)
Pages (from-to)84-89
Number of pages6
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume133
Issue number1-4
DOIs
StatePublished - Dec 2 1997
Externally publishedYes

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Keywords

  • Cobalt silicide
  • Metal-semiconductor contacts
  • Molecular beam epitaxy
  • Silicon germanium alloys

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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