Structure and stability of cobalt-silicon-germanium thin films

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

Research output: Contribution to journalArticle

9 Citations (Scopus)

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
StatePublished - Dec 2 1997
Externally publishedYes

Fingerprint

Germanium
Silicon
Cobalt
germanium
cobalt
Thin films
silicon
thin films
Reflection high energy electron diffraction
Sheet resistance
templates
Agglomeration
Annealing
pinholes
Atoms
agglomeration
in situ measurement
Substrates
Experiments
electrical resistivity

Keywords

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

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Instrumentation
  • Surfaces and Interfaces

Cite this

Structure and stability of cobalt-silicon-germanium thin films. / Goeller, Peter T.; Boyanov, Boyan I.; Savers, Dale E.; Nemanich, Robert.

In: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, Vol. 133, No. 1-4, 02.12.1997, p. 84-89.

Research output: Contribution to journalArticle

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N2 - 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.

AB - 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.

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