Pt. Goeller et al., STRUCTURE AND STABILITY OF COBALT-SILICON-GERMANIUM THIN-FILMS, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 133(1-4), 1997, pp. 84-89
Citations number
21
Categorie Soggetti
Instument & Instrumentation","Nuclear Sciences & Tecnology","Physics, Atomic, Molecular & Chemical
The phase formation and stability of CoSi2 on strained epitaxial Si0.8
0Ge0.20/Si (001) thin films has been investigated. Silicide films prep
ared via direct deposition of cobalt (Co/SiGe), and via co-deposition
of silicon and cobalt (Co+2Si/SiGe), were compared. EXAFS, XRD, and sh
eet-resistance measurements indicated that co-deposited Co+2Si films a
nnealed at 400-700 degrees C exhibit the expected low-resistivity CoSi
2 structure but were susceptible to roughening, pinhole formation, and
agglomeration. In contrast, the Co/SiGe structure formed CoSi2 only a
fter annealing at 700 degrees C and silicide formation was accompanied
by Ge segregation in the contact region. In situ RHEED experiments in
dicated that growth of CoSi2 co-deposited on SiGe at 400-500 degrees C
results in immediate island formation. Template methods, which are of
ten 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 s
itu EXAFS measurements of 2 A Co films deposited on SiGe substrates an
d annealed at 450 degrees C suggested that the failure to achieve two-
dimensional growth th may be due to preferential bonding of Co to Si a
toms at the interface. which prevents the formation of a continuous Co
Si2 template. (C) 1997 Elsevier Science B.V.