Jm. Gay et al., EPITAXIAL-GROWTH AND LATTICE MATCH OF COBALT AND NICKEL DISILICIDES SI(111) GOLD AND COBALT DOPING OF NISI2/, Physica. B, Condensed matter, 221(1-4), 1996, pp. 90-95
We report on an X-ray diffraction study of the epitaxial growth of thi
ck films of cobalt and nickel disilicides on silicon. The lattice para
meters both parallel and normal to the interface are measured at room
temperature (RT) for various samples prepared by solid phase epitaxy o
r reactive deposition epitaxy with annealing at high temperature (600-
800 degrees C). The formation of a rigid disilicide:silicon interface
with a dislocation network frozen below a critical temperature T-D, es
timated at 600 degrees C for CoSi2 and at 710 degrees C for NiSi2, is
the likely growth mechanism of the thick disilicide films. CoSi2 and N
iSi2 layers are indeed tetragonally strained at RT with a lateral mism
atch equal to that of the relaxed material at T-D, i.e. -0.87% and +0.
17% respectively. The tetragonal distortion results from the different
thermal expansion coefficients of silicon and silicides. Doping NiSi2
with 10% Co, i.e. smaller atoms, leads to a close in-plane lattice ma
tch. Introducing 6% Au atoms increases the lattice parameter of NiSi2,
and also favours the relaxation of the film after annealing. With 12%
Au-doping, quasi-total relaxation is observed but the layer is no lon
ger uniform. Doping in all cases induces a decrease of the critical te
mperature T-D of dislocation freezing.