作者:
A Bächli，MA Nicolet，L Baud，C Jaussaud，R Madar
关键词:
Nickel；Reaction；Film
摘要:
The reactions induced in a vacuum furnace (5×10 617 Torr) between an electron-beam-evaporated Ni film a few hundred nm thick and a (001)-oriented (i.e. Si-face-oriented) single crystalline 3C–SiC substrate are investigated by 3.2 MeV 4 He 2+ backscattering spectrometry, X-ray diffraction, secondary ion mass spectrometry, and scanning electron microscopy. Samples are characterized before and after annealing at temperatures of 400–700 o C for 30 min. At 450 o C, carbon diffuses throughout the Ni film and forms a carbon-rich layer at the Ni surface of a thickness of a few nm which remains unchanged during subsequent annealing. Some nickel silicides were detected at this initial stage but could not be clearly identified. At 450 o C (after 120 min) the Ni 31 Si 12 phase starts to form. This is the only detected phase at 500 o C. The Ni 2 Si phase, the silicide that is thermodynamically stable with SiC and carbon, forms first at the surface and grows toward the SiC substrate. At 600 o C, this reaction has consumed about half of the Ni 31 Si 12 phase and at 700 o C, Ni 2 Si is the only silicide in the reacted film. In all the reacted samples the carbon distribution is alike and consists of three distinct layers: a first zone with a constant carbon concentration that extends from near the SiC/silicide interface through most of the films thickness. The second zone is 6570 nm thick and is deficient of carbon. The third zone is the thin graphite layer at the surface. There is oxygen in the film too, the distribution of which is related increasingly clearly to the carbon profile as the annealing temperature rises.
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