FORMATION OF BETA-SIC FILMS BY ION-BEAM MIXING OF SI/C MULTILAYERS

We deposited Si/C multilayers of nearly equiatomic composition by ion sputtering of Si and C targets using 1.2 keV Ar+ ions. Ion mixing of these samples was performed with 250 keV Xe+ ions at temperatures ranging between 700 and 900 degrees C. The behaviour of beta-SiC formation on mixing was investigated using three techniques: Fourier transform IR spectroscopy, transmission electron microscopy and X-ray diffraction. In addition, X-ray reflectometry measurements were taken to determine the film density. The films produced by mixing at 700 degrees C are amorphous but subsequent annealing at 950 degrees C results in the formation of crystalline beta-SiC. Complete mixing of the multilayers is only obtained at 800 degrees C after ion doses higher than 3 x 10(16) cm(-2), as indicated by cross-sectional electron microscopy. These results demonstrate that ion mixing at moderate temperatures T similar to 800 degrees C of Si/C multilayers may provide an alternative method for the formation of beta-SiC films.