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 t hese samples was performed with 250 keV Xe+ ions at temperatures rangi ng between 700 and 900 degrees C. The behaviour of beta-SiC formation on mixing was investigated using three techniques: Fourier transform I R spectroscopy, transmission electron microscopy and X-ray diffraction . In addition, X-ray reflectometry measurements were taken to determin e the film density. The films produced by mixing at 700 degrees C are amorphous but subsequent annealing at 950 degrees C results in the for mation 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 res ults demonstrate that ion mixing at moderate temperatures T similar to 800 degrees C of Si/C multilayers may provide an alternative method f or the formation of beta-SiC films.