A STUDY OF STRAIN IN THIN EPITAXIAL-FILMS OF YTTRIUM SILICIDE ON SI(111)

We present the results of an x-ray diffraction analysis of epitaxial y ttrium silicide films grown on Si(111), with thicknesses ranging from 14 to 100 Angstrom A. The macroscopic strain along the out-of-plane di rection for films containing pits or pinholes follows the trend observ ed previously in films of thicknesses up to 510 Angstrom A. The out-of -plane lattice parameter decreases linearly with film thickness. We sh ow preliminary evidence that pinhole-free films do not follow the abov e trend, and that strain in these films has the opposite sign than in films with pinholes. Finally, our results also indicate that the mode of growth, coupled to the interfacial thermal properties of the films, affects the observed value for the strain in the films.