SUBSTRATE-TEMPERATURE DEPENDENCE OF HOMOEPITAXIAL GROWTH OF SI USING MASS-SELECTED ION-BEAM DEPOSITION

Homoepitaxy of silicon at low temperature has been achieved using low- energy mass selected silicon ion beams. Reflection high-energy electro n diffraction and Rutherford backscattering spectrometry have been uti lized to assess the quality of silicon films deposited from 15 eV Si-2 8+ beams in the temperature range of 50-350-degrees-C. Auger electron spectroscopy was used to monitor the contaminant levels on the surface s. The films deposited at 350-degrees-C are epitaxial and of a quality near that of the original substrate. The growth rate at 350-degrees-C is almost-equal-to 200 times faster than that for solid phase epitaxy . At 50 and 200-degrees-C layer-by-layer epitaxial growth was inhibite d and evidence for formation of three-dimensional islands in the early stage of growth followed by transition to an amorphous phase was obse rved. The transition to an amorphous phase occurred at lower film thic kness (smaller ion dose) for lower temperatures. It is shown that smal l amounts of N2+ impurity in the Si-28+ beam, sufficient to add 1.4 at . % N to the silicon film, result in amorphous films, even at the high est temperature used, 350-degrees-C. The effects of substrate temperat ure, contamination, and surface damage on the growth mechanism are dis cussed.