LOW-TEMPERATURE HOMOEPITAXIAL GROWTH ON NONPLANAR SI SUBSTRATES

The kinetics associated with the breakdown of epitaxy at low temperatures are studied for growth onto a number of Si surfaces, including (001), (117), (115), and (113). These surfaces are all initially generated at trench edges on a single patterned substrate. Growth on each of these surfaces at low temperatures is shown to result in a well-defined crystalline-to-amorphous transition. The epitaxial thicknesses h(epi) have been measured over a range of substrate temperatures below 280 degrees C, and activation energies characteristic of this transition were determined. In general, the breakdown in epitaxy occurs such that h(epi)(001) > h(epi)(117) > h(epi)(115) > h(epi)(113). Growth at slightly higher temperatures, T-substrate > 300 degrees C, shows a different microstructure than that at lower temperatures. Epitaxial growth continues for longer times on (113) facets, as compared with (001). These results are discussed in terms of a recently proposed model explaining the breakdown of epitaxy at lower temperatures and an epitaxial temperature for Si.