Facet formation during silicon selective epitaxial growth

Epitaxial growth and, more specifically, the selective epitaxial growth (SEG) of silicon on patterned substrates are important techniques that may help the realisation of new generations of HBT and BiCMOS technologies. However, within typical applications the final shape of the growth front is often very important and a detailed understanding of the growth rate of individual growth planes and thereby facetformation is required. In this work we present a study of the growth rates of planes and the formation of facets during the selective epitaxial growth of silicon by low pressure chemical vapour deposition (LPCVD). Growth on {100}, {111} and {110} silicon substrates with growth rates in the range 7 to 16nm/min at 1 Torr and 950- 980oC are utilised to ensure that detailed data are obtained for different phases. Analysis of the different growth rates are considered with reference to all of the growth and crystalline parameters. A model of the system ultimately provides growth rate multiplication factor, M(hkl), that is shown to accurately match experimental growth rates. This model also accurately predicts our experimental observations of facet formation and thus, provides a useful tool that can help to predict the final shape of growth fronts that emerge from the SEG growth for any substrate orientation or seed plane.