Facet evolution of selectively grown epitaxial Si_{1− x}Ge_x fin layers in sub-100 nm trench arrays

We selectively grew epitaxial Si_{1− x}Ge_x fin layers with x in the range of 0.36–0.63 in oxide trench arrays with trench width of 40, 65, and 90 nm. The dominant facet of the Si_{1− x}Ge_x layers changed from {1 1 1} to {1 1 3} at x = 0.56, and three types of facets were found for the layers with Ge content in the observed range. The relationship between the facet evolution and the growth rate of the facets was investigated. Blanket Si_{1− x}Ge_x layers grown on three substrates with orientations of (0 0 1), (1 1 1), and (1 1 3) were used for comparing the growth rate of each facet during the facet evolution. The results obtained for the blanket layers were found to be consistent with the facet evolutions in the Si_{1− x}Ge_x fin layers with Ge content in the range of 0.36–0.63.