Epitaxial growth of C40 structure silicides on (111)Si

Abstract

C40-type, hexagonal VSi₂, MoSi₂ and WSi₂ have been grown epitaxially on (111)Si. V, Mo or W thin films, 250–300 rA in thickness, were electron gun deposited on (111)Si. Epitaxial growth of metal disilicides were induced by thermal annealing in vacuum. For VSi₂ on (111)Si, epitaxial regions, 1–2 μm in size, were found to grow in samples 400–1000°C two-step annealed. MoSi₂ grains, 0.2–2 μm in size, were observed to grow epitaxially on (111)Si following 1100°C annealing. WSi₂ epitaxy, 0.4–1.2 μm in size, on (111)Si was obtained in samples annealed at 1050–1100°C. The orientation relationships between these metal silicides MSi₂ and substrate Si were determined to be $\text{(0001)}\text{MSi}{}_2\text{(111)}\text{Si}\text{, (22}\text{4}\text{0)}\text{MSi}{}_2\text{(22}\text{4}\text{)}\text{Si}$ and $\text{(20}\text{2}\text{0)}\text{MSi}{}_2\text{(20}\text{2}\text{)}\text{Si}$. Regular interfacial dislocation networks were observed at silicides/Si interfaces. The dislocations were identified to be of edge type with ₆¹〈112〉 Burgers vectors. The average spacings of dislocations are 250, 100 and 40 Å for VSi₂/Si, MoSi₂/Si and WSi₂/Si systems, respectively. The disparities in dislocation spacings are attributed to the differences in lattice mismatches and thermal expansion coefficients among these silicide/Si systems. The discovery of a number of new epitaxial silicides presents the exciting possibilities that novel devices with desirable characteristics may be realized.