Endotaxial growth of CoSi2 within (111) oriented Si in a molecular beam epitaxy system

A new mode of growth is reported in which buried metallic layers can be fabricated within a single-crystal semiconductor through preferential subsurface growth on previously-grown ‘‘seed’’ regions. The deposition of Co at 800 °C at a rate of 0.01 nm/s on (111) Si substrates containing buried CoSi2 columns 40–100 nm below the Si surface results in the growth and coalescence of these subsurface columns. The formation of a CoSi2 layer on the Si surface is suppressed by this growth mode. It is proposed that the high diffusion rate of Co at 800 °C, coupled with the high growth rate of CoSi2 at the subsurface columns, is responsible for this preferred ‘‘endotaxial’’ growth mode. This growth technique was used to produce a continuous buried single-crystal layer of CoSi2 under a single-crystal Si capping layer.