Scalable fabrication and electrical contact formation process for vertically oriented silicon nanopillars in trenches

Vertical silicon nano-pillars (Si N-Pls) inside the cylindrical trenches have been fabricated as a prospective platform for the development of silicon nanowire based devices. Deep reactive ion etching (DRIE) has been used to etch these features in a silicon substrate. In the present case, the fabricated Si N-Pls are ~15 μm in length and 200–500 nm in diameter, while the trenches are of the diameter 12–25 μm. Alumina (Al₂O₃) discs of 50 nm thickness and diameter in the range of 200–500 nm, obtained via e-beam evaporation, have been used as a hard mask for defining the Si N-Pls during DRIE. Further, a proof of concept has been provided for obtaining electrical contact to the top-ends of these vertically oriented nano-pillars. The proposed platform involving nano-pillars in trenches can be extended for realizing microfluidic-channels containing an array of vertically oriented and electrically addressable silicon nanowires for several applications including chemical sensing.