Controlled Patterning of Vertical Silicon Structures Using Polymer Lithography and Wet Chemical Etching.

In order to improve their performance for various applications, a facile method for the wafer-scale fabrication of micro/nano-patterned vertical silicon (Si) structures such as silicon nanowires (SiNWs), silicon nanorods (SiNRs), and porous silicon (p-Si) was developed. The method is based on the combination of lithography techniques (photolithography, thermal nano-imprint lithography, nanosphere lithography) and wet chemical etching (electro-chemical etching, metal-assisted chemical etching) processes. Micro-patterned p-Si with various pore diameters from 30 nm to 1.2 um were fabricated via electro-chemical etching. Micro/nano-patterned Si microstructures, nanorods, and nanowires were also successfully fabricated by changing the thickness of the metal layer of 5 nm or 20 nm in the metal-assisted chemical etching process. This study also investigated the effect of the etching time and patterning on the etched SiNWs length. This method provides advantages of simplicity, speed, large-scale production, easy size and shape manipulation, and low cost.