Fabrication of high aspect ratio nanoporous array on silicon

In this study, a simple method for the fabrication of high aspect ratio silicon nanoporous arrays is developed. A N-type silicon wafer is used as the material; a micro-scale pattern of the desired porous array is transferred to the front surface of the silicon wafer by photolithography; the wafer is placed in a home-made fixture to efficiently expel the etching generated air and promptly hold the back-side illumination light; a halogen lamp is used as the light source for backside illumination to enhance the electron-hole pairs generation; anodization is then processed using a new etchant which consists of the hydrofluoric acid and the EtOH and EMSO mixed surfactant to effectively polish the pore surface and sharp the tips of the etched pores. A nanochannel array with nano-tip being 61.4 nm is obtained.