Fabrication of nanopores and nanoslits with feature sizes down to 5 nm by wet etching method

This paper presents an improved three-step wet etching method for the fabrication of single-crystal silicon nanopores and nanoslists. A diffusion model was built to analyze the influence of the color-based feedback mechanism on the final pore size. Reference structures were added aside normal pore patterns, to obtain a more precise control of the pore size during the pore opening process. By using this method, square nanopores with the minimum size of 8 nm x 8 nm, rectangle nanopores and nanoslits with feature sizes down to 5 nm were successfully obtained. Focused ion beam cutting revealed that the nanopore profile keeps well the inverted-pyramid shape, with an included angle of 54.7 degrees.