Shrinking of silicon nanopore arrays by direct dry-oxygen oxidation

Abstract

Solid-state nanopores have emerged as useful single-molecule sensors for DNA and proteins. Dry-oxygen oxidation was proposed to directly shrink pyramidal silicon (Si) pore arrays. With this method, inverted-pyramid Si nanopore arrays with feature sizes of over 60 nm, prepared using a combination of dry and wet etching, were shrunk to be less than 20 nm with nanometer precision. The shrinkage was found to be dominated by the deposition of the SiO2 layer on the nanopore surface and its surface-tension-driven mass flow. The inner structure of the nanopore after the shrinkage kept its typical inverted-pyramid shape, which theoretically permits high-resolution DNA sequencing. Furthermore, this method can process many nanopore samples at one time and reduce the inbuilt stress in the Si nanopores during the annealing.