The controlled fabrication of nanopores by focused electron-beam-induced etching

Abstract

The fabrication of nanometric holes within thin silicon-based membranes is of greatimportance for various nanotechnology applications. The preparation of such holes withaccurate control over their size and shape is, thus, gaining a lot of interest. In this work wedemonstrate the use of a focused electron-beam-induced etching (FEBIE) process as apromising tool for the fabrication of such nanopores in silicon nitride membranes and studythe process parameters. The reduction of silicon nitride by the electron beamfollowed by chemical etching of the residual elemental silicon results in a lineardependence of pore diameter on electron beam exposure time, enabling accurate controlof nanopore size in the range of 17–200 nm in diameter. An optimal pressure of5.3 × 10−6 Torr for the production of smaller pores with faster process rates, as a result of masstransport effects, was found. The pore formation process is also shown to be dependent onthe details of the pulsed process cycle, which control the rate of the pore extension, and itsminimal and maximal size. Our results suggest that the FEBIE process may play a key rolein the fabrication of nanopores for future devices both in sensing and nano-electronicsapplications.