Fabrication of nano structures in thin membranes with focused ion beam technology

In recent years, Focused Ion Beam (FIB) technology has emerged as an important tool for nanotechnology [V.J. Gadgil, F. Morrissey, Encyclopaedia of Nanoscience and Nanotechnology, vol. 1, American Science Publishers, ISBN: 1-58883-057-8, 2004, p101.]. In this paper, applications of focused ion beam technology to fabrication of nanostructures are presented. The structures are fabricated on free standing silicon nitride membranes. Nanopores are nanometer diameter holes used in bio medical research for high speed DNA sequencing [D.K. Stewart, L.A. Stern, G. Foss, G. Hughes and P. Govil, Proc. SPIE 21, 1990, 1263.]. FIB was used to mill nanopores in the membrane. The pores were further reduced using epitaxial deposition using electron beam, at a controlled rate. A STEM detector was used to monitor the pore in situ. Nanowires can be fabricated using shadow mask technique. The shadow mask for nanowires was fabricated using FIB. The mask was used to produce nanowires. Fabrication method and FIB process parameters for the fabrication are reported. Results of the nanopore fabrication are presented with STEM images. Results of the nanowire fabrication are presented. Various strategies employed to achieve the desired nanostructures are discussed.