Fabrication of silicon micro-mould for polymer replication using focused ion beam

Focused ion beam sputtering was used to fabricate microscale moulds of circular conical structures in silicon. As scan strategy, a continuous slicing method (CSM) modified from a two-dimensional (2D) slice-by-slice approach combined with a spiral scan was tested experimentally. With carefully chosen ion beam conditions and processing parameters, moulds were fabricated as a function of the ion dose for specific dwell times. Using the fabricated moulds, polymeric polydimethylsiloxane (PDMS) and polyurethane acrylate (PUA) microstructures were replicated and compared with the mould dimensions. Using PUA, the resolution of the polymer structure was examined on a nanoscale. In addition, mould-making failure due to both beam overlap and the field of view (FOV) is discussed. Finally, micro-lenses of different sizes were fabricated successfully.