Writing FIB implantation and subsequent anisotropic wet chemical etching for fabrication of 3D structures in silicon

The further miniaturization of silicon micromechanical structures in combination with the highly developed microelectronic technology at the micrometre and sub-micrometre level will lead to a new generation of microdevices. A modern technique to fabricate three-dimensional micromechanical structures is the combination of high-concentration p(+)-doping by writing ion implantation using a focused ion beam (FIB) and subsequent anisotropic and selective wet chemical etching. FIB-patterned and chemically etched 3D Si structures with nanoscale thickness have been fabricated using 35 keV Ga+ ion implantation and subsequent anisotropic etching in KOH/H2O solution. Design and fabrication considerations to achieve freestanding Si structures are discussed and some typical structures are shown.