Fabrication of single-crystal Si microstructures by anodization

We have investigated the application of the anodization process to the fabrication of microstructures consisting of single-crystal Si. When anodization is carried out in the dark, porous Si is preferentially formed in a p-type region. The porous region can be used as a sacrificial region. The unanodized Si region forms the components of the microstructures. The shape of the porous region can be controlled by varying the profiles of the n- and p-type regions and their resistivity. It has been found that, by utilizing these characteristics, various microstructures can be formed from single-crystal Si. Fabrication of a cantilever and a piezoresistive gauge for a pressure sensor are demonstrated.