Porous Silicon Micromachining Technology

In this chapter, silicon electrochemical micromachining (ECM) technology is reviewed with particular emphasis to the fabrication of complex microstructures and microsystems, as well as to their applications in optofluidics, biosensing, photonics, and medical fields. ECM, which is based on the controlled electrochemical dissolution of n-type silicon under backside illumination in acidic (HF-based) electrolytes, enables microstructuring of silicon wafers to be controlled up to the higher aspect ratios (over 100) with sub-micrometer accuracy, thus pushing silicon micromachining well beyond up-to-date both wet and dry microstructuring technologies. Both basic and advanced features of ECM technology are described and discussed by taking the fabrication of a silicon microgripper as case study.