Bulk silicon microelectromechanical devices fabricated from commercial bonded and etched-back silicon-on-insulator substrates

In this work a new and simple technology for the fabrication of bulk silicon microelectromechanical devices is presented. The microstructures are defined in the silicon active layer of commercially available bonded and etched-back silicon-on-insulator (BESOI) substrates by a single photolithographic step and anisotropic dry etching. The thickness of the structures is only limited by the performance of the dry-etching process. In this work a thickness of 20 mu m is used. Various devices have been fabricated, including electrostatic micromotors, microturbines and electrostatically actuated microrelays. An interesting feature of this technology is that the use of BESOI substrates allows the integration of electronic circuits on the substrate used to fabricate the microelectromechanical devices.