Fabrication of single crystal Si cantilevers using a dry release process and application in a capacitive-type humidity sensor

A process is presented for the fabrication of suspended silicon microstructures, such as cantilevers and open type membranes, constituting the movable plate of a capacitor at a small distance over the silicon substrate. The process relies on the silicon fusion bonding of two wafers and features dry release of the suspended silicon structures at the final stage of the process, as a step to prevent stiction. With the addition of a hydrophilic polymer film on the Si cantilevers, a capacitive type humidity sensor is fabricated; the moisture-dependent bending of the microcantilever reflects on the measured capacitance between the microcantilever and substrate. (C) 2002 Elsevier Science B.V. All rights reserved.