Micromechanical fabrication of robust low-power metal oxide gas sensors

A fabrication process for miniaturized low-power metal oxide gas sensor arrays is presented. This process, which is based on silicon-on-insulator (Sol) wafers, leads to thermally insulated silicon hot plate structures, which successfully combine low-power consumption with mechanical ruggedness and a high process yield. A second important feature of our process is that it consists of a standard-silicon front-end and a sensor-specific back-end module. This separation into front-end and back-end modules is a prerequisite for an efficient workshare between silicon foundries and SME sensor manufacturers in the industrialization of low-power gas sensor arrays. In the first part of the paper we present an outline of the fabrication flow consisting of the front-end fabrication of micromachined low-power heater platforms and the back-end fabrication of gas-sensitive layers. In the second part we report on the results of extensive mechanical, thermal and gas sensing measurements on such miniaturized devices. (C) 2003 Elsevier Science B.V. All rights reserved.