Fabrication of a MEMS micro-hotplate

Abstract

With the development of microelectronics and micromachining technology, micro-hotplate as a micro-heater is a very important component in micro-sensor. So far, it has wide applications in pressure detection, gas detection and so on. In this paper, a micro-hotplate based on micro-bridge structure was designed and fabricated. Here we present a micro-hotplate with SOI (silicon-on-insulator) as the substrate and metal Au as the heating electrode material. It shows low thermal conductivity coefficient, good electrical insulation, low power consumption, and excellent resistance to high temperature and low pressure. Some IC (integrated circuit) processes such as magnetron sputtering of Ni/Cr, ion beam sputtering of Au, dry and wet etching processes are employed to fabricate the device. Anisotropic wet etching of silicon and thin film deposition were mainly studied. To protect the front side micro structure during the wet etching process, a special apparatus was designed and fabricated. The optimization process for anisotropic wet etching was obtained for releasing the micro-bridge after a large number of experiments and the micro-hotplate was successfully fabricated. The electrical, thermal characteristics of the micro-hotplate were tested and approved it a well functional device.