Characteristics of cantilever beam fabricated by silicon micromachining for flow sensor application

In this paper we report the thermal stress characteristics of multiarray cantilever beam and the result of experimental researches. The cantilever beam was fabricated using porous silicon micromachining techniques, surface tension and the difference in the thermal expansion coefficients between the two films on the cantilever beam. Then the height of the curled cantilever beam is measured as a function of the annealing temperature and time. Using these results, Piezoresistive flow sensors with micro cantilever structure were fabricated using (100), n/n⁺/n three layer silicon wafer and their characteristics were then investigated. The proposed micro flow sensor consists of four identical silicon cantilever beam with piezoresistors. The total resistance and sheet resistance were obtained about 1KΩ and 50Ω respectively. The results show the dependence of the sensitivity on cantilever length and geometry.