Automated full-field interferometric characterization of micromachined silicon membrane

Among the current commercial micromachined devices, pressure sensors are by far the most successful and popular products. They work to sense the displacement-induced stresses of a silicon membrane with the thickness at the micro-scale. The miniature dimension of such devices, coupled with the demand of accurate deflection measurement for performance characterization, make suitable metrological tools in immediate need. In this paper, we present a digital micro-holo interferometric method for realizing highly sensitive measurement of the full-field displacement over the global test structure. Through the analysis on the system principles, the pressure-induced membrane deflection are accurately measured, and further determination of strain and stress is accomplished based on the verified FE model. From the obtained stress-pressure relation, the sensitivity of the pressure sensor is thus characterized.