A titanium-based composite-type MEMS Pirani gauge for wafer-level packaging

In order to obtain a wide-range vacuum sensor for monitoring the gas pressure in a micro cavity encapsulating a MEMS device, this report provides a composite MEMS Pirani gauge which consists of two different sizes of Pirani gauges to extend the measurement range. The advantages of the composite-type Pirani gauge include simple fabrication process, low processing cost and wide range. By comparing different materials, we choose titanium to form the heating resistor. The final temperature and circuit simulation by COMSOL Multiphysics and NI Multisim conclude that the composite-type Pirani gauge has a continuous range of 0.03~ 2×10⁵Pa and an average sensitivity of 44mV/dec, superior to the performance of a single Pirani gauge. The structure and fabricating process of the MEMS Pirani gauge are optimized for wafer level packaging.