Analysis of the capacitive pressure sensor with ring mesa structure

The capacitive pressure sensor with ring mesa structure has been simulated and fabricated in order to replace the bulky and inaccurate mechanical pressure sensor which is currently used in laundry machines. A ring mesa structure has been adopted with the same 100 μm width and positioned at 250 μm distance from the substrate with 50 μm distance. The center displacement of diaphragm were measured with a good linearity and increased from 0.408 μm (M 6025) to 1.578 μm (M 6045) depending on the location of ring mesa structure with the same circular radius of diaphragm. When the ring mesa structure is located 250 μm distance from the substrate, the simulated capacitance according to the water pressure showed a good linearity with less than 1.3% best-fit nonlinearity error. However, as the location of ring mesa moved to the center of diaphragm, the characteristic curves of capacitance has been changed from quasi-linear to nonlinear curves with the best-fit nonlinearity errors, 3.8% (M 6030) and 11.2% (M 6035), respectively. Based upon the simulation and experiments, one candidate device has been chosen and will replace the current bulky sensor in the near future.