Research on Coplanar Capacitive Sensor Design for Film Thickness Measurement

Abstract

Coplanar capacitive sensors have been widely applied in many fields with its characterstics of non-invasion, lowcost and fast response. A complex structure of coplanar capacitive sensor is designed to be used for the film thickness measurement. Firstly, three types of coplanar capacitive sensors with different shapes are designed, and according to the experimental reuslts, the parameters affecting the sensor signal strength and sensitivities are discussed, the electric field distributions of sensors are simulated by COMSOL.Then the fringe capacitance of a series of spiral-type sensors are measured and analyzed. The experimental results indicate the rational geometrical parameter design about the coplanar capacitive sensor can improve the sensor performance obviously.