A self-packaged capacitive humidity sensor with low leakage loss

Abstract

A capacitive humidity sensor based on a flip-chip self-packaged process is presented. An air gap was applied to separate two electrodes of the sensitive capacitor and reduce the leakage loss especially in high humidity environment. Two typical structures of the sensor were developed. Both static and dynamic properties of fabricated sensors were evaluated. The dielectric loss tangent of both structures were less than 8‰ even at 95%RH. Meanwhile, both response time and recovery time of the sensors were short because one side of the sensitive layer was open to the air.