Formation of the nano-scale archipelago shape upper electrode of capacitive humidity sensor

Abstract

We present a clean and convenient technology to form a nano-scale archipelago shape upper electrode of capacitive humidity sensor to substitute the lift-off technology in this kind of process. In our fabrication process of humidity sensor, only the 0.25 second of the beginning of the discharge in a sputtering was used to form the nano-scale archipelago shape electrode. Moreover, the humidity sensitive material which is the key factor in humidity sensor has not been contacted with both acetone and photoresist which were usually used in the process of lift-off. Observed by AFM(Atomic force microscope), the average diameter of island electrode of this archipelago shape electrode is 30 nanometers. The test result showed that this kind of sensor has a wide range of sensing ambient relative humidity from 25% RH to 95%RH. The performance of this capacitive humidity sensor showed that the very short time discharge of sputtering can be an effective, clean and easier method to form the upper electrode of capacitive humidity sensor.