The Effects of Fabrication Process on the Performance of a CMOS Based Capacitive Humidity Sensor

Abstract

Measuring the change in electrical properties of materials in the presence of moisture is a widely used method for humidity measurement. During the fabrication of a thin film humidity sensor, different layers of the device, as well as its moisture sensing film, undergo a series of commonly used manufacturing steps. Plasma treatment is one of these steps, primarily used for dry etching. However, exposing a moisture sensing film to plasma can modify physical and chemical properties of the film and affect sensor performance. We have examined the response of two humidity sensors fabricated using polyimide sensing film, one of them received plasma treatment during fabrication and the other did not. Despite the fact that the sensors were of similar design they exhibited different responses. Further investigations were conducted by examining the effects of plasma treatment on blanket polyimide films and the results are presented in this paper.