Design and Manufacturing of an In-Package Relative Humidity Sensor with Multi-Width Interdigital Electrodes Towards Enhanced Sensitivity for Characterization of Packaging Encapsulation Materials

This study presents a novel manufacturing process and design towards an enhanced sensitivity of an in-package relative humidity sensor. The device comprises multi-width interdigital electrodes which make oxide pillars appear during wet chemical etching in the fabrication process. Those oxide pillars appear only in wider areas while completely etched away in narrower areas providing semi-floating metal fingers. Therefore, after wafer molding, the packaging encapsulation material such as the epoxy molding compound covers larger area around the electrodes and increases the sensitivity by confining more of the electrical field lines. The results confirm the enhanced sensitivity of the proposed humidity sensor for characterization and monitoring of the aging properties of packaging encapsulation materials.