Porous Ceramic Packaging for a MEMS Humidity Sensor Requiring Environmental Access

Microelectromechanical systems (MEMS) chemical sensors typically require access to the ambient environment in order to operate as intended. However, this required access to the environment can subject the sensor die to damaging mechanical contact and to particulate contamination which can degrade performance. This paper presents a technique for integrating a filtering structure into the die packaging substrate, so that the sensor has environmental access without the risk of damaging mechanical contact or particulate contamination. The die carrier is fabricated through screen printing electrical traces onto a porous ceramic substrate. The sensor die is then flip chip-bonded onto the porous ceramic carrier and sealed using a packaging dam material. A suitable packaging process is developed. A demonstration prototype is realized for a MEMS humidity sensor and environmental evaluation is performed. The developed packaging technique can readily be applied to similar commercial off-the-shelf MEMS chemical sensors using conventional thick film processing techniques.