Environmental Sensing Hub on Single Chip Using Double-Side Post-CMOS Processes

Abstract

This research reports a monolithically integrated Humidity/Thermometer/Pressure sensor to realize an environment sensing hub. The environment sensing hub is designed and implemented using the TSMC $0.18 \mu \mathrm{m}$ 1P6M CMOS platform and the follow-up double-side post-CMOS micromachining processes. Features of this study are: (1) Small footprint with less packaging effort: monolithic integration of H/T/P sensors on a single chip, (2) Fast response time of relative-humidity (RH) sensor: removal of backside silicon by double-side post-CMOS process to enhance vapor diffusion of capacitive RH sensor. (3) Double-side post-CMOS process: simultaneously fabricating backside cavities for H/P sensors. Measurement results indicate the performances of the environment sensing hub: humidity sensor with sensitivity of 4.06fF/%RH and response time of 3.1sec (15.7sec for the reference type of conventional design), and pressure sensor with sensitivity of 0.79fF/kPa, thermometer with response of 15.8mV/°C.