Monolithic Integration of Pressure/Humidity/Temperature Sensors for CMOS-Mems Environmental Sensing Hub with Structure Designs for Performances Enhancement

Abstract

This study presents a monolithic integration of pressure, humidity and temperature sensing units to achieve an environmental sensing hub (Fig. 1). The proposed environmental sensing hub is realized using the TSMC $0.18\mu \mathrm{m}$ 1P6M CMOS platform, and follow-up in-house post-CMOS processes. The presented environmental sensing hub has three merits: (1) single-side microfabrication processes: for monolithic integration of pressure, humidity, and temperature sensors, (2) vertical integration design: for the temperature sensor and the high sensitive pressure sensor with corrugated diaphragm, and (3) novel capacitive humidity sensor design: pillar sensing electrodes array and surrounded polyimide filler for response time enhancement. Measurements show performances of proposed environmental sensing hub are: sensitivity of pressure sensor with corrugated structure is 0.969fF/kPa (0.197fF/kPa for reference type w/o corrugated structure), humidity sensor with sensitivity of 2.897fF/%RH and response time of 12.1 seconds, and resistance temperature detector with sensitivity of 0.26%/°C.