An all-capacitive sensing chip for temperature, absolute pressure, and relative humidity

This paper presents an all-capacitive sensing chip for temperature, absolute pressure, and relative humidity. The temperature sensors are based on a Si/Au bimorph structure contacting a fixed electrode and produce a sensitivity of 14fF//spl deg/C from 20 to 100/spl deg/C. The absolute pressure sensors have a sensitivity of 15fF/Torr and can be combined to span 500-1200Torr. The relative humidity sensor responds with 39fF/%RH from 20-95%RH. The three-transducer chip uses a bulk- and surface- micromachined silicon-on-glass process and combines anodic bonding with silicon/gold eutectic solder to realize vacuum-sealed cavities along with low-impedance (6/spl Omega/) electrical feedthroughs.