Title :
A CMOS capacitive vertical-parallel-plate-array humidity sensor with RF-aerogel fill-in for sensitivity and response time improvement
Author :
Chung, Vincent P. J. ; Chao-Lin Cheng ; Ming-Chuen Yip ; Weileun Fang
Author_Institution :
Power Mech. Eng. Dept., Nat. Tsing Hua Univ., Hsinchu, Taiwan
Abstract :
This paper reports a high-sensitivity and high-speed capacitive humidity sensor. A novel capacitive vertical parallel-plate (VPP) array had been monolithically integrated with an on-chip ring oscillator (RO) using the standard TSMC 0.18μm CMOS process and subsequent in-house post-processes. Resorcinol-formaldehyde (RF) aerogel, a new kind of moisture-sensitive polymer, was deposited and defined in columns in the VPP array. Measurements show that the typical fabricated device has a sensitivity of 0.566% capacitance change per percent-relative-humidity (%RH) and a response time of 6s. The monolithic integration of the humidity sensor with RO is also demonstrated to provide a sensitivity of 3.8 kHz/%RH. Further improvement in sensitivity is required by varying the operating frequency of RO.
Keywords :
CMOS analogue integrated circuits; aerogels; capacitance measurement; capacitive sensors; humidity sensors; microfabrication; microsensors; oscillators; polymers; sensor arrays; CMOS capacitive vertical-parallel-plate-array humidity sensor; MEMS; RF-aerogel fill-in; RO; VPP array; in-house post-processes; moisture-sensitive polymer; monolithically integrated on-chip ring oscillator; percent-relative-humidity; resorcinol-formaldehyde aerogel; size 0.18 mum; standard TSMC CMOS process; Arrays; CMOS integrated circuits; Electrodes; Humidity; Sensitivity; System-on-chip; Time factors; CMOS MEMS; Capacitive sensor; Humidity sensor; RF-aerogel; Vertical-parallel-plate array;
Conference_Titel :
Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on
Conference_Location :
Estoril
DOI :
10.1109/MEMSYS.2015.7051071
