Abstract
A humidity microsensor integrated with a readout circuit on-a-chip fabricated using the commercial 0.18 μm CMOS (complementary metal oxide semiconductor) process was presented. The integrated sensor chip consists of a humidity sensor and a readout circuit. The humidity sensor is composed of a sensitive film and interdigitated electrodes. The sensitive film is titanium dioxide prepared by the sol-gel method. The titanium dioxide is coated on the interdigitated electrodes. The humidity sensor requires a post-process to remove the sacrificial layer and to coat the titanium dioxide. The resistance of the sensor changes as the sensitive film absorbs or desorbs vapor. The readout circuit is employed to convert the resistance variation of the sensor into the output voltage. The experimental results show that the integrated humidity sensor has a sensitivity of 4.5 mV/RH% (relative humidity) at room temperature.
Highlights
Humidity sensors are important devices for application in industrial and electronic equipment.Various traditional sensors have been miniaturized as microsensors using micromachining technology.Micromachined sensors have the benefits of high performance, low cost, small size, and easySensors 2014, 14 mass-production [1]
The humidity sensor without readout circuit was set in the test chamber, and its resistance variation under different humidity was measured by the LCR meter
A humidity sensor equipped with a readout circuit was successfully manufactured using the commercial 0.18 μm complementary metal oxide semiconductor (CMOS) process and a post-process
Summary
Humidity sensors are important devices for application in industrial and electronic equipment. Many humidity microsensors have been manufactured using micromachining technology. Chen et al [2] used micromachining technology to fabricate a capacitive relative humidity sensor in which its sensitive material was zinc oxide. Chen et al [6] proposed a humidity microsensor with a micromachined silicon dioxide cantilever beam. Fabricated a capacitive humidity microsensor using complementary metal oxide semiconductor (CMOS)-MEMS technique. A capacitive humidity microsensor, proposed by Zhao et al [9], was fabricated using the CMOS process. The microsensor was composed of a polysilicon heater, aluminum interdigitated electrodes and a humidity-sensing film of polyimide. Both the hysteresis and the recovery time of the sensor were improved based on the polysilicon heater. The post-process contains etching the sacrificial oxide layer and depositing the sensitive film
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