A Capacitive Ammonia Sensor Using the Commercial 0.18 μm CMOS Process

Abstract

The project presents an ammonia sensor with heater on-a-chip manufactured using the commercial 0.18 μm CMOS (complementary metal oxide semiconductor) process. The ammonia sensor is composed of a sensitive film, interdigital electrodes and a polysilicon heater. The sensor is a capacitive type and the sensitive film is ZrO2that is prepared by sol-gel method. The sensor requires a post-process to remove the sacrificial oxide layer and coat the ZrO2film on the interdigital electrodes. When the sensitive film absorbs ammonia vapor, the capacitance of the sensor generates a change. Experimental results show that the sensitivity of the ammonia sensor is 2.47 pF/ppm at 270 °C.