Development of High Sensitive Integrated Dual Sensor to Detect Harmful Exhaust Gas and Odor for the Automotive

A dual micro gas sensor array was fabricated using nano sized <TEX>SnO₂</TEX> thin films which had good sensitivities to CO and combustible gases, or <TEX>H₂S</TEX> gas for air quality sensors in automobile. The already existed air quality sensor detects oxidizing gases and reducing gases, the air quality sensor(AQS), located near the fresh air inlet detected the harmful gases, the fresh air inlet door/ventilation flap was closed to reduce the amount of pollution entering the vehicle cabin through HVAC(heating, ventilating, and air conditioning) system. In this study, to make <TEX>SnO₂</TEX> thin film AQS sensor, thin tin metal layer between 1000 and <TEX>2000</TEX> thick was oxidized between 600 and <TEX>800∘C</TEX> by thermal oxidation. The gas sensing layers such as <TEX>SnO₂</TEX>, <TEX>SnO₂</TEX>(pt) and <TEX>SnO₂</TEX>(+CuO) were patterned by metal shadow mask for simple fabrication process on the silicon substrate. The micro gas sensors with <TEX>SnO₂</TEX>(+Pt) and <TEX>SnO₂</TEX>(CuO) showed good selectivity to CO gas among reducing gases and good sensitivity to <TEX>H₂S</TEX> that is main component of bad odor, separately.