CMOS Humidity Sensor System Using Carbon Nitride Film as Sensing Materials

An integrated humidity sensor system with nano-structured carbon nitride film as humidity sensing material is fabricated by a 0.8 μm analog mixed CMOS process. The integrated sensor system consists of differential humidity sensitive field effect transistors (HUSFET), temperature sensor, and operational amplifier. The process contains two poly, two metal and twin well technology. To form CN(x) film on Si(3)N(4)/Si substrate, plasma etching is performed to the gate area as well as trenches. CN(x) film is deposited by reactive RF magnetron sputtering method and patterned by the lift-off technique. The drain current is proportional to the dielectric constant, and the sensitivity is 2.8 μA/%RH.