Fabrication of Thin Film Vanadium Oxide for Microbolometer

One important issue for microbolometer fabrication is how to get high temperature coefficient of resistance (TCR) sensing material together with IC compatible process. Thin film vanadium pentoxide,V₂O₅ , with very high negative TCR up to -2.4% has been achieved by d.c. reactive sputtering at unheated substrates as well as low temperature annealing of 400 °C. It realizes the fabrication feasibility of microbolometer of V₂O₅ sensors after CMOS process. This is quite different from the conventional process by ion sputtering at heated substrates up to 400 °C, or high temperature annealing more than 500 °C to get the vanadium oxides. The properties of vanadium oxides are dependent on the process condition and their crystalline phases. The properties were studied as function of the oxygen content in the sputtering atmosphere and annealing temperature. X-ray diffraction is used to identify their phases.