| Vanadium oxide(VOx)thin films are ideal material in microbolometer for its high temperature-resistance coefficient(TCR). In this work, vanadium oxide thin films were deposited by using direct current facing targets magnetron sputtering and ion beam sputtering. The effects of SiO2 substrate and Si3N4 substrate on composition of vanadium oxide thin films deposited using direct current facing targets magnetron sputtering at high substrate temperature were investigated. Vanadium oxide thin films with phase transition were fabricated by thermal oxidated process and thermal deoxidated process, and the effects of composition, microstructure, crystallization of the formed vanadium oxide thin films on their phase transition temperature and TCR were analysed.The thermal sensitivity of VOx thin films in the structure of VOx/PS/Si and VOx/Si were compared.In high temperature, with the increase of chemical activity of SiO2 substrate and Si3N4 substrate increase, the amount of oxygen particles increas on the surface of SiO2, but decreas on the surface of Si3N4. At the same oxygen partial pressure, the valence of VOx thin film on SiO2 is higher than that on Si3N4; the valence of VOx thin films on SiO2 increases with substrate temperature increasing, but the valence of VOx thin films on Si3N4 decreases with substrate temperature increasing.Phase transition vanadium oxide thin films were fabricated by using two different methods. One is low valence vanadium oxide thin films were deposited by direct current facing target magnetron sputtering firstly, and then thermal oxidated; the other is high valence vanadium oxide thin films were deposited by ion beam sputtering, then thermal deoxidated. Vanadium oxide thin films with phase transition were obtained at the lower thermal process temperature 300℃, which is compatible with MEMS technologys. The composition of VOx thin film fabricated by first method includes mainly VO2, V2O3 and VO, the TCR is -2.25%/K, the TCR gradually increases with phase transition temperature decreases. The composition of VOx thin film fabricated by the second method includes mainly VO2, V2O5 and V2O3 , and the resulting VOx thin filmTCR is -3.0%/K. The TCR of phase transition vanadium oxide thin films made by second method is higher than that made by first method for the existance of V2O5 in thin films. Vanadium oxide thin films were deposited by ion beam sputtering with high oxygen partial pressure and then thermal annealed two times at 450℃for 3h. High TCR of -4.7%/K is obtained.Two kinds of multi-layer structure of VOx/PS/Si and VOx/Si were fabricated, and the effects of porous silicon on the composition of vanadium oxide thin films were analysed. The results show that, if porous silicon is used as thermal insulator in the multi-layer structure, VOx thin films still keep high thermal sensitivity even when input power is very lower as 20μW, the change ratio of resistance and power on porous silicon is 20 times than that on silicon. Vanadium oxide thin films deposited on porous silicon is suits for microbolometer when the deposited parameter optimized. The valence of VOx thin films deposited on porous silicon is higher than that on SiO2 because of higher chemical activity of SiO2 on porous silicon at high substrate temperature.
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