| The trends of infrared(IR) detector are being uncooled, cheaper and more convenient. Bolometer which is a dominant low-cost uncooled thermal infrared detector based on thermistor have attached more and more attention by researchers around the world. Emphases are focused on two aspects, one is to improve the property of thermistor material continually to obtain high detector performace; the other is the research and improvement on thermal isolation structure of detector.Vanadium oxide with outstanding thermal sensing property is an ideal thermistor material for bolometer application and the fabrication of vanadium oxide thin film with high temperature coefficient of resistance (TCR) and suitable film resistance is the base of high detectivity of microbolometer. In this paper, Vanadium oxide thin film with nanostructure was deposited by novel facing targets DC reactive sputtering technique using V metal as target and the effect of deposition parameters including ratio of Ar/O2, sputtering power, work pressure, substrate temperature, sustrate types and vacuum annealing on the performance of vanadium oxide thin films is analyzed by choosing different level of these parameters in the orthogonal experiment. Optimal deposition parameters were defined. X-ray photoelectron spectroscopy analysis revealed the vanadium oxygen state of the film, which included V2O5,VO2 and a few V2O3. Atomic force microscopy surface morphology indicated a planar and compact film surface. TCR becomes higher (lower) as the higher (lower) sheet resistance. In the VOx films with high TCR and moderate sheet resistance, the average valence of vanadium is about +4. The optimal deposition parameters of vanadium oxide film on Si3N4 substrate, which is a common MEMS structure material in microbolometer use, were defined as follow: Working pressure: 2.0 Pa, gas flow ratio: Ar:O2 =48:0.5, substrate temperature 200℃, sputtering power: 210W. The temperature coefficient of resistance (TCR) as-deposited was high up to -3.17%/℃and the sheet resistance was about 14KΩ/□around room temperature. This deposition process has nice repetitivity and can be compatible with semiconductor process, which implied promising application in uncooled microbolometer infrared (IR) detectors.porous silicon,used as sacrificial layers or thermal insulator in the multi-layer structure can provide new methods to the fabrication of thermal isolation structure, the contrast result of the thermal sensing property of VOx resistance under a small power input deposited on porous silicon substrate and silicon substrate revealed good thermal isolation property of porous silicon layer. Otherwish, Porous silicon prepared by double-cell electrochemical etching has a high removing speed and it is found a trench was formed with almost the same pattern with the mask and flat bottom after etching, which implicit it is suitable for sacrificial material application.The finite element method was used in the design of microbridge structure for mcirobolometer, the temperature distributing analysis indicate the best uniformity in the structure supporting on diagonally position. Optimizing analysis of the Key scale parameters of microbridge was carried out in the seting scale space using a finite element model, the effect of these parameters on deformation was analysed.
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