【作者】 梁继然；

【导师】 胡明；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2007， 博士

【摘要】 氧化钒薄膜具有高的电阻温度系数（TCR）,是制备微测辐射热计的理想热敏感材料。高的电阻温度系数和良好的绝热结构是获得高性能微测辐射热计的前提。本论文采用直流对靶磁控溅射和射频离子束溅射两种方法制备了氧化钒薄膜,研究了高基底温度状态SiO₂和Si₃N₄基底表面对氧化钒薄膜组分的影响,采用热氧化低价态氧化钒薄膜和热还原高价态氧化钒薄膜的方式分别制备了具有相变特性氧化钒薄膜,分析了相变特性氧化钒薄膜的组分、结晶结构对相变温度和室温电阻温度系数的影响,设计与制作了VO_x/PS/Si结构与VO_x/Si结构,并对氧化钒薄膜的温度灵敏度进行了比较,获得了一些有意义的结果。SiO₂和Si₃N₄基底在500℃高基底温度下,表面活性增加,SiO₂表面参与氧化钒薄膜生长的氧增加,Si₃N₄表面参与氧化钒薄膜生长的氧减少,从而影响其上生长的氧化钒薄膜的成分,相同氧分压下,SiO₂基底表面氧化钒薄膜的价态高于Si₃N₄基底表面氧化钒薄膜的价态;升高基底温度时,SiO₂基底表面氧化钒薄膜的价态升高,Si₃N₄基底表面氧化钒薄膜的价态降低。分别采用直流对靶磁控溅射制备低价态氧化钒薄膜再附加热氧化处理的方式,和射频离子束溅射制备高价氧化钒薄膜附加热还原处理的方式获得了具有相变特性的氧化钒薄膜,第一种方式获得相变特性氧化钒薄膜的热处理温度最低为300℃,克服了以往高温条件下热处理不能与MEMS工艺兼容的缺点;相变特性氧化钒薄膜的组分以VO₂为主,含有V2O3和VO_,室温TCR为-2.25%/K;室温电阻温度系数随相变温度的降低逐渐升高;采用第二种方式获得的相变氧化钒薄膜的组分以VO₂为主,含有V2O5和V2O3,室温TCR可达-3.0%/K;分析发现,具有相变特性的氧化钒薄膜中含有V2O5时,室温电阻温度系数明显增大。利用射频离子束溅射方法制备氧化钒薄膜,对氧气比例为48.83%制备的氧化钒薄膜进行连续2次450℃/3h热处理,获得了室温电阻温度系数高达-4.7%/K的氧化钒薄膜。对比了VO_x/PS/Si结构与VO_x/Si结构中氧化钒薄膜电阻对温度的热敏感性能,研究了多孔硅基底温度升高对氧化钒薄膜组分的影响。多孔硅基底上的氧化钒薄膜电阻具有比硅基底上的氧化钒薄膜电阻更高的温度灵敏度,电阻值随功率的变化率是硅的20倍;通过调节制备条件,在多孔硅基底上获得了适合微测辐射热计应用的氧化钒薄膜;高温状态下,多孔硅表面覆盖的SiO₂层活性高,获得的氧化钒薄膜中钒被氧化的程度更高。更多还原

【Abstract】 Vanadium oxide（VO_x）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 VO_x thin films in the structure of VO_x/PS/Si and VO_x/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 VO_x thin film on SiO₂ is higher than that on Si₃N₄; the valence of VO_x thin films on SiO₂ increases with substrate temperature increasing, but the valence of VO_x 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 VO_x 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 VO_x thin film fabricated by the second method includes mainly VO₂, V2O5 and V2O3 , and the resulting VO_x 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 VO_x/PS/Si and VO_x/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, VO_x 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 VO_x 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.更多还原