The Research And Fabrication Of High Temperature Superconductor Filters

Since High Temperature Superconductor (HTS) was discovered, the good performance of the superconducting material has caused attention paid by the world. The microwave devices made from the superconducting material have excellent performance and great commercial applied value. Among them, scientists in this field have been focused their research on the HTS filter which has such advantages as less insert loss, more steep edge and good out-of-band rejection etc compared with the common metal filters . While been applied in the front-ends of mobile communication base station, it also has the following advantages, such as, saving frequency resources, increasing the coverage of the base station, improving anti-jamming ability, raising the capacity and quality of communication and reducing power radiation. In addition, there are wide broad application in those fields such as medical instruments, satellite, military communication and aerospace etc.Because of the high request to the HTS films, in this thesis we researched the effects of physical characteristics on YBCO HTS thin film by photolithography process and have done the measurement and analysis. At the same time, we also systematically researched the effects of physical characteristics on YBCO HTS thin film by argon ion beam etching. Finally, we fabricated high performance HTS filter. In this thesis we have focused on the problems in photolithography and fabrication processes of the HTS filter, and further detailed discuss the solution. After an amount of experimental contrast and analysis, we summarized a set of experiment parameters. Two kinds of etching methods--wet method and dry method for the HTS thin film have been designed and some new fabrication methods have been applied. The gold electric pole has been patterned by photolithography.Additionally, packaging is one of an important issue to the performance of the HTS filter. In this thesis we discuss the details in the designing of shielding box, to avoid the influence on the filter's performance. The conjunction has been successful settled between PIN and gold electric pole by supersonic spot welding. Smaller contact resistance and better mechanical intensity can be attained.