Study On High Power Impulse Magnetron Sputtering(HiPIMS) And Ferroelectric Tunable Microwave Components

High power pulsed magnetron sputtering(HiPIMS) is an emerging sputtering technology. HiPIMS can generate high-density plasma in an instant and effectively improve the film properties, which is of great significance in the development of thin film industry. The tunable microwave components based on ferroelectric thin films are expected to have important applications in modern communication systems and have received widespread attention. This dissertation studied three aspects: thin film deposition by HiPIMS, preparation of barium strontium titanate(BST) thin films and varactors, and the design of tunable microwave components.HiPIMS provides very high power in an instant and generates high-density plasma, based on ionized physical vapor deposition technology, to produce high-density deposition flux, and it is mainly applied to the preparation of carbon films and various metal films at present. This dissertation studied in depth working mechanism of HiPIMS and discussed its plasma characteristic. Zirconium oxide thin films were successfully prepared by HiPIMS, and it has been analyzed that different sputter gas ratio, excitation power of sputtering cavity, and pulse parameters impact on film properties.The study found that a more uniform and stable plasma can be produced by selecting appropriate oxygen-argon ratio and driving pulse duty cycle. The minimum roughness of films deposited on glass and Indium Tin Oxide(ITO)-glass substrates were only 1.1 nm and 1.3 nm, respectively, while their transmittance were more than 90% and 84%, respectively. The energy band gaps of films on glass were close to 5.86 eV; however, the band gaps of films on ITO substrates were limited and were only 3.8 eV. Ultra-thin zirconia films showed a low leakage current that was superior to 84 10?? A/m.In this dissertation, BST thin films were deposited by RF sputtering. The influences of oxygen pressure, substrate temperature and the excitation power of sputtering cavity on deposition rate of BST films have been discussed. A varactor was successfully prepared with the structure of metal-BST-metal(MIM), and a highest tunability of 44.4% was obtained. Based on the study mentioned above, an ITO varactor with the new structure of metal-BST-ITO was prepared for the first time. Due to oxygen vacancy mechanism, the capacitance-voltage characteristic of ITO varactors decreased monotonically and the tunability was 8.5%.Ferroelectric phase shifter has been designed based on ferroelectric thin-film varactor. 3-dB periodic load transdirectional couplers have been simulated by HFSS. BST film varators were adopted in Mach-Zehnder electro-optic modulator structure to design ferroelectric thin-film phase shifters. The simulated results showed that the phase shifter has a maximum phase shift 219.2° with a frequency bandwidth of 232 MHz. At last, two high gain array antennas have been designed, based on the phase shifter with new structure studied in the dissertation. The maximum gain of the antenna was 29.8 dBi. With conical elements, the dual-polarized antenna obtained a broader bandwidth of 19.52%. The study provides evidence to prepare microwave tunable devices such as tunable antennas in future.