Design And Preparation Of TaN Thin Film And High-frequency High-power Termination

With the development of technologies such as satellite, radar, communications,aerospace, microwave devices and components is becoming more and moreminiaturized, with high-frequency and high-power. Microwave terminations are widelyused as matched load and protecting systems from burning in microwave circuits. Inthis paper, we will expand the research work of microwave matched terminations withthe following two aspects:In the aspect of material research, with method of reaction magnetron sputteringfabricating samples of Ta-N. During the research we investigate influences of multilayerof Ta and Ta-N, Rapid Thermal Annealing and doping of silicon conditions on thestructures and electrical properties. Compare experimental results we found: as time ofsputtering Ta increase, resistivity of the thin film multilayer Ta-N decreases from240μΩ.cm to110μΩ.cm, temperature coefficient of resistance(TCR) changes from-240ppm/℃to70ppm/℃. Undoped Ta-N thin films using rapid thermal annealing innitrogen with temperature of400℃,500℃,600℃,700℃, resistivity of the thin filmgrows from250μΩ.cm to700μΩ.cm, TCR decreases from-200ppm/℃to-50ppm/℃，and then grows to-250ppm/℃. Resistivity of thin film doped with silicon grows from700μΩ.cm to20000μΩ.cm, TCR grows from-50ppm/℃to-700ppm/℃In the aspect of design and simulation: the terminations are simulated withsoftware of ADS and HFSS using the method of standing wave ratio, it makes thedesign of termination simple, quickly and accurately. Four terminations are designed:termination0is working at35GHz, with5GHz bandwidth and10W power load;termination1is working at DC-12GHz,with20W power load; termination2is workingat DC-18GHz, with60W power load; termination3is working at35GHz, with5GHzbandwidth and100W power load. All these terminations’ VSWR is below1.2. Thesurfaces’ temperature of termination are below100centigrade with help of softwareePhysics. In the aspect of fabrication and design of termination: according to the structuralparameters we fabricate terminations by using reaction magnetron sputtering andpatterned technology. All the terminations are tested by vector network analyzer (VNA)and the results shows their VSWR is below1.3. All the terminations’ surfacetemperature is not higher than125centigrade.