Optimization Of Process Of Cu/CuNi Thin-film Thermocouple And Study On Its Sensitivity

In the complex environment, measuring the transient temperature accurately and efficiently has been one of the research focuses. For the thin-film thermocouple(TFTC) combined the thin-film technology with the principle of thermocouple, it not only achieve a basic function of thermocouple but also can measure the minor response of transient temperature. In order to prepare a TFTC with high thermoelectric property, the effects of preparation process on conductivity of thin-film and thermoelectricity of TFTC were studied. The ways of improving TFTC’s sensitivity were discussed after the preparation process of thin-film had been optimized.First of all, after the critical dimension of thin-film was determined, an orthogonal experiment with four factors of base temperature, substrate-to-target distance, sputtering power and air pressure was designed and the resistivity of thin-film was selected as investigation index. The results show that the base temperature is the key factor to thin-film resistivity, which decrease with the base temperature increasing in a certain range, and the optimal preparation process for the lowest resistivity has been verified. Then, the relationship between annealing process and thin-film resistivity also was studied. It can be seen from the results that the thin-films which were annealed show a higher conductivity, and the resistivity decrease gradually with the annealing temperature for the same thin-film. Next, based on the thin-film theory of conductance and combined with the film microstructure and surface morphology, the influence rules of preparation process and annealing process on thin-film resistivity were explained.According to the process parameters determined by orthogonal experiment, 3 kinds of Cu/CuNi TFTCs with different film resistivity had been made by RF magnetic sputtering. Node method was used to static-calibrate the TFTC resistivity, and the sensitivities were obtained respectively. From the test results it can be known that there is a significant regularity between thermocouple and thin-film resistivity, and the lower conductivity of thin-film, the higher sensitivity of Cu/CuNi TFTC. Except that, the highest resistivity thermocouple was chosen as the test object for annealing, and its sensitivity increase after annealing. The results correspond with the previous conclusion, and provide methods and basis for improving performance of Cu/CuNi TFTC.