Effect of film deposition rate on the thermoelectric output of tungsten-rhenium thin film thermocouples by DC magnetron sputtering

Abstract

In micro–nano manufacturing, the deposition rate is one of the most basic parameters for the preparation of the film. In this paper, we use the tungsten–rhenium (W-5Re and W-26Re) alloy thin films as the research object and choose direct current (DC) magnetron sputtering to fabricate films on the alumina substrate. With the help of three factors and three levels of an orthogonal table, nine orthogonal experiments are designed to study the influences of argon flow rate, sputtering power and vacuum degree on the deposition rate. Thickness and composition are measured by scanning electron microscopy and x-ray diffraction respectively. In order to maintain the integrity of the film, the deposition thickness of the film is controlled by simulation so that the thermal stress is within the required range. In addition, the thermoelectric output is improved by comparing tungsten-rhenium thin film thermocouples (TFTCs) with different deposition rates. Experimental results show that sputtering power has a greater effect than other factors. The deposition rate of the W-5Re and W-26Re film can reach 24.911 nm min−1 and 25.756 nm min−1 at 600 W. The output of the TFTCs prepared at 600 W is about 10% higher than that at 200 W. TFTCs made with the fastest deposition rate parameters have excellent characteristics which could continuously work at 1273 K and the maximum EMF is 39.7 mV and the average Seebeck coefficient at 1273 K is 31.2 μV K−1.