Abstract: Platinum (Pt) is a common sensitive material for temperature sensors. In order to improve the electrical properties of Pt films, the effect of annealing was studied. Pt films with tantalum (Ta) adhesion layer were grown on sapphire substrates by RF magnetron sputtering. The diffe-rences in microstructure and electrical properties of the Pt films with different annealing parameters, including temperature, atmosphere and time were investigated. The results show that annealing improves crystallization of the film and causes grain growth, which effectively reduces the resistivity of the film. However, excessive annealing, such as temperature above 1 000 ℃ or long annealing time, may cause excessive diffusion of Ta into the Pt film, thereby increasing the resistivity of the Pt film. Compared to Pt films annealed in high purity N2 (99.999%) or ultrapure N2 (99.999 9%), Pt films annealed in air have the lowest resistivity. The reason is that oxygen in the air diffuses through the Pt film to the Ta adhesion layer during annealing, forming stable Ta2O5, thus reducing the diffusion of Ta into the Pt film. Annealing also increases the linearity of the change in Pt film resistance with temperature, and the temperature coefficient of resistance (TCR) of the film. The TCR of the film annealed at 900 ℃ for 1 hour in air is 3.909×10-3/℃, very close to the value of the bulk platinum. This result is important for improving the sensitivity of the Pt film temperature sensor.
汪国军, 白煜, 胡少杰, 张敏, 王书蓓, 万飞. 退火工艺对磁控溅射生长的Pt薄膜微观结构及电性能的影响[J]. 材料导报, 2019, 33(Z2): 56-60.
WANG Guojun, BAI Yu, HU Shaojie, ZHANG Min, WANG Shubei, WAN Fei. Effect of Annealing Process on Microstructure and Electrical Properties ofPlatinum Films Grown by Magnetron Sputtering. Materials Reports, 2019, 33(Z2): 56-60.
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