Materials Reports 2019, Vol. 33 Issue (Z2): 56-60 |
INORGANIC MATERIALS AND CERAMIC MATRIX COMPOSITES |
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Effect of Annealing Process on Microstructure and Electrical Properties ofPlatinum Films Grown by Magnetron Sputtering |
WANG Guojun1,2, BAI Yu2, HU Shaojie1, ZHANG Min2, WANG Shubei2, WAN Fei2
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1 State Key Laboratory for Mechanical Behaviour of Materials, Xi’an Jiaotong University, Xi’an 710049; 2 Xi’an Jiaotong University Suzhou Academy, Suzhou 215123 |
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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.
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Published: 25 November 2019
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Fund:This work was financially supported by National Natural Science Foundation of Youth Science Fund China (21805221), Jiangsu Province Fundamental Research Grant (BK20160389), Suzhou City Key Industry Technological Innovation (Perspective Application Research) Grant (SYG201832). |
About author:: Guojun Wang, born in 1994, received his bachelor’s degree in materials chemistry from Anhui University in 2017. He is currently a master’s student at Xi’an Jiaotong University, researching MEMS pressure sensor functional thin film materials and devices. Yu Bai, born in 1980, received his Ph.D. degree in material science and engineering from the Massachusetts Institute of Technology in 2011. He is currently an associate professor at Xi’an Jiaotong University. His research inte-rests include semiconductor thin film materials and micro-nano sensor devices. |
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