The work aims to select NiCr as the sensitive layer of a strain sensor and investigate the effects of sputtering power, argon flow rate, and substrate temperature on the quality of NiCr thin films prepared by magnetron sputtering, so as to determine the optimal deposition parameters. A 3-inch NiCr target with a purity of ≥99.99% was used, and NiCr thin films were deposited on silicon substrates by DC magnetron sputtering. The base pressure of the sputtering chamber was set to 5×10-5 Pa, the working argon pressure was 1.2 Pa, the substrate rotation speed was 5 r/min, and the substrate bias was 20 V. Prior to deposition, the substrates were cleaned with an ion source (working pressure 0.8 Pa, current 2 A) for 5 min at 5 r/min. The sputtering time was fixed at 30 min. Film thickness, surface roughness, and resistivity were characterized with atomic force microscopy (AFM) and a micro-resistivity meter. As the sputtering power increased from 40 W to 200 W, the average roughness increased by 7.99 nm, the average film thickness increased by 258.92 nm, and the resistivity decreased by 7×10-10 Ω·m. When the argon flow rate increased from 20 mL/min to 60 mL/min, the average roughness decreased by 1.7 nm, the average film thickness increased by 76 nm, and the resistivity decreased by 2×10-10 Ω·m. As the substrate temperature rose from 25 ℃ to 200 ℃, the average roughness decreased by 5.09 nm, the average film thickness increased by 7.71 nm, and the resistivity decreased by 2×10-10 Ω·m. Increasing the power significantly enhances the deposition rate and reduces the resistivity, but leads to an increase in surface roughness. As the argon gas flow rate increases, the film thickness also increases, while both roughness and resistivity decrease slightly. Raising the substrate temperature significantly reduces both roughness and resistivity, with little effect on film thickness. By optimizing these three process parameters, a smooth NiCr film with low resistivity is successfully prepared, providing an experimental basis for further improving sensor performance.
Key words
NiCr thin film /
magnetron sputtering /
process parameters /
surface quality /
resistivity
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Funding
National Key Research and Development Program of China (2022YFB4701000)
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