Research Center on Advanced Materials and Technologies, Department of Exact and Natural Sciences, Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iasi, 700506 Iasi, Romania
Dr. VASILE TIRON
Research Center on Advanced Materials and Technologies, Department of Exact and Natural Sciences, Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iasi, 700506 Iasi, Romania
High power impulse magnetron sputtering (HiPIMS) is a very attractive ionized physical vapour deposition technique which has been of great interest over the last decade. Thanks to the high ionization degree of the sputtered material (typically >50%), this technique is used mainly for enhancing and tailoring coating properties. However, the lower deposition rate compared to the conventional direct-current (dc) magnetron sputtering process still represents a major drawback of HiPIMS. In this contribution, a study of the ability to control the peak target current in HiPIMS discharge through certain experimental parameters and, thus, to overcome the deposition rate limitation is presented. The HiPIMS was operated with ultra-short pulse durations (<20 μ s) and two different operation modes have been used: single-pulse mode and multi-pulse mode, respectively. The peak target current was controlled by changing the target voltage, pulse duration, magnetic field, and target erosion depth. For a certain favorable combination of experimental parameters, it was found that the deposition rate value can be increased by a factor of up to 3.5, reaching values only 20% lower than those found in dc.
In this contribution, based on the detailed understanding of the processes’ characteristics during reactive high-power impulse magnetron sputtering (HiPIMS), we demonstrated the deposition of silicon oxide (SiO2) thin films with improved optical and mechanical performances. A strategy for stabilizing the arc-free HiPIMS of Si target in the presence of oxygen was investigated. Arcing was suppressed by suitable pulse configurations, ensuring good process stability without using any feedback control system. It was found that arcing can be significantly alleviated when ultra-short HiPIMS pulses are applied on the target. The optical and mechanical properties of SiO2 coatings deposited at various pulsing configurations were analyzed. The coatings prepared by ultra-short pulse HiPIMS exhibited better optical and mechanical performance compared to the coatings prepared by long pulse HiPIMS. The optimized SiO2 coatings on quartz substrates exhibited an average transmittance of 98.5% in the 190–1100-nm wavelength range, hardness of 9.27 GPa, hardness/Young’s modulus ratio of 0.138, and critical adhesion load of 14.8 N. The optical and mechanical properties are correlated with the film morphology, which is inherently related to energetic conditions and process stability during film growth.