Abstract
Despite its great potential for thin films deposition and technological applications, the HiPIMS technology has its own limitations including the control of ion energy and flux towards the substrate when coping with the deposition of electrical insulating films and/or the deposition onto insulating/electrically grounded substrates. The bipolar-HiPIMS has been recently developed as a strategy to accelerate the plasma ions towards a growing film maintained at ground potential. In this work, the benefits of bipolar-HiPIMS deposition onto floating or nonconductive substrates are explored. The effect of bipolar-HIPIMS pulsing configuration, magnetic balance-unbalance degree, and substrate’s condition on plasma characteristics, microstructure evolution, and mechanical properties of CrN coatings was investigated. During the deposition with a balanced magnetron configuration, a significant ion bombardment effect was detected when short negative pulses and relative long positive pulses were used. XRD analysis and AFM observations revealed significant microstructural changes by increasing the positive pulse duration, which results in an increase in hardness from 7.3 to 16.2 GPa, during deposition on grounded substrates, and from 4.9 to 9.4 GPa during the deposition on floating substrates. The discrepancies between the hardness values of the films deposited on floating substrates and those of the films deposited on grounded substrates become smaller/larger when a type I/type II unbalanced magnetron configuration is used. Their hardness ratio was found to be 0.887, in the first case, and 0.393, in the second one. Advanced application-tailored coatings can be deposited onto floating substrates by using the bipolar-HiPIMS technology if short negative pulses, relative long positive pulses together with type I unbalanced magnetron are concomitantly used.
Highlights
In physical vapour deposition (PVD) systems, the control of ion energy and ion-toneutral flux ratio is essential for optimizing the mechanical properties of the deposited thin films [1]
Previous studies have shown that the fraction of accelerated ions during bipolarHiPIMS strongly depends on the pulsing configuration [22]
The selection of the positive pulse duration appears as an interesting approach to control the ion bombardment without changing the parameters of the plasma generated during the main negative high-power impulse magnetron sputtering (HiPIMS) pulse
Summary
In physical vapour deposition (PVD) systems, the control of ion energy and ion-toneutral flux ratio is essential for optimizing the mechanical properties of the deposited thin films [1]. An appropriate choice of processing parameters, such as pulsing configuration [3], magnetic field topology [4], substrate bias voltage [5,6], and deposition temperature, enables the control of the thermodynamic and kinetic conditions during the growth process. Both microstructure and mechanical properties can be significantly improved by increasing the ad-atom mobility during this process. During PVD process, the ad-atom mobility can be improved by heating the substrate or by applying a substrate bias voltage Both methods are difficult to be adopted when dealing with the deposition onto temperature-sensitive and electrical non-conductive substrates. More than that, using a high substrate bias is commonly accompanied by the generation of high defect density [7] and high residual stress in the coatings [2]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
