Influence of HPPMS on Hybrid dcMS/HPPMS (Cr,Al)N Processes

Due to their beneficial properties, chromium-based nitride hard coatings deposited by physical vapor deposition (PVD) are applied as protective coatings in many technical applications. In the deposition of these coatings, hybrid dcMS/HPPMS processes consisting of direct current and high power pulse magnetron sputtering can be used in order to benefit from both processes, dcMS and HPPMS. While dcMS provides a considerably higher deposition rate, coatings deposited by HPPMS usually exhibit a significantly higher hardness and show a denser morphology and a smoother surface. The overall aim of this work is to achieve an improved understanding of the hybrid process dcMS/HPPMS. Different nitride (Cr,Al)N coatings were investigated. These were deposited by industrial-like coating processes using an industrial coating unit equipped with six cathodes on the quenched and tempered tool steel AISI 420 (X42Cr13, 1.2083). The aim of the investigations was to analyze the influence of HPPMS on the hybrid dcMS/HPPMS process within the coating plasma at the substrate side and with regard to the deposited coatings. In a first step, the (Cr,Al)N coating plasma was analyzed with a fine spatial resolution along the rotation line of the substrates using dcMS, HPPMS and hybrid dcMS/HPPMS processes. Changes in the plasma composition were investigated from the substrate position using optical emission spectroscopy (OES). In a second step, (Cr,Al)N coatings were deposited using the same process parameters. The coatings were analyzed regarding morphology and deposition rate using scanning electron microscopy (SEM). Furthermore, the contents of Al and Cr in the coatings were analyzed by energy dispersive X-ray spectroscopy (EDS). By comparing the measurements, the influence of HPPMS on the plasma within the hybrid dcMS/HPPMS process was analyzed and compared to the resulting coating properties morphology, deposition rate and chemical composition. This new experimental methodology was introduced before using a large-volume coating unit, but modified with only two cathodes. Within the scope of this work, it was for the first time transferred to an industrial coating unit with six cathodes, different targets and applied under industrial-like process conditions. •Substrate-sided plasma diagnostics within an industrial PVD coating unit•OES of dcMS, HPPMS and hybrid dcMS/HPPMS plasmas under comparable process conditions•Spatially resolved plasma and coating properties•Plasma homogeneity of