Martin Engels

Fundamental study of an industrial reactive HPPMS (Cr,Al)N process

In this work, a fundamental investigation of an industrial (Cr,Al)N reactive high power pulsed magnetron sputtering (HPPMS) process is presented. The results will be used to improve the coating development for the addressed application, which is the tool coating for plastics processing industry. Substrate-oriented plasma diagnostics and deposition of the (Cr,Al)N coatings were performed for a variation of the HPPMS pulse frequency with values from f = 300 Hz to f = 2000 Hz at constant average power P = 2.5 kW and pulse length ton = 40 μs. The plasma was investigated using an oscilloscope, an intensified charge coupled device camera, phase-resolved optical emission spectroscopy, and an energy-dispersive mass spectrometer. The coating properties were determined by means of scanning electron microscopy, glow discharge optical emission spectroscopy, cantilever stress sensors, nanoindentation, and synchrotron X-ray diffraction. Regarding the plasma properties, it was found that the average energy within the pl...

Correlative plasma-surface model for metastable Cr-Al-N: Frenkel pair formation and influence of the stress state on the elastic properties

Correlatively employing density functional theory and experiments congregated around high power pulsed magnetron sputtering, a plasma-surface model for metastable Cr0.8Al0.2N (space group Fm 3 ¯m) is developed. This plasma-surface model relates plasma energetics with film composition, crystal structure, mass density, stress state, and elastic properties. It is predicted that N Frenkel pairs form during Cr0.8Al0.2N growth due to high-energy ion irradiation, yielding a mass density of 5.69 g cm−3 at room temperature and Youngs modulus of 358–130 GPa in the temperature range of 50–700 K for the stress-free state and about 150 GPa larger values for the compressive stress of 4 GPa. Our measurements are consistent with the quantum mechanical predictions within 5% for the mass density and 3% for Youngs modulus. The hypothesis of a stress-induced Youngs modulus change may at least in part explain the spread in the reported elasticity data ranging from 250 to 420 GPa.

Space-resolved plasma diagnostics in a hybrid (Cr,Al)N process

The concurrent usage of direct current magnetron sputtering (dcMS) and high power pulsed magnetron sputtering (HPPMS), the so-called dcMS/HPPMS hybrid technology, enables the combination of the advantages of both technologies. These are well known to be a higher deposition rate, compared to HPPMS processes, as well as an improved roughness, microstructure, and mechanical properties, compared to dcMS processes. However, there have not been investigations which thematically focus on the understanding of the influence of different dcMS/HPPMS plasma zones on the deposition rate and the coating properties. Hence, in the present work, a dcMS/HPPMS hybrid (Cr,Al)N process was analyzed regarding the plasma and coating properties. The measurements were carried out in an industrial scale physical vapor deposition coating unit. The plasma was analyzed space-resolved and substrate oriented to map the entire area in front and beside of the cathodes. The mean ion energy decreased from the area in front and beside of th...