Effect of the degree of high power impulse magnetron sputtering utilisation on the structure and properties of TiN films

Abstract

TiN films were deposited using High Power Impulse Magnetron Sputtering (HIPIMS) enabled four cathode industrial size coating system equipped with HIPIMS power supplies. The standard version of this system allows control over the ion bombardment during coating growth by varying the strength of the electromagnetic field of the unbalancing coils and bias voltage applied to the substrate. The coatings were produced in different coating growth conditions achieved in combined HIPIMS-direct current (DC) unbalanced magnetron sputtering (HIPIMS/UBM) processes where HIPIMS was used as an additional tool to manipulate the ionisation degree in the plasma. Four cathode combinations were explored with increasing contribution of HIPIMS namely 4UBM (pure UBM), 1HIPIMS+ 3UBM, 2HIPIMS+2UBM and 2HIPIMS (pure HIPIMS) to deposit TiN coatings. Optical emission spectroscopy (OES) measurements were carried out to examine the plasma generated by the various combinations of HIPIMS and UBM cathodes. The micro-structural study was done by scanning electron microscopy (SEM). X-ray diffraction (XRD) technique was used to calculate the residual stress and texture parameter. It has been revealed that the residual stress can be controlled in a wide range from-0.22 GPa to-11.67 GPa by intelligent selection of the degree of HIPIMS utilisation, strength of the electromagnetic field of the unbalancing coils and the bias voltage applied to the substrate while maintaining the stoichiometry of the coatings. The effect of the degree of HIPIMS utilisation on the microstructure, texture and residual stress is discussed. Combining HIPIMS with dc-UBM sputtering is also seen as an effective tool for improving the productivity of the deposition process.

Effect of chamber pressure on defect generation and their influence on corrosion and tribological properties of HIPIMS deposited CrN/NbN coatings

“…While depositing the coatings, UBM-DC was combined with HIPIMS to achieve a higher deposition rate [15]. All multilayer CrN/NbN coatings were produced by operating one Cr and one Nb target in HIPIMS mode and the other two targets (1 Cr and 1 Nb) in UBM mode.…”

“…Due to the denser microstructure and smaller grain size, HIPIMS deposited coatings exhibited lower surface roughness, higher hardness, improved adhesion, excellent wear and corrosion resistance [12][13][14]. Although the deposition rate during the HIPIMS process is quite low, this drawback can be eradicated by combining HIPIMS with the Unbalanced Magnetron Sputtering (UBM) process [15].…”

“…Additionally, previous research revealed that HIPIMS generated plasma is free from the droplet phase [8][9][10]15,16]. For the HIPIMS process, applied power is not constant; rather HIPIMS is associated with a pulsed power supply where the peak power exceeds the average power by typically two orders of magnitude [10].…”

Growth defects in CrN/NbN coatings deposited by HIPIMS/UBM techniques

“…In HIPIMS, the metal ion to neutral ratio is much higher which prevents the void formation and hence can be used to deposit void free dense coatings [35][36][37]102]. The benefits of using HIPIMS and a higher bias voltage can be observed from the [46]. This study suggested that sufficiently high metal ionisation can eradicate these defects (i.e.…”

“…It has been widely published that the HIPIMS technique is an excellent tool to deposit coatings with very dense structure without inter-columnar voids but shows a relatively lower deposition rate. On the other hand, the conventional UBM technique has higher deposition rate but can produce porous coatings [15,35,[46][47][48]. A combination of both techniques, however can eradicate these problems and produce coatings with a high deposition rate and very dense structure [46,49].…”