Cathodic Magnetron Sputtering Research Articles

Electron trapping efficiency of a magnetron sputtering cathode

A common feature of all types of magnetron sputtering (MS) assemblies is an effective confinement of electrons by an appropriate combination of electric and magnetic fields. Therefore, studying the motions of electrons in the fields of magnetron assemblies is of particular importance. Here, we systematically analyze the electrons motions in front of a typical DC MS cathode. We first calculate the profiles of the magnetron’s magnetic field for balanced and two types of unbalanced configurations. Then, we compute the profiles of the cathode’s electric field before the gas discharge and after the plasma formation. A semi-analytical model is utilized to compute the plasma potential. We then track the motions of electrons released from the target and electrons produced through impact ionization of the background gas in the prescribed fields. A Monte Carlo model is implemented to consider electron-gas collisions and a mixed boundary condition is employed to account for electron-wall interactions. The study analyzes the impact of field profiles on the cathode’s efficiency in trapping electron by examining electron escape from the magnetic trap and electron recapture at the target surface. It is shown that the presence of plasma in all configurations leads to a significant increase in the trapping efficiency and the ionization performance, as well as a decrease in the recapture probability. These effects are attributed to the high electric field developed in the cathode sheath. Moreover, we statistically analyze the trapping efficiency by illustrating the spatial distributions of electrons locations in both axial and radial dimensions. It is demonstrated that during their azimuthal drift motion, the electrons released from the middle region at the target surface have the smallest range of axial and radial locations, in all configurations in the absence of plasma. Finally, the impact of field profiles on the average energies of electrons is discussed.

Optimizing the Thickness Uniformity of Magnetron Sputtering Deposited Films on a Large-Scale Curved Workpiece Surface

This study prepared magnetron-sputtering deposition film on a large-scale curved workpiece with a favorable thickness uniformity using a rectangular target cathode. For a substrate rotation structure with eccentric rotation/revolution composite motion, the geometrical model of the thickness distribution of the coating film on a large substrate was established in combination with the principle of rectangular cathode magnetron sputtering. The integral formula of the film thickness was derived, and various film thickness distribution patterns under different parameters were simulated. According to the present research results, the film thickness distribution can be optimized by adjusting the revolution-to-rotation radius and eccentric ratios. At an eccentric distance of 400 mm and a radius ratio of 2.78, the most favorable uniformity degree of 0.87 was obtained, which was controlled by the motion path of the fixed point on the substrate. The proposed approach helps to obtain large-scale films with favorable uniformity on the substrate.

Enhanced corrosion resistance of graphite-like carbon coatings via dense ta-C interlayer encapsulating

Taking the combination of atomic bond density, in this work, the tetrahedral amorphous carbon (ta-C) layer with high sp3 bond were especially introduced into the sp2-riched graphite-like carbon (GLC) coatings, using a hybrid filtering cathodic arc and magnetron sputtering deposition technique. The focus was elaborated on the electrochemical behavior of coatings against the stimulated chloride solutions for marine applications. Results showed that inserting dense ta-C layer significantly encapsulated the intrinsic pore defects within GLC growth, thereafter enhancing the corrosion resistance remarkably. In particular, the coating porosity was reduced from 10.84 % for pristine GLC system to 3.19 % for GLC with ta-C sealing layer, accompanying with a reduction in corrosion current to 7.8 × 10−9 A/cm2 and an increment in protective efficiency to maximum value of 95.49 %. The small angle X-ray scattering (SAXS) analysis evidenced qualitatively that the coating porosity was suppressed greatly, which were well consisted with the enhanced corrosion resistance of GLC coating with ta-C sealing layer. Furthermore, the balance between pores sealing and interfacial matching could be tailored by controlling the thickness ratio of ta-C and GLC layers, enabling the achievement of both the compact structure and the superior corrosion resistance. These observations offer a new promising strategy to develop the protective coatings for harsh marine environment that required both excellent capability against corrosion and friction with long lifetime.

Physico-chemical and biological properties of titanium nitride doped with copper and silver by combined methods of cathodic arc evaporation and magnetron sputtering

Physico-chemical and biological properties of titanium nitride doped with copper and silver by combined methods of cathodic arc evaporation and magnetron sputtering

Structural Characterization of ZnO Thin Films Deposited onto Silicon Substrates using Cathodic Magnetron Sputtering

In this study, we analyzed Zinc Oxide (ZnO) thin films deposited on silicon substrates using magnetron sputtering. These films have numerous applications in photovoltaic and optoelectronic devices due to their excellent physique properties. We used two structural characterization techniques: X-ray diffraction and scanning electron microscopy. We found that the ZnO films had good crystallinity and a columnar structure on the substrate surface, as indicated by the (002) orientation. These findings could potentially be useful for the development of ZnO-based devices such as solar cells and piezoelectric sensors. our results are consistent with those found by other researchers.

Investigation of Ion Release and Antibacterial Properties of TiN-Cu-Nanocoated Nitinol Archwires

Background: The use of nitinol (NiTi) archwires in orthodontic treatment has increased significantly due to unique mechanical properties. The greatest obstacle for safe orthodontic treatment is chemically or microbiologically induced corrosion, resulting in nickel (Ni) release. The aim of this investigation was to enhance corrosion resistance and introduce antibacterial properties to NiTi archwires by coating them with copper (Cu) doper titanium nitride (TiN-Cu). Methods: NiTi archwires were coated with TiN-Cu using cathodic arc evaporation (CAE) and direct current magnetron sputtering (DC-MS). The morphology of the sample was analyzed via field emission scanning electron microscopy (FESEM) and chemical composition was assessed using energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR). Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to estimate the ion release. The biocompatibility of samples was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Antibacterial activity was tested against Streptococcus mutans and Streptococcus mitis. Results: Physicochemical characterization revealed well-designed coatings with the presence of TiN phase with incorporated Cu. TiN-Cu-nanocoated archwires showed a statistically lower Ni release (p < 0.05). Relative cell viability was the highest in 28-day eluates of TiN-Cu-nanocoated archwires (p < 0.05). The most remarkable decrease in Streptococcus mitis concentrations was observed in the case of TiN-Cu-coated archwires (p < 0.05). Conclusion: Taking into account biocompatibility and antibacterial tests, TiN-Cu-nanocoated archwires may be considered as a good candidate for further clinical investigations.

High-rate deposition of ultra-thick silver film by hollow cathode magnetron sputtering

The deposition of high-performance micro-sized ultra-thick silver films is a critical issue. Hollow cathode magnetron sputtering is one of the promising techniques for depositing ultra-thick silver films. A novel cylindrical “three-dimensional magnetron sputtering” (3-DMS) magnet pack presented here was developed based on a conventional hollow cathode magnet pack to deposit high-performance ultra-thick silver film at a high rate. A stable process condition at the average power of 4 kW is realized by the new cylindrical “3-DMS” magnet pack's 137.5 mm diameter targets and a specially designed cooling well. Comparison of deposition rates with different power supplies and at different average power levels are discussed. The behavior of electrons on the target surface in this magnetic field arrangement is investigated using COMSOL Multiphysics software. The composition, topography, mechanical properties and residual stress of the ultra-thick silver film deposited by different sputtering modes (DCMS, HIPIMS, and Pulsed DCMS) are also discussed.

Hybrid deposition of Cr–O/Al–O hard coatings combining cathodic arc evaporation and high power impulse magnetron sputtering

Arc-evaporated (Cr, Al)2O3 coatings with high hardness and excellent chemical inertness are promising protective layers for cutting tools. However, the high surface roughness restrains their further applications in advanced machining. In this work, Cr–O/Al–O coatings were fabricated using a hybrid deposition technique combining cathode arc evaporation and high-power impulse magnetron sputtering (HiPIMS) to reduce growth defects. Process conditions involving the gas inlet, duty cycle of HiPIMS, and bias potential were optimized to deposit Cr–O/Al–O coatings with high hardness. When the O2 inlet is close to the arc evaporation cathode, hybrid deposition can proceed stably and produce oxide coatings with an oxygen content above 50 at.%. The maximum hardness of 26.9 GPa for the Cr–O/Al–O coating was achieved at a duty cycle of 2.5 % and a bias potential of −50 V. In addition, the hybrid Cr–O/Al–O coating exhibits a dominated face-centered cubic structure with a nano-multilayer geometry formed by alternating Cr–O and Al–O sublayers.

Microstructure, mechanical and tribological properties of Ti doped ta-C films deposited by a hybrid coating system

Ti doped ta-C films were deposited by a hybrid coating system with filtered cathodic vacuum arc and pulsed DC magnetron sputtering. The microstructure, mechanical and tribological properties of ta-C: Ti films were investigated. Results showed that the Ti content in the films linearly increased from 0 to 19.9 at. % by increasing the Ti target current from 0 to 2 A. Without and with small amount of Ti doing, ta-C films presented typical amorphous characteristic. TiC phase was formed in the film at Ti content of 5.5 at. %, and as the Ti content further increased, the microstructure of the films gradually transformed to nanocomposite structure, where TiC nanocrystalls were embedded in amorphous carbon matrix. The sp3 bonding fraction was decreased with increasing Ti content, accordingly, the hardness and residual stress of films also decreased with diminishing sp3 content. In addition, the Ti doping had a positive impact on the adhesion force between films and substrates. ta-C film with Ti doping content of 5.5 at. % had the lowest friction coefficient and the lowest wear rate under different friction temperatures, corresponding to 0.09 and 3.6 × 10−8 mm3/N·m at room temperature, and 0.25 and 22.5 × 10−8 mm3/N·m at 400 °C, respectively, which was mainly attributed to the relative high hardness, lower residual stress, good adhesion of the film.

Balancing the corrosion resistance and conductivity of Cr-Al-C coatings via annealing treatment for metal bipolar plates

Metal bipolar plates (BPs) with excellent corrosion resistance and good conductivity have been becoming one of key issues to explore proton exchange membrane fuel cells (PEMFCs). Here, we fabricated the high-performance protective Cr-Al-C coatings on stainless steel 316L using a combined cathodic arc and magnetron sputtering deposition with subsequent annealing. The electrochemical measurements in 0.5 M H2SO4 + 5 ppm HF solution and interfacial contact resistance (ICR) tests indicated that all the coatings exhibited enhanced corrosion resistance and excellent conductivity. As the annealing time increased, enhanced conductivity and corrosion current density were observed. Particularly, the sample annealed at 550 °C for 2 h exhibited the best comprehensive performance in balancing the corrosion current density of 3.02 × 10-7A cm−2 and ICR of 4.5 mΩ cm2 under 140 N cm−2, respectively. The present work provides the alternative strategy to apply the promising Cr-Al-C coatings for high-performance metal BPs used in PEMFCs.

Thermal stability of Si/SiC/ta-C composite coatings and improvement of tribological properties through high-temperature annealing

We report the structure, mechanical properties, thermal stability, and durability of Si/SiC/ta-C composite (Si–ta-C) coatings fabricated using simultaneous filtered cathodic vacuum arc deposition and direct current unbalanced magnetron sputtering. Si concentration of 1.25–6.04 at.% was achieved by increasing the unbalanced magnetron sputtering power from 25 to 175 W. Si addition provided functionality to the coating, such as heat resistance, while retaining the high hardness of ta-C coatings. The Si–ta-C coatings were stable up to 600 °C regardless of the Si content, while the coating containing 3.85 at.% Si was stable up to 700 °C. The friction behavior and mechanical properties were dependent on the coating film before and after annealing at 100–200 °C; however, annealing at 300–400 °C decreased disk wear and increased counterpart wear due to an increase in film hardness on account of an endothermic reaction that increased the number of Si–C bonds. This indicates that the basic hardness characteristics of the ta-C coating and the high-temperature structural change of the Si–ta-C coating are important for ensuring high-temperature durability. These characteristics were verified through the low coefficient of friction and wear rate of the 1.25 at.% Si–ta-C coating after annealing at 500 °C.

Comparative study of structural and stoichiometric properties of titanium nitride films deposited by cathodic cage plasma deposition and magnetron sputtering

Comparative study of structural and stoichiometric properties of titanium nitride films deposited by cathodic cage plasma deposition and magnetron sputtering

Microstructure, oxidation behavior and tribological properties of AlCrN/Cu coatings deposited by a hybrid PVD technique

• AlCrN/Cu coatings were deposited combining cathodic arc evaporation and magnetron sputtering. • Epitaxial growth of Cu sublayers on AlCrN achieves a hardness greater than 30 GPa. • Excessive Cu-incorporation causes the disintegration of the multilayered structure. • Temperate CuO oxide with fine grain size contributes to decreased friction coefficients. • Severe oxidation related to Cu-content leads to inferior tribological properties. Achieving high hardness and low friction at elevated temperatures for nitride-based hard coatings has substantial scientific interest and application significance. In this study, AlCrN/Cu coatings were deposited by a hybrid PVD technique combining arc evaporation from an Al 60 Cr 40 target and magnetron sputtering from a Cu target in a mixed Ar and N 2 atmosphere. The microstructure, oxidation behavior, and tribological properties of the coatings were investigated. AlCrN/Cu coatings show a dual-phase structure of (Al, Cr)N solid solution and Cu metallic phase. Excessive sputtering power of the Cu target induces the disintegration of interlayer interfaces of the nano-multilayered geometry, accompanied by a decline in hardness from above 30 GPa to 22.7 GPa. Moreover, the formation of fine CuO grains on the coating surface is conducive to reducing the friction coefficient of AlCrN/Cu when exposed to air at high temperatures. The AlCrN/Cu coating with a sputtering power of 0.5 kW obtains a friction coefficient of 0.39 ± 0.05 after pre-oxidation at 800 °C, distinctly lower than that of AlCrN, which exhibits a friction coefficient of ∼0.65. The further transformation of CuO to cubic Cu(Al, Cr) 2 O 4 , which stems from the solid-state reaction of CuO, Al 2 O 3 , and Cr 2 O 3 , would cause a rise in friction coefficient and wear loss. The mechanism of oxidation and tribological behavior of the AlCrN/Cu coatings related to the temperature and Cu content was discussed.

Working principle and layout logic of closed magnetic field in sputtering

Closed magnetic field constructed by unbalanced magnetron sputtering (MS) cathodes has been a general means of developing the MS coating system. However, owing to the difficulties in characterizing the complex plasma behaviors, there are still no quantitative criteria or design bases for some critical points, such as the effective object, the working mechanism, the closure condition, the layout logic and the effectivity of the closed magnetic field. Here in this work, out of the movements of charged particles in magnetic field, the motion behaviors of electrons and ions in the vacuum chamber are studied and it is also revealed that the closed magnetic field can affect mainly the electrons and further control the distributions of ions. A Monte-Carlo collision (MCC) model of the closed magnetic field MS coating system is established by test-electron to characterize the plasma transport characteristics, and the electron constraint and coating deposition efficiency are studied by different layouts of the magnetron cathodes and the ion sources. The simulation results show that the cathode numbers and vacuum chamber size determine the constraint effect on electrons in closed magnetic field. By 8 MS cathodes and the chamber radius of 0.5 m, the proportion of the overflow electrons can decrease to 1.77%. To increase the proportion of the electrons in the coating region, four coupled magnetic fields are introduced in the center of vacuum chamber. The studies of cathode type, rotation angle and magnetic field direction reveal that the proportion of the overflow electrons is less than 3%. A local dense plasma distribution and a continuous uniform plasma distribution can be observed in the vacuum chamber, corresponding to the same and opposite layout in magnetic poles of the MS cathodes and the ion sources, and the proportion of the electrons in the coating region significantly increases to 53.41% and 42.25%, respectively.

Complex study of protective Cr3C2–NiAl coatings deposited by vacuum electro-spark alloying, pulsed cathodic arc evaporation, magnetron sputtering, and hybrid technology

Coatings were obtained by vacuum electro-spark alloying (VESA), pulsed cathodic arc evaporation (PCAE), magnetron sputtering (MS) techniques and VESA-PCAE-MS hybrid technology using Cr3C2–NiAl electrodes. The structure of the coatings was analyzed using scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive spectroscopy. Mechanical properties were determined by nanoindentation, while tribological properties were assessed using pin-on-disk tribometer. Corrosion resistance was estimated by voltammetry in 1 N H2SO4 and 3.5%NaCl solutions. Oxidation resistance tests were performed at 800°С in air. The VESA coating had the highest thickness, low friction coefficient and high wear resistance. PCAE coating demonstrated the highest hardness (24 GPa) and elastic recovery (59%), oxidation resistance and superior corrosion resistance both in 1 N H2SO4 (icorr = 70 μА/cm2) and 3.5%NaCl (icorr = 0.74 μА/cm2) solutions. The MS coating had average mechanical properties and low corrosion current density (71 μА/cm2) in 1 N H2SO4. Deposition of coatings using VESA-PCAE-MS hybrid technology led to an increase in corrosion and oxidation resistance at least by 1.5 times in comparison with the VESA coating.

Microstructure and adhesion characteristics of duplex coatings with different plasma‐nitrided layers and a Cr‐Al‐Ti‐B‐N physical vapor deposition coating

AbstractA duplex treatment consisting of plasma nitriding (PN) and physical vapor deposition (PVD) significantly improves the thermal, tribological, and corrosion resistance of forming tools, and especially if they are intended for applications subject to high mechanical loads. This study investigates the influence of nitriding on the properties of a conventionally heat‐treated AISI D2 tool steel, coated with a Cr‐Al‐Ti‐B‐N layer, while the effect of the presence or absence of a compound layer is discussed. PN is performed at 510–520°C using different N2‐H2 gas mixtures. The Cr‐Al‐Ti‐B‐N layers are deposited at 480°C using a combination of cathodic arc evaporation and magnetron sputtering. The samples are characterized using electron probe microanalysis with wavelength‐dispersive X‐ray spectroscopy, optical and scanning electron microscopy, glancing‐angle X‐ray diffraction, surface hardness measurements, profilometry, Rockwell indentation, and scratch tests. These techniques reveal relationships between the depth gradient of the chemical composition and microstructure of the nitrided interlayer, the adhesion of the PVD coating, and the hardness of the tool steel. Although the PVD process induces a structural transformation in the compound layer, this transition does not have a negative influence on the adhesion of the PVD coating.

Tribological Properties of Ti-Doped Diamond-Like Carbon Coatings Under Boundary Lubrication With ZDDP

Abstract Diamond-like carbon (DLC) coatings containing 0.7%, 5.8%, and 23.3% Ti were deposited via pulsed cathodic arc deposition and magnetron sputtering on AISI 316L stainless steel substrates. The varied Ti content was controlled by setting Ti target current at 3, 5, and 7A. The composition, microstructure, mechanical, and tribological properties of Ti-doped DLC (Ti-DLC) coatings were investigated using X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and ball-on-disc tribometer. The results show that TiC formed when Ti content in the coating was higher than 5.8 at% and the ID/IG ratios increased gradually with the increasing Ti content. Ti-DLC with 0.7 at% Ti had the highest H/E and H3/E2 ratios and exhibited optimal tribological properties under lubrication, especially when zinc dialkyldithio-phosphate (ZDDP) was contained in the oil. Furthermore, ZDDP tribofilms played an important role in wear reduction by protecting the rubbing surfaces against the adhesion and suppressing the tribo-induced graphitization of DLC coatings.

Influence of the nitrogen content on the structure and properties of MoNbTaVW high entropy alloy thin films

The influence of nitrogen incorporation on the chemical composition, structure, mechanical, and electrical properties of refractory (MoNbTaVW)1−xNx high entropy alloy thin films is investigated. The films were synthesized by two different physical vapor deposition methods, cathodic arc deposition and direct current magnetron sputtering, onto silicon and polyimide substrates. Regardless of the deposition method, a change from body centered cubic to face centered cubic structure was observed with increasing nitrogen content in the film. This structural change was accompanied by an increase in hardness as measured by nanoindentation but also by a material embrittlement as determined from tensile straining tests.

Effect of thermal annealing on sensing properties of optical fiber sensors coated with indium tin oxide nano-overlays

In this work we discuss an effect of thermal annealing on optical and electrical properties of indium tin oxide (ITO) thin films deposited on a short section of multimode polymer-clad silica (PCS) optical fiber core. ITO films were deposited using different configuration of high power impulse magnetron sputtering (HiPIMS) and radio frequency magnetron sputtering (RF MS) cathodes. Due to tuned ITO film thickness it was possible to observe for these structures a lossy-mode resonance (LMR) and trace changes in properties of the films. Electrical resistance of the ITO overlays was also measured. Both optical and electrical measurements were repeated after annealing at 200°C in a tube furnace and nitrogen atmosphere. The measurements have shown that thermal annealing changes optical response to external refractive index (RI) of the fiber sensor and also changes the ITO layer resistivity. As an effect of thermal annealing we observed a shift of the LMR towards longer wavelengths. In addition as a result of annealing, the resistivity of the ITO layer was reduced. Full Text: PDF ReferencesM. Sobaszek et al., "Optical monitoring of thin film electro-polymerization on surface of ITO-coated lossy-mode resonance sensor", Proc. SPIE, vol. 10323, pp. 103234W, 2017. CrossRef I. Del Villar et al., " Generation of lossy mode resonances by deposition of high-refractive-index coatings on uncladded multimode optical fibers", J. Opt., vol. 12, no. 9, pp. 95503, 2010. CrossRef M. Śmietana et al., "Simultaneous optical and electrochemical label-free biosensing with ITO-coated lossy-mode resonance sensor", Biosensors and Bioelectronics, vol. 154, pp. 112050, 2020. CrossRef P. Niedziałkowski et al., " Electrochemical performance of indium-tin-oxide-coated lossy-mode resonance optical fiber sensor", Sensors and Actuators B: Chemical, vol. 301, no. 12, pp. 1-10, 2019. CrossRef V. Stranak et al., "Effect of mid-frequency discharge assistance on dual-high power impulse magnetron sputtering", Surface & Coatings Technology, vol. 206, no. 11-12. pp. 2801-2809, 2012. CrossRef I. Del Villar et al., "Design rules for lossy mode resonance based sensors", Appl. Opt., vol. 51, no. 19, pp. 4298-4307, 2012. CrossRef W. F. Wu and B. S. Chiou, "Effect of annealing on electrical and optical properties of RF magnetron sputtered indium tin oxide films", Appl. Surf. Sci., vol. 68, no. 4, pp. 497-504, 1993. CrossRef M. Smietana et al., "Optical Monitoring of Electrochemical Processes With ITO-Based Lossy-Mode Resonance Optical Fiber Sensor Applied as an Electrode", J. Light. Technol., vol. 36, no. 4, pp. 954-960, 2018. CrossRef M. Śmietana et al., "Study on Combined Optical and Electrochemical Analysis Using Indium‐tin‐oxide‐coated Optical Fiber Sensor", Electroanalysis, vol. 31, no.2, pp. 398-404, 2019. CrossRef

Advanced protection against environmental degradation of silver mirror stacks for space application

Protection of silver mirror stacks from environmental degradation before launching is crucial for space applications. Hereby, we report a comparative study of the advanced protection of silver mirror stacks for space telescopes provided by SiO2 and Al2O3 coatings in conditions of accelerated aging by sulfidation. The model silver stack samples were deposited by cathodic magnetron sputtering on a reference silica substrate for optical applications and a surface-pretreated SiC substrate. Accelerated aging was performed in dry and more severe wet conditions. Optical micrographic observations, surface and interface analysis by Time-of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and reflectivity measurements were combined to comparatively study the effects of degradation. The results show a lower kinetics of degradation by accelerated aging of the stacks protected by the alumina coating in comparable test conditions.