Magnetron Sputtering System Research Articles

Effects of Ag-doped Content on Antimicrobial Activity and Substrate Color of Chromium Thin Films Deposited by DC Magnetron Sputtering

Silver ions (Ag+) show promise as excellent antimicrobial agents to inhibit microbial growth on high-touch surfaces. In this study, Ag-doped Cr films were deposited using a DC magnetron sputtering system from a mosaic target. The Cr-Ag mosaic target was a 0.125-inch-thick Cr base (99.95% pure) with different diameters of Ag circle sheets mounted on the Cr target. The sputtering condition was kept at a DC power of 100W, working pressure of 8.3x10-3 mbar with Ar as the sputtering gas, and sputtering times of 15 and 30 min. The antimicrobial activity and efficiency were determined by standard testing (JIS Z 2801: 2000). The antibacterial performance was calculated from the antibacterial inhibition of the Ag-doped Cr films in bacterial solution (Staphylococcus aureus and Escherichia coli) after 24 h. The results showed that the Ag content was between 0.27 at% and 6.11 at% depending on the diameter of Ag and the deposition time. The minimum Ag content of 4.05 at% had an inhibition efficiency of 99.98% (E. coli) and 96.33% (S. aureus). The contact angle testing of Ag-doped Cr films showed hydrophobic behavior with the angle greater than 90 degrees. The optical color of the Ag-doped films was characterized by UV-vis spectroscopy (CIE testing). The film colors were significantly changed by the addition of Ag into the Cr films. The total color difference (DE) increased by 3-10 units compared to the reference chromium film and the Ag doping mainly affected +L* (Lightness). Keywords: sputtering PVD; antibacterial agent; silver; mosaic target; ROS; gram-negative; gram-positive; CIE-L*ab *Corresponding author: Tel.: (+66)934598942 E-mail: 62609006@kmitl.ac.th

Study of morphological, physical and mechanical properties of thin NbN films synthesized via DC magnetron sputtering system

PurposeNiobium Nitride (NbN) was interesting material for its applications in the medicinal tools or tools field (corresponding to saline serum media) as well as in mechanical properties. The aim of this work was depositing NbN thin films on two types of substrates (stainless steel (SS304) and silicon (100)) using plasma technique at varied powers (100–150 W).Design/methodology/approachDC magnetron sputtering technique at different powers were used to synthesis NbN films. Film structure was studied using X-ray diffraction (XRD) pattern. Rutherford elastic backscattering and energy dispersive X-ray were used to examine the deposited film composition. The films morphology was studied via atomic force microscopy and scanning electron microscopy images. Corrosion resistance of the three NbN/SS304 films was studied in 0.9% NaCl environment (physiological standard saline).FindingsAll properties could be controlled by the modification of DC power, where the crystallinity of samples was changed and consequently the corrosion and microhardness were modified, which correlated with the power. NbN film deposited at higher power (150 W) has shown better corrosion resistance (0.9% NaCl), which had smaller grain size (smoother) and was thicker.Originality/valueThe NbN films have a preferred orientation (111) matching to cubic structure phase. Corrosion resistance was enhanced for the NbN films compared to SS304 substrates (noncoating). Therefore, NbN films deposited on SS304 substrate could be applied as medicinal tools as well as in mechanical fields.

Study on the effect of counter ball materials on fretting wear behavior of solid lubricating films

Solid self-lubricating film can undoubtedly play a superior role in improving the micromotion behavior. The friction pairs of different materials have different fretting behavior and wear mechanism due to their different mechanical properties and surface adhesion properties. Investigating the influence of mechanical properties and surface adhesion on the fretting behavior can make the self-lubricating solid film play a better effect in the practical fretting working conditions. Here, DLC film and MoS2 film are deposited on AISI 304 stainless steel using a TeerUDP-650 unbalanced magnetron sputtering system. The fretting performance of DLC and MoS2 films resistance to GCr15, Al2O3, SiC and Si3N4 balls are studied. The results demonstrate that the fretting characteristics of DLC film are highly dependent on the mechanical properties and adhesion behavior of counter balls. Thereinto, Al2O3 balls show excellent fretting behavior, while SiC and Si3N4 balls make DLC film ineffective due to their high hardness and high adhesion. The MoS2 film maintains low friction and low wear state against any counter ball. DLC film achieves anti-fretting wear via graphitization, while MoS2 film primarily relies on slip and plastic flow. This work provides a theoretical reference for proper selection of solid lubricating films and counter balls under practical fretting conditions and reveals the different tribological mechanisms of friction pairs.

Effect of CH4 Flow Rate on the Tribological Behaviors of TiCN Films against Si3N4 Ceramic and Steel Ball

Control of the structural, mechanical and tribological properties of TiCN films play an important role in its numerous applications, including the cutting tools, mechanical components, aeronautical and biomedical engineering industries. Direct-current magnetron sputtering (DCMS) system was applied to deposit TiCN films onto n-type silicon (100) at room temperature. The Ti-TiN interlayer was used to enhance the adhesive strength between the coating and the substrate. The composition and microstructure of the TiCN films were studied using X-ray photoelectron spectroscopy (XPS) and field-emitted scanning electron microscopy (FESEM). The mechanical properties of the films as a function of methane (CH4) flow ratio were then characterized using nano-indentation measurements. The tribological behavior of TiCN films was investigated by UMT-2MT tribometer against a Si3N4 ceramic and AISI52100 steel ball. After the tribological tests, the wear rate of the films was obtained by the 3D surface profiler and the component content of wear debris was evaluated by energy dispersive X-ray spectroscopy (EDS). The results show that the tribological properties of TiCN films are a function of CH4 flow rates. The film obtained at a 10 sccm CH4 flow rate possesses a minimum average COF value of 0.1964 and reaches 72,000 cycles against a Si3N4 ball over the test duration. Furthermore, the wear rate was only 2.076 × 10−6 mm3/N·m. Furthermore, the TiCN films exhibited longer lifespan against the Si3N4 ball than against the steel ball under the normal load of 1 N, indicating that the TiCN films present better lubricative properties when against low-hardness counterparts than high-hardness counterparts.

High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V content

Chromium nitride (CrN) coating is considered as one of the best candidates for wear protection in many forming application where adhesive wear and galling dominate. However, its relatively high coefficient of friction against soft metals hinders its applicability. Vanadium nitride (VN), on the other hand has attracted increasing interest as VN is easily oxidized to form Magneli phase vanadium oxides with easy slipping shear planes, on one hand leading to self-lubricating properties but also to deteriorated wear resistance. This can be overcome by forming CrVN coatings. However, there is a lack of information how such coatings perform in terms of galling resistance and V-concentration in typical forming conditions and against soft metals.Therefore, the aim of this work was to study friction properties of nano-layered PVD (Cr,V)N coatings at room and elevated temperature and how V-content influences on friction and galling resistance against typical work materials. Nanolayered (Cr,V)N coatings with V in concentrations from 15 to 30 % were deposited by industrial DC magnetron sputtering system and tested using Load-Scanner against AA2024 aluminum alloy and low-carbon steel at room and elevated temperature of 300 °C and 600 °C, respectively. Results were evaluated in terms of coefficient of friction level and stability, critical loads for galling initiation and volume of adhered work material. Results show that (Cr,V)N coatings do not necessarily improve galling resistance, being strongly dependent on V concentration and contact temperature. For forming Al alloys positive results are obtained with coatings containing 20–25 at.% V and for low-carbon steels above 25 at.%, with marked improvement obtained only at elevated temperatures.

High-Temperature Oxidation Behaviour of CrSi Coatings on 316 Austenitic Stainless Steel.

In this study, a closed-field unbalanced magnetron sputtering system, which is environmentally friendly and has high deposition efficiency, was used to deposit CrSi coatings on 316 austenitic stainless steel. This system utilised separate Cr and Si targets, and the appropriate content of Cr and Si of the coatings was adjusted by changing the currents applied to the targets. A series of CrSi coatings with different Si/Cr ratios were produced, and their oxidation behaviour at elevated temperatures was investigated. By analysing the weight gain, surface morphology and microstructure, composition and phase constituents, the oxidation behaviour at 600 °C, 700 °C and 800 °C was investigated and the optimized coating to protect the stainless steel has been identified. The outcome of the research indicated that a small amount of Si (between 4-7 at.%) in Cr coatings is effective in protecting the austenitic stainless steel against oxidation at high temperatures, while a high Si content (around 10 at.% or more) makes the coating more brittle and prone to cracking or delamination during oxidation at 800 °C.

Epitaxial growth of (Ba0.7Sr0.3)TiO3 thin films on GdScO3 substrates by magnetron sputtering

Epitaxial growth of Ba0.7Sr0.3TiO3 (BST70) thin films on GdScO3 (GSO) substrates had been realized using the radio frequency magnetron sputtering system with the epitaxial alignment [001]BST70||[110]GSO and [010]BST70||[001]GSO. Reciprocal space mapping and transmission electron microscope results confirm the epitaxial growth without an impurity phase at the interface. The Fourier-filtered image shows that the BST70 thin film grew well with few dislocations. The out-of-plane parameter of the as-deposited film was elongated due to strain, which was induced by the differences in the thermal expansion coefficients between the film and the substrate, and oxygen vacancies. The highly strained as-deposited BST70 films could be relaxed by the post-annealing procedure at 800 °C in an O2-rich atmosphere for better epitaxial quality.

Color control of titanium nitride thin films

Titanium nitride (TiN) films were deposited on 304 stainless steel substrates using a radio frequency-powered magnetron sputtering system. The influence of the argon:nitrogen gas ratio (90:10, 80:20, 70:30) and the substrate temperature (room temperature, 200 °C, 400 °C) were investigated. X-ray diffractograms revealed a crystal orientation along the (111) plane with lattice parameters ranging from 4.268 to 4.319 Å. Colorimetric analysis of the deposited films revealed a color difference (ΔEab∗) from actual gold that ranged from 2.6 to 33.2. The hardness data of the TiN-coated (ΔEab∗=2.6) revealed a 53% increase compared to the bare substrates. 300-h salt spray test showed no significant corrosion for the TiN-coated substrates. With a gold-like finish coupled with excellent mechanical properties, the TiN films can be used as a durable decorative coating for the creative industries.

Improvement on Plasma Intensity Uniformity in Rectangular DC Magnetron Sputter by Optimizing Structures of Substrate Electrode

DC magnetron sputtering is widely used for thin film deposition in the field of displays. By adding magnet arrays to a large rectangular magnetron sputtering system, while the ionization and deposition rate are increased, the film properties can be nonuniform, and the local target erosion rate can be increased. Film properties strongly depend on uniform plasma density and energy. Although the ferromagnetic shield has been used to decrease the magnetic field locally, the plasma remains nonuniform at the corners of the rectangular shape target. In this study, a plasma simulation was conducted to analyze the plasma distribution in a DC magnetron sputtering system. The plasma uniformity was improved by optimizing the thickness and shape of the substrate electrode, carefully controlling the distance between the target and substrate electrode based on Paschen’s law, leading to the reduction of local high plasma intensity.

Ultrasensitive nitric oxide gas sensors based on Ti-doped ZnO nanofilms prepared by RF magnetron sputtering system

It is aimed to explore the advantages of titanium doping and magnetron sputtering as opposed to chemical-based methods on the surficial and electrical characteristics of ZnO films and their gas sensing performance in particular. RF magnetron sputtering was employed to synthesize a pure ZnO nanofilm as a reference and Ti-doped ZnO nanofilms with various Ti contents. The doping process was done by sputtering Ti-doped ZnO targets developed through solid-state reaction, and doping content was determined by EDS analysis. All nanofilms exhibited pure hexagonal wurtzite structure and relatively flat and homogenous surfaces with a clear distribution of nanoparticles in the Ti-doped samples. The observed enhancement in the properties of the nanofilms was reflected in the ultimate performance of the gas sensor. In this regard, the sensor with 1 wt% Ti content showed the best gas sensing performance with an ultra-sensitivity of 1.72 for 1 ppm and 0.9 for 1 ppb NO gas at a relatively low working temperature of 167 °C. The sensor also acquired outstanding stability, quick responsivity, reproducibility and superior selectivity required for NO monitoring.

Depth distribution analysis of alloying and impurity elements in Ni-Ti alloy thin films using secondary ion mass spectrometer

Ni-rich Ni-Ti thin films of various compositions and thickness (69 nm - 141 nm) were deposited on Si (111) substrate by magnetron sputtering system using equiatomic NiTi alloy sputtering target. X-ray reflectivity analysis of the thin films deposited at room temperature showed the presence of a layered structure as: NiO/Ni-Ti/NiO/SiO2 on Si substrate. Secondary ion mass spectrometry (SIMS) was used to determine the qualitative (intensity) depth distribution of elements Ni, Ti, O and Si in the films using MCs+ approach. Relative sensitivity factor values were utilized to convert the qualitative depth profiles to concentration depth profiles. Surface and depth distribution of alloying elements in the deposited films were investigated. It was observed that the films deposited at high sputtering power and working pressure resulted in more non-uniform depth distribution of alloying elements compared to films deposited at low sputtering power and working pressure. SIMS depth profile data showed the presence of high oxygen contaminations at the surface and at the interface of the films. The Ti concentration in the deposited films depends upon the background oxygen contamination present in the deposition chamber during sputtering process. The concentration of Ni in the films deposited under similar working pressure increases with increase in the sputtering power. However, with increase in working pressure during deposition process results in decrease in the concentration of both Ni and Ti in the deposited films. In order to study the effect of insitu substrate heating on the distribution of alloying and impurity elements, one of the film was deposited on heated Si substrate. The film deposited on heated substrate represents the layer structure as NiTiO3 on Si substrate. The concentration of oxygen in the film deposited on heated substrate is comparatively higher than those deposited at room temperature.

Particle-in-Cell Simulations for the Improvement of the Target Erosion Uniformity by the Permanent Magnet Configuration of DC Magnetron Sputtering Systems

Improving the target erosion uniformity in a commercial direct current (DC) magnetron sputtering system is a crucial issue in terms of process management as well as enhancing the properties of the deposited film. Especially, nonuniform target erosion was reported when the magnetic flux density gradient existed. A two-dimensional (2D) and a three-dimensional (3D) parallelized particle-in-cell (PIC) simulation were performed to investigate relationships between magnetic fields and the target erosion profile. The 2D PIC simulation presents the correlation between the heating mechanism and the spatial density profiles under various magnet conditions. In addition, the 3D PIC simulation shows the different plasma characteristics depending on the azimuthal asymmetry of the magnets and the mechanism of the mutual competition of the E × B drift and the grad-B drift for the change in the electron density uniformity.

Combinatorial Synthesis of AlTiN Thin Films

Nitrides of aluminum (Al) and titanium (Ti) mixtures have long been studied and used as commercial coatings because of their high hardness and high oxidation resistance due to the formation of an alumina layer on the coating surface. To fully understand the contribution of Al and Ti to the properties of the film, a combinatorial deposition approach was employed using half-disk targets. Film growth was carried out using a magnetron sputtering system powered by a 13.56 MHz radio frequency power supply with varying argon (Ar) and nitrogen (N2) gas ratios. Depending on the location of the substrate relative to the target, atomic percent gradients of 0.60–0.70 Al and 0.30–0.40 Ti across the substrate surface were obtained from energy dispersive X-ray spectral analysis. X-ray diffraction peaks at 43.59°, 74.71° (face-centered cubic), and 50.60° (wurtzite) confirmed the presence of aluminum titanium nitride (AlTiN) mixtures, with an increasing amount of wurtzite phase at higher Al concentrations. For all samples, cauliflower-like nanograins were obtained and samples of the 80:20 Ar:N2 gas pressure ratio showed the smallest grain size among the three gas ratio combinations. The 80:20 Ar:N2 films revealed a relatively high hardness compared to the other gas ratios. All thin films exhibited good adhesion to 304 stainless steel substrates.

Plasmonic Nanostructuring by Means of Industrial-Friendly Laser Techniques

The continuously growing demand for functional plasmonic devices or systems urges the implementation of economical and accelerated nanostructuring techniques. Laser annealing represents a promising approach to address this challenge, given its widespread usage in industry and research, as well as its unique advantages. This study proposes a scalable, rapid, versatile, and cost-efficient method to grow self-assembled nanostructures on metallic ultrathin films and multilayers, with high precision and patterning freedom. By employing industrial-grade equipment, specifically a 1070 nm nanosecond fiber laser and magnetron sputtering system, we directly grew self-assembled nanoparticles on Ag ultrathin films and AgPd multilayers deposited on Corning glass, via laser annealing at ambient conditions. The self-assembled nanoparticles were formed in designated areas by varying several laser parameters and exhibited intense localized surface plasmon resonances. Optical and structural characterization were realized via UV–Vis spectroscopy and atomic force microscopy, respectively. The plasmonic characteristics were found to depend on the initial film thickness and laser annealing parameters. Laser-treated films exhibited remarkable plasmonic behavior, demonstrating that this method does not lack nanostructuring quality while offering scalability and practicality. Further optimization of the laser settings can refine the process and result in an even faster, cheaper, and more qualitative nanostructuring method.

Silicon wafer as a feasible candidate for tribological characterization of thin coatings under high contact stress?

Silicon (Si) wafer is generally used as the substrate for structural analysis and residual stress measurement of thin coatings. A few studies can be found for mechanical and tribological characterization wherein Hertzian contact stress never exceeded 1 GPa. Si, being single crystal, pure, and having low surface roughness (Ra) is an ideal potential candidate for thin coating analysis. However, Si wafer breaks immediately under higher contact stress. The current study aims to push the contact stress limit to test thin coatings on Si wafer especially for friction and wear testing. To serve the purpose, different bias DLC coatings (−120 V, −80 V, −40 V, Zero V, +40 V, +80 V, +120 V) were deposited on Si wafer employing closed field unbalanced magnetron sputtering (CFUMS) system. Using conveniently available experimental approach, Hertzian contact stress in tribological tests has been pushed up to 2.6 GPa successfully on DLC coated Si wafer. Thus, it is feasible to test thin coatings on Si wafer at high contact stress which will provide useful and consistent friction and wear data such that further test using the steel substrate will be reduced by a significant margin. A thorough mechanical, tribological and structural (Raman) analysis is presented. It was found that −120 V possessed the highest hardness (H: 17.6 GPa), modulus (E: 184 GPa) and residual stress (4.5 GPa). The same coating produced the lowest sp2/sp3 ratio, wear rate using contact stress (0.092 × 10−13 mm4/N) and wear/friction energy (0.071 × 10−13 mm3/J2) in comparison to other coatings used in the study. Counter body analysis for −120 V shows the minimum scratch area depicting friction between transfer film and DLC hence the lowest coefficient of friction (0.061) was obtained. Moreover, surface topography is explained with the aid of atomic force microscope (AFM) images and surface roughness (Ra) data. AFM revealed craters and bumpy like surfaces for positive and negative biased samples respectively.

Large Tunneling Magnetoresistance in Perpendicularly Magnetized Magnetic Tunnel Junctions Using Co75Mn25 / Mo/Co20Fe60B20 Multilayers

We study the magnetic and electrical transport properties of magnetic tunnel junctions (MTJs) consisting of a ${\mathrm{Co}}_{75}{\mathrm{Mn}}_{25}{/\mathrm{Mo}/\mathrm{Co}}_{20}{\mathrm{Fe}}_{60}{\mathrm{B}}_{20}$ multilayer prepared using a mass-production-compatible magnetron sputtering system. The ${\mathrm{Co}}_{75}{\mathrm{Mn}}_{25}{/\mathrm{Mo}/\mathrm{Co}}_{20}{\mathrm{Fe}}_{60}{\mathrm{B}}_{20}$ multilayer sandwiched between two MgO layers exhibits remarkable perpendicular magnetic anisotropy, and a uniaxial magnetic anisotropy constant as large as $0.2\phantom{\rule{0.2em}{0ex}}{\mathrm{MJ}/\mathrm{m}}^{3}$ is achieved by optimizing the ${\mathrm{Co}}_{75}{\mathrm{Mn}}_{25}$ layer thickness as well as the annealing temperature. The current-in-plane tunneling measurement reveals a large tunneling magnetoresistance of over 100% in perpendicularly magnetized MTJs. These experimental results indicate the applicability of ${\mathrm{Co}}_{75}{\mathrm{Mn}}_{25}$ alloy for magnetic random access memory devices.

Crystallinity Study of Cu Thin Film Deposited by Indigenously Developed DC Magnetron Sputtering Setup

AbstractThe copper thin films have a huge application in the field of material science research and they also act as a catalytic substrate which helps to deposit various carbon‐based polymers that can be used for sensors. There are several thin film development techniques available in the industries out of which magnetron sputtering technique shows some remarkable properties essential for depositing metal thin film efficiently. The main objective of this work is to develop copper thin films utilizing an indigenously designed and developed DC magnetron sputtering system. The X‐ray diffraction (XRD) pattern of the developed thin films display prominent peaks of copper (111) plane along with cuprous oxide (110), (111), and (220), respectively. This work also aims to study in detail the crystallinity of the deposited copper thin films by analyzing the XRD results for optimization.

The influence of post-annealing temperatures on XPS, XZ height of nanoparticles, and optical properties of Cu–Al doped ZnO films

In this article, using a radio frequency magnetron sputtering system at room temperature, Cu–Al doped ZnO films were deposited on quartz substrates. XPS studies have shown that the broad bands at around 932.5, 943, and 952 eV correspond to the Cu 2 P3/2 peak of Cu+1, Cu 2p3/2 of Cu+2, and Cu 2p1/2, respectively. In the case of Al2p3/2, the peak with binding energy 74.2 eV may be attributed to the presence of Al3+ oxide. The optical density, D opt, of films annealed at 600 °C has a maximum value about of 0.25. Films annealed at 600 °C have a minimum value of the fractal dimensions, D f, about 2.65. It is observed that films annealed at 500 °C, have a maximum value of the single layer. The minimum value of dissipation factor occurred in films annealed at 500 °C. It can be seen that with doping Cu and Al atoms into ZnO films, the oxygen vacancies were nearly removed and the quality of films was increased; hence the porosity which is introduced in ZnO films can be removed by Cu–Al doping of ZnO films. Due to high evaporation in films annealed at 600 °C, they were rougher and they have a maximum value of RMS roughness at about 4.68 nm. Films annealed at 400 °C have a minimum value of dissipation factor.

Comprehensive effect of grain size and original target morphology on sputtering behavior of magnetron sputtering target

In this paper, the etching morphology, surface roughness, target voltage, and light emission line intensity of the copper target were investigated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The results show that the morphology of the sputtering zone, the target voltage value, the surface roughness, and the OEM value are significantly correlated with the grain size of the target. After sputtering, the original target's morphology dramatically influences the surface roughness and OEM value.

Mechanical properties, electrochemical performance and interfacial contact resistance of as-deposited and annealed NbxAlyC and CrxAlyC coatings on stainless steel 316L substrates

NbxAlyC and CrxAlyC coatings (where x is the Nb or Cr target current and y is the Al target current) were deposited on stainless steel 316L substrates using a radio frequency unbalanced magnetron sputtering system. The sputtered NbxAlyC and CrxAlyC coatings were vacuum annealed at 800°C and 750°C for 1 h, respectively. The cross-sectional and surface morphologies of the as-deposited coatings showed a columnar structure and a loose surface, respectively. The X-ray diffraction results showed that the annealed NbxAlyC and CrxAlyC coatings contained Nb2AlC and Cr2AlC MAX crystalline phases, respectively, The MAX crystalline phase improved the hardness, corrosion resistance, and electrical conductivity of the coatings. The annealed coatings also formed an Al2O3 layer with a small cluster size and a dense surface, which significantly improved the corrosion resistance compared to that of the as-deposited coatings. The electrochemical test results showed that the corrosion current density (Icorr) and interfacial contact resistance (ICR) values of all the annealed coatings were lower than those of the as-deposited coatings and were consistent with the standard for the bipolar plates in commercial proton exchange membrane fuel cells. Among all the coatings, the annealed Nb2.5Al0.5C-H coating showed the lowest Icorr and ICR values.