Dual Magnetron Sputtering Research Articles

Using the macroscopic scale to predict the nano-scale behavior of YSZ thin films

In this work, Yttria-stabilized zirconia (YSZ) thin films were deposited using dual reactive magnetron sputtering. By varying the deposition conditions, the film morphology and texture of the thin films are tuned and biaxial alignment is obtained. Studying the crystallographic and microstructural properties of the YSZ thin films, a tilted columnar growth was identified. This tilt is shown to be dependent on the compositional gradient of the sample. The variation of composition within a single YSZ column measured via STEM–EDX is demonstrated to be equal to the macroscopic variation on a full YSZ sample when deposited under the same deposition parameters. A simple stress model was developed to predict the tilt of the growing columns. The results indicate that this model not only determines the column bending of the growing film but also confirms that a macroscopic approach is sufficient to determine the compositional gradient in a single column of the YSZ thin films.

Influence of the target–substrate distance on the growth of YSZ thin films

The reduction of yttria-stabilized zirconia (YSZ) thickness is one of the aims of current studies to lower the process temperature of the Solid Oxide Fuel Cells. Bulk YSZ has been extensively used as electrolyte. However, thin films change the fundamental aspects of the oxygen ion conduction due to the occurrence of nano-effects. Therefore, the understanding of the microstructure and crystallinity would open the possibility to manipulate the YSZ properties. This work describes some features of YSZ thin films produced by dual magnetron sputtering. Target–substrate distance was varied creating a compositional gradient along the films. Moreover, a tilt of the lattice from 0° to 45° was identified when changing the yttrium content. The use of a simple stress model allows predicting this tilt, when taking into consideration the compositional gradient in any region of the YSZ layer. The calculated tilt angles, based on experimental results from SEM, EDX and profilometry, are in good agreement with the results obtained via the azimuthal angle from XRD measurements.

Mechanical and Corrosion Resistance of (Ti,Cr)N Grown by DC Magnetron Sputter on H13 Tool Steel

Abstract This research studied properties of (Ti,Cr)N film prepared by co-deposition from dual unbalanced DC magnetron sputtering techniques at various temperatures. All samples were prepared at different growth temperatures for (Ti,Cr)N compound layer with atomic ratio Ti: Cr approximately 1: 1. The lattice parameter of the film is 4.18 Å, which is a value between those of TiN and CrN. It was found that both hardness and adhesion increased with an increase of growth temperature. The highest hardness value obtained is 24.78 GPa for film growth at 190 °C and film adhesion was significantly improved by increasing growth temperature. The growth temperature also plays an important role on corrosion resistance. Ecorr increases from −466 mV to −195 mV, while Icorr decreases from 188.21 nA/cm2 to 3.20 nA/cm2 with increasing the growth temperature to 190 °C. At highest growth temperature surface roughness decrease. The improved properties, both mechanical and corrosion properties, as well as surface uniformity are due to the change of film structure from columnar to equiaxial, which produces a denser film.

Structural and mechanical properties of TIN/BCN coatings

Monolayer TiN and a-BCN and nanolayer TiN/BCN coatings are deposited by dual magnetron sputtering. The effect of discharge power, flow rates of gases, and substrate bias voltage on the mechanical properties of the deposited nanolayer coatings is studied. The structure, chemical bonding, mechanical properties, adhesion, and friction coefficient of the coatings are analyzed. It is established that the deposited nanolayer coatings have nc-TiNx/a-BNO+a-C structure. The Knoop hardness of the nanolayer TiN/BCN coatings is found to reach 45 GPa on average. The nanohardness is lower than the Knoop hardness (by 20–30%). The deposited nanolayer coatings can be recommended as wear-resistant and protective coatings for mechanical engineering.

Ag+ release and corrosion behavior of zirconium carbonitride coatings with silver nanoparticles for biomedical devices

Zirconium carbonitride coatings with silver nanoparticles were produced by DC unbalanced dual magnetron sputtering system, using two targets, Zr and Zr/Ag in an Ar, C2H2 and N2 atmosphere. Stainless steel 316L and silicon (100) substrates were used for electrochemical and structural characterization, respectively. Silver was found to be well distributed throughout the coatings, maintaining the films' composition in depth, while its diffusion to the electrolyte decreases as immersion time increases, stopping its release after 7 to 8days of immersion. Electrochemical characterization revealed very stable films that have improved base material, without any diminished corrosion resistance due to the silver content.

Influence of an External Magnetic Field on the Growth of Nanocrystalline Silicon Films Grown by MF Magnetron Sputtering

The effects of an external magnetic field originating from two solenoid coils on the magnetic field configuration, plasma state of a dual unbalanced magnetron sputter system and the structure of nanocrystalline Si films were examined. Numerical simulations of the magnetic field configuration showed that increasing the coil current significantly changed the magnetic field distribution between the substrate and targets. The saturated ion current density J(i) in the substrate position measured by using a circular flat probe increased from 0.18 to 0.55 mA/cm(2) with the coil current ranging from 0 to 6 A. X-ray diffraction and Raman results revealed that increasing the ion density near the substrate would benefit crystallization of films and the preferential growth along [111] orientation. From analysis of the surface morphology and the microstructure of Si films grown under different plasma conditions, it is found that with increasing the J(i), the surface of the film was smoothed and the alteration in the surface roughness was mainly correlated to the localized surface diffusion of the deposited species and the crystallization behavior of the films.

The fictional transition of the preferential orientation of yttria-stabilized zirconia thin films

The fundamental study of the microstructural and textural evolution of yttria-stabilized zirconia (YSZ) thin films is of great importance given that the crystallographic properties are intimately related to their extrinsic or functional properties. In order to study these properties, YSZ thin films were obtained using dual magnetron sputtering. The results of a polar plot graph, based on X-ray diffraction (XRD) data, seem to indicate a transition from [200] out-of-plane preferential orientation to [111], indicating a dependence on composition and yttrium target–substrate (Y T–S) distance at low pressure. However, no transition is identified at high pressure, showing only [111] out-of-plane orientation, independent of composition and Y T–S distance. Scanning electron microscopy (SEM) indicates a tilt in the columnar structure of the film but no other microstructural change is in evidence, possibly related to the growth transition from [200] to [111]. Pole figures were used to clarify the texture transition in the YSZ thin films. These results indicate that there is indeed no transition in the preferential orientation of the films from [200] to [111] but a tilt of the [200] orientation towards the zirconium source. Detailed study using pole figures and SEM, clearly indicated that no growth zone transition was present and the effect is caused by geometrical configuration, contradicting expectations from standard θ/2θ XRD measurements.

Investigation of surface defects and parameter optimization of chromium oxide films in a mid-frequency dual-magnetron sputtering

Aiming at identifying the mechanisms to cause macro-particles and caves on coating surface, and optimizing the process parameters, a series of chromium oxide films were deposited using a reactive mid-frequency dual-magnetron sputtering system. Orthogonal design and variance analysis were then used to optimize the process parameters and to reveal the influences of the target currents, the gas pressures, and the substrate bias voltages on the densities of the surface defects. Results show that: (i) the target current is the most influential factor to the defect density; (ii) the effects of the pressures and the substrate bias voltages tend to decrease recursively; and (iii) the buffer layer of Cr with thickness of ~200nm facilitates to optimize the Cr/CrxOy multilayered films with superior combined properties, and the film can be coated with the setting conditions of target current at 16A, gas pressure at 0.31Pa, and bias voltages in a range of −120–−240V.

Apatite Formation on Rutile TiO2 Film Deposited Using Dual Cathode DC Unbalanced Magnetron Sputtering

Rutile TiO 2 films were deposited on unheated stainless steel type 316L using dual cathode DC unbalanced magnetron sputtering. The effects of deposition time ranging 30, 60, 90, and 120 mins on the films structure were investigated. Moreover, all the samples were immersed in SBF for period times of 3 and 5 days also considered. The crystal structures were characterized by thin film X-ray diffraction (TF-XRD). The film’s thickness and surface morphology were evaluated using atomic force microscopy (AFM). The crystallinity, roughness, thickness, and grain size of rutile with only (110) plane increased with increased deposition time. After immersed samples in SBF for 3 day the highest and moderate crystallinity of apatite was observed on the 30 min and 90 min, respectively. However, the films deposited with 60 and 120 min cannot be observed the peak of apatite. An increase crystallinity of apatite clearly observed when after immersed in SBF for 5 day.

Sputter deposition of MgxAlyOz thin films in a dual-magnetron device: a multi-species Monte Carlo model

A multi-species Monte Carlo (MC) model, combined with an analytical surface model, has been developed in order to investigate the general plasma processes occurring during the sputter deposition of complex oxide films in a dual-magnetron sputter deposition system. The important plasma species, such as electrons, Ar+ ions, fast Ar atoms and sputtered metal atoms (i.e. Mg and Al atoms) are described with the so-called multi-species MC model, whereas the deposition of MgxAlyOz films is treated by an analytical surface model. Target–substrate distances for both magnetrons in the dual-magnetron setup are varied for the purpose of growing stoichiometric complex oxide thin films. The metal atoms are sputtered from pure metallic targets, whereas the oxygen flux is only directed toward the substrate and is high enough to obtain fully oxidized thin films but low enough to avoid target poisoning. The calculations correspond to typical experimental conditions applied to grow these complex oxide films. In this paper, some calculation results are shown, such as the densities of various plasma species, their fluxes toward the targets and substrate, the deposition rates, as well as the film stoichiometry. Moreover, some results of the combined model are compared with experimental observations. Note that this is the first complete model, which can be applied for large and complicated magnetron reactor geometries, such as dual-magnetron configurations. With this model, we are able to describe all important plasma species as well as the deposition process. It can also be used to predict film stoichiometries of complex oxide films on the substrate.

Structural characteristics and optical properties of plasma assisted reactive magnetron sputtered dielectric thin films for planar waveguiding applications

Thin films of aluminum oxide (Al2O3), tantalum pentoxide (Ta2O5), titanium oxide (TiO2), yttrium oxide (Y2O3) and zirconium oxide (ZrO2) were deposited by plasma assisted reactive dual magnetron sputtering to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The effect of deposition parameters such as cathode, plasma power and oxygen gas flows were studied and the operational working points were determined. Both power and lambda control were used to optimize the optical quality of each material. By using lambda control feedback system, the magnetron power fluctuates to sustain a fixed oxygen flow in the target area reducing the compound layer growth on the material and maintaining a healthy deposition rate. The optical properties, structure and crystalline phase of each film were found to be dependent on the process parameters. X-ray diffraction (XRD) analysis revealed that the thin films varied from amorphous to highly crystalline depending on the deposition conditions. X-ray photoelectron spectroscopy (XPS) was utilized for surface compositional analysis revealing that films had varying stoichiometric ratios which are controlled for each material by the deposition parameters chosen. The waveguide loss for the thin film layers was investigated and Ta2O5 was shown to have a slab waveguide loss of ~1dB/cm at both visible and infra-red wavelengths making it ideal for planar waveguide and laser applications. TiO2, Y2O3 and ZrO2 were found to deposit in a highly crystalline phase. Waveguiding in the TiO2 layers was not possible at 633nm or in the infrared region. The Y2O3 samples gave low loss (2–4dB/cm) at the 1.3 and 1.5μm wavelengths but no waveguiding at 633nm or 833nm was possible. Atomic force microscopy showed rough surface topography for TiO2, Y2O3 and ZrO2 akin to their crystalline growth with the SEM images confirming the regular crystalline columnar structure for the case of Y2O3 and ZrO2.

Si<sub>x</sub>C<sub>y</sub> Thin Films Deposited at Low Temperature by DC Dual Magnetron Sputtering: Effect of Power Supplied to Si and C Cathode Targets on Film Physicochemical Properties

A DC dual magnetron sputtering system with graphite (C) and silicon (Si) targets was used to grow stoichiometric and non-stoichiometric silicon carbide (SixCy) thin films at low temperature. Two independently DC power sources were used to enable the total discharge power be shared, under certain proportions, between the Si and C magnetron cathodes. The motivation was to control the sputtering rate of each target so as to vary the stoichiometric ratio x/y of the deposited films. The species content, thickness and chemical bonds of as-deposited SixCy films were studied by Rutherford backscattering spectroscopy (RBS), profilometry analysis and Fourier transform infrared absorption (FTIR), respectively. Overall, the present work reveals a new reliable plasma sputtering technique for low temperature growth of amorphous SixCy thin films with the capability of tuning the degree of formation of a-SiC, a-Si and a-C bonds in the film bulk.

Influence of the Substrate Bias Voltage on the Structure of Rutile TiO<sub>2</sub> Films Prepared by Dual Cathode DC Unbalanced Magnetron Sputtering

Rutile TiO2 films are normally used as biomaterial that synthesized on unheated stainless steel type 316L and glass slide substrates by dual cathode DC unbalanced magnetron sputtering. The influence of the substrate bias voltages (Vsb), from 0 V to-150V, on the structure of the as-deposited films was investigated. The crystal structure was characterized by grazing-incidence X-ray diffraction (GIXRD) technique, the films thickness and surface morphology was evaluated by atomic force microscopy (AFM) technique, respectively. The results show that the as-deposited films were transparent and have high transmittance in visible regions. The crystal structure of as-deposited films show the XRD patterns of rutile (110) with Vsb at 0V and shifted to rutile (101) with increasing Vsb. The films roughness (Rrms) and the thickness were 3.0 nm to 5.7 nm and 420 nm to 442 nm, respectively.

Properties of Hydrogenated Amorphous Silicon-Germanium Alloys Deposited by Dual Target Reactive Magnetron Sputtering

ABSTRACTHydrogenated amorphous silicon-germanium alloy thin films (a-Si1-xGex:H) were deposited using reactive magnetron sputtering. Dual targets of silicon and germanium were sputtered in an argon + hydrogen atmosphere using rf excitation. Films with x = 0.4 were deposited as a function of substrate temperature and hydrogen partial pressure, and were evaluated by dark and photoconductivity, infrared absorption, and optical transmission. Photosensitivity reached a maximum value of about 5000 between 150 and 200 °C. Using the stretching modes in the region of 2000 cm-1, the hydrogen bonding was characterized in terms of the preferential attachment ratio (PA), which represents the ratio of H bonded to silicon to that bonded to germanium. The PA shows a systematic increase with increasing temperature, independent of hydrogen partial pressure. The interplay between thermodynamic and kinetics effects in determining PA and film quality will be discussed.

Effect of Magnetron Discharge Power and N2 Flow Rate for Preparation of TiCrN Thin Film

Titanium Chromium Nitride (TiCrN) multilayer coatings on cutting tools, press molds and dies can be used to prolong their life cycle because of their superior corrosion and oxidation resistance. We investigated on three effecting conditions, which are the magnetron discharging powers of Ti, Cr targets and N2 flow rate. TiCrN multilayer coatings were prepared by dual DC magnetron sputtering, and their crystallography and microstructure were investigated. The crystalline structures were obtained the cubic and mixed phase of Ti0.5Cr0.5N with the mean lattice parameters of a = b = c = 4.238Å and TiCrN2 with mean lattice parameters of a = b = c = 4.1835Å for the condition of discharging powers on Ti and Cr target, respectively. However, the N2 flow rate condition, the orthorhombic oriented structure had been added to the structure with the mean lattice parameters of a = 2.962Å, b = 4.130Å and c = 2.875Å. The morphology of TiCrN thin films show mean gain size ∼ 100–200nm, and the thickness of ∼1μm Cr-layer, ∼0.5μm CrN-layer and ∼2μm TiCrN-layer.

Antimicrobial Potential of Copper‐Containing Titanium Surfaces Generated by Ion Implantation and Dual High Power Impulse Magnetron Sputtering

AbstractThe application of antimicrobial surfaces to titanium alloy (Ti) implants would be beneficial to prevent implant‐associated infections of joint endoprostheses and osteosyntheses. Copper (Cu) could be advantageously applied for this purpose, since it exhibits a well‐known antimicrobial activity and is a trace element in the human body, i.e., it is non‐toxic in small concentrations. This approach was evaluated with two plasma‐based surface modification procedures: Implantation of Cu ions into Ti by means of plasma immersion ion implantation (PIII) and Coating of Ti surfaces with CuTi films by means of dual high power impulse magnetron sputtering (dual HiPIMS). In this manner, the surfaces could be equipped with various amounts of Cu, as it was analyzed by X‐ray photoelectron spectroscopy (XPS). The surfaces released up to 8 mmol · L−1 of Cu within 24 h, measured with atomic absorption spectroscopy (AAS). Hence, the surfaces possessed an antimicrobial potential against typical infect‐associated bacteria (Staphylococcus aureus). Surfaces with a higher Cu release prepared by HiPIMS technique revealed a higher antimicrobial effect, while surfaces implanted by PIII were less cytotoxic to osteoblasts (MG‐63 cells). These results show that Cu doped and coated implants could be useful for prevention and therapy of implant‐associated infections.

Dynamic Study of Dual High-Power Impulse Magnetron Sputtering Discharge by Optical Emission Imaging

Fast optical emission imaging was employed for dynamic study of dual-high-power impulse magnetron sputtering discharge. The sputtering sources were equipped with reversed polarity of magnets, i.e., so-called closed magnetic field between magnetrons. Plasma is confined in closed magnetic field between targets alternately employed as cathode/anode. This type of magnetic confinement affects the transport of electrons and also the ionization processes of neutral particles present in the plasma, as will be shown in this paper.

Deposition of alumina thin film by dual magnetron sputtering: Is it γ-Al2O3?

Alumina thin films were deposited by reactive dual magnetron sputtering at 550°C on cemented carbide substrates. A Young’s modulus of 315GPa and a Vickers hardness of 2348 were determined by nanoindentation and were compared to reference materials. The crystal structure of such films is usually referred to as γ-Al2O3; however, the crystal structure of cubic γ-Al2O3 is not well defined, not even for bulk materials. The alumina grain size of the films was about 50nm as measured by dark-field imaging in a transmission electron microscope. The energy-filtered electron diffraction patterns were segmented: one part showed an amorphous intensity distribution, not known for γ-Al2O3, the other part contained reflections arranged in rings, the brightest of which had lattice spacings of the (400) and (440) reflections of γ-Al2O3. Therefore, the structure of the thin films is referred to as pseudo γ-Al2O3. This nomenclature expresses that this phase is different from γ-Al2O3 but among the Al2O3 phases is most closely related to this phase. Differences between the two crystal structures are highlighted and discussed with respect to lattice spacings, intensities of the various reflections, chemical composition and other physical properties. The pseudo γ-Al2O3 films contained an Al/Ar mole fraction ratio of about 17 as determined by energy-dispersive X-ray spectroscopy.

Corrosion Behavior of Cr(Si)N/301 Stainless Steel System

In this paper, the electrochemical behavior of Cr(Si)N coatings deposited on AISI 301 stainless steel (SS) substrate is investigated. Cr(Si)N films with different Si contents were prepared by dual magnetron sputtering. Potentiodynamic polarization measurements were carried out in NaCl 1% solution to evaluate resistance to localized and general corrosion. These measurements were performed on Cr(Si)N coatings deposited on SS and glass substrates, using a customized electrochemical cell, with the purpose to determine the contribution of SS to the electrochemical response of the coating/SS system. The morphology, composition and microstructure of the surface layers were examined by complementary characterization techniques including XRD, ERD, and SEM. It has been shown that the Cr(Si)N coatings improved significantly the pitting resistance of SS with not pits observed up to 1000 mV anodic polarization as compared to bare SS where the pitting potential was 330 mV. Moreover, the polarization curves of the coated SS exhibited passive-transpassive behavior with slight improvement in the corrosion properties as Si content is increased. This response is the result of electrochemical reactions at the Cr(Si)N/electrolyte interface as demonstrated by the polarization measurements on the coating/glass system.

Studies of Hydroxyapatite Thin Coating Produced by Dual RF Magnetron Sputtering for Biomedical Applications

In this present work, we characterize HAp thin films deposited by dual magnetron sputtering device DMS on silicon (Si/HAp). The sputtering RF power was varied from 90 watts to 120 watts and deposition times from 60 to 180 minutes. The argon and oxygen pressure were fixed at 5.0 mTorr and 1.0 mTorr, respectively. Grazing incidence X-ray diffraction (GIXRD) from synchrotron radiation, infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used for the structural characterization. At lower deposition times, a crystalline phase with preferential orientation along apatite (002) and a disordered nanocrystalline phase were identified. The coating crystallinity was improved with the increase of the deposition time besides the sputtering power.