High Power Impulse Magnetron Sputtering Technique Research Articles

Characterization of Ta/TaN multi-graded thin film coating synthesized by HiPIMS technique

Background The significance of multi-graded thin film coatings finds its devastating relevance in tribological applications due to their unique properties of friction and wear. This research aims to synthesize and characterize the multi-graded Ta/TaN thin film coatings on AISI 52100 steel, employing the high-power impulse magnetron sputtering technique. Methods The investigation includes the microstructure, coating thickness, elemental composition, microhardness, and tribological performance using scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDS), x-Ray diffraction analysis (XRD), microhardness tester, and pin-on-disc tester, respectively. Results Based on this systematic study, a noticeable reduction in the coefficient of friction was obtained due to the improved adhesion value exhibited by the multi-graded coating on the substrate. Conclusions The overall findings highlight the potential suitability of the multi-graded Ta/TaN thin film coating within the field of tribological applications.

Dense Cr/GLC multilayer coating by HiPIMS technique in high hydrostatic pressure: Microstrusctural evolution and galvanic corrosion failure

The dense Cr/GLC multilayer coatings were fabricated by high power impulse magnetron sputtering (HiPIMS) with various duty cycles. HiPIMS-deposited GLC coatings with high density displayed the lower corrosion current density by five times than DC- deposited GLC, due to the higher C+ ionization rate and larger incident ions energy. Noted that, after 425 h immersion with 15 MPa, though a laminar-like spallation occurred in the Cr/GLC interfaces instead of the coating/substrate interfaces, the lower galvanic corrosion current density was particularly achieved at 2.04 × 10−9 A·cm−2 for the HiPIMS-coatings with reduced porosity, emulating an excellent tolerance of long-term corrosion resistance for deep-sea.

Mechanical and Thermal Properties of W-Ta-B Coatings Deposited by High-Power Impulse Magnetron Sputtering (HiPIMS).

We present the deposition and characterization of tungsten-tantalum diboride (W,Ta)B2 coatings prepared by the high-power impulse magnetron sputtering technique. We evaluated the influence of pulse duration and substrate bias on the properties of (W,Ta)B2 films. A high hardness of up to 35 GPa measured by nanoindentation was simultaneously obtained with good elastic properties. Changing the pulse duration greatly affected the B/(W+Ta) atomic ratio, which influenced the properties of the coatings. The deposited films are thermally stable at up to 1000 °C in vacuum and are able to withstand oxidation at 500 °C.

High-power impulse magnetron sputter deposition for enhanced optical transmittance and electrical conductivity of flexible coating

A transparent conductive material, mostly transparent conductive oxide (TCO), is essential and indispensable for flexible electronics. Different from the conventional, single-layered TCO, multilayered oxide/metal/oxide (OMO) structures have been investigated as a promising alternative. The metal layer serves to reduce the electrical resistance of the oxides and the transparency is enhanced by suppressing the reflection from middle metal layer and substrate. Meanwhile, due to the limited temperature tolerance of the flexible polymeric substances, high-power impulse magnetron sputtering technique has been used to deposit the OMO structures at a substrate temperature lower than 70 °C. Two different OMO multilayered structures, including ZnO/Ag/ZnO and ZnO/Cu/ZnO, are deposited on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), and soda lime glass. The effects of layer thickness and metal type on the transmission and resistivity of the obtained OMO structures are investigated. The correlation between OMO structure characteristics and the resulting photoelectric properties are also studied. A 35-nm ZnO/20-nm Ag/30-nm ZnO having excellent resistivity of 6.2 × 10−5 Ωcm (7.2 Ωsq−1) and transmittance of 87.7% is demonstrated. Furthermore, after 3000 bending cycles, the multilayered OMOs on PET and PEN retain their superior electrical properties, exhibiting resistivity of 3.8 × 10−4 and 1.3 × 10−4 Ωcm, respectively.

Improvement of c-axis (002) AlN crystal plane by temperature assisted HiPIMS technique

PurposeThis study aims to investigate the effect of temperature applied at the initial deposition of Aluminium Nitride (AlN) thin-film on a silicon substrate by high-power impulse magnetron sputtering (HiPIMS) technique. Design/methodology/approachHiPIMS system was used to deposit AlN thin film at a low output power of 200 W. The ramping temperature was introduced to substrate from room temperature to maximum 100°Cat the initial deposition of thin-film, and the result was compared to thin-film sputtered with no additional heat. For the heat assistance AlN deposition, the substrate was let to cool down to room temperature for the remaining deposition time. The thin-films were characterized by X-ray diffraction (XRD) and atomic force microscope (AFM) while the MIS Schottky diode characteristic investigated through current-voltage response by a two-point probe method. FindingsThe XRD pattern shows significant improvement of the strong peak of the c-axis (002) preferred orientation of the AlN thin-film. The peak was observed narrowed with temperature assisted where FWHM calculated at 0.35° compared to FWHM of AlN thin film deposited at room temperature at around 0.59°. The degree of crystallinity of bulk thin film was improved by 28% with temperature assisted. The AFM images show significant improvement as low surface roughness achieved at around 0.7 nm for temperature assisted sample compares to 3 nm with no heat applied. Originality/valueThe small amount of heat introduced to the substrate has significantly improved the growth of the c-axis AlN thin film, and this method is favorable in the deposition of the high-quality thin film at the low-temperature process.

Comparative investigations of DCMS/HiPIMS reactively sputtered WO3 thin films for photo-electrochemical efficiency enhancements

Abstract In this work, different sets of WO3 thin films were separately deposited and compared based on reactive direct current magnetron sputtering (DCMS), and reactive high-power impulse magnetron sputtering (HiPIMS) techniques. Both sets of as-deposited WO3 thin films also underwent a thermal annealing treatment at 400 °C for 2 h in an air ambience for thorough investigations. After annealed treatments, the HiPIMS technique as observed from XRD and Raman spectroscopy showed well-pronounced WO3 film structures, and those as observed from the ellipsometry confirmed the increased film density based on high refractive index. The WO3 thin film prepared by the HiPIMS technique was found to have a higher photocurrent from water oxidation, and more stability than the prepared by DCMS technique due to the preferred crystalline structure with exposed highly active (002) facets. This work provides the potential of HiPIMS deposition technique to deposited semiconductor film for energy and environmental applications as well.

In vitro and in vivo biocompatibility study of surface modified TiN deposited on Ti6Al4V using high-power impulse magnetron sputtering technique

Although Ti6Al4V alloy is commonly used as a surgical implant, the toxicity of vanadium is always a serious concern. As a stable and protective coating for Ti6Al4V, TiN deposited using a high-power impulse magnetron sputtering (HiPIMS) technique exhibits great polarization resistance in simulated body fluid and shows excellent cell viability of osteoblast-like MG63 cell. Herein, we report further study on the in vitro and in vivo biocompatibility of the HiPIMS-deposited TiN coatings with various surface modifications. For the in vitro study, the effect of O2 plasma treatment, acrylamide (AAm) graft polymerization, and bone morphogenetic protein-2 (BMP2) immobilization on the viability of osteoblast-like MG63 cell were examined using the MTT assay. For the in vivo study, the pro-inflammatory cytokines and skin pathology in mice using subcutaneous sensitivity test were conducted. In vitro investigation shows that cell viability is significantly improved for TiN having BMP2 on the surface. When BMP2 was coated on bare TiN, the MG63 cell proliferation decreases with time. However, with surface pre-treatment of TiN using O2 plasma and AAm grafting, BMP2 coated TiN exhibits increasing MG63 cell proliferation with time. Likewise, in vivo investigation shows such sample has enhanced wound healing capability, significant increase of the body weights, obvious decrease of pro-inflammatory cytokines, and improved skin section structure, as compared to the bare Ti6Al4V. The pathological result shows that the TiN treated with O2 plasma and AAm graft polymerization, and with a surface BMP2 layer gives long-term stable immobilization of BMP2 and the best in vivo biocompatibility among all the samples.

N doped ZnO (N:ZnO) film prepared by reactive HiPIMS deposition technique

In this paper, we report a nitrogen (N) doped zinc oxide (N:ZnO) film grown by the reactive high power impulse magnetron sputtering (HiPIMS) technique on glass substrates, where nitrogen gas (N2) is used as the N source. The proposal is to investigate the influence of process parameters on the alteration of the N:ZnO film from n- to p-type conductivity and the stability of the p-type behavior. It is obtained that the n- or p-type behavior of the as-deposited N:ZnO film is affected by the N2 flow rate, deposition temperature, and inductively coupled plasma (ICP) assistance, of which the ICP assistance had a great impact. It is noticed that, owing to the improved ionization rate of the N2 dopant by ICP, the N:ZnO film almost totally prefers to exhibit p-type behavior. Based on the measurement by temporal resolution optical emission spectroscopy, the components in plasma are obtained and the ion reaction in film growth is confirmed: a high concentration of active N+ in the ICP-assisted plasma reacts with sputtered Zn+ in vapor to form No defect in the p-type N:ZnO film. We then forecast that a stable p-type N:ZnO film can be grown using the HiPIMS technique.

The Influence of AlN Intermediate Layer on the Structural and Chemical Properties of SiC Thin Films Produced by High-Power Impulse Magnetron Sputtering.

Many strategies have been developed for the synthesis of silicon carbide (SiC) thin films on silicon (Si) substrates by plasma-based deposition techniques, especially plasma enhanced chemical vapor deposition (PECVD) and magnetron sputtering, due to the importance of these materials for microelectronics and related fields. A drawback is the large lattice mismatch between SiC and Si. The insertion of an aluminum nitride (AlN) intermediate layer between them has been shown useful to overcome this problem. Herein, the high-power impulse magnetron sputtering (HiPIMS) technique was used to grow SiC thin films on AlN/Si substrates. Furthermore, SiC films were also grown on Si substrates. A comparison of the structural and chemical properties of SiC thin films grown on the two types of substrate allowed us to evaluate the influence of the AlN layer on such properties. The chemical composition and stoichiometry of the samples were investigated by Rutherford backscattering spectrometry (RBS) and Raman spectroscopy, while the crystallinity was characterized by grazing incidence X-ray diffraction (GIXRD). Our set of results evidenced the versatility of the HiPIMS technique to produce polycrystalline SiC thin films at near-room temperature by only varying the discharge power. In addition, this study opens up a feasible route for the deposition of crystalline SiC films with good structural quality using an AlN intermediate layer.

Recent progress on high power impulse magnetron sputtering (HiPIMS): The challenges and applications in fabricating VO2 thin film

High power impulse magnetron sputtering (HiPIMS) is well known in modern physical vapor deposition (PVD) owing to its high peak power density, high degree of ionization, high plasma density and hence high ion flux towards the substrate that allows ones to deposit high quality thin films in comparison with conventional magnetron sputtering technology. The present short review on HiPIMS intends to provide readers with a summary of the current status of this emerging PVD technique: the developmental history, the plasma characterization, and the applications in hardness and functional thin film fabrications. Several items on the distinctive feature of HiPIMS, including self-sputtering mechanism, low deposition rate, arcing phenomenon and key factors of deposition process are reviewed in detail. To limit the scope, the emphasis is put on thermo-chromic VO2 thin film deposited by HiPIMS. Based on this typical issue, some classical ideas and approaches on fabrication of the functional thin films through HiPIMS technique are demonstrated.

XPS and XAS preliminary studies of diamond-like carbon films prepared by HiPIMS technique

X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) were employed for the investigations of diamond-like carbon (DLC) films prepared by highpower impulse magnetron sputtering technique (HiPIMS). The measurements were done ex-situ, i.e. the prepared DLC samples were exposed to air during transferring from the deposition to analysis chambers. It is inevitable that the surface of the samples was contaminated by absorbed air molecules. XPS analyses revealed that the main surface contaminants are carbon and oxygen, which introduce the difficulties for the determination of carbon species in the DLC films. In this work, a complementary XAS technique was used for analyzing carbon species in the DLC films. It was found that the DLC film contain more sp2 than sp3 carbon. The discrepancy in the sp2/sp3 ratio from the two techniques is different as a result of the difference in depth/surface sensitivity.

Influence of bias voltage on the microstructure, mechanical and corrosion properties of AlSiN films deposited by HiPIMS technique

AlSiN films were deposited with various bias voltages ranging from 0 V to - 150 V by high power impulse magnetron sputtering (HiPIMS) technique. The effects of bias voltage on the microstructure, mechanical and corrosion behavior were investigated. The AlSiN films exhibited an over-stoichiometric N content and both cubic and hexagonal AlN were observed in films. All deposited films showed a typical surface feature of granular structure and the cross-sectional images exhibited that all films possessed columnar structure, which was changed from coarse columnar to denser columnar structure with increasing the bias voltage. The AlSiN film deposited at - 150 V possessed the densest structure and exhibited the best mechanical properties, including hardness, toughness and nano-wear resistance. The corrosion test showed that all coated samples had better corrosion resistance compared to SUS304 in 3.5 wt.% NaCl solution and the AlSiN film deposited at bias voltage of - 150 V possessed the best corrosion resistance due to denser microstructure, which could act as a barrier layer for blocking the diffusion of corrosive substances.

Manufacturing and Characterization of a Carbon-Based Amorphous (a-CNX) Coating Material

A thick 400-micron amorphous carbon nitride (a-CNX) coating material was synthesized by means of plasma-enhanced chemical vapor deposition process. High-power impulse magnetron sputtering technique was used to sputter a pure graphite target plate in reactive argon (Ar), nitrogen (N2) and acetylene (C2H2) environment for depositing the composite coating. Structural and chemical/elemental composition of the a-CNX composite material was investigated by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and micro-Raman spectroscopy. The root-mean-square surface roughness (Sq) and structure were estimated by atomic force microscopy. Mechanical properties such as hardness and Young’s modulus (Oliver–Pharr method) at room temperature were characterized by Vickers micro-indentation test. Operational temperature test of the deposited a-CNX coating reveals that it can withstand up to 400 °C without cracking. An inverted shaker test, based on central impedance method, was adopted to investigate the dynamic damping property of the coating material, and it was found that the first bending mode damping lossfactor of the reported a-CNX coating is 0.015 ± 0.001 and corresponding loss modulus (Young’s modulus multiplied by lossfactor) is 0.234 ± 0.011 GPa.

Surface characteristics for the Ti[sbnd]Al[sbnd]N coatings deposited by high power impulse magnetron sputtering technique at the different bias voltages

High power impulse magnetron sputtering (HIPIMS) is the new PVD technique that has been widely used to deposit hard coatings. In this work, titanium-aluminum nitride (TiAlN) coatings were synthesized through using the HIPIMS technique with various bias voltages from −50 to −200 V. The influence of bias voltage on the microstructure, mechanical, and tribological properties of the TiAlN coatings were investigated. The results indicate that the Al content in TiAlN coatings decreased due to the selective re-sputtering. The preferred orientation altered from (111) to (200) and the peak shifted to lower 2θ values which occurred as the bias voltage increased. The coatings with the best mechanical and tribological properties were obtained at the bias voltage of −150 and −100 V respectively. The influence of coating texture, surface roughness, and residual stress on the properties of the coatings was discussed.

Influence of plasma pretreatment on the performance of industrial tungsten carbide coatings deposited at low temperature on 100Cr6 bearing steel substrates

Abstract The study concerns different surface pretreatment procedures of the 100Cr6 bearing steel substrates using DC magnetron sputtering and high-power impulse magnetron sputtering. The influence of the pretreatment technique on structure, adhesion and overall performance of the deposited tungsten carbide tribological coatings is characterized. The substrate pretreatment and deposition processes are maintained at process temperatures lower than 180 °C in order not to affect the intrinsic structural and mechanical properties of the bearing steel substrates. It is shown that the pretreatment method does not influence the structure and composition of the coatings. On the other hand, it strongly affects the surface structure and more important the adhesion and the tribological properties of the coatings. It is shown that the high-power impulse magnetron sputtering technique in combination with a high bias voltage can be a valuable tool for substrate surface pretreatment to obtain a good adhesion even at low process temperature.

Use of Cr Interlayer to Promote the Adhesion of SiC Films Deposited on Ti-6Al-4V by HiPIMS

In this paper, chrome (Cr) thin films were deposited and used as interlayer between SiC films and Ti-6Al-4V substrates. Films and interlayers were obtained by using HiPIMS (High Power Impulse Magnetron Sputtering) technique. Interlayers were growth for 5, 30, and 60 minutes. The films were analyzed with respect to morphology, stoichiometry, thickness, roughness, and adhesion. The results showed that the HiPIMS technique was efficient to produce dense thin films and that the adhesion increased with Cr thickness.

Properties of TiO2 films deposited on flexible substrates using direct current magnetron sputtering and using high power impulse magnetron sputtering

Mixture phases of anatase and rutile, TiO2 thin films are deposited on flexible polyethylene terephthalate (PET) substrates by direct current magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS), using a ceramic TiO2 target in an argon gas environment, at temperatures ranging from room to 150 °C. The Taguchi method for the design of a robust experiment, with an orthogonal array, a signal-to-noise ratio and an analysis of variance are used to analyze the performance characteristics of the deposition parameters. This study determines the effect of the deposition parameters, such as the dc power (W), the sputtering pressure (Pa) and the substrate temperature (°C) on the structural and photocatalytic characteristics of the TiO2 films. For both dcMS- and HiPIMS-grown films, the (110), (200) and (210) peaks of the rutile structure and the (200) peak of the anatase structure are observed. Compared to the coatings onto PET substrates using dcMS, the samples deposited using HiPIMS exhibited excellent photoinduced hydrophilicity and high photocatalytic activity. The contact angles are decreased to less than 4.1° after UV irradiation for 9 min, and the absorbance of the methylene blue aqueous solution is reduced to 0.3 for 240 min UV irradiation. Furthermore, the XRD diffraction peaks of the TiO2 films using HiPIMS become sharper and more intense, which demonstrates that the crystalline structure of the TiO2 films is improved. Higher visible-light photocatalytic efficiency was achieved with HiPIMS technique.

Influence of high power impulse magnetron sputtering pulse parameters on the properties of aluminum nitride coatings

The aluminum nitride thin film has recently gained importance due to its unique properties, which include good thermal and chemical stabilities as well as dielectric property. In this work, aluminum nitride thin films were fabricated using the high power impulse magnetron sputtering (HIPIMS) technique. Effects of duty cycle and pulse frequency of HIPIMS power on the microstructure and mechanical property evolution of AlN coatings were explored. The ionization ratio of Al+ species in HIPIMS plasma was characterized to be around 55%. The peak power density increased to 1.60kWcm−2 as duty cycle decreased to 3.5%. The deposition rate increased from 1.74 to 4.50nm/min as repetition frequency reached to 833Hz at a fixed duty cycle of 3.5%. Strong preferred orientation of hcp-AlN (002) was discovered for AlN films with lower oxygen contamination. In addition to the hcp-AlN phase, the α-Al2O3 phase was found when the oxygen concentration was higher than 3.0at.%. The hardness enhancement effect was brought by the HIPIMS technique. The hardness increased with decreasing duty cycle and increasing peak power density. Greater hardness of around 26.5 to 28.0GPa was achieved for the crystalline over-stoichiometric AlN thin film when the coating was fabricated using a 3.5% duty cycle. Meanwhile, the adhesion property was improved with increasing duty cycle and frequency. The AlN coating with both high hardness of 27GPa and adequate adhesion property was fabricated at a repetition frequency of 1250Hz and duty cycle of 3.5%.

Influence of negative bias voltage and deposition temperature on microstructure and properties of superhard TiB2 coatings deposited by high power impulse magnetron sputtering

It is critical to utilize the substrate bias voltage to attract the sputtered ions in high power impulse magnetron sputtering (HIPIMS) plasmas which contain a large amount of target ion species. In this work, superhard titanium diboride (TiB2) coatings were synthesized from TiB2 compound target by a HIPIMS technique at deposition temperatures of 200°C and 300°C, respectively. The substrate bias voltage was altered from 0V to −200V. The influence of the bias voltage at 200°C and 300°C on the chemical composition, phase structure, microstructure, surface morphology, mechanical and nanowear properties of the TiB2 coatings was investigated. The results indicated that the chemical composition and microstructure were significantly altered by increasing the bias voltage. At 200°C, the moderate bias voltage of −50V to −100V lead to enhanced ion energy and surface adatom mobility while the resputtering effect was induced as the bias voltage further increased from −100V to −200V. The TiB2 coating deposited at −100V exhibited the best mechanical and nanowear properties and lowest surface roughness. At 300°C, the continuous increase of the surface adatom mobility as the bias voltage increased from 0V to −200V acted as the dominant influence factor for the coating properties. The TiB2 coating with the best mechanical and nanowear properties and lowest surface roughness was obtained at −200V.

Effects of duty cycle and pulse frequency on the fabrication of AlCrN thin films deposited by high power impulse magnetron sputtering

High power impulse magnetron sputtering (HIPIMS) is a newly developed coating technology, characterized by its ultra-high peak current and peak power density to achieve unique thin film properties, such as high hardness, good adhesion and tribological performance. In this study, an AlCr alloy target was used to deposit AlxCr1−xN coatings on various substrates by the HIPIMS technique. The aim of this work was to systematically study the microstructure evaluation and mechanical properties of AlxCr1−xN coatings as a function of duty cycle and pulse frequency. The experimental results showed that the peak power density increased linearly as the duty cycle decreased from 5% to 2% at constant frequency of 1000Hz. A maximum peak power density of 2.76kWcm−2 was achieved at the duty cycle of 2% and repetition frequency of 833Hz. A mixture of cubic and hexagonal AlxCr1−xN phases was found for each coating. The x value of AlxCr1−xN thin films changed from 0.72 to 0.75 and showed no direct relationships with duty cycle and repetition frequency. The peak power density had great influence on the microstructure evolution and altered the microstructure from coarse columnar to fine columnar structure. Re-nucleation grains were also found between columnar grains. The hardness increased with increasing frequency at constant duty cycle of 2% and reached the optimum hardness of 39.9GPa at x=0.75. Good adhesion and wear resistance was observed for each coating. The critical load increased as the repetition frequency increased from 500 to 1250Hz at the same duty cycle of 2%. Since the wear resistance for each coating was excellent, the duty cycle and pulse frequency showed limited influence on the wear resistance of thin films.