Impulse Magnetron Sputtering Deposition Research Articles

High-Power Impulse Magnetron Sputter Deposition of Ag on Self-Assembled Au Nanoparticle Arrays at Low-Temperature Dewetting Conditions.

Plasmons have facilitated diverse analytical applications due to the boosting signal detectability by hot spots. In practical applications, it is crucial to fabricate straightforward, large-scale, and reproducible plasmonic substrates. Dewetting treatment, via applying direct thermal annealing of metal films, has been used as a straightforward method in the fabrication of such plasmonic nanostructures. However, tailoring the evolution of the dewetting process of metal films poses considerable experimental complexities, mainly due to nanoscale structure formation. Here, we use grazing-incidence small- and wide-angle X-ray scattering for the in situ investigation of the high-power impulse magnetron sputter deposition of Ag on self-assembled Au nanoparticle arrays at low-temperature dewetting conditions. This approach allows us to examine both the direct formation of binary Au/Ag nanostructure and the consequential impact of the dewetting process on the spatial arrangement of the bimetallic nanoparticles. It is observed that the dewetting at 100 °C is sufficient to favor the establishment of a homogenized structural configuration of bimetallic nanostructures, which is beneficial for localized surface plasmon resonances (LSPRs). The fabricated metal nanostructures show potential application for the surface-enhanced Raman scattering (SERS) detection of rhodamine 6G molecules. As SERS platform, bimetallic nanostructures formed with dewetting conditions turn out to be superior to those without dewetting conditions. The method in this work is envisioned as a facile strategy for the fabrication of plasmonic nanostructures.

High-power impulse magnetron sputter deposition of TiBx thin films: Effects of pulse length and peak current density

We report on a systematic study of the effect of pulse length (ton=25−200μs), and peak target current density (JT,peak=0.25−2.0A/cm2) during HiPIMS deposition of AlB2-phase TiBx thin films from a TiB2 target at a pressure of pAr=1.33Pa(10mTorr) and substrate temperature Ts=500°C. All films are under-stoichiometric with B/Ti = 1.36–1.89, with the higher values corresponding to longer pulses and higher JT,peak values. While the deposition flux, including both ions and neutrals, in general increases with increasing ton and JT,peak, the Ti+ ion flux saturates, resulting in the higher B/Ti values under these conditions. Thus, the relative amount of Ti ionization, and the degree to which these ions are guided toward the substrate by magnetic fields, are main modulators determining the composition of TiBx thin films.

Influence of Voltage, Pulselength and Presence of a Reverse Polarized Pulse on an Argon–Gold Plasma during a High-Power Impulse Magnetron Sputtering Process

This work aims to provide information about the deposition of gold via bipolar high-power impulse magnetron sputtering (HIPIMS) in order to identify suitable process parameters. The influences of voltage, pulse length and the kick-pulse on an argon–gold plasma during a bipolar high-power impulse magnetron sputtering deposition process were analysed via optical emission spectroscopy (OES) and oscilloscope. The voltage was varied between 700 V and 1000 V, the pulse length was varied between 20 µs and 100 µs and the process was observed once with kick-pulse and once without. The influence of the voltage on the plasma was more pronounced than the influence of the pulse width. While the intensity of several Au I lines increased up to 13-fold with increasing voltages, only a less-than linear increase in Au I brightness with time could be identified for changes in pulse length. The intensity of excited argon is only minimally affected by changes in voltages, but follows the evolution of the discharge current, with increasing pulse lengths. Contrary to the excited argon, the intensity emitted by ionized argon grows nearly linearly with voltage and pulse length. The reverse polarised pulse mainly affects the excited argon atoms in the plasma, while the influence on the ionized argon is less pronounced, as can be seen in the the spectra. Unlike the excited argon atoms, the excited gold atoms appear to be completely unaffected by the kick-pulse. No ionization of gold was observed. During the pulse, a strong rarefaction of plasma takes place. Very short pulses of less than 50 µs and high voltages of about 1000 V are to be preferred for the deposition of gold layers. This paper offers a comprehensive overview of the gold spectrum during a HIPIMS process and makes use of optical emission spectroscopy as a simple measuring approach for evaluation of the reverse polarized pulse during a bipolar process. Future uses of the process may include the metallization of polymers.

Understanding ion and atom fluxes during high-power impulse magnetron sputtering deposition of NbCx films from a compound target

A combination of time-averaged mass spectroscopy (MS), time-averaged optical emission spectroscopy (OES), and plasma transport modeling was employed to understand the transport processes of ions and atoms in high-power impulse magnetron sputtering discharges resulting in changes in the stoichiometry of NbCx films during their deposition from a stoichiometric NbC compound target at different repetition frequencies and duty cycles. Mass spectrometry showed that the fluxes of ions originating from the elements of the target increase with increasing pulse power density (and decreasing pulse length) due to an increasing electron density and, thus, electron-impact ionization probability. Due to the higher ionization energy and much lower ionization cross section of C (compared to Nb), it was found that the contribution of C+ ions to the deposition flux is practically negligible. Additionally, OES tracked the densities of ions and atoms at different distances from the target. The OES analysis revealed that the atom densities decreased as the pulse power density increased. In contrast, the ion densities exhibited an increase, which is consistent with the findings of MS. Using the data from MS, OES, and modeling, we were able to estimate the fluxes of atoms to the substrate. Our observations demonstrated a transition from C-rich toward Nb-rich flux of film-forming species with increasing pulse power density, corresponding to changes in the film composition. We further discuss the role of internal plasma processes that are responsible for this transition.

Low-cycle fatigue behavior of zirconium fuel cladding with Cr coatings deposited by High-power Impulse Magnetron Sputtering

In this paper, the work reports on finding of an experimental investigation of the low cycle fatigue performance of Cr-coated zirconium fuel cladding. Cr coatings were fabricated by utilizing High-power Impulse Magnetron Sputtering (HiPIMS) and Direct Current Magnetron Sputtering (DCMS) deposition techniques, respectively. The experimental results have indicated that, due to the different discharge characteristics of DCMS and HiPIMS, the microstructure and mechanical performances of the deposited Cr coating are significantly different. The film morphology alter from columnar for DCMS-Cr coating to dense for HiPIMS-Cr coating, and the hardness of HiPIMS-Cr coating is higher than the values of DCMS-Cr coating. The low cycle fatigue performance of HiPIMS-Cr coated zirconium fuel cladding is better than that of DCMS-Cr coated ones, which revealed that the dense Cr coating benefitted the low-cycle fatigue life of the zirconium alloy cladding tube.

The Behavior of TiAlN and TiAlCrSiN Films in Abrasive and Adhesive Tribological Contacts

Chromium and silicon are often introduced to increase the performance of TiAlN hard coatings in dry tribological contacts. The addition of Cr and Si during a high-power impulse magnetron sputtering (HiPIMS) deposition process leads to high-quality TiAlCrSiN films. In this paper, the analysis of friction and wear of these films is conducted by oscillation tribometry under dry conditions with a subsequent mapping of the surface topography. Both abrasion- and adhesion-dominated conditions are realized using different steel counter bodies. Oscillation-frequency-dependent experiments show a significant impact of the compositional variation on friction and wear. It is shown that the TiAlCrSiN coating investigated has a higher coefficient of friction and a lower wear resistance compared to counterparts made of 100Cr6. The friction coefficient could be reduced by using a V2A counterpart. The results can be understood in terms of a reduced adhesion of both oxidic and metallic wear debris at the TiAlCrSiN surface. The study provides valuable progress towards the development of advanced cutting tools, e.g., for stainless steel.

On the surface biasing effectiveness during reactive high-power impulse magnetron sputter deposition of zirconium dioxide

In this study, we investigate the effect of surface biasing during high-power impulse magnetron sputter deposition of non-conductive zirconium dioxide films on substrates with different capacitances. We employ reactive high-power impulse magnetron sputtering to deposit ZrO2 films using a circular Zr target in a pure oxygen atmosphere. The deposition experiments are conducted on two types of substrates: high-capacitance (thin thermally grown SiO2 on Si) and low-capacitance (soda-lime glass). By varying the time shift between the target voltage pulse and the negative substrate bias voltage pulse, we analyze the impact on the preferred crystal orientation of the deposited ZrO2 films and the deposition rate. We measure the current and voltage waveforms during the deposition process and utilize a surface charging model to understand the charging behavior of the growing film. Additionally, time- and energy-resolved ion mass spectra are measured to gain insights into the ion behavior during film growth. Our results demonstrate that energetic ion bombardment and appropriate timing of substrate biasing can influence the crystal orientation of ZrO2 films, favouring specific orientations over others. We also explain the different behavior observed on low- and high-capacitance substrates.

(AlCrNbSiTi)N/TiN multilayer films designed by a hybrid coating system combining high-power impulse magnetron sputtering and cathode arc deposition

We designed a hybrid physical vapor deposition coating system equipped with high-power impulse magnetron sputtering (HiPIMS) and cathode arc deposition (CAD) systems. With this technique, we fabricated (AlCrNbSiTi)N/TiN multilayer films consisting of alternating layers of (AlCrNbSiTi)N, a high-entropy alloy nitride (HEAN) with enhanced thermal stability, and TiN, a material known for its high hardness. For this hybrid coating system, a new nucleation and growth model was proposed to explain the thin film deposition phenomenon. Film growth occurred through a self-induced repeated nucleation mechanism. The effects of the modulation period on the microstructural, mechanical, and oxidation resistance properties of the coatings were investigated using scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and nanoindentation. All coatings exhibited a B1-NaCl-type face-centered cubic crystal structure. High-resolution TEM imaging revealed misfit dislocations between the HEAN and TiN layers and low-angle boundary dislocations between the subgrains. The 64-layer coating displayed outstanding mechanical, oxidation resistance, and tribological properties compared with those of previously reported multilayer coatings. The plastic deformation index, H3/E2, of the mono- and multilayer coatings increased from 0.17 to 0.37 GPa. After oxidation at 800 °C for 2 h in an ambient atmosphere, the thickness of the oxidation layer decreased from 1228 to 85 nm. Furthermore, the maximum flank wear of a coated tool after the milling test was less than that of the uncoated tool (201 vs. 528 μm), suggesting a large improvement in lifetime.

Insights on film growth conditions on a floating substrate during reactive Ar/O2 bipolar high power impulse magnetron sputter deposition

We report several effects found in reactive bipolar high-power impulse magnetron sputtering (abbreviated as bipolar HiPIMS or BPH) discharges at the substrate level. The role of the negative peak current and the positive pulse voltage, U, on the deposition flux at the electrically insulating substrate is discussed and the results are compared to conventional DC discharges. In particular, the normalized energy flux, ϕ n , delivered to the substrate is found higher under BPH conditions at U = +300 V ( eV·nm−3) as compared to the HiPIMS ( eV·nm−3) and DCMS ( eV·nm−3) regimes which is assumed to be provoked by an intensification of the positive ion bombardment. Accordingly, the mean energy and the count of positively charged metal and gaseous ions increase in line with U as measured by energy-resolved mass spectrometry. Contrariwise, our analysis has shown a significant decrease (≈20 %) of negative oxygen ion count under BPH conditions.

Diblock copolymer pattern protection by silver cluster reinforcement.

Pattern fabrication by self-assembly of diblock copolymers is of significant interest due to the simplicity in fabricating complex structures. In particular, polystyrene-block-poly-4-vinylpyridine (PS-b-P4VP) is a fascinating base material as it forms an ordered micellar structure on silicon surfaces. In this work, silver (Ag) is applied using direct current magnetron sputter deposition and high-power impulse magnetron sputter deposition on an ordered micellar PS-b-P4VP layer. The fabricated hybrid materials are structurally analyzed by field emission scanning electron microscopy, atomic force microscopy, and grazing incidence small angle X-ray scattering. When applying simple aqueous posttreatment, the pattern is stable and reinforced by Ag clusters, making micellar PS-b-P4VP ordered layers ideal candidates for lithography.

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.

On the role of ion potential energy in low energy HiPIMS deposition: An atomistic simulation

We study the effect of the so-called ion potential or non-kinetic energies of bombarding ions during ionized physical vapor deposition of Cu using molecular dynamics simulations. In particular we focus on low energy high power impulse magnetron sputtering (HiPIMS) deposition, in which the potential energy of ions can be comparable to their kinetic energy. The ion potential, as a short-ranged repulsive force between the ions of the film-forming material and the surface atoms (substrate and later deposited film), is defined by the Ziegler-Biersack-Littmark potential. Analyzing the final structure indicates that, including the ion potential leads to a slightly lower interface mixing and fewer point defects (such as vacancies and interstitials), but resputtering and twinning have increased slightly. However, by including the ion potential the collision pattern changes. We also observed temporary formation of a ripple/pore with 5 nm height when the ion potential is included. The latter effect can explain the pores that have been observed experimentally in HiPIMS deposited Cu thin films by atomic force microscopy.

Study of TiAlN coatings deposited by continuous high power magnetron sputtering (C-HPMS)

TiAlN coatings are widely used in high-speed cutting, machining, and other high-temperature applications. However, owing to the high cathode temperature, large amounts of metal droplets are produced during fabrication in arc ion plating (AIP) and the shadowing effect introduces particles and voids in the coatings. Continuous high-power magnetron sputtering (C-HPMS) can produce high ionization rates similar to high-power impulse magnetron sputtering (HiPIMS) and high deposition rates similar to AIP. In this work, the morphology, adhesion strength, tribological properties, corrosion resistance, and oxidation resistance of Al-rich TiAlN coatings prepared by C-HPMS are studied systematically. Higher Al and Ti ionization rates and deposition rates are achieved by increasing the power density. The largest deposition rate is 0.45 μm/min and coating hardness is 34.4 GPa. More importantly, no particles are produced as manifested by small surface roughness of 17.8 nm.

Characterization of silicon oxynitride films deposited by a high-power impulse magnetron sputtering deposition technique.

In this research, silicon oxynitride films were prepared by high-power impulse magnetron sputtering with 45/955 pulse on/off time. The extinction coefficient was smaller than 1×10-3 from 250 to 700 nm after introducing 2.2 sccm O2 gas at room temperature. A three-layer of AlF3/SiOxNy AR coating was designed and fabricated on double-sided quartz, and a high transmittance of 99.2% was attained at 248 nm. The silicon oxynitride films deposited at 350°C had the better mechanical and optical properties in the visible range. The hardness of all deposited films was greater than 19 GPa, and the greatest hardness could reach to 29.8 GPa. A film structure of six-layer transparent hard coating/glass/four-layer AR coating was designed and deposited. Its average transmittance was 96.0% in the visible range, while its hardness was 21 GPa and its surface roughness was 0.23 nm.

Angular-dependent deposition of MoNbTaVW HEA thin films by three different physical vapor deposition methods

Within this work, MoNbTaVW high entropy alloy thin films were synthesized by dc magnetron sputter deposition, high power impulse magnetron sputtering and cathodic arc deposition to study the influence of the growth conditions on structure and properties of the films. For deposition angles ranging from 0 to 90°, the deposition rate, chemical composition, morphology and crystal structure as well as the mechanical properties were analyzed. All films showed the formation of a solid solution with body centered cubic structure regardless of deposition angle and method, whereas higher energetic growth conditions were beneficial for improved mechanical properties.

Effect of composition and surface characteristics on fuel retention in beryllium-containing co-deposited layers

We have investigated retention of deuterium in beryllium-containing, laboratory-made films whose properties resemble co-deposits observed on JET-ILW or predicted for ITER. The samples were prepared using High Power Impulse Magnetron Sputtering and Thermo-ionic Vacuum Arc Deposition. We have observed that retention depends on the flux of D atoms on the growing film, but even more prominently on its composition, structure, and morphology. Especially, inclusion of carbon by 10–15 at% in the layers can increase retention by a factor of 2–10. This we attribute to increasing number of defects as well as aromatic and aliphatic C–D bonds in the samples. Other impurities do not significantly alter the D inventory while more D is retained in samples with rough or highly modified surfaces. Our results show that reproducing the reported D concentrations of ∼5 at% in JET-ILW-like deposits requires keeping the sample temperature at 100–200 °C during the production phase and optimizing the uniformity of deposition fluxes. Data from Be–D samples further indicate that fuel retention in more ITER-relevant co-deposits would be around 1–2 at%.

High-power impulse magnetron sputtering deposition of high crystallinity vanadium dioxide for thermochromic smart windows applications

Vanadium dioxide (VO2) is one of the most promising thermochromic materials for smart windows application because of its ability to modulate infrared radiation (IR) by reversibly transform from semiconductor-like monoclinic VO2 (M) to metallic rutile VO2 (R) above its transition temperature (τc). Despite the promising potential, VO2 has not been commercialized due to various technical difficulties which hinder its feasibilities outside of laboratories environment. One of those is the efficiency of high quality VO2 thin-film fabrication process. In this paper, we presented a method utilizing high-power impulse magnetron sputtering (HiPIMS) to deposit VO2 thin-film on a commercial material such as soda-lime glass substrate with a respectable deposition rate of 5.7 nm/min. The VO2 deposited on soda-lime glass exhibits excellent crystallinity and thermochromic properties (highest luminous transmission Tlum ≈ 30.4%, and solar modulation ΔTsol ≈ 12%) in comparison with similarly prepared VO2 on high temperature glass and quartz substrates. The high crystallinity rendered by short deposition duration and high ionization in HiPIMS process opens opportunities to apply high quality VO2 thin-film onto a variety of substrate more efficiently.

High-power impulse magnetron sputter deposition of TiBx thin films: Effects of pressure and growth temperature

Titanium boride, TiBx, thin films are grown in pure Ar discharges by high-power impulse magnetron sputtering (HiPIMS) from a compound TiB2 target. Film compositions are determined by time-of-flight elastic recoil detection analysis and Rutherford backscattering spectrometry as a function of deposition temperature (Ts = 25–900 °C) and Ar pressure (pAr = 0.67–2.67 Pa, 5–20 mTorr). For reference, films are also grown by direct current magnetron sputtering (dcMS) under similar conditions. The HiPIMS waveform, average target power PT, and resulting film compositions are strongly dependent not only on pAr, but also on Ts. At high pressures the effect of varying Ts on PT is minimal, while at lower pAr the effect of Ts is more pronounced, due to substrate-temperature-induced gas rarefaction. Films grown by HiPIMS at 0.67 Pa are understoichiometric, with B/Ti = 1.4–1.5, while at 2.67 Pa, B/Ti decreases from 2.4 to 1.4 as Ts increases from 25 to 900 °C. dcMS-deposited films are overstoichiometric (B/Ti ≃ 3) when grown at low pressures, and near-stoichiometric (B/Ti ≃ 1.9–2.2) for higher pAr. All experimental results are explained by differences in the ionization potentials of sputtered Ti and B atoms, together with pAr- and Ts -dependent gas-phase scattering.

The comparative study of electrical, optical and catalytic properties of Co3O4 thin nanocrystalline films prepared by reactive high-power impulse and radio frequency magnetron sputtering

This paper deals with the investigation of optical and electrical properties of Co3O4. Their impact on catalytic activity in ethanol dehydrogenation is observed. The change in conductivity is provided by intentionally heating the samples in-situ, variation of oxygen flow rate, introduction of the forming gas (10% H2 in N2) and the application of different deposition regimes. Pure Co3O4, as well as deposited catalysts under a forming gas atmosphere are studied. The deposition of the samples on glass and stainless steel substrates is carried out by means of magnetron sputtering. Both radio-frequency and high power impulse magnetron sputtering deposition technologies are applied. By means of these deposition regimes we managed to obtain films with different conductivity and crystalline structure. The morphology of the films is studied by scanning electron microscopy. The crystalline structure and the surface chemical composition of Co3O4 are investigated using X-ray diffraction and X-ray photoelectron spectroscopy. Electrical and optical properties of catalysts are studied by resistance and optical spectroscopy measurements. The catalytic activity of the films is tested on the reaction of ethanol dehydrogenation by means of selected ion flow-drift tube mass spectrometry.

Bioapplication of TiN thin films deposited using high power impulse magnetron sputtering

Titanium nitride (TiN) has been deposited on TiAl6V4 using a reactive high-power impulse magnetron sputtering (HiPIMS) deposition technique and investigated for use as a bio-coating. During HiPIMS deposition, the peak current of the Ti target was varied from 75 to 175 A through adjusting the frequency from 200 to 100 Hz. Plasma diagnosis shows that, as compared to DC sputtering deposition process, all the peak currents and maximum powers are higher in the HiPIMS deposition process. The high peak current and maximum power in the HiPIMS process help the ionization of the sputtered Ti and also increase the amount of N2+ species in the plasma, hence leading to a high N/Ti ratio of the TiN film. Therefore, the resulting TiN exhibits great corrosion resistance in simulated bodily fluid and shows excellent cell viability against the osteoblast-like MG-63 cells among other TiN samples.