Alloy Target Research Articles

Chemical Composition and Microstructure Characterization of High Purity CuMn Alloy for Integrated Circuit

High purity copper and copper alloy targets are the key supporting materials for the interconnection of integrated circuits in advanced processes. In this article, the chemical composition and microstructure of Cu-0.6wt%Mn alloy were characterized by means of Glow Discharge Mass Spectrometry, Inductive Coupled Plasma Emission Spectrometer, Optical Microscope and Scanning Electron Microscope. The results show that the total impurity content for Cu-0.69wt%Mn alloy is less than 1 ppm. The three key impurities contents of Ag and Fe and Si could meet the requirement of electronic materials for integrated circuits by use of high purity raw material and appropriate melting and casting methods. Mn content at different positions along the diameter direction fluctuates slightly between 0.66~0.72 wt%, and completely distributed uniformly in the Cu matrix without any trace of aggregation. Due to the influence of raw materials and casting technology, defects such as porosity and carbon inclusion are easy to appear in as-cast microstructure. Therefore, it is necessary to develop new casting mould and casting processing to improve the quality of ingots.

Microscopic evidences of nanocomposite structure in hard and optically transparent ternary AlSiN coating

In this work AlSiN ternary coatings were deposited by radio frequency magnetron sputtering in Ar/N2 reactive atmosphere. AlSi alloy target of composition 86:14 wt% has been used to deposit the coatings on float glass substrate by varying the Ar:N2 ratio i.e., 20:4, 20:6, 20:8, 20:13 and 20:15. The effect of different Ar:N2 ratio on microstructure, mechanical and optical property were studied using x-ray diffraction (XRD), stylus profilometry, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), High Resolution Transmission Electron Microscopy (HRTEM), UV–visible spectrometry and manoindentation. The XRD measurements show the formation h-AlN phase for coating deposited for 20:6 only and confirm the crystalline nature of the coating whereas at higher and lower Ar: N2 ratio, the measurements show the amorphous nature of the coatings. 20:6 deposited coating developed a wurtzite-AlN nanocrystalline structure. The thickness of the coatings decreased with respect to the increasing Ar: N2 ratio. The FESEM shows uneven and dense microstructure of the coatings. HRTEM study confirms the amorphous nature of 20:4 and 20:13 Ar: N2 ratio, and the polycrystalline nature of 20:6 coating. The elemental compositions were confirmed by EDS. The optical transparency of the coating was more than 95% for all the coatings in the visible range. The roughness of the samples was also measured in scanning probe microscopy imaging that showed an average roughness value Ra of ∼3 nm. The maximum hardness of 31 GPa was observed for the coating prepared with an Ar: N2 ratio of 20:6.

Comparing the kinetics of ionized and neutral atoms from single and multi-element laser-produced plasmas

Kinetics of ion and neutral atom emission features were compared for nanosecond laser-produced plasmas generated from several metal targets (i.e., Al, Ti, Zr, Nb, Ta) and an alloy containing all of these as principal alloying elements. Plasmas were produced by focusing 6 ns, 1064 nm pulses from an Nd:YAG laser on the targets of interest in a vacuum. A Faraday cup was used for collecting ion temporal features while spatially and temporally resolved emission spectroscopy was used for measuring the optical time of flight of various neutral atomic transitions. Our results highlight that most probable ion and atom velocities decay with increasing atomic mass. Trends for ions from the alloy target represent a weighted average where all ions contribute. For both ions and atoms, velocities decrease with increasing heat of vaporization and melting temperature, consistent with the thermal mechanisms that contribute to nanosecond laser ablation. Kinetic energies for neutral atoms from pure metal targets have some variability with atomic mass, whereas kinetic energies for atoms from the alloy target are more similar. These more similar kinetic energies observed for neutral atoms in the multi-element plasma may be attributed to collisions between species from all elements in the Knudsen layer.

High spin polarization and spin signal enhancement in non-local spin valves with Co–Fe alloy injectors and detectors

For applications such as spin accumulation sensors for next-generation hard disk drive read heads, and for fundamental research, it is desirable to increase the spin signal in metallic non-local spin valves, which are central devices in spintronics. To this end, here, we report on the integration of high-spin-polarization Co–Fe binary alloy ferromagnetic injectors and detectors in Al-based non-local spin valves. Room-temperature deposition on amorphous substrates from an alloy target is shown to generate smooth, polycrystalline (110-textured), solid-solution body-centered-cubic Co75Fe25 films, which we characterize by energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray reflectivity, atomic force microscopy, and electronic transport. Simple integration into transparent-interface Al non-local spin valves is then shown to realize up to a factor of ∼5 enhancement of the spin signal relative to Co, with full quantitative analysis yielding strikingly temperature-independent current spin polarizations exceeding 60%. We make a detailed quantitative comparison of these values with prior literature, concluding that Co–Fe alloys present a remarkably facile route to higher spin polarization and spin signals in non-local spin valves, with minimal barrier to adoption.

Effect of Gradient Multilayer Design on Tribological Performance of TiN/TiSiN Coatings Prepared by Cathodic Arc Ion Plating

Hard coatings, such as transition metal nitrides, have been widely applied to improve the mechanical properties and tribological performance of cutting tools. The coatings in various multilayered or gradient structures have been designed to meet the demands of more severe service environments and more precise processing requirements. In this work, TiN/TiSiN coatings in several gradient and multilayered structures were deposited on cemented carbides by cathodic arc ion plating using Ti and TiSi alloy targets. The modulation period (Λ) of the multilayer gradually varies with thickness, ranging from 6 to 46 nm. The gradient multilayer coatings consist of a nanocrystalline-amorphous composite with compact growth. The coating with a modulation period first increasing and then decreasing has the highest hardness of 38 GPa, and the maximum residual compressive stress of −2.71 GPa, as well as the minimum coefficient of friction (COF) and wear rate. Gradient and multilayer structures moderate the brittleness caused by the presence of amorphous SiNx phase and optimize the mechanical properties and tribological performances of the coatings.

Numerical framework for multi-scale modeling planar DC magnetron sputtering

In this study, we propose a numerical framework for multi-scale modeling planar Direct Current (DC) magnetron sputtering for a single alloy target. In the model, we account for electromagnetics, fluid dynamics, discharge chemistry and thermal transport across multiple length scales. Specifically, we employ Lattice Boltzmann Method (LBM) for transport phenomena, Finite Elements Method (FEM) for magnetron discharge transport, and binary collision approximation Monte-Carlo method for sputtering and atomic deposition. Our modeling framework could predict the composition, uniformity, and deposition flux of deposited thin film alloys. Furthermore, the simulation also provides the information of plasma in the chamber such as electron, ion densities, argon ion energy and argon ion flux bombarding on the target. Through parametric analyses, we found that substrate film composition is scaled with both chamber pressure and inverse chamber temperature, although the effect of chamber temperature is considerably marginal under low pressure conditions. We also found that magnetic fields do not influence the film composition, but it significantly affects the substrate deposition flux and film uniformity. Our work provides useful insights to operational heuristics involved in magnetron sputtering and other physical chemical processes.

In situ determination of sputtered Ni–Cu film composition from emission intensities

In situ elemental analysis of films comprising multielements deposited by sputtering is necessary to improve the reliability of the films because small changes in the film composition affect the properties of the films. Recently, we developed a method to determine the composition of Cu–Zn films by measuring the intensities of emission lines of Cu and Zn during sputter deposition. However, this method was only applicable to a constant chamber pressure, and only a narrow composition range (65.9–80.6 at. % of Cu in the target) was investigated. In this study, the applicability of this method was investigated for a wide range of film compositions, and the combination of emission lines that can be used to determine the film composition regardless of the chamber pressure was determined. This was achieved using Ni–Cu alloy targets, whose Cu composition ranged from 29.4 to 85.3 at. %, by evaluating the linearity (R2 value) between the emission intensity ratio of Ni/Cu lines and the atomic ratio of Ni/Cu in the films. An R2 value of 0.9870 was obtained for the combination of Ni 338.1 nm and Cu I 296.1 nm lines at chamber pressures from 1 to 5 Pa. This result indicates that the composition of Ni–Cu films can be determined from the intensities of the emission lines of Ni and Cu during sputter deposition regardless of the chamber pressure.

Determination of Trace Thorium and Uranium Impurities in Scandium with High Matrix by ICP-OES.

High-purity scandium oxide is the principal raw material of high-purity scandium metal and aluminum scandium alloy targets for electronic materials. The performance of electronic materials will be significantly impacted by the presence of trace amounts of radionuclides due to the increase in free electrons. However, about 10 ppm of Th and 0.5-20 ppm of U are typically present in commercially available high-purity scandium oxide, which it is highly necessary to remove. It is currently challenging to detect trace impurities in high-purity scandium oxide, and the detection range of trace thorium and uranium is relatively high. Therefore, it is crucial to develop a technique that can accurately detect trace Th and U in high concentrations of scandium solution in the research on high-purity scandium oxide quality detection and the removal of trace impurities. This paper adopted some advantageous initiatives to develop a method for the inductively coupled plasma optical emission spectrometry (ICP-OES) determination of Th and U in high-concentration scandium solutions, such as spectral line selection, matrix influence analysis, and spiked recovery. The reliability of the method was verified. The relative standard deviations (RSD) of Th is less than 0.4%, and the RSD of U is less than 3%, indicating that this method has good stability and high precision. This method can be used for the accurate determination of trace Th and U in high Sc matrix samples, which provides an effective technical support for the preparation of high purity scandium oxide, and supports the production of high-purity scandium oxide.

The improved thermoelectric properties of Mg2Sn/Mg multilayer films with nano-sized period by layer interface

The Mg2Sn/Mg multilayer films with different nano-sized modulation period were successfully prepared on single crystalline Si substrate with 500 ​nm thickness SiO2 layer by alternately sputtering using high pure metal Mg target and Mg–Sn alloy target. The chemical composition, surface and cross-sectional morphology, phase composition, carrier transport process and thermoelectric properties of deposited films were deeply investigated. The results show that the deposited films possess obvious layered structure, which is composed of metal Mg layer and antifluorite cubic Mg2Sn layer. The atom ratio [Mg]/[Sn]<2.0 in Mg2Sn layer between metal Mg layers and deposited films are p-typed semiconductor due to the existence of Mg vacancy in Mg2Sn lattice. The carrier concentration, mobility and thermal conductivity at room temperature decrease with reducing the modulation period of the multilayer films due to scattering of layer interface, at which depletion layer and built-in electric field form, impeding motion of the carriers. The electrical conductivity slightly decrease, but the Seebeck coefficient, power factor and figure of merit (ZT) greatly increase with reducing modulation period due to the scattering of the carriers. The ZT value of the film with the smallest modulation period of 171 ​nm reaches 0.51. The introduction of the layer interface greatly strengthens the carrier scattering process and improves the thermoelectric properties of the deposited films. This work demonstrates that introduction of heterogeneous interfaces composed of the same elements into films can effectively improve its thermoelectric properties.

Electrical and optical properties of nanocrystalline ZnSnN2

The electron density of ZnSnN2 prepared in many experiments is as high as 1019 cm−3 and it is challenging to prepare ZnSnN2 with electron density of 1016 cm−3. Here it is shown that nanocrystalline ZnSnN2 with electron density of 1016 cm−3 can be deposited with sputtering an alloy target at relatively lower sputtering power and substrate temperature. The structural, electrical and optical properties of nanocrystalline ZnSnN2 are studied. The effect of annealing on the properties of nanocrystalline ZnSnN2 with electron density of 1016 cm−3 is also investigated. The results show that the electron density of ZnSnN2 remains to be 1016 cm−3 after being annealed at 300 °C.

Stretchable and Flexible Snake Skin Patterned Electrodes for Wearable Electronics Inspired by Kirigami Structure

AbstractHerein, snake‐skin‐patterned electrodes, with high versatility and excellent biocompatibility, are developed by combining the Kirigami structure and biomimicry. The snake‐skin electrode has excellent stretchability owing to the integration of the Kirigami structure and patterning. The snake skin patterns are optimized through finite element analysis (FEA) simulations to determine the most stretchable pattern structure. Based on the FEA results, we fabricated the optimal pattern on a polyurethane (PU) substrate by sputtering the AgPdCu alloy target. Even at high strains of 30% and 50%, the electrode exhibits much better stretchability compared with the electrode without the snake skin pattern. The best stretchable electrode exhibits a resistance change (ΔR) of less than 1.5 when it is severely stretched at up to 50% strain. Additionally, the dynamic stretching fatigue test, reveals that it exhibits stable conductivity, thus proving the effectiveness of using snake‐skin pattern for stretchable electrodes. The bending, rolling, folding and twisting tests confirm that the electrode has outstanding flexibility, too. A wearable temperature sensor with a snake‐skin‐patterned electrode exhibits stable and highly sensitive temperature sensing properties. In addition, light emitting diodes connected to the stretchable electrode exhibits stable brightness despite severe deformation of the electrodes.

Phase Composition, Hardness, and Thermal Shock Properties of AlCrTiN Hard Films with High Aluminum Content

TiCrAlN hard films based on TiN or CrN show superior properties in terms of hardness, wear resistance, and thermal stability due to the addition of alloying elements. AlCrTiN films based on AlN may have higher thermal shock properties, but the knowledge of AlCrTiN films with high Al content has been insufficient until now. In this study, two sets of AlCrTiN hard films with different Al contents of 48 at.% and 58 at.% among metal components were prepared via multi-arc ion plating so as to investigate the effect of Al content on the phase composition, hardness, and thermal shock resistance of the films. The same microstructures, morphologies, and thicknesses of the fabricated film samples were achieved by changing the combination of cathode alloy targets and adjusting the arc source current during deposition. The surface chemical composition, cross-sectional elemental distribution, microstructure, morphology, phase composition, surface hardness, film/substrate adhesion strength, and thermal shock performance of the AlCrTiN films were examined. The obtained results reveal that the two sets of AlTiCrN hard films are face-centered cubic solid solutions with a columnar fine grain structure and a preferred growth orientation of (200) crystal plane. The hardness of the AlCrTiN films can be improved up to HV2850 by properly reducing the Al content from 58 at.% to 48 at.%. Meanwhile, the film/substrate adhesion performance is strong enough in terms of critical loads greater than 200 N. Furthermore, the AlCrTiN films maintain high thermal shock resistance at 600 °C when the Al content decreases from 58 at.% to 48 at.%. The optimal composition of the AlCrTiN hard films is 25:13:15:47 (at.%), based on the consideration of hardness, adhesion, and thermal shock cycling resistance. This optimal AlCrTiN hard film can be suggested as an option for protective coatings of hot process die tools.

Mechanical, Oxidative Properties, and Wear Behaviors of CrAlSiN Coatings Applied on Cutting Tools

In this study, we investigated the mechanical and oxidation properties of WC-Co and CrAlSiN-coated turning inserts and analyzed their wear behaviors. CrAlSiN films were synthesized by radio-frequency magnetron sputtering from alloy targets. X-ray diffraction analysis indicated that all the prepared films have a cubic structure without any hexagonal phase. The average microhardness increased from 27 GPa for WC-Co up to 37 GPa for CrAlSiN, whereas the average frictional coefficient decreased from μ＝0.50 for WC-Co down to μ＝0.17 for CrAlSiN. During dynamic oxidation, the maximum exothermic peak in the differential thermal analysis curve was observed at 549 ℃ for WC, the main component of WC-Co, and at 1384 ℃ for CrAlSiN. Corresponding to the exothermic reactions, the mass gain determined by thermogravimetric analysis increased from 23% for WC to 6% for CrAlSiN. The wear behaviors of WC-Co and CrAlSiN-coated inserts were verified through the in situ measurement of cutting resistance and the observation of their flank wear after cutting tests. The minimum cutting resistance and width of flank wear were confirmed for CrAlSiN-coated inserts.

Annealing effect on the structural and optoelectronic properties of Cu-Cr-O thin films deposited by reactive magnetron sputtering using a single CuCr target

Abstract The aim of this study is to explore the structural and optoelectronic properties of Cu-Cr-O thin films when processed by the magnetron sputtering method using a single equimolar CuCr alloy target. These films were then post-annealed in a controlled Ar atmosphere at 500°C to 800°C for 2 h. The as-deposited Cu-Cr-O thin film consisted of an amorphous phase and exhibited extremely poor optoelectronic properties. After annealing was conducted at 500°C, monoclinic CuO and spinel CuCr2O4 phases were simultaneously formed in the film. Upon increasing the annealing temperature to 600°C, the CuCr2O4 phase reacted completely with the CuO phase and transformed into the delafossite CuCrO2 phase, possessing optimal optoelectronic performance. It has an electrical resistivity of 41 Ω-cm and a light transmittance of 49.5%, making it suitable for p-type transparent conducting electrodes. A further increase in annealing temperature resulted in larger grains and greater surface roughness and void density, which, in turn, degraded the optoelectronic performance.

Effects of aluminum addition on microstructures and mechanical properties of NbTiVZr high-entropy alloy nitride films

In this study, the effects of Al addition on the phase evolution, morphology and mechanical properties of (NbTiVZrN)100-xAlx (x = 0, 0.7, 2.3, 3.6, 4.0) high-entropy alloy nitride films (HEANFs) were investigated. The films were prepared by co-sputtering of NbTiVZr alloy target and Al target with a constant N2/Ar flow ratio. The XRD patterns revealed FCC structure and the preferred orientation transferred from TiN(200) to (Nb, Zr)N(111) as the Al content increased. The results of the corresponding selected-area electron diffraction patterns agreed well with the XRD results. Cross-sectional SEM and TEM observations exhibited ultra-fine columnar structure. The nanoindentation test was performed to acquire the mechanical properties of the films. The hardness, reduced modulus and fracture toughness of nitride film increased with the increasing Al content and reached the maximum values of 28.1 GPa, 253 GPa and 2.08 MPa × m0.5, respectively, at x = 3.6. The significant improvement could be ascribed to solid solution strengthening, inverse Hall-Petch effect and the replacement of dominant nitride compounds. As the Al content increased from 0 to 4 at.%, the coefficient of friction decreased from 0.082 to 0.065. The relationship among the composition, structure and mechanical properties was studied for the (NbTiVZrN)100-xAlx HEANFs in this work. Comparisons with (NbTiVZr)100-xAlx HEAFs without nitridation and other nitride films were also made.

Tunability of optical properties of InSb films developed by pulsed laser deposition

The InSb thin films were successfully prepared from binary alloy target by Pulsed Laser Deposition (PLD) onto heated Si/SiO2 substrates at various deposition temperatures (Td) ranging from room temperature to 400 °C. The evolutions of structural (XRD, XPS), microstructural (AFM, SEM) and optical (XPS, FTIR, RAMAN) properties as a function of deposition temperature were systematically taken into account. The analyzed results indicate that the films are well crystallized with Zinc Blende (ZB) structure for Td ≥ RT. Increasing Td induces significant signature of preferentially crystal orientations of (h11) accompanied by distinctive microstructural evolution from continuous fashion (Td ≤ 300 °C) to almost isolated islands feature (Td ≥ 350 °C). Derivations of crystallite sizes, lattice strain, dislocation density, Lotgering orientation factor, and root mean square roughness were correlated with Raman shift and XPS analysis, and optical properties. The developed thin films allow to observe the flexibility of optical band gap energy (from 0.18 eV to 0.50 eV), which is directly related to the quantum confinement effect coupled with the band-filling effect of Burstein–Moss shift.

Microstructure and mechanical properties of FeCoCrNiAl0.1N high entropy alloy nitride coatings synthesized by cathodic arc ion plating using alloy target

To promote the industrial application of high entropy alloy nitride (HEAN) coatings, the cathodic arc ion plating deposition process was explored to deposit FeCoCrNiAl0.1 N using casting HEA alloy targets. We investigated the impacts of nitrogen pressure and bias voltage on the microstructure, mechanical characteristics, and friction behaviors. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to analyze the microstructures. It was found that compositions for all coatings were uniformly and the coatings mainly consisted of FCC-HEA, CrN, AlN, and FeN phases. The nano hardness and plastic deformation resistance, characterized by nano-indentation, both increased with the nitrogen pressure and certain bias voltage (<150 V). Coating deposited with 2.0 Pa and 150 V presented the maximum hardness of 32.9 GPa and the highest H3/E2 value of 0.1 GPa. The hardening mechanism was focused. Coatings deposited with low nitrogen pressure presented better crack resistance under scratch load. The friction behaviors were presented based on the combined studies of friction curves, wear track profiles, and morphologies. FeCoCrNiAl0.1 N coatings revealed excellent wear resistance with relatively lower COF (ranging from 0.43 to 0.51).

Microscopic studies on transparent AlSiN ternary hard coating

In this work AlSi nanocomposite coating were deposited by RF magnetron sputtering in Ar/N2 reactive atmosphere. AlSi alloy target of composition 86:14 wt % have been used to deposit the coating on float glass substrate by varying the deposition time: starting from 0.5 h to 2 h. The substrate temperature and target power were fixed at 250 °C and 100 W respectively. The effect of deposition time on microstructure, mechanical and optical property were studied by usingX-ray Diffraction (XRD), Stylus profiler, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), UV–Visible Spectrometer and Nanoindentation techniques. The XRD shows the formation h-AlN phase for film deposited for 2 h which shows that with increase in deposition time, the film structure changes from amorphous to polycrystalline, the coating deposited for 2 h develops wurtzite-AlN nanocrystalline structure. The thickness of the coating increases with respect to the increasing deposition time which was confirmed from stylus profiler. The FESEM study shows the uneven and randomly oriented grains present in the coating. TEM study confirms the amorphous and polycrystalline nature of the films with low and high thickness respectively. The elemental composition was confirmed by EDS. UV–Visible Spectrometer delivers the optical transparency of the film which is >90% for all the coatings in the visible range spectra. The roughness of the samples was also measured from scanning probe microscope image, which showed average roughness (Rã) value below 2 nm. The maximum hardness obtained is 31 GPa for the coating deposited 2 h with 490 nm thickness, it has an elastic recovery of 92% which suggest its resistance to elasticity as well as plastic deformation.

Manipulation of the Martensitic Transformation and Exchange Bias Effect in the Ni45Co5Mn37In13 Ferromagnetic Shape Memory Alloy Films

The martensitic phase transition and exchange bias effect of the Ni-Mn-based ferromagnetic shape memory alloys (FSMAs) Ni45Co5Mn37In13 (Ni-Co-Mn-In) films are investigated in this paper. The martensitic transformation properties of the Ni-Co-Mn-In alloy target material are manipulated by the process of electric arc melting, melt-fast quenching, and high-temperature thermal pressure. The Ni-Co-Mn-In alloy films with martensite phase transition characteristics are obtained by adjusting deposition parameters on the (001) MgO substrate, which shows a significant exchange bias (EB) effect at different temperatures. With increasing sputtering power and time, the film thickness increases, resulting in a gradual relaxation of the constraints at the interface between the film and the substrate (the interfacial strain decreases as the increase of thin film thickness), which promotes the martensite phase transition. Between zero-field cooling (ZFC) and field-cooled (FC) curve obvious division zone, the decrease of exchange bias field (HEB) and coercive force field (Hc) with an increase in test temperature is due to ferromagnetic (FM) interaction begins to dominate, resulting in a reduction of antiferromagnetic (AFM) anisotropy at the interface. The maximal HEB and Hc reach ~465.7 Oe and ~306.9 Oe at 5 K, respectively. The manipulation of the martensitic transformation and EB effect of the Ni-Co-Mn-In alloy films demonstrates potential application in the field of information and spintronics.

Influence of sintering temperature on microstructure and properties of 90W-10Ti alloy targets prepared by hot oscillating pressing

The 90W-10Ti refractory alloy was sintered by the hot oscillating pressing (HOP) and hot pressing (HP) under vacuum conditions with no contamination of oxygen and hydrogen. The effects of different sintering temperatures on the microstructure, hardness, and electrochemical corrosion properties of the resulting samples were investigated. Compared to the sample made by HP at the same temperature, the relative density, microstructure uniformity (W-W grain contiguity and βTi(W) bonding phase thickness) and properties of HOP sintering samples were significantly improved. Moreover, the sintering temperature and the activation energy were effectively reduced to inhibit grain growth by HOP. The results show that W-Ti targets with high density, fine grain size, high hardness and excellent corrosion resistance could be obtained by HOP.