Sputtering Target Research Articles

Evolution Mechanism of Sputtered Film Uniformity with the Erosion Groove Size: Integrated Simulation and Experiment.

In this work, Cu thin films were experimentally fabricated at different target-substrate distances by 2-inch and 4-inch circular planar magnetron targets. Meanwhile, the sputtering deposition of Cu thin films was investigated via an integrated multiscale simulation, where the magnetron sputtering discharge was modeled using the Monte Carlo (MC) method, and the sputtered particle transport was simulated using a coupled Monte Carlo (MC) and molecular dynamics (MD) method. Experimental results indicated that, as the target-substrate distance increased from 30 to 120 mm, the film thickness distribution of the 2-inch target sputtering changed from a bell-shaped curve to a line-shaped curve, while that of the 4-inch target sputtering varied from a saddle-shaped curve to a line-shaped curve. The simulation results were accordant with the experimental results. The simulation results revealed that, at a target-substrate distance of 30 mm, the sputtering particle flow from the 2-inch target overlapped strongly near the substrate center, leading to a bell-shaped film thickness distribution, while the increased diameter of the erosion groove on the 4-inch target reduced the superposition effect of the sputtering particle flow near the substrate center, resulting in a saddle-shaped film thickness distribution. In addition, when the target-substrate distance ranged from 30 to 120 mm, the film thickness uniformity of 4-inch target sputtering was superior to that of 2-inch target sputtering, and the underlying mechanism was discussed in detail.

Effect of nanopowder preparation method on the sintering behavior and microstructure of Mo[sbnd]W alloy

Molybdenum‑tungsten (MoW) alloy sputtering targets are widely used in electronic, displays, and solar cells due to their favorable thermal and electrical conductivities, low thermal expansion coefficient, and corrosion resistance. Herein, we examined the impact of two different MoW nanopowders preparation methods, i.e., mixed oxide-reduction and mechanical alloying, on the sintering behavior and microstructure of sintered compacts. The sintered compacts produced with oxide-reduced nanopowders exhibited higher density and purity, and a finer microstructure, making them more suitable for sputtering targets compared with those made with mechanically alloyed nanopowders. This study provides valuable insights into the effect of powder fabrication processes on the consolidation of MoW sintered compacts, which is crucial for the development of high-quality sputtering targets.

Effects of deposition temperature on the mechanical and structural properties of amorphous Al–Si–O thin films prepared by radio frequency magnetron sputtering

Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.

Investigation of the Al-Mo-B(CN) Coatings Deposited Using Magnetron Sputtering of Al-Mo-B4C Target Produced by Detonation Spray Coating

In this work, a metal–ceramic composite target for magnetron sputtering was manufactured by a robotic complex for detonation spraying of coatings equipped with a multi-chamber detonation accelerator. The powder composition (30Mo-30Al-40B4C) was sprayed onto the copper plate base of the composite target cathode. The obtained cathode target with Al-Mo-B4C coating (thickness 280–300 μm) was used to deposit the Al-Mo-B(CN) coating (DC mode) on flat specimens of AISI 316 steel and silicon using equipment for magnetron sputtering UNICOAT 200. The Al-Mo-B4C coating has a lamella-type structure with inclusions of boron carbide particles. The structure and morphology of the coatings were studied using methods of optical analysis, scanning electron microscopy, atomic force microscopy, X-ray analysis, and X-ray photoelectron spectroscopy. Mechanical and tribological properties of the Al-Mo-B(CN) thin coatings were studied using a nanoindenter, a scratch tester, and a tribometer under a fluid-free friction regime at room temperature. The Al-Mo-B(CN) coating (thickness ~1 μm) exhibited a dense homogeneous fine-grained design without columnar elements and had an amorphous structure. The formation of the MoB2 and AlN phase with an admixture of oxygen in the form of aluminum oxide, molybdenum oxide, and boron oxide was determined using XPS analysis. The Al-Mo-B(CN) coating possessed a hardness of 13 GPa, an elasticity modulus of 114 GPa, an elastic recovery of 45%, a friction coefficient of 0.8 against a steel 100 Cr6 ball, and an adhesion strength of 11 N.

Deposition-controlled phase separation in CuNb metallic alloys

Vapor co-deposited metal nanocomposites with immiscible components have shown to have several superior properties including mechanical performance, radiation tolerance, and enhanced functionalities. The morphology and structural design of these nanocomposites are important in determining the expression of these properties. The conditions used to deposit thin film nanocomposites are the governing factors in determining the final nanostructure. In this work, we link the effects of process gas pressure, substrate temperature, and sputtering target power on resultant Cu/Nb thin film nanostructures. We find that for films with equiatomic phase fractions of Cu and Nb, inhomogeneous precipitate segregation dominated the structure at lower substrate temperature depositions while higher temperatures distributed the Cu and Nb phases more uniformly. Increasing process gas pressure during deposition lead to a spatially homogeneous, nanocrystalline structure of Cu/Nb. In situ annealing of this sample shows that the phase separated morphology of the two immiscible materials depends on the initial composition. Finally, compositions of Cu and Nb that were highly disparate lead to interface segregation of the minority phase. The morphological evolution observed in the Cu/Nb system is compatible with modified structural zone models for immiscible thin film systems.

Research status of phase change memory and its materials

Phase change memory technology is a new technology in non-volatile memory technology. Phase change memory technology has many advantages, such as non-volatility, high reading and writing speeds, better data retention, and strong compatibility with CMOS technology, and has been paid attention to by many researchers. Phase change materials are mainly chalcogenide compound materials. Researchers have done a lot of research on Ge-Sb-Te, Ge-Te, and Sb-Te-based phase change materials and developed some new phase change material systems. In addition, researchers have carried out in-depth research on the phase transition mechanism, but the existing atomic umbrella jump theory, multiple ring theory, resonance bond theory, octahedral structure theory, etc. have not formed a unified understanding of the phase transition mechanism. At present, phase change memory is mainly prepared by magnetron sputtering of phase change material targets, which results in fast deposition and high purity of the prepared film. In this paper, based on the development of phase change storage materials, the system of phase change materials and its phase change mechanism, the phase transition mechanism of phase change memory, the preparation and characterization methods of phase change films, the industrialization progress, and other research work are reviewed.

Progress in manufacturing and processing of Al-Sc alloy targets

The development of the fifth-generation mobile communication technology (5G) puts forward higher requirements for radio frequency (RF) filters. Due to its higher frequency and larger bandwidth, bulk acoustic wave (BAW) filter will become the mainstream RF filter solution. Scandium doped aluminium nitride (AlScN) piezoelectric film has attracted much attention due to its excellent piezoelectric response coefficients and electromechanical coupling coefficients. The doped Sc concentration will directly affect the piezoelectric coefficient and electromechanical coupling coefficient of the film. The most common technique for producing AlScN thin films is magnetron sputtering of targets made of Al-Sc alloy. However, with the increase of Sc content, the solid-liquid solidification interval, the number of intermetallic compounds, and the brittleness of the material will all increase significantly. Additionally, it will result in component macro-segregation, uneven phase distribution, and poor processing deformability. Therefore, it is extremely difficult to manufacture and process Al-Sc alloy targets. The mainstream processes for preparing Al-Sc alloy targets are divided into direct reaction method and powder metallurgy method. This paper reviews the research progress in manufacturing and processing of Al-Sc alloy targets.

Enhancing piezoelectric response in (002)-Oriented TaxAl(1−x)N films by magnetron-sputtering composition-tunable AlTa alloys

Aluminum nitride (AlN) films suffer from poor piezoelectric response due to the local hexagonal symmetry of wurtzite crystal structure. The fundamental mechanism of improving piezoelectric response in Ta-doped AlN thin films has not been fully understood. Here, we report that composition-tunable AlTa alloys, instead of Al and Ta individual sputtering targets, can be employed to deposit (002)-oriented TaxAl(1-x)N films by magnetron-sputtering, where Ta-doping ratio is tunable by changing Al:Ta composition ratio of the AlTa alloys. Importantly, Ta-doping enhances spontaneous polarization to improve piezoelectricity significantly, as suggested by a threefold increase of the effective piezoelectric coefficients (d33,eff) upon doping 7 at.% Ta. A better alignment of spontaneous polarization for stronger piezoelectric response originates from the reduction in point defects and crystalline disorder in the reduced-symmetrical wurtzite structure by doping Ta in the TaxAl(1−x)N. This study provides significant insights in improving piezoelectric response in AlN for the development of high-performance film-bulk-acoustic-resonators.

Fabrication of CoFeB–SiO2 Films With Large Uniaxial Anisotropy by Facing Target Sputtering and its Application to High-Frequency Planar-Type Spiral Inductors

Fabrication of CoFeB–SiO₂ Films With Large Uniaxial Anisotropy by Facing Target Sputtering and its Application to High-Frequency Planar-Type Spiral Inductors

Exploring RF Magnetron Sputtering Growth Composite Thin Film BiFeO3-Bi2Fe4O9 on C-Plane Al2O3 Substrate.

Nanocomposite films of BiFeO3-Bi2Fe4O9 were fabricated on a sapphire substrate Al2O3 using the method of gas discharge high-frequency cathodic sputtering of a ceramic target with a stoichiometric composition in an oxygen atmosphere. The results of the film analysis using X-ray structural analysis, Raman scattering, XPS, and atomic force microscopy are presented. The lattice parameters, surface topography, chemical composition of the films, concentration, and average sizes of the crystallites for each phase were determined. It was shown that the ratio of the BiFeO3 to Bi2Fe4O9 phases in the obtained film is approximately 1:2. The sizes of the crystallites range from 15 to 17 nm. The optical and magnetic properties of the nanocomposite layers were studied, and the band gap width and magnetization hysteresis characteristic of ferromagnetic behavior were observed. The band gap width was found to be 1.9 eV for the indirect and 2.6 eV for the direct interband transitions. The magnetic properties are characterized by a hysteresis loop resembling a "wasp-waist" shape, indicating the presence of magnetic anisotropy.

Hard and Highly Adhesive AlMgB14 Coatings RF Sputtered on Tungsten Carbide and High-Speed Steel

We report a new industrial application of aluminum magnesium boride AlMgB14 (BAM) coatings to enhance the hardness of tungsten carbide ceramic (WC-Co) and high-speed steel tools. BAM films were deposited by RF magnetron sputtering of a single dense stoichiometric ceramic target onto commercial WC-Co turning inserts and R6M5 steel drill bits. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. Very smooth (6.6 nm RMS surface roughness onto Si wafers) and hard AlMgB14 coatings enhance the hardness of WC-Co inserts and high-speed R6M5 steel by a factor of two and three, respectively. Complete coating spallation failure occurred at a scratch adhesion strength of 18 N. High work of adhesion and low friction coefficient, estimated for BAM onto drill bits, was as high as 64 J/m2 and as low as 0.07, respectively, more than twice the surpass characteristics of N-doped diamond-like carbon (DLC) films deposited onto nitride high-speed W6Mo5Cr4V2 steel.

Deposition of Superconducting Nb3Sn Coatings Using Multiple Magnetron Sputtering Techniques

This paper describes the elemental and phase composition, microstructure, and superconducting properties of Nb3Sn deposited by magnetron sputtering. The films were deposited on sapphire substrates using three different techniques: co-evaporation, layer-by-layer deposition of Nb and Sn, and sputtering of a stoichiometric Nb3Sn target. The influence of magnetron operation mode on the as-deposited film element composition is described. After high-temperature annealing at 700–900 °C, the results indicate the formation of superconductive films. The highest critical temperature of 16.9 K was obtained for the film deposited at a stoichiometric Nb3Sn target and annealed at a temperature of 800 °C for 12 h. These results could be used for superconducting radio-frequency applications.

Crystallization features and physical properties of the thin-film heterostructure of lead zirconate titanate – lead oxide

Various diagnostic techniques aimed at studying the structure and physical properties (synchronous thermal analysis, atomic force microscopy operating in the current measurement mode, electron-probe X-ray spectral microanalysis, dynamic method for determining the pyroelectric response) were used to study the crystallization features and physical properties of the thin-film heterostructure PZT – PbO1+x formed by a two-stage technique of RF magnetron sputtering of a ceramic target. During the first stage, amorphous films were deposited on a “cold” platinized silicon substrate, while the second stage involved high-temperature annealing in air. It was shown that annealing of amorphous films and crystallization of the intermediate pyrochlore phase are accompanied by additional oxidation of the structure resulting in the formation of lead orthoplumbate and lead dioxide and additional oxidation of organic inclusions. The presence of a liquid phase of lead oxide contributes to the formation of the pyrochlore phase. It was found that lead oxide layers have significantly higher through conductivity than perovskite blocks. It was assumed that the increased conductivity of lead oxide layers is associated with lead dioxide, which has high conductive properties. Self-polarized thin films were detected to have an abnormal electrical response to the strobing thermal exposure, including the typical pyroelectric response, local photoconductivity shunted by layers of the perovskite phase, and through photoconductivity. The presence of photoconductivity is also associated with the conductive properties of lead dioxide

Sputtering Heterogeneous Tungsten Carbide Targets by Light Ions Bombardment

Background:: This paper presents a model for sputtering heterogeneous two-component materials with light ions. Method:: The model, based on two sputtering mechanisms, makes it possible to calculate the total sputtering coefficients of the target components, and it is easily transformed for the case of sputtering different types of targets. Model testing was conducted for the case of sputtering homogeneous tungsten carbide targets with ions of different energies. Results:: The results of the calculations are given in comparison with experimental data and the results of computer simulation. The comparison shows good agreement of the calculated values with the data of other authors. The proposed model was used to describe stationary (stoichiometric) sputtering of tungsten carbide targets. Using this model, the concentrations of components in the modified target layer were calculated, and the thickness of the modified layer was also estimated. Conclusion:: The method of calculating the concentration of target components in the modified layer and the thickness of this layer can be the basis of the technology of creating materials with given properties of the surface layer.

Formation of thin films via cold-rolled/annealed nickel sputtering targets

Nickel (Ni) thin films are commonly used in the integrated circuit field. Magnetron sputtering is a common method for thin film deposition, and the sputtering target is the key raw material in the magnetron sputtering process. In this work, cold-rolled and annealed Ni targets were prepared. The microstructures and magnetic properties of the Ni targets were analyzed. Then, Ni films were prepared by direct current magnetron sputtering with the above two Ni targets. The Ni films were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence x-ray diffraction, x-ray reflectivity, and four-probe testing. Finally, the surface morphologies of the targets were compared before and after sputtering, and the relationships between the Ni targets and the Ni films were discussed. The results show that with the same conditions, the annealed Ni target is more efficiently utilized, and the electrical properties of the Ni films are good when the film is macrostructurally smooth and microstructurally compact. This is due to the target texture, magnetic properties, etc.

Hot-Pressing Deformation Yields Fine-Grained, Highly Dense and (002) Textured Ru Targets.

Ruthenium (Ru) is a refractory metal that has applications in the semiconductor industry as a sputtering target material. However, conventional powder metallurgy methods cannot produce dense and fine-grained Ru targets with preferred orientation. Here, we present a novel method of hot-pressing deformation to fabricate Ru targets with high relative density (98.8%), small grain size (~4.4 μm) and strong (002) texture. We demonstrate that applying pressures of 30-40 MPa at 1400 °C transforms cylindrical Ru samples into disk-shaped targets with nearly full densification in the central region. We also show that the hardness and the (002)/(101) peak intensity ratio of the targets increase with the pressure, indicating enhanced mechanical and crystallographic properties. Our study reveals the mechanisms of densification and texture formation of Ru targets by hot-pressing deformation.

Martensitic ternary FeCrMn thin films sputtered from austenitic AISI 202 stainless steel target: Phase transition and corresponding magnetic properties under the influence of deposition rate

The nanostructured materials exhibit quite different properties from their bulk counterparts. Therefore, in this work, phase transition from a commercial austenitic AISI 202 (Bulk FeCrMn) stainless steel to martensitic ternary FeCrMn thin films under variation of deposition rate were studied. The films were easily sputtered onto a flexible amorphous polymer substrate from the target by a DC magnetron. X-ray diffraction analysis showed that austenitic phase of the target converted into a mixture of martensitic and a very weak of austenitic phase of the films at the deposition rates of 0.04 and 0.06 nm/s. With a further increase of the deposition rate, martensitic phase in the films increased, and at the highest deposition rate, the film with 100 % martensite phase was obtained. According to magnetic analysis, austenitic target consists of paramagnetic and ferromagnetic components as oppose to the paramagnetic phase stated in the literature. The films obtained by sputtering of austenitic target have ferromagnetic character with an increasing saturation magnetization, MS as the deposition rate increases. The increase of the MS from 117 to 346 emu.cm−3 may be explained by the increase of the % martensite that may increase the ferromagnetic character. Also, the increase of the coercivity of the films from 31 to 196 Oe may have come from the increase of % martensite and the increase of grain sizes with increasing deposition rates which may induce the stress in the films. It is seen that the nanostructured ternary FeCrMn thin films exhibit quite different phase and corresponding magnetic properties from their bulk counterpart. With sputtering, martensitic phase transition of ternary FeCrMn thin films can be controlled by varying deposition rates. It presents a potential usage for data storage and micro electric-electronic devices on flexible substrates.

Photocatalytical and corrosion behavior of sputtered zirconium oxynitride thin films doped with titanium

ZrTiON coatings were deposited by reactive magnetron sputtering process of a single Zr target, while Ti was added by placing Ti ribbons on the erosion track of the Zr sputtering target. The variation of parameters such as the number of Ti ribbons, the applied sputtering current, and the reactive gas flow led to obtaining different sample configurations. The coatings were analyzed in terms of chemistry (chemical composition and chemical states) by X-ray Photoelectron Spectroscopy, morphology by Atomic Force Microscopy, surface energy, photodegradation tests, electrochemical studies, and accelerated corrosion tests. It was found that the coatings show features of oxides, nitrides, and oxynitrides, depending on the deposition conditions applied. The photodegradation efficiency regarding methylene blue solutions under visible light varies between 58% and 96%, depending on the type of illuminant and the sample characteristics, while the lowest corrosion rate was exhibited by the reference samples deposited without the addition of Ti. The samples doped with Ti and deposited with 1.5 A sputtering current exhibited a more efficient photodegradation effect, compared to the reference ZrON sample. The accelerated corrosion tests showed that the coatings deposited with an applied current of 2 A behaved significantly better than the ones deposited with 1.5 A sputtering current after 8 h of exposure to the water vapor and sulfur dioxide gas atmosphere.

High-performance broadband photodetectors based on sputtered NiOx/n-Si heterojunction diodes

High-performance broadband photodetectors based on NiOx/n-Si heterojunction were fabricated by radio frequency (rf) sputtering of NiO target at room temperature using 40, 60 and 80 W of power. The open circuit voltage is almost independent of the rf power with value of ∼0.33 V under illumination with red light with optical power of 3.71 mW/cm2, while the short circuit current depends on the sputtering power and has the highest value of 1.3 × 10−7 A (J = 1.45 × 10−3A/cm2) for diodes fabricated at 60 W. The responsivity (R) and specific detectivity in self-powered mode (Vb = 0 V) are higher for the 60 W photodiodes. The R values are 0.39, 0.61, 0.67 and 0.95 A/W under illumination with red, green, blue and UV lights with optical powers of 3.71, 1.03, 1.31 and 0.335 mW/cm2. The On/Off ratio of these diodes at Vb = 0 V is 1.5 × 104, 6.7 × 103, 9.4 × 103, 9.4 × 103 for illumination with the four lights. Capacitance-Voltage measurements indicate high quality of the NiOx/Si interface with low interface defect density and low density of bulk traps in NiOx for diodes obtained at the three powers. The responsivity of the heterojunction diodes obtained at 60 W at Vb = 0 V is among the highest reported in the literature for photodiodes based on NiOx. The quality of the rf sputtered NiOx layers and the low deposition temperature make them attractive for application in flexible optoelectronic devices.

Impedance characteristics under different voltages of n-β-FeSi2/p-Si heterojunctions constructed via facing target sputtering

Impedance characteristics under different voltages of n-β-FeSi2/p-Si heterojunctions constructed via facing target sputtering