Magnetron Sputter Deposition System Research Articles

Sub-2 nm size and density tunable platinum nanoparticles using room temperature tilted-target sputtering

This paper describes a tilted-target RF magnetron sputter deposition system to grow nanoparticles in a controlled way. With detailed characterization of ultra-high density (up to 1.1 × 1013 cm−2) and ultra-small size Pt nanoparticles (0.5–2 nm), it explains their growth and crystalline properties on amorphous Al2O3 thin films. It is shown that Pt nanoparticle size and number density can be precisely engineered by varying selected experimental parameters such as target angle, sputtering power and time of deposition to control the energy of the metal atoms in the deposition flux. Based on rate equation modelling of nanoparticle growth, three distinct growth regimes, namely nucleation dependent, coalescence dependent and agglomeration dependent regimes, were observed. The correlation between different nanoparticle growth regimes and the consequent crystal structure transformation, non-crystalline clusters → single crystalline nanoparticles → polycrystalline islands, is also discussed.

Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

ZnO films have been reactively deposited on sapphire substrates at 300 °C using a high impulse power magnetron sputtering deposition system and characterized structurally, optically and electronically. The unintentionally doped n-type ZnO films exhibit high transparency, moderate carrier concentration (∼5 × 1018 cm−3) and a Hall mobility of 8.0 cm2 V−1 s−1, making them suitable for electronic device applications. Pt/ZnO Schottky diodes formed on the HiPIMS deposited ZnO exhibited rectification ratios up to 104 at ±2 V and sensitivity to UV light.

Characterization of the energy flux toward the substrate during magnetron sputter deposition of ZnO thin films

The characterization of energy influxes from plasma to substrate during sputter deposition of ZnO films is presented and discussed. Measurements were carried out in a triple rf magnetron sputter deposition system using calorimetric probes in various Ar/N2 and Ar/H2 mixtures at typical substrate positions. By variation of the probe bias the different contributions originating from the kinetic energy of charge carriers, the recombination of charge carriers (electrons and ions) at the surface as well as the contributions from the impact of neutral sputtered particles and subsequent film growth were determined. Radial scans in the substrate plane were recorded to obtain information about inhomogeneities in the total energy influx.The results show that the crystallinity reaches its optimum at that Ar/N2 ratio where the influence of the bombarding ions reaches its lowest value, indicating the destructive character of ion impact. Radial measurements indicate the influence of the magnetic field on the homogeneity of the energy influx caused by the superposition of the three (balanced) magnetic configurations. The superposition leads to an ‘unbalanced character’ resulting in a lowering of the electron trapping. The admixture of H2 leads to a drastic increase in the energy influx due to molecule formation at the (substrate/probe) surface.

Molecular dynamic simulation of binary ZrxCu100−x metallic glass thin film growth

In this work, we employed classical molecular dynamics simulations model to study ZrxCu100−x (3≤x≤95) metallic glass films deposited on a silicon (100) substrate. Input data were chosen to fit with the experimental operating conditions of a magnetron sputtering deposition system. The growth evolution is monitored with variable compositions of the incoming atom vapor. The Zr–Zr, Cu–Cu and Zr–Cu interactions are modeled with the Embedded Atom Method (EAM), the Si–Si interaction with Tersoff potential, the Zr–Si and Cu–Si interactions with Lennard-Jones (12-6) potential. Different film morphology and structure were detected and analyzed when the Zr to Cu ratio is varied. The results are compared with X-ray diffraction and scanning electron microscopy analyses of experimentally deposited thin films by magnetron sputter deposition process. Both simulation and experiment results show that the structure of the ZrxCu100−x film varies from crystalline to amorphous depending on the elemental composition.

Fabrication and Evaluation of Large Area Mo/Si Soft X-Ray Multilayer Mirrors at Indus SR Facilities

Large area Mo/Si multilayer (ML) mirrors with high reflectivity are fabricated using magnetron sputtering deposition system. Thin film growth is optimized for film roughness, density, and interface quality by changing process parameters through fabrication of thin films. Mo/Si MLs are fabricated with varying thickness ratio, number of layer pairs, and periodicity from 0.3 to 0.45, 5 to 65, and 40 to 100 Å, respectively. The samples are characterized using hard X-ray reflectivity and transmission electron microscopy. Soft X-ray performance tests of MLs are done by soft X-ray reflectivity using Indus-1 synchrotron radiation. ML coating with thickness errors of ~0.03% per layer and interface roughness in the range of 2 to 5 Å has been realized. The lateral variation of the periodicity is controlled within 0.5 Å over the mm2 area of the plane substrate by using substrate motion and appropriate masking arrangement. Maximum variation of periodicity from run to run is less than 0.5 Å. Peak reflectivity of ~63% at wavelength of ~127 Å is achieved for incident angle of 71 degree.

Sputter yield amplification by tungsten doping of Al2O3 employing reactive serial co-sputtering: process characteristics and resulting film properties

The deposition rate of reactively sputtered Al2O3 coatings is demonstrated to increase by 80% upon tungsten doping of the used aluminium target. This effect is based on the recoil of the sputtering species at implanted dopants below the target surface and is termed sputter yield amplification. For the investigation of this effect, a novel type of magnetron sputter deposition system is employed that facilitates serial co-sputtering. In this technique doping of the elementary target is enabled by a dynamic sputtering process from an auxiliary cathode. In our case, the rotating aluminium target is dynamically coated with tungsten from this auxiliary cathode. Since the primary target rotates, the auxiliary cathode is placed in series with the primary erosion zone. The deposition rate of Al2O3 can be considerably increased in this process already for very low concentrations of approximately 1% of tungsten in the resulting film. A characterization of the dynamics of reactive sputtering as a function of target rotation speed is performed.

Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study.

Effect of Sputtering Power on Structure, Adhesion Strength and Corrosion Resistance of Nitrogen Doped Diamond-Like Carbon Thin Films

Nitrogen doped diamond-like carbon (DLC:N) thin films were deposited on highly conductive p-Si substrates using a DC magnetron sputtering deposition system. The DLC:N films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle measurement and micro-scratch test. The XPS and Raman results indicated that the sputtering power significantly influenced the properties of the films in terms of bonding configuration in the films. The corrosion performance of the DLC:N films was investigated in a 0.6 M NaCl solution by means of potentiodynamic polarization testing. It was found that the corrosion performance of the films could be enhanced by higher sputtering powers.

Effect of Working Pressure on Corrosion Behavior of Nitrogen Doped Diamond-Like Carbon Thin Films Deposited by DC Magnetron Sputtering

Nitrogen doped diamond-like carbon thin films were deposited on highly conductive p-silicon(100) substrates using a DC magnetron sputtering deposition system by varying working pressure in the deposition chamber. The bonding structure, adhesion strength, surface roughness and corrosion behavior of the films were investigated by using X-ray photoelectron spectroscopy, micro-Raman spectroscopy, micro-scratch test, atomic force microscopy and potentiodynamic polarization test. A 0.6 M NaCl electrolytic solution was used for the corrosion tests. The optimum corrosion resistance of the films was found at a working pressure of 7 mTorr at which a good balance between the kinetics of the sputtered ions and the surface mobility of the adatoms promoted a microstructure of the films with fewer porosities.

Elucidating the asymmetric behavior of the discharge in a dual magnetron sputter deposition system

A magnetron discharge is characterized by drifts of the charged particles’ guiding center, caused by the magnetic field, in contrast to unmagnetized discharges. Because of these drifts, a pronounced asymmetry of the discharge can be observed in a dual magnetron setup. In this work, it is found that the shape of the discharge in a dual magnetron configuration depends on the magnetic field configuration. In a closed configuration, strong drifts were observed in one preferential direction, whereas in a mirror configuration the deflection of the discharge was not so pronounced. Our calculations confirm experimental observations.

Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

Influence of carbon sputtering power on structure, corrosion resistance, adhesion strength and wear resistance of platinum/ruthenium/nitrogen doped diamond-like carbon thin films

Platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films were deposited on conductive p-Si substrates using a DC magnetron sputtering deposition system by varying carbon sputtering power. The chemical composition, bonding structure, surface morphology and adhesion strength of the PtRuN-DLC films were investigated using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), and micro-scratch test, respectively. The corrosion behavior of the PtRuN-DLC films in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test. The corrosion results indicated that the corrosion resistance of the PtRuN-DLC films increased with increased carbon sputtering power probably due to decreased porosity level in the films with increased growth rate and film thickness. The wear performance of the PtRuN-DLC films was investigated with a ball-on-disc micro-tribometer. It was found that the increased carbon sputtering power significantly improved the wear performance of the films by enhancing the adhesion strength of the films.

Inductively coupled plasma-assisted RF magnetron sputtering deposition of boron-doped microcrystalline Si films

An innovative custom-designed inductively coupled plasma-assisted RF magnetron sputtering deposition system has been developed to synthesize B-doped microcrystalline silicon thin films using a pure boron sputtering target in a reactive silane and argon gas mixture. Films were deposited using different boron target powers ranging from 0 to 350 W at a substrate temperature of 250 °C. The effect of the boron target power on the structural and electrical properties of the synthesized films was extensively investigated using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and Hall-effect system. It is shown that, with an initial increase of the boron target power from 0 to 300 W, the structural and electrical properties of the B-doped microcrystalline films are improved. However, when the target power is increased too much (e.g. to 350 W), these properties become slightly worse. The variation of the structural and electrical properties of the synthesized B-doped microcrystalline thin films is related to the incorporation of boron atoms during the crystallization and doping of silicon in the inductively coupled plasma-based process. This work is particularly relevant to the microcrystalline silicon-based p– i– n junction solar cells.

The Research on Endothelialization of the Ti-O Films Surface Modified by Plasma Implantation and Immobilized with Ln and Fn

In this paper, the Ti-O films were prepared by unbalanced magnetron sputtering deposition system. The films were then treated by plasma immersion ion implantation (PIII) using ammonia gas in order to introduce amino group to Ti-O films surface. The content of amino group on modified Ti-O films can be tested by Acid Orange II. The surface structure, roughness and the chemical composition of elements, were analyzed by x-ray diffraction(XRD),atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). After that, laminin (Ln) and fibronectin (Fn) were covalently immobilized to the surface by the amidogen. The human umbilical vein endothelial cells (HUVEC) were seeded in vitro onto the modified and unmodified Ti-O films surfaces for evaluating the cell compatibility and endothelialization trend. The morphology of endothelial cells (EC) was examined by optical microscopy.The Acid Orange II and XPS results show that the modified Ti-O films treated by plasma immersion ion implantation (PIII) contain amino groups. Endothelial cell culture experiment suggests The Laminin and Fibronectin can further enhance HUVEC adhesion and proliferation. And the PIII treated Ti-O film sample co-immobilized with Ln and Fn possess the best endothelial cell compatibility.

The Development of a Nanostructured, Graded Multilayer Cr-Cr<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB>-Cr<SUB>1−<I>x</I></SUB>Al<SUB><I>x</I></SUB>N Coating Produced by Pulsed Closed Field Unbalanced Magnetron Sputtering (P-CFUBMS) for Use in Aluminum Pressure Die Casting Dies

The main objective of this research is to design an optimized 'coating system' that extends die life by minimizing premature die failure. The concept of the multilayer coating system with desired combinations of different kinds of single-layer coatings was introduced. A pulsed closed field unbalanced magnetron sputtering (P-CFUBMS) deposition system has been used to deposit Cr-CrxNy-Cr1-xAlxN compositionally graded multilayer coating structures. In this study, three power law scenarios have been adopted to vary the aluminum concentration in the graded Cr1-xAlxN layer: (i) p = 1, the aluminum concentration was increased linearly in the Cr1-xAlxN layer. (ii) p = 0.2, the Cr1-xAlxN layer is an aluminum-rich graded layer, and (iii) p = 2, the Cr1-xAlxN layer is a chromium-rich graded layer. It was found that all the graded coatings exhibit lower residual stress and higher adhesion strength than the homogeneous Cr1-xAlxN (x = 0.585) film. However, different power law grading architectures have significant influence on the hardness and wear resistance of the films. When p = 2 and p = 1, the graded films exhibited relatively low hardness values (24 and 26 GPa respectively) and high COF (0.55 to 0.60). When p = 0.2 the graded film exhibited both high hardness (34 GPa) and good wear resistance (COF = 0.45) due to the structural consistency in the graded zone. The paper discusses the correlation between the pulsing parameters and coating architecture with the resulting nanostructure and tribological properties of this Cr-CrxNy-Cr1-xAlxN coating system.

High-rate, room temperature plasma-enhanced deposition of aluminum-doped zinc oxide nanofilms for solar cell applications

A custom-designed inductively coupled plasma (ICP)-assisted radio-frequency magnetron sputtering deposition system has been employed to synthesize aluminium-doped zinc oxide (ZnO:Al) nanofilms on glass substrates at room temperature. The effects of film thickness and ZnO target (partially covered by Al chips) power on the structural, electrical and optical properties of the ZnO:Al nanofilms are studied. A high growth rate (∼41 nm/min), low electrical sheet resistance (as low as 30 Ω/□) and high optical transparency (>80%) over the visible spectrum has been achieved at a film thickness of ∼615 nm and ZnO target power of 150 W. The synthesis of ZnO:Al nanofilms at room temperature and with high growth rates is attributed to the unique features of the ICP-assisted radio-frequency magnetron sputtering deposition approach. The results are relevant to the development of photovoltaic thin-film solar cells and flat panel displays.

Deposition of dense and smooth Ti films using ECR plasma-assisted magnetron sputtering

We report high quality Ti films grown in a novel electron cyclotron resonance (ECR) plasma-assisted magnetron sputtering (PMS) deposition system. The films are compared with films deposited by conventional direct current (DC) magnetron sputtering. Using ECR-PMS, the argon plasma bombardment energy and Ti film deposition rate can be controlled separately, with the substrate bias voltage under feedback control. Results from SEM, AFM, XRD and PAS (scanning electron microscopy, atomic force microscopy, X-ray diffraction and positron annihilation spectroscopy) show that the properties of Ti films prepared by ECR-PMS are greatly improved compared with conventional sputtering. SEM and AFM confirmed that ECR-PMS Ti films have a dense, smooth, mirror-like surface. Increasing the substrate bias of the ECR plasma from − 23 V to − 120 V while keeping a fixed sputtering bias voltage of − 40 V, the intensity of the (100) reflection of Ti film was a little strengthened, but (002) remained strongly preferred orientation. The XRD peak broadening of ECR-PMS Ti films is more than for conventional magnetron sputtering, due to grain refinement induced by Ar ion bombardment. Doppler broadening of PAS analysis reveals that the Ti films have fewer vacancy defects compared with films prepared by the conventional magnetron.

Sputter-deposited Mg–Al–O thin films: linking molecular dynamics simulations to experiments

Using a molecular dynamics model the crystallinity of MgxAlyOz thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al2O3 film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the Mg–Al–O film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline Mg–Al–O films have a MgO structure with Al atoms in between.

P-type doping of ZnO by means of high-density inductively coupled plasmas

A custom-designed inductively coupled plasma assisted radio-frequency magnetron sputtering deposition system has been used to fabricate N-doped p-type ZnO (ZnO:N) thin films on glass substrates from a sintered ZnO target in a reactive Ar + N 2 gas mixture. X-ray diffraction and scanning electron microscopy analyses show that the ZnO:N films feature a hexagonal crystal structure with a preferential (002) crystallographic orientation and grow as vertical columnar structures. Hall effect and X-ray photoelectron spectroscopy analyses show that N-doped ZnO thin films are p-type with a hole concentration of 3.32 × 10 18 cm − 3 and mobility of 1.31 cm 2 V − 1 s − 1 . The current–voltage measurement of the two-layer structured ZnO p– n homojunction clearly reveals the rectifying ability of the p– n junction. The achievement of p-type ZnO:N thin films is attributed to the high dissociation ability of the high-density inductively coupled plasma source and effective plasma-surface interactions during the growth process.

Effect of nitride film coatings on cell compatibility

Objective To evaluate the cytotoxicity of nickel-based alloy surfaces after nitride film coatings. Methods A total of 120 disc-shaped specimens (1.5 × 12.0 mm) were prepared from nickel (Ni) alloy ingots and metallurgically ground with silicon carbide (SiC) sandpaper to 1200 grit and used as the ground group. Ninety specimens from the ground group were selected and further polished with 1.0 μm aluminum powder slurry and assigned as the polished group. Titanium nitride (TiN) and titanium–aluminum nitride (TiAlN) film coatings were deposited onto 30 polished specimens each by a reactive radio frequency magnetron sputter deposition system and used as coated groups, respectively. The morphological changes and cytoskeleton of tested human gingival fibroblasts were observed using fluorescence microscopy at 3 h and 24 h time periods, respectively. An MTT assay was used to assess cell viability at 24 h. The results were statistically analyzed ( n = 5, ANOVA, Scheffe’, p < 0.05). Results After 3 h of incubation, cells began to spread on the test surfaces. Spindle-shaped fibroblasts with well-developed cytoskeleton and distinct actin fibers were observed at the 24 h incubation point on the polished and coated specimens. Results of the MTT assay revealed that the TiN and TiAlN film coated groups were significantly higher in cell proliferation and viability than the polished and control groups ( p < 0.05). Significance The biocompatibilty of Ni-based alloy was increased significantly after nitride film coating.