DC Magnetron Sputtering Deposition Research Articles

Influence of particle and energy flux on stress and texture development in magnetron sputtered TiN films

The real-time stress evolution during reactive dc magnetron sputter deposition of TiN films in Ar+N2 plasma discharge was measured in situ using a multiple-beam optical stress sensor, while the film texture was determined ex situ using x-ray diffraction. The influence of atomic N/Ti flux and energy flux, previously quantified by combining plasma characterization and Monte Carlo simulations (2009 J. Phys. D: Appl. Phys. 42 053002), was investigated by varying either the N2 partial pressure at fixed total pressure, the total working pressure or the bias voltage applied to the substrate. The contribution of thermal stress was carefully taken into account from thermal probe measurements to evaluate the intrinsic (growth) stress from the measured film force data. A clear correlation between stress, film texture and energy flux is evidenced: while underdense (1 1 1)-textured TiN films with ‘V’-shaped columnar growth (zone T) are under tensile stress (up to +0.6 GPa), dense TiN films with zone II microstructure develop a (0 0 2) texture and large compressive stress (up to 3 GPa) when the energy flux is higher than ∼150 eV per incoming particle. However, it is shown that a positive or negative bias voltage, though increasing the energy flux, did not promote a (0 0 2) texture. It is concluded that compressive stress development and (0 0 2) preferential growth are both kinetically driven processes in magnetron sputtered TiN layers, but exhibit distinct dependence with the substrate fluxes.

Effect of substrate temperature and film thickness on the characteristics of silver thin films deposited by DC magnetron sputtering

Silver (Ag) films were prepared by DC magnetron sputtering deposition at different substrate temperatures (25–450 °C) and film thicknesses (100–800 nm) and their morphological, optical, electrical and structural properties were investigated. Atomic force microscopy (AFM) was employed to study the surface topography of the thin films. The grain size as well as surface roughness of the films is strongly dependent on the temperature and the film thickness. X-ray diffraction experiments showed the intensity enhancement by increasing substrate temperature, also by increasing film thickness. The optical properties were determined by means of spectrophotometric analysis. It is found that the optical reflection is not affected significantly with substrate temperature and film thickness. The electrical resistivities of films were determined by four-point probe measurements. The experimental results indicate that the films with higher thickness and deposition temperature have the lowest resistivity.

Improvement of Interface Roughness in Platinum/Carbon Multilayers for X-Ray Mirrors

We present a study of the improvement in interface roughness of platinum/carbon multilayers for X-ray mirrors. The X-ray reflectivity of multilayers strongly depends on interface quality. In an effort to reduce the interface roughness caused by crystallization during deposition, carbon doping of platinum was proposed, and its effectiveness was evaluated. We compared 45-nm-thick single-layer platinum to carbon-doped platinum films. The films were deposited on a silicon (100) substrate by dc magnetron sputtering deposition. The surface roughness and X-ray diffraction spectrum of each film were measured by atomic force microscopy and X-ray diffraction, respectively. We concluded that the increase in carbon concentration suppresses the crystallization of platinum and causes the surface roughness to decrease.

Electronic structure of chromium-containing amorphous hydrogenated carbon thin films studied by X-ray absorption spectroscopy

C K-, Cr L3.2-, and K-edge X-ray absorption near-edge structure (XANES) analysis, high-resolution transmission electron microscopy examination, and optical absorptance have been examined to obtain a correlation between the optical absorptance and electronic structure of chromium-containing amorphous hydrogenated carbon thin films (a-C:H/Cr) deposited using a dc magnetron sputter deposition technique. It was found that the C 2pCr 3d hybridization gradually increases as the Cr nanoparticle (NP) size decreases, accompanied by a C 2p interband transition. The amount of CH bonding and the change in crystalline structure are the main factors affecting the optical absorptance of the thin films. The size of the Cr NP affects the absorption wavelength range of the films. The optical absorptance and C K-edge XANES spectra indicate that a decrease in the size of Cr NP raises the conduction-band-minimum and may also increase the bandgap.

Influence of the Interactions on the Magnetotransport Properties of Fe–Ag Granular Thin Films

Fe(x)Ag(100-x) granular thin films, 25 < or = x < or = 40, have been prepared by DC-Magnetron sputtering deposition. These samples are composed of small Fe nanoparticles (2.5-3 nm) embedded in an Ag matrix, and their size remains nearly constant with increasing Fe content. A crossover in the collective magnetic behaviour of the samples near x = 35, had been previously reported for these samples. In this article, we show that the transport and magnetotransport properties are clearly correlated with these magnetic behaviours, and that the resistivity, the magnetoresistance and the Hall resistivity depend on the nature of the most relevant interactions, dipolar or direct exchange, as a function of the thermal evolution and the Fe content.

Controlling the deposition rate during target erosion in reactive pulsed DC magnetron sputter deposition of alumina

Alumina coatings were synthesized by reactive pulsed DC magnetron sputtering in an industrial-scale deposition system. The aim of this study was to investigate the influence of target erosion (racetrack depth) on the deposition rate. Hysteresis curves, showing the cathode voltage as a function of oxygen flow, were mapped out for different target erosion depths and temperatures, revealing significant variations, e.g. in the metallic mode voltage level. Each deposition was made with a fixed cathode voltage and the cathode current was controlled by adjusting the oxygen flow in a feedback loop by means of which a constant power was maintained. Keeping the power constant, this procedure was repeated for various cathode voltages within the hysteresis transition region and at different racetrack depths and deposition temperatures. The corresponding deposition rates were observed to depend mainly on the relative cathode voltage set-point in-between the oxide and metallic voltage levels in the hysteresis region. This result enables control of the deposition rate by maintaining a constant relative cathode voltage as the target erodes.

Structure and Microscopic Magnetism of Epitaxial Ni–Mn–Ga Films

AbstractWe report on the structural and magnetic properties of epitaxial thin films of the ferromagnetic shape memory material Ni–Mn–Ga prepared by DC magnetron sputter deposition. Different substrate materials, i.e., MgO(100) and Al2O3(11−20) allow for a tailored epitaxial growth. Using a sacrificial chromium buffer layer freestanding epitaxial films are obtained. In combination with photolithography partially freestanding structures such as microbridges are fabricated. The complex martensite crystal structure in substrate‐constrained and freestanding films is studied by means of X‐ray diffraction. The identified asymmetric twin variant configuration is associated with a macroscopic surface pattern observed by optical microscopy. The absence of magnetic‐field induced strain in the (100) oriented samples is explained on basis of the detected twin variant configuration using a simplified model. Taking advantage of the thin film geometry spectroscopic methods are applied to the samples. The measurements provide the first experimental test for changes in the electronic structure of the involved 3d metals during a martensitic transition. Exploiting the X‐ray magnetic circular dichroism quantitative information on the element‐specific spin and orbital magnetic moments are accessed. In addition, angular‐dependent experiments allow us to trace the microscopic origin of the magnetic anisotropy in Ni2MnGa improving the fundamental understanding of this material.

Characterization of Failed Surface of Ti and Imidex (PI) Film for Different Inter-layer Thicknesses of Ti Film

For miniaturized biomedical devices, laser joining of dissimilar materials offers excellent potential to make precise joints. An important system for consideration is titanium (Ti) coated glass joined with biocompatible imidex polyimide (PI). Metallic Ti with various thicknesses was deposited on top of pyrex 7740 borosilicate glass by using DC-magnetron sputtering deposition method. Effect of bond strength between Ti coated glass and imidex polyimide (PI), due to thickness variation of sputtered Ti coating was studied. Three different Ti inter-layer thicknesses were considered, 50, 200, and 400 nm. Tests results indicated that the thinner film produced lower shear strength and higher thickness produced higher shear strength. It has been observed that thicker film (200 and 400 nm) enhanced considerably the bond strength with enhancing the film roughness as well. Higher roughness resulted in more contact area at the interface, results higher number of chemical bonds and increased mechanical interlocking; which in turn increase the laser joint strength. For stronger bond with higher thickness, mixed mode failure was observed which included cohesive failure of polymer, interface failure of Ti/glass and failure on the glass itself. On the other hand, for weak bond with thinner film, mostly interface failure was observed for this system of Ti coated glass/imidex. For thicker film, chemical bond of Ti-C and Ti-O were observed. The role of both surface characteristics and chemical bonding for laser joints were investigated by using advanced techniques such as X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy.

States of Particles in DC Magnetron Sputtering Deposition of Titanium Metallic

A DC magnetron sputtering of titanium metallic was diagnosed in terms of the states and the spatial distribution of particles in the plasma by a single Langmuir probe. The investigations were carried out with the deposition system previously reported with high quality titania films and under described conditions. The simple experimental set-up had been known for decades but with caution on the extremely complicated of analyses. The experimental accuracy and the plasma characteristics obtained must not only be discussed with theoretical treatments, however, the refinement of the whole process deems necessary. The concurrent of results; the transport of atoms by the knowledge of magnetic field profiling coupled with electron density distributions, the energetic of particles which believed to be responsible for differences in phases formation, would vividly explains the deposition process of the films. Furthermore, the results obtained with a variety of theoretical treatments whether a Maxwellian/non- Maxwellian distribution and on viable of collisionless plasma and the generation of secondary electrons would be discussed with the measured data.

Thickness effect on laser-induced-damage threshold of indium-tin oxide films at 1064 nm

Laser-induced-damage characteristics of commercial indium-tin oxide (ITO) films deposited by DC magnetron sputtering deposition on K9 glass substrates as a function of the film thickness have been studied at 1064 nm with a 10 ns laser pulse in the 1-on-1 mode, and the various mechanisms for thickness effect on laser-induced-damage threshold (LIDT) of the film have been discussed in detail. It is observed that laser-damage-resistance of ITO film shows dramatic thickness effect with the LIDT of the 50-nm ITO film 7.6 times as large as the value of 300 nm film, and the effect of depressed carrier density by decreasing the film thickness is demonstrated to be the primary reason. Our experiment findings indicate that searching transparent conductive oxide (TCO) film with low carrier density and high carrier mobility is an efficient technique to improve the laser-damage-resistance of TCO films based on maintaining their well electric conductivity.

Realization of a Wideband Microwave Noise Filter Used Magnetic Multilayer Thin Films by Using Exchange Bais Stacks Structure

The microwave magnetic dynamic properties of the [NiFe(40nm)/IrMn(15nm)]6/[NiFe(30nm)/IrMn(15nm)]7/[NiFe(20nm)/IrMn(15nm)]10 multi-stacks structure films, prepared by high vacuum DC magnetron sputtering deposition, have been investigated at the frequency range from 10 MHz to 6 GHz. By changing the thickness of the ferromagnetic (FM) NiFe layer in bottom [NiFe(t nm)/IrMn(15nm)]6 stack part, a tunable lower frequency range used magnetic multilayer can be realized. The influence of the NiFe layer thickness in bottom stack to static and dynamic magnetic properties were obtained and analyzed. Combining with the top [NiFe(30nm)/IrMn(15nm)]7/[NiFe(20nm)/IrMn(15nm)]10 two stacks used in the higher frequency, a kind of multi-stacks structure magnetic thin films were fabricated for the wideband microwave noise filter.

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.

Optical and electrical properties of transparent conducting B-doped ZnO thin films prepared by various deposition methods

B-doped ZnO (BZO) thin films were prepared with various thicknesses up to about 500 nm on glass substrates at 200 °C by dc or rf magnetron sputtering deposition, pulsed laser deposition (PLD), and vacuum arc plasma evaporation (VAPE) methods. Resistivities of 4–6 × 10−4 Ω cm were obtained in BZO thin films prepared with a B content [B/(B + Zn) atomic ratio] around 1 at. % by PLD and VAPE methods: Hall mobilities above 40 cm2/Vs and carrier concentrations on the order of 1020 cm−3. All 500-nm-thick-BZO thin films prepared with a resistivity on the order of 10−3–10−4 Ω cm exhibited an averaged transmittance above 80% in the wavelength range of 400–1100 nm. The resistivity in BZO thin films prepared with a thickness below about 500 nm was found to increase over time with exposure to various high humidity environments. In heat-resistance tests, the resistivity stability of BZO thin films was found to be nearly equal to that of Ga-doped ZnO thin films, so these films were judged suitable for use as a transparent electrode for thin-film solar cells.

Optical Properties of Ultrathin Copper Thin Films Sandwiched between Nb-Doped TiO2 Films Studied with Spectroscopic Ellipsometry

Cu thin films sandwiched between Nb-doped TiO2 (NTO) thin films were grown on glass substrates using tilted-dual target DC magnetron sputtering deposition. The thicknesses of the top and bottom NTOs were nominally 30 nm, and the thicknesses of the Cu films (t) varied between 1.5 nm and 50 nm. We measured the ellipsometric angles (Ψ,Δ) of the NTO/Cu/NTO/glass by using spectroscopic ellipsometry and estimated the thicknesses and dielectric functions of the Cu films by using a multi-layer model analysis. Transmission electron microscopy measurements showed that the Cu layers evolved from aggregates of Cu nanoparticles to coalesced Cu thin films as the Cu film thickness increased. Sheet resistance data also showed that the t = 8 nm film was near the percolation threshold, suggesting that films thinner than 8 nm were aggregations of Cu nanoparticles that were not well-connected. The films thicker than 8 nm were above the percolation threshold. From the Drude model, we estimated the plasmon frequency (ωp) and the electron relaxation time (τ), which were found to increase with increasing film thickness. By applying standard critical point analysis to the second derivatives of the dielectric function spectra, we found several peaks near 1.5, 2.1, 2.5, 3.5, and 4.3 eV, and attributed to interband transitions. The peak energies (except 1.5 eV) matched to the band structure calculations of bulk Cu found in the literature.

Thermo-electrochemical activation of Cu 3Sn negative electrode for lithium-ion batteries

A Cu 3Sn film electrode (thickness = ca. 3 μm) is prepared by DC magnetron sputtering deposition of Sn on Cu substrate and subsequent annealing at 300 °C for 30 h. At 25 °C, this Cu–Sn binary intermetallic compound is inactive for lithiation, but becomes active at elevated temperatures due to facilitation of Cu–Sn bond cleavage for the conversion-type lithiation. The lithiated product at 120 °C is the most Li-rich Li–Sn alloy (Li 17Sn 4). Upon de-lithiation, the Cu–Sn intermetallics of different compositions are generated by the reaction between the metallic Sn that is restored from Li 17Sn 4 and the idling metallic Cu. The nature of the resulting intermetallics is dependent on the de-lithiation temperature: Cu 10Sn 3 at 120 °C and Cu 6Sn 5 at 25 °C. Only the latter is active for lithiation in the subsequent room-temperature cycling. That is, Cu 3Sn is thermo-electrochemically activated to be Cu 6Sn 5 by lithiation at 120 °C and subsequent de-lithiation at 25 °C. The higher lithiation activity observed with the more Sn-rich phase (Cu 6Sn 5) compared to the initial one (Cu 3Sn) has been accounted for by the higher equilibrium lithiation potential (thermodynamic consideration) and smaller number of Cu–Sn bonds to be broken (kinetic consideration).

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.

Palladium Nanostructures Synthesis by Sputtering Deposition on HOPG Surfaces

The synthesis of palladium thin films and shell nanostructures by dc-magnetron sputtering deposition on highly ordered pyrolytic graphite (HOPG) surfaces is described. Electrospun polymer fibers mats were used as templates for the Pd shell nanostructures formation. The morphology was characterized with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Pd nanostructures were used as catalysts for oxygen reduction reaction (ORR). The ORR activity was evaluated in sulfuric acid and the methanol tolerance in 1 M methanol solutions saturated with oxygen. The Pd shell nanostructures have better ORR activity than Pd thin films.

Effect of inserting a buffer layer on the characteristics of transparent conducting impurity-doped ZnO thin films prepared by dc magnetron sputtering

In transparent conducting impurity-doped ZnO thin films prepared on glass substrates by a dc magnetron sputtering (dc-MS) deposition, the obtainable lowest resistivity and the spatial resistivity distribution on the substrate surface were improved by a newly developed MS deposition method. The decrease of obtainable lowest resistivity as well as the improvement of spatial resistivity distribution on the substrate surface in Al- or Ga-doped ZnO (AZO or GZO) thin films were successfully achieved by inserting a very thin buffer layer, prepared using the same MS apparatus with the same target, between the thin film and the glass substrate. The deposition of the buffer layer required a more strongly oxidized target surface than possible to attain during a conventional dc-MS deposition. The optimal thickness of the buffer layer was found to be about 10 nm for both GZO and AZO thin films. The resistivity decrease is mainly attributed to an increase of Hall mobility rather than carrier concentration, resulting from an improvement of crystallinity coming from insertion of the buffer layer. Resistivities of 3 × 10 − 4 and 4 × 10 − 4 Ω cm were obtained in 100 nm-thick-GZO and AZO thin films, respectively, incorporating a 10 nm-thick-buffer layer prepared at a substrate temperature around 200 °C.