Reactive sputter deposition of titanium dioxide

The microstructural, optical and electrical properties of reactively sputtered TiO_x films have been examined at points along the reactive deposition hysteresis curve. The deposition process utilizes feedback control loops of the current and oxygen/argon flowrates for operation in the internal region of the hysteresis curve. The variations in the optical properties are well correlated to the process conditions and the microstructure. For thicknesses of 60–100 nm, the films are polycrystalline for low deposition/high oxygen flow rates, and become amorphous for high deposition/low oxygen flow rates. Electron diffraction ring patterns of the polycrystalline phase are best fit to the d-spacings of the rutile structure. The index of refraction at 550 nm for the rutile phase polycrystalline films (10 nm grain size) is 2.6, this falls to 2.4 as the films become amorphous, and rises to 2.5 as the films become oxygen substoichiometric. We find the variation of the optical band gap of TiO_x to be less than 1%, and is less indicative of chemical and/or microstructural changes than the extinction coefficient at higher energies in the visible. The index of extinction at 350 nm shows a minimum at the same point as the index of refraction at 550 nm. We find the indirect fit of Tauc to the index of extinction gives the most linear fit. Variations in the complex index of refraction are consistent with the processing of r.f. sputtered films from titania targets.     

Morphology of sputter deposited Al alloy films

Morphology of Al–2.0at%Ta and Al–2.0 at.% Nd alloy films before and after annealing was investigated for applications of interconnections for liquid crystal displays. It was found that the morphology and the microstructure of Al–2.0 at.% Nd alloy films changed markedly by annealing at the temperature region from 200°C to 300°C, while the morphology of Al–2.0 at.% Ta alloy films did not change by annealing up to 400°C. For the case of Al–2.0 at.% Nd alloy films, the incline of the <111> fiber texture to the substrate normal was observed during annealing. Structural characteristics of the Al films were investigated by TEM, SAD and XRD to determine the influence of alloying elements on the morphology and the fiber texture. From these results, it was concluded that the microstructures strongly influence the morphology and the grain orientation of Al alloy films.     

磁过滤阴极真空弧沉积法制备TiAlN薄膜的研究

采用磁过滤阴极真空弧沉积技术在不同的真空室压强（N2流量）状态下制备TiAlN薄膜，讨论了N2流量对TiAlN薄膜各项性能的影响。并对薄膜的成分、结构和性能进行了测试。测试结果表明：获得薄膜较好，真空室压强对薄膜的厚度、摩擦系数和纳米硬度都有着重要的影响。     

Ag surfactant effects of TiO2 films prepared by sputter deposition

The surfactant effect of Ag on the thin film structure of TiO₂ by radio frequency magnetron sputtering has been investigated. Comparisons between the atomic force microscopy images revealed that the surface roughness of TiO₂ film mediated by Ag was smaller than that of the TiO₂ film without Ag. The surface segregation effect of Ag was confirmed using X-ray photoelectron spectroscopy. The results of X-ray diffraction revealed that the initial deposition of a 0.4 nm thick Ag surfactant layer onto a Fe buffer layer prior to the deposition of the TiO₂ film reduced the rutile (110) growth and enhanced the anatase (100) growth. It was concluded that Ag was an effective surfactant for changing the thin film structure of TiO₂ on the Fe buffer layer. The photocatalytic effect of the fabricated TiO₂ film was also investigated using the remote oxidation process. TiO₂ films with the Ag surfactant exhibited higher photocatalytic activity than conventionally deposited TiO₂ films.     

Microstructure of ZnO thin films produced by magnetron sputter oblique deposition

ZnO films deposited at different oblique angles of 40, 60 and 80°, under different Ar pressures 0.27, 0.67, 1.33 and 2.67 Pa, DC currents of 0.15 and 0.25 A, and distances of 10-15 cm from the target were studied. It was found that the film grains grow at an angle to the substrate when deposition angle is above 40°. It was shown that the grains consisted of a number of small crystals growing one on top of the other and shifted towards the target with the crystal orientation not along the grain growth but perpendicular to the substrate. Crystal size decreased with the deposition angle and internal stress disappeared when α = 80°. It was found that 1.33 Pa pressure provided the best balance between the deposition parameters. Growth rate reached maximum, samples had the biggest crystal size and high crystal density. However, crystal spatial alignment changed gradually with pressure and distance.     

Thick magnesium films produced by deposition techniques

Thick magnesium alloy films were prepared by both vapor deposition and sputter deposition techniques. It was found that the properties of the deposited films depend on the substrate material, deposition temperature and release agent, as well as substrate motion. Processing parameters were related to the physical integrity of the deposited film. A direct comparison between an alloy film produced by vapor deposition and an alloy film produced by sputter deposition was also made. It is concluded that sputter deposition is superior to vapor deposition, as the former method can produce a film not only more uniform in thickness, but also with much closer control of chemical composition.     

Reactive and non-reactive high rate sputter deposition of Tungsten carbide

Tungsten carbide coatings were deposited onto molybdenum and cemented carbide substrates using d.c. and r.f. magnetron sputtering. Tungsten targets were used in reactive (argon plus acetylene) atmospheres and tungsten carbide targets were used in non-reactive (argon) atmospheres. Substrates were r.f. biased with d.c. potentials of up to -1000 V. Sputtering from WC targets produced carbon-deficient mixed-phase structures with β-WC_1-x as the main component. Reactive deposition led to highly disordered W-C films which X-ray studies showed to be almost amorphous. Fractograms revealed very fine-grained to fractured amorphous film structures in all deposition modes. Hardness values higher than 3000 HV 0.05 were reached using non-reactive d.c. sputtering.     

The low-temperature electric conductivity of YBaCuO and LaSrMnO dielectric films obtained by a pulsed laser sputter deposition technique

We have studied the electric conductivity of YBaCuO and LaSrMnO dielectric films obtained by pulsed laser sputtering of targets possessing metallic conductivity. The plots of the sample resistance versus temperature R=R(T) measured at T<T _cr(T _cr=160–240 K) exhibit regions where R is independent of the temperature. This phenomenon is probably related to manifestations of the quantum confinement effects upon the conversion of small grains into quantum dots. In the region of T<T _cr, the electric conductivity of the system is determined by a mechanism of the phononless electron tunneling with participation of the atomic-type states belonging to small grains (clusters) featuring metallic conductivity in the amorphous matrix.     

Single- and dual-ion-beam sputter deposition of titanium oxide films

The optical properties and the surface morphologies of single-ion-beam sputtering (SIBS) and dual-ion-beam sputtering (DIBS) depositions of titanium oxide films are investigated and compared. In the DIBS process, the ion-assisted deposition by the voltage of a low ion beam ranged from 50 to 300 V at a 0% and 44% oxygen percentage. Cosputtering with materials of Si, SiO(2) (fused silica), and Al is also utilized in SIBS to improve amorphous-structure film. For the low-absorption and surface-roughness film, the optimum deposition condition of DIBS and postdeposition baking temperature for SIBS and DIBS are essential to the process.     

Radiofrequency sputter deposition of germanium-selenide thin films for resistive switching

The superionic conducting properties of Ag-doped GeSe thin films make this material a promising candidate for future, resistively switching-based memories allowing for high integration densities and short switching times. This paper reports on the radiofrequency sputter deposition of GeSe thin films and on the properties of the deposited thin films with respect to non-volatile memory applications. As sputter deposition is a widely used deposition method for industrial applications, we focused on the influences of deposition parameters as power and pressure to examine the suitability of sputter deposition for fabricating random access memories using GeSe-based resistive memory cells. Multiple characterization methods were utilized to determine the quality of the deposited thin films. The results of our measurements showed that we obtained smooth, dense and amorphous layers, which reveal good switching properties after doping with Ag, suitable for the use in GeSe-based memories.     

Optical properties of amorphous carbon thin films prepared by plasma deposition in a graphite hollow cathode

Carbon films have been produced using a graphite hollow cathode and an r.f. plasma of hydrogen or hydrogen and argon. No hydrocarbon gas was used. The films were subjected to heat treatments up to 700 °C in air. The optical properties of the films were studied using Fourier transform IR, UV-visible, Raman, ellipsometry and photoluminescence techniques before and after the annealing. Films prepared without argon have a narrower band gap and a different photoluminescence response from films prepared with argon. The index of refraction was seen to have values between 1.7 and 2.2 depending on the preparation conditions. The optical band gap of the films was generally greater than 2 eV and the annealing process both increased the gap and reduced the density of states responsible for the large photoluminescence signal.     

Synthesis and characterization of hard ternary AlMgB composite films prepared by sputter deposition

Hard and superlight thin films laminated with boron carbide have been proposed as candidates for strategic use such as armor materials in military and space applications. Aluminum magnesium boride (AlMgB) films are excellent candidates for these purposes. We prepared AlMgB films by sputter deposition using multiple unbalanced planar magnetrons equipped with two boron and one AlMg targets. The film morphology changed and the film's root mean square (rms) roughness varied from 1.0 to 18 nm as the power density of the AlMg target increased from 0.2 to 1.0 W/cm² while the power density of each boron target was maintained at 2 W/cm². Chemical analyses show dominating Al, Mg, B and trace elements of oxygen, carbon and argon. The film composition also varies with altering the power density supplied to the AlMg target. The film with an atomic ratio of Al:Mg:B = 1.38:0.64:1 exhibits the highest hardness (~ 30 GPa). This value surpasses the hardness of hydrogenated diamond-like carbon films (24-28 GPa) prepared by plasma enhanced chemical vapor deposition.     

Nanocrystalline Pd alloy films coated by electroless deposition

The structures of palladium and palladium alloys thin films deposited from organic electrolytes onto metallic substrates by electroless plating method have been investigated. The coatings are dense, pore-free 0.005-1 microm thick films with high adhesive strength to the substrate surface. EDX, XRD, SEM and TEM methods were used to determine the composition and structure of alloy coatings of the following binary systems: Pd-Au, Pd-Ag, Pd-Ni, Pd-Pb, and ternary system Pd-Au-Ni. The coatings of Pd-Au, Pd-Ag and Pd-Ni have a solid solution structure, whereas Pd-Pb is intermetallic compound. It has been found that the deposited films consist of nanocrystalline grains with sizes in the range of 11-35 nm. Scanning and transmission electron microscopy investigations reveal the existence of clusters formed by nanocrystalline grains. The origin for the formation of nanocrystalline structures of coating films is discussed.     

Ag surfactant effects of TiO2 films prepared by sputter deposition

The surfactant effect of Ag on the thin film structure of TiO₂ by radio frequency magnetron sputtering has been investigated. Comparisons between the atomic force microscopy images revealed that the surface roughness of TiO₂ film mediated by Ag was smaller than that of the TiO₂ film without Ag. The surface segregation effect of Ag was confirmed using X-ray photoelectron spectroscopy. The results of X-ray diffraction revealed that the initial deposition of a 0.4 nm thick Ag surfactant layer onto a Fe buffer layer prior to the deposition of the TiO₂ film reduced the rutile (110) growth and enhanced the anatase (100) growth. It was concluded that Ag was an effective surfactant for changing the thin film structure of TiO₂ on the Fe buffer layer. The photocatalytic effect of the fabricated TiO₂ film was also investigated using the remote oxidation process. TiO₂ films with the Ag surfactant exhibited higher photocatalytic activity than conventionally deposited TiO₂ films.     

Effects of deposition and post-annealing conditions on electrical properties and thermal stability of TiAlN films by ion beam sputter deposition

TiAlN films were deposited by ion beam sputter deposition (IBSD) using a Ti-Al (90/10) alloy target in a nitrogen atmosphere on thermal oxidized Si wafers. Effects of ion beam voltage, substrate temperature (T_s) and post-annealing conditions on electrical properties and oxidation resistance of TiAlN films were studied. According to the experimental results, the proper kinetic energy provided good crystallinity and a dense structure of the films. Because of their better crystallinity and predomination of (200) planes, TiAlN films deposited with 900 V at low T_s (50 °C) have shown lower resistivity than those at high T_s (250 °C). They also showed better oxidation resistance. If the beam voltage was too high, it caused some damage to the film surfaces, which caused poor oxidation resistance of films. When sufficient kinetic energy was provided by the beam voltage, the mobility of adatoms was too high due to their extra thermal energy, thus reducing the crystallinity and structure density of the films. A beam voltage of 900 V and a substrate temperature of 50 °C were the optimum deposition conditions used in this research. They provided good oxidation resistance and low electrical resistivity for IBSD TiAlN films.     

脉冲磁过滤阴极弧等离子体制备四面体非晶碳膜

介绍了脉冲磁过滤阴极电弧法制备四面体非晶碳膜(tetrahedral amorphous carbon即ta-C),并对制得的薄膜表面形貌、硬度、电阻等进行了测试.结果表明,脉冲磁过滤阴极电弧法制备的ta-C膜有优良的性能.拉曼光谱分析显示,制得的薄膜为非晶结构,有明显的sp3结构特征,符合ta-C膜的特征峰.     

Reactive magnetron deposition of transparent conductive films

Transparent conductive films of In₂O₃:SnO₂ were reactively sputter deposited using a d.c. planar magnetron cathode in the moving deposition mode. Deposition times of 1.25–6 min were used to coat soda-lime glass 1 ft² with films of optical thickness one-half of a wavelength ($\text{λ =}\text{5500}\text{A}\text{?}$). The films had a higher transmittance and a lower sheet resistivity R_s than those generally used for the small liquid crystal displays in watches or calculators. The as-deposited films were either a hard transparent oxide with a high R_s or a soft opaque metal-rich material with a low R_s.After sputtering, the films were annealed in air or in a reducing atmosphere at temperatures from 300 to 500°C; thus optical transmissions in excess of 90% (including glass substrates) and sheet resistivities below Ω/□ were obtained. An investigation of films deposited onto sapphire demonstrated that impurity diffusion from soda-lime glass substrates may lead to an anomalous dependence of R_s on the annealing conditions.It was found that the type of film deposited, namely oxidized or metal rich, depended on the history of the target. The significance of this observation is discussed with reference to process reproducibility.     

Controlled nanostructuring of Ag films by ion beam sputter deposition for surface plasmon resonance applications

The growth of Ag nanostrucutres on borosilicate glass substrates by ion beam sputter deposition in the Ar ion energy range from 150 to 600 eV is demonstrated. Rates of deposition as low as 0.01 nm/s are achieved at an Ar ion energy of 150 eV. This leads to the formation of a random array of nearly spherical Ag particles with a mean size of approximately 100 nm, separated by distances of similar order of magnitude. The particles organize themselves into arrays over lengths of at least 10 microm. As the thickness is increased from 3 to 18 nm there is a transition in morphology from an array to linear chains and finally a dense continuous film. There is a similar microstructural evolution as a function of increasing ion energy. The plasmon resonances can be tuned depending on shape, size and interparticle distances. As the thickness of the films increase, the main plasmon peaks can be tuned from 380 to 680 nm. The spheroidal shape of the particles induces additional peaks (localized surface plasmons) centered around 430 +/- 10 nm. Detailed simulations have been carried out based on Maxwell Garnett theory to distinguish the effects of shape and size on plasmon resonances. It is demonstrated that shape rather than the size of the particles has a stronger influence on the shift in plasmon resonances.