Ion Beam Sputter Deposition Process Research Articles

Optimization of dielectric films with dual ion beam sputtering deposition for high reflectivity mirrors

Abstract Dielectric thin films deposited by Ion beam sputtering deposition technique have superior properties of good adhesion and customized optical properties suits to many optical filters for electro-optical sensors. In the present work Tantalum Pentoxide (Tantala) and Silicon Dioxide (Silica) thin films are fabricated with dual ion beam sputtering deposition process. The process parameters are optimized to achieve better surface quality and optical constants. The effect of the assist ion beam on the film properties is evaluated. Multi-layer dielectric mirrors realized with 1000 ppm loss on optimization of single-layer Silica and Tantala films, which will be suitable for linear and Ring Laser Resonators. The films are characterized by ellipsometer, non-contact optical profiler, spectrophotometer, and cavity ring-down loss meter. The multi-layer mirrors were subjected to vacuum annealing and the effect of annealing on film reflectivity is evaluated. The work emphasizes the process requirements of Ion Beam Sputtering to realize high reflectivity and low loss mirrors of Tantala and Silica films from Ta2O5 and SiO2 target materials. It gives an insight into the process deficiencies in matching the theoretical design of multi-layer mirrors from the practical aspects of coatings.

Assessing a growth anomaly in ion-beam sputtered non-stoichiometric NiOx

Nonstoichiometric NiOx thin films were grown on single crystal substrates of c-plane (0001) sapphires by ion-beam sputter-deposition (IBSD) of a Ni metal target in a mixed argon and oxygen atmosphere. Structural characterization was carried out by X-ray diffraction and scanning electron microscopy. All samples grew (111)-oriented out-of-plane and with a defined in-plane orientation relationship relative to the crystalline substrate. The chemical bonding information of the films was examined by X-ray photoelectron spectroscopy showing that the composition x could be varied by adjusting the oxygen-to-argon ratio in the IBSD process. However, a growth anomaly was detected for a certain range of synthesis parameters, standing out due to an enhanced growth rate, nickel excess, and unusually elongated surface structures. With joint solid-state and plasma diagnostic tools, the underlying processes on the atomic scale were studied. An increased proportion of atomic oxygen species in the intermediate range of the oxygen-to-argon gas flux ratio was identified to be responsible for an enhanced generation of NiOx species. Optical emission spectroscopy was found to be a tool especially well-suited, since the in situ examination of various locations of interest (plasma, ion beam, and vicinity of the target) is feasible nonintrusively.

Thermoelectric Properties and Morphology of Si/SiC Thin-Film Multilayers Grown by Ion Beam Sputtering

Multilayers (MLs) of 31 bi-layers and a 10-nm layer thickness each of Si/SiC were deposited on silicon, quartz and mullite substrates using a high-speed, ion-beam sputter deposition process. The samples deposited on the silicon substrates were used for imaging purposes and structural verification as they did not allow for accurate electrical measurement of the material. The Seebeck coefficient and the electrical resistivity on the mullite and the quartz substrates were reported as a function of temperature and used to compare the film performance. The thermal conductivity measurement was performed for ML samples grown on Si, and an average value of the thermal conductivity was used to find the figure of merit, zT, for all samples tested. X-ray diffraction (XRD) spectra showed an amorphous nature of the thin films. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the film morphology and verify the nature of the crystallinity. The mobility of the multilayer films was measured to be only 0.039 to 1.0 cm2/Vs at room temperature. The samples were tested three times in the temperature range of 300 K to 900 K to document the changes in the films with temperature cycling. The highest Seebeck coefficient is measured for a Si/SiC multilayer system on quartz and mullite substrates and were observed at 870 K to be roughly −2600 μV/K due to a strain-induced redistribution of the states’ effect. The highest figure of merit, zT, calculated for the multilayers in this study was 0.08 at 870 K.

Systematic investigation of the reactive ion beam sputter deposition process of SiO2

Ion beam sputter deposition (IBSD) is an established physical vapour deposition technique that offers the opportunity to tailor the properties of film-forming particles and, consequently, film properties. This is because of two reasons: (i) ion generation and acceleration (ion source), sputtering (target) and film deposition (substrate) are locally separated. (ii) The angular and energy distribution of sputtered target atoms and scattered primary particles depend on ion incidence angle, ion energy, and ion species. Ion beam sputtering of a Si target in a reactive oxygen atmosphere was used to grow SiO2 films on silicon substrates. The sputtering geometry, ion energy and ion species were varied systematically and their influence on film properties was investigated. The SiO2 films are amorphous. The growth rate increases with increasing ion energy and ion incidence angle. Thickness, index of refraction, stoichiometry, mass density and surface roughness show a strong correlation with the sputtering geometry. A considerable amount of primary inert gas particles is found in the deposited films. The primary ion species also has an impact on the film properties, whereas the influence of the ion energy is rather small.

Full-atomistic nanoscale modeling of the ion beam sputtering deposition of SiO2 thin films

The previously developed high-performance parallel method of the atomistic simulation of the ion beam sputtering deposition process is applied to the SiO2 thin films. Structural properties of deposited films such as density, concentration of point defects, ring statistics, as well as effects arising from the interaction of high energy sputtered Si atoms with the growing film are discussed.

Linear Ion Beam Applications for Roll-to-Roll Metal Thin Film Coatings on PET Substrates

Linear ion beams have been introduced for the ion beam treatments of flexible substrates in roll-to-roll web coating systems. Anode layer linear ion sources (300 mm width) were used to make the linear ion beams. Oxygen ion beams having an ion energy from 200 eV to 800 eV used for the adhesion improvement of Cu thin films on PET substrates. The Cu thin films deposited by a conventional magnetron sputtering on the oxygen ion beam treated PET substrates showed Class 5 adhesion defined by ASTM D3359-97 (tape test). Argon ion beams with 1~3 keV used for the ion beam sputtering deposition process, which aims to control the initial layer before the magnetron sputtering deposition. When the discharge power of the linear ion source is 1.2 kW, static deposition rate of Cu and Ni were 7.4 and <TEX>$3.5{\AA}/sec$</TEX>, respectively.

Ion beam sputter deposition of epitaxial Ag films on native oxide covered Si(1 0 0) substrates

Epitaxial Ag films were grown on native oxide covered Si(100) substrates by an ion beam sputter deposition process at elevated deposition temperatures. At RT, films were observed to be non-epitaxial but with preferred (111) orientation. However, elevated substrate temperatures and under highly energetic sputter deposition process assist the growth of Ag films, that exhibit an epitaxial relationship with the underlying Si(100) substrates. With increasing deposition temperature an increase in the crystalline quality was observed with a narrowing mosaic distribution of crystallites and a decrease in the fraction of 1st order twins. The lowest epitaxial growth temperature was observed to be as low as 100°C.

Composition-Dependent Characterization of Sb2Te3 Thin Films Prepared by Ion Beam Sputtering Deposition

The optimization of ion beam sputtering deposition process for Sb2Te3 thin films deposited on BK7 glass substrates is reported. The influence of composition ratio on the thermoelectric properties is investigated. X-ray diffraction shows that the major diffraction peaks of the films match with those of Sb2Te3. Hall effect and Seebeck coefficient measurement reveal that all the samples are of p-type. The Sb2Te3 thin films exhibit the Seebeck coefficient of 190 μVk−1 and the electrical conductivity of 1.1 × 103 Scm−1 when the atomic ratio of Sb to Te is 0.65. Carrier concentration and motility of the films increase with the increasing atomic ratio of Sb to Te. The Sb2Te3, film with a maximum power factor of 2.26 × 10−3 Wm−1K−2 is achieved when annealed at 400° C. Raman measurement shows that the main peaks are at about 120 cm−1, 252 cm−1 and 450 cm−1, in agreement with those of V-VI compound semiconductors.

Effects of nitrogen partial pressure on electrical properties and thermal stability of TiAlN films by ion beam sputter deposition

TiAlN films prepared using ion beam sputter deposition (IBSD) method are planed to be used as both the bottom electrode and diffusion barrier for a metal-insulator-metal (MIM) (Ba,Sr)TiO 3 (BST) capacitor in our study. We had shown the effects of ion beam voltage, substrate temperature on electrical properties, and thermal stability of TiAlN films in our previous study. In this paper, effects of nitrogen partial pressure ( P N2) during the IBSD process on TiAlN films properties and their effect on the electrical resistivity and thermal stability were investigated. It was found that P N2 affects the crystallographic structure, crystallinity, and composition of the films, resulting in varied performance in electrical resistivity and thermal stability. As P N2 increased, the degree of predominance in the (200) plane and the crystallinity of films decreased, resulting in the increase of electrical resistivity. It is believed that the diminishing degree of predominance in the (200) plane and the crystallinity of the films can be attributed to a decreased kinetic energy of adatoms with increasing P N2. Changing the amount of P N2 also affected the composition of deposited films. Thermal stability decreased with decreasing Al content and the crystallinity of films. It is worth mentioning that due to the dense film quality nature of the IBSD method, the TiAlN films deposited under optimum conditions ( P N2 = 4.4 × 10 −3 Pa) exhibited good thermal stability up to 700 °C in an oxygen atmosphere and the resistivity remained lower than 500μΩ × cm.

Structure and Catalytic Properties of PtRu Alloy Thin-film

A PtRu alloy thin-film used for catalytic electrodes of fuel cells was fabricated by ion beam sputtering(IBS).The structure,surface layer structure,chemical composition,surface chemical state,and morphology of the PtRu alloy thin-film were characterized using X-ray diffraction(XRD),grazing incidence X-ray diffraction(GIXD),X-ray photoelectron spectroscopy(XPS),and atomic force microscopy(AFM).It was shown that the surface chemical state and structure in the top layer(from 15-40 nm)of PtRu alloy thin-film were changed due to the strong interaction between Pt+ and Ru+ during the ion beam sputtering deposition process,which also affected the catalytic activity of the PtRu alloy thin-film.In particular,when the atomic ratio of xPt/xRu was 0.64,enrichment of the Ru solid solution and amorphous phase Pt39Ru61 were observed on the surface layer of PtRu alloy thin-film.

TiO_2-Ta_2O_5 composite thin films deposited by radio frequency ion-beam sputtering

TiO2--Ta2O5 composite films were prepared by a radio frequency ion-beam sputtering deposition process, and the refractive indices and extinction coefficients of the composite films were found to be between those of the TiO2 and Ta2O5 films. The structure of the as-deposited films was amorphous, and the surface roughness was approximately 0.1 nm. The residual stress of the composite films was less than that of pure TiO2 film. The structure of the composite films after annealing was amorphous, with low surface roughness and slightly increased residual stress. The film containing 6.3% TiO2 displayed better properties than either the pure TiO2 or the pure Ta2O5 film.

EFFECT OF SEED LAYER AND DEPOSITION ATMOSPHERE ON ORIENTATION AND FERROELECTRIC PROPERTIES OF SBN60 THIN FILMS

ABSTRACT Sr0.6Ba0.4Nb2O6 (SBN60) thin films with thin Sr0.3Ba0.7Nb2O6 (SBN30) seed layer were deposited on top of an oriented Pt(100)/TiO2/SiO2/Si(100) substrate using ion beam sputter deposition process. Effects of seed layer thickness, oxygen-to-argon partial pressure ratio and annealing temperature on the orientation and ferroelectric properties of SBN60 thin films are discussed. The orientation was developed primarily along the c-axis, i.e. [001] direction. It was found that the seed-layer and the oxygen-to-argon pressure ratio influenced the degree of c-axis orientation.

LP‐8: Late News Poster: Ion Beam Sputter Deposition Process of Inorganic Vertical Alignment Layers

AbstractThe research results of silicon dioxide thin films alignment properties is presented. The films was deposited by oblique ion beam sputtering on glass substrate. Films thickness and angle condensation influences on the value of pretilt angle of liquid crystal vertical alignment mode is shown. Role of the surface morphology of alignment layers is discussed. The highly uniform vertical alignment layers can be produced using ion beam coating on the substrates with dimensions 300 × 400mm and more.

Preparation of films of (Tb,Dy)Fe 2 giant magnetostrictive alloy by ion beam sputtering process and their characterization

Giant magnetostrictive (Tb,Dy)Fe 2 films were prepared using an ion beam sputtering (IBS) process. In spite of an amorphous like structure of the films analyzed, significantly larger values of magnetization and magnetostriction were obtained in contrast with those of amorphous like films prepared by a flash evaporation process. The effect was caused by Ar in the films that was included during the IBS deposition process.

Epitaxial Y1Ba2Cu3O7−δ thin films with (103)/(110)- and (100)/(010)-orientation on NdGaO3 and SrTiO3 substrates grown by ion-beam sputter deposition

A fully oxygen-compatible ion-beam sputter deposition process (IBS) has been implemented for investigation of four film/substrate couples: (103)/(110)YBCO on (110)SrTiO3 (STO) and on (100)NdGaO3 (NGO), and (100)/(010)YBCO on (110)NGO and on (100)STO. For comparison, some (103)/(110)YBCO films have also been prepared by off-axis rf-magnetron sputtering. Below about 600 °C semiconducting, sub-nm flat, and perfectly single-crystalline YBCO films crystallize on these substrates with a crystallographic unit cell of about 1/3 of the Cu-O subcell of YBCO and perfect registration with the Ti4+-O and Ga3+-O sublattice of STO and NGO, respectively. At higher temperature superconducting YBCO films grow coherently epitaxially in the first ∼100 nm thickness; in thicker films the lattice-misfit strain relaxes to the “free” lattice constants. Above ∼680 °C a faceted (103)YBCO orientation grows on (110)STO and (100)NGO substrates with uniform in-plane orientation of the [010]YBCO direction parallel to [001]STO and [001]NGO. Along [010]YBCO the (103)YBCO films exhibit high crystalline perfection and intrinsic superconducting properties approaching those of (001)YBCO films in the plane; i.e., Tc,0 &gt; 88 K, ΔTc,0 &lt; 0.6 K, R300/R100 &gt; 2.9, ρ100 &gt; 250 μ°Cm, and jc (77 K) ⋚106 A/cm2. Practical use of (103)YBCO films is hampered by the large surface roughness. Above ∼680 °C a mixed (100)/(010)YBCO orientation grows on (110)NGO substrates, exhibiting a very smooth surface but less attractive superconducting properties; typically, Tc,0 ⋚ 80 K, ΔTc,0 ∼ 1 K, R300/R100 ∼ 1.2, ρ100 &gt; 3 m°Cm, and jc (77 K) ⋚105 A/cm2. On (100)STO substrates the YBCO film orientation varies from pure (100)YBCO between ∼580 and ∼630 °C and mixed (100)/(010)YBCO below ∼660 °C to pure (001) YBCO above ∼670 °C. With rising temperature the surface roughness increases from &lt;2 to ∼6 nm-rms, while the other parameters continuously improve to state-of-the-art values for c⊥-oriented films. Specifically, mixed (100)/(010)YBCO films reach Tc,0 &gt; 86 K, δc,0 ∼ 1 K, R300/R100 &gt; 2.8, ρ100 &lt; 3 m°Cm, and jc (77 K) &gt; 105 A/cm2. (100)/(010)YBCO films on (100)STO are a promising candidate for sandwich-type SIS-JJ.

Ion-beam sputter deposition process for Y1Ba2Cu3O7-δ thin-film structures

Ion-beam sputter deposition (IBS) has been developed to a fully oxygen-compatible technology for growth of complex oxides, such as Y1Ba2Cu3O7−δ (YBCO) thin films. The IBS system consists of an rf-plasma ion source with molybdenum grids for sputtering, a dc-plasma electron source for space charge compensation, stoichiometric YBCO and NGO targets, a beam chopper with BaO2, Cu, and Nd blades for stoichiometry control, and an ECR-oxygen-plasma source for in situ film oxidation and photoresist removal. Due to its complexity the IBS process is fully computer-controlled. A salient feature of IBS is the excellent crystallographic and morphological properties of thin (100)/(010)- and (103)-oriented YBCO films on SrTiO3 (STO) and NdGaO3 (NGO) substrates. Sharp interfaces and good superconducting properties render this technology feasible for the fabrication of SIS-ramp-junction SQUID's.

Post-deposition heat treatments for ion beam sputter deposited calcium phosphate coatings

Calcium phosphate coatings produced using the ion beam sputter deposition process are amorphous. To produce crystalline coatings, a series of different post-deposition heat treatments were conducted. Heat treatments conducted at temperatures less than 500 C did not produce crystalline phases in the coatings. A 500°C post-deposition heat treatment provided the energy required to produce a hydroxyapatite (HA)-type coating as determined using X-ray diffraction and Fourier transform IR spectroscopy (FTIR). Although post-deposition heat treatments can reduce the adhesion of a coating to its substrate, the 500°C heat treatment did not decrease the coating bond strength. Heat treatments conducted at 600°C were found to produce crystalline HA-type coatings but these heat treatments significantly reduced the coating bond strength. Cracks were observed on the surface of the 600 C heat treated coatings. FTIR analysis revealed a new absorption band at 820cm −1 for the 600 C heat treated coatings, suggesting the formation of a new phase.