STM and molecular dynamics simulations are used to study Au(001) 5×25 reconstructed surfaces after Ar+ bombardment at 600 eV and ion doses from 0.05 to 1 ML+. Surface 2D dislocation dipoles, identified as such in a previous investigation, are shown to have dislocation properties and to be formed by anisotropic diffusion of surface vacancies along the ridges of the reconstructed topmost layer. A new vacancy diffusion mechanism involving intermediate states with de-localized vacancies is identified. Increasing ion fluences is shown to lead to the formation of vacancy islands that are nucleated at the dislocation dipoles.

We have investigated the growth of Co deposited on Ag(100) with ultra low energy ion beam deposition. The preferred sites of nucleation, the island densities and heights are determined with scanning tunneling microscopy. Submonolayers of Co were ion beam deposited at 300 K using energies between 5 and 30 eV. Preferential growth of islands on the upper side of the mono-atomic Ag steps (i.e. step decoration) is observed for deposition energies of 5 and 15 eV. In addition, 3–4 ML deep holes are formed in the Ag substrate for deposition at 5 eV. At higher deposition energies, the number of holes per surface area decreases. The results are compared with experiments on thermal deposition of Co on Ag(100) as a function of substrate temperature, performed in a previous study.

We present a simulation study of the long range diffusion behavior of impinging atoms during ionized physical vapor deposition conditions with focus on grazing angles of incidence and kinetic energies in the range of 35 eV to 50 eV. Two different types of long range diffusion processes are observed and investigated: (1) diffusion of atoms ultimately adsorbing and (2) diffusion of atoms that eventually desorb. The simulations reveal that the second case is particularly pronounced for grazing angles and high kinetic energies, since the adsorption probability is very low under those conditions. In a further step, information about diffusion lengths is incorporated into a previously developed level set profile simulator to predict thin film topologies. These feature scale simulations show that long-range diffusion diminishes “macroscopic” grooving.

Surfaces with artificial roughness were generated by deposition of nanoparticles on single crystalline substrates. Nanoparticles with an average size ≈ 15 nm were produced by inert gas condensation and deposited in situ on the substrate mounted inside a modified ultra high vacuum (UHV) transmission electron microscope (TEM). We have investigated the smoothing behavior on annealing based on the difference in surface energies between cluster and substrate and their heat of mixing. The cluster substrate combination Co/Cu(100) was chosen as a model system in which the cluster has a significantly higher surface energy than the substrate. Upon deposition at 600 K, the clusters do not remain on the surface, but rather burrow into the substrate. This is confirmed by a detailed strain analysis of the particles. Nanoparticles in the system Ge/Si(100) in contrast have a lower surface energy than the substrate and are completely miscible. The particles assume the substrate orientation around 700 K. At 900 K coherent islands form which are arranged in clusters of 4 in the form of a square. The reason for this previously unobserved pattern is not yet understood.

Surface processing of microelectronic materials by bombardment with nanoparticles of condensed gases (i.e., clusters) in the form of an ion beam, makes possible etching and smoothing of those surfaces to very high figures of merit. As this is not possible with any conventional ion method, gas-cluster ion-beam systems have great potential in manufacturing. The formation of gas clusters and their collision with surfaces provides an interesting arena for novel physics and surface science. This paper outlines a physical model for the clusters and surface interactions, and provides examples of surface processing. In particular, the reduction of surface roughness while etching by cluster-ion bombardment is illustrated for various materials utilized in microelectronics.

Biaxially textured MgO buffer layers were deposited on metal substrates using “inclined substrate deposition” (ISD). The influence of the substrate inclination angle, deposition rate, and film thickness on the texture is shown. Scanning electron microscopy reveals columnar growth. We developed a growth model to explain the texturing. To test this model we have carried out 3D Monte-Carlo simulations. We find that the preferred orientation arises from mutual shadowing of the columns and directional surface diffusion due to their initial momentum.

YBa2Cu3O7 (YBCO) films deposited on the ISD buffer layers are highly textured. The ab-planes of the YBCO are tilted with respect to the surface by typically 25° towards the direction of MgO vapor incidence. Therefore, the critical current density jc is anisotropic with up to 8 × 105 MA/cm2 in one direction and 4 × 105 MA/cm2 in the other. For tape coating the MgO deposition direction can be chosen so that the high jc is along the tape.

Biaxially aligned film growth by dual-ion-beam sputtering methods were studied for fluorite type (Zr0.85Y0.15O1.93(YSZ), Hf0.74Yb0.26O1.87, CeO2), pyrochlore type (Zr2Sm2O7), and rare-earth C type (Y2O3, Sm2O3) oxides on polycrystalline Ni-based alloy substrates. Cubetextured (all axes aligned with a <100> axis substrate normal) films were obtained for fluorite and pyrochlore ones by low energy (<300 eV) ion bombardment at low temperatures (< 300 °C). Besides, cube textured Y2O3 films were obtained in far narrower conditions with a quite low energy (150 eV)-ion bombardment at the temperature of 300 °C. The assisting ion energy dependence was discussed in connection with lattice energies for these oxide crystals.

Biaxially textured yttria stabilized zirconia (YSZ) buffer layers were deposited on long polycrystalline metallic tapes by an ion-beam-assisted deposition process (IBAD) to serve as templates for high-current carrying Y1Ba2Cu3O7-x (YBCO) films. YSZ was deposited by a dualionbeam equipment with two 11 cm Kaufman ion sources. The coating of large-area technical substrates, large in comparison with the ion sources, requires substrate movements to render YSZ films of homogeneous texture quality. These movements can hinder cooling of the metallic tapes in the absence of a thermal contact. Therefore, the temperature of those small-heat-capacity substrates could rise to above 100 °C within minutes, causing a decrease of the in-plane alignment of YSZ. The investigation of the temperature dependence of the IBAD process reveals that the best results of the in-plane alignment could be obtained by room temperature deposition. Applying high tape velocities hinder a rise of the deposition temperature to above 90 °C. Therefore, it is possible to deposit YSZ films on metal tapes (up to 60 mm × 1000 mm) with in-plane textures down to 15° full width at half maximum (FWHM), which allow their coating with highcurrent-carrying YBCO films.

Ion-beam assisted deposition was used to fabricate biaxially aligned cubic zirconia on flexible metal substrates. These films were used as templates for heteroepitaxially deposited YBa2Cu3O7-δ (YBCO) films. The quality of the crystalline texture of the template films has a direct influence on the superconducting properties of the final YBCO films. We describe our efforts to fabricate high-quality cubic zirconia templates on short-length substrates processed in stationary mode and meter-long substrates processed in continuous mode. Our best phi scan FWHM values for the films on the meter-long tapes were 12.6 degrees for the template and 6.1 degrees for the overcoated YBCO. This meter-long tape had a self-field, 75 K, superconducting critical current of 122 amps.

We have developed a computer simulation based on analytic calculation of reflection high energy electron diffraction (RHEED) patterns in the kinematic approximation for mosaic polycrystalline films for given values of electron beam incidence angle, polycrystalline texture, in-plane orientation distribution, and grain size. Although RHEED is most appropriately modeled using dynamical scattering theory, the computational efficiency of the kinematic approximation has enabled the development of a model suitable for real time measurement of crystallographic texture and in-plane orientation distributions for biaxially-textured films grown by ion beam-assisted deposition (IBAD). Using the simulation, we can quantitatively determine how RHEED spot shapes and relative intensities depend on the crystallographic texture and in-plane orientation distribution of polycrystalline films. RHEED patterns taken at 25 keV with incidence angle in the range 1–5 degrees from 10 nm thick, nominally [100]-textured MgO films grown on amorphous Si3N4 by IBAD were analyzed by comparing experimental RHEED phi rocking curves with those predicted by the simulation. For some films, an additional 200 nm thermally-grown MgO homoepitaxial layer was grown on top of the IBAD MgO layer. The model enables a quantitative correlation between biaxial texture and RHEED measurements. RHEED results are compared to X-ray rocking curve film analysis.

The effect of low-energy ion bombardment on the microstructure of copper films will be described. The copper films have been deposited on SiNx-coated, oxidized Si wafers by magnetron sputtering with a simultaneous bombardment of low-energy argon ions (60 eV). The films were annealed at 450°C in HV. The ion bombardment leads to a stronger and sharper {111} texture of the as-deposited films. After annealing, the ion-bombarded films had a significantly smaller grain size than films produced without ion bombardment. The experimental results will be discussed relating the textures of the as-deposited films with the grain sizes obtained after annealing. Details will be given describing how the microstructure of Cu films can be tailored using low-energy argon ion bombardment.

This paper reviews the use of glancing-angle ions for modifying surfaces and thin film growth processes. Ions impinging on a flat surface at oblique incidence angles are mostly reflected without penetrating, providing very low sputtering rates along with minimal damage and implantation. They also provide a unique selectivity, where ion energy is coupled to defects or rough portions of the surface, while flat portions are essentially unaffected. This allows one to clean contaminated surfaces and smoothen rough surfaces, with little or no ion damage. In addition, recent results indicate that the ion energy couples directly to adatoms during epitaxial growth of GaAs(001). This was observed by a decrease in the time required for diffusion across terraces on a vicinal GaAs surface, as the glancing-angle Ar ion current was increased. It was also found that ion-enhanced diffusion shifted the growth mode from two-dimensional island nucleation to step-flow growth, and resulted in flatter growth surfaces. Finally, glancing-angleions can be used to introduce biaxial texture into polycrystalline GaAs films.

Molecular Dynamics computer simulations were used to explore a number of complex phenomena that occur during film growth and ion-surface interactions. A few examples are discussed. (1) Strong surface patterns develop when a Mo film is grown on a Mo(110) substrate, whereas they are absent for Mo on Mo(100). (2) Depositing a Mo film on a substrate containing two antiparallel (100)/(910) grain boundaries leads to complicated film morphologies in the grain boundary regions. Stresses, mosaic spread, and regions of fcc Mo are observed, and their stability is examined. (3) Cu films deposited on a Mo(110) substrate, a model system for interconnects in modern IC technology, are affected by the strong fcc/bcc interface mismatch. The Cu film properties are analyzed for thermally evaporated films and for films grown by argon ion-beam assisted deposition (IBAD).

We fabricated TFTs on a glass substrate using poly-Si films crystallized by an excimer laser with a SiO2 capping pattern placed exactly on the channel regions. This process greatly improves the uniformity of the TFT characteristics compared to conventional excimer laser-crystallized poly-Si TFTs, because the capping pattern controls nucleation and produces grains that are aligned along the capping pattern. However, the average mobility produced by the capping method is not as good as that produced by the conventional method. This study clarified that a thermal gradient can control grain structure and is effective in achieving uniformity, and that the maximum temperature of molten Si must be increased to obtain higher mobility.

Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanopanicles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry.

Patterning of magnetic multilayer structures of the type used for MRAMs (e.g. NiFeCo/CoFe/Cu/CoFe/NiFeCo) is generally performed with ion milling, but this can degrade the coercivity of small (micron-size) MRAM elements and lead to sidewall redeposition. In high ion density reactive plasmas (Cl2/Ar) it is possible to produce ion-enhanced desorption of otherwise involatile halogenated reaction products, and achieve practical etch rates (∼600 Å/min) for the multilayers. However, removal of the chlorinated etch products from the feature sidewalls is critically important to avoid corrosion. We have used de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas for removal of these etch residues. Some slight degradation in magnetization was observed in O2 plasma treated structures, but the other cleaning procedures produced no change in magnetic properties and excellent long-term stability. UV illumination of the sample surface during etching is also found to enhance etch rates, as has been reported previously for room temperature etching of Cu.[1]

Steel surface saturation by nitrogen (nitriding) results in a high increase in surface hardness and a decrease in friction rate. This treatment is widely used to increase the lifetime of cutting tools and wearing parts in machines.

A new approach of steel surface treatment by using the vacuum arc discharge in nitrogen is presented. The apparatus uses two arc vacuum discharges. The first discharge is a metal vapor discharge and serves for both the cleaning- heating of the treated surface and for the initiation of the second vacuum arc discharge in nitrogen. The vacuum arc source of metallic plasma allows us the simultaneous implantation of desirable metals and surface saturation by nitrogen. The developed arc vacuum discharge method shortens the nitriding time 2 to 3 times in comparison to the glow discharge technology. The suggested method of the surface treatment is suitable for a wide variety of steels. The hardness measurement results of nitriding and combined chromium with nitriding treatments of several steel samples are presented and discussed.

Silicon carbide, a wide-bandgap semiconductor, is currently used to fabricate an efficient high temperature hydrogen sensor. When a palladium coating is applied on the exposed surface of silicon carbide, the chemical reaction between palladium and hydrogen produces a detectable change in the surface chemical potential. Rather than applying a palladium film, we have implanted palladium ions into the silicon face of 6H, n-type SiC samples. The implantation energies and fluences, as well as the results obtained by monitoring the current through the sample in the presence of hydrogen are included below. The exposure to hydrogen of this kind of sensor while monitoring the current flow with respect to time, has revealed a completely different behavior than the samples that have Pd deposited as a surface layer.

The SiGe graded buffer layer is one of the most promising virtual substrates for future Si based high speed devices. The production of the SiGe buffer layer is, however, hampered by the time consumed by the synthesis of the several μm thick epitaxial layer. Low energy plasma enhanced chemical vapour deposition (LEPECVD) is a growth technique developed for low temperature epitaxy at high rates. Here we study the possibility to combine LEP-ECVD for graded SiGe buffer layer growth with other techniques for the growth of the electrically active layer.

Patterned Zn nuclei were formed by exposure with a single shot of an ArF excimer laser through a patterned photo mask onto a Si substrate which adsorbed DMZ (dimethylezinc). A ZnS thin film was then grown only onto the patterned Zn nuclei by KrCl excimer lamp irradiation of the substrate which was sealed in the chamber along with DMZ and H2S.