Search

Cathodic arc deposition, in spite of all its advantages, including feasible alloying evaporation, high deposition rate and considerable adhesion, faces the challenge of macroparticles. In this arti...

Numerical calculations of the accumulation kinetics of point defects—vacancies and divacancies—under the irradiation of Si with ions having masses of M1 ≤ 31 amu and energies of E ≤ 100 keV under various irradiation conditions are performed. The previously proposed diffusion-coagulation model is used without application of the “weak diffusion” approximation, which was performed during its analytical implementation. The main peculiarities of the dependences of the concentrations of vacancies and divacancies on the dose, ion-current density, and temperature under irradiation are analyzed. A physical interpretation of these results is given. The developed computing complex is rather flexible and makes it possible to analyze the influence of model input parameters by means of their variation and include additional processes into consideration if necessary.

An atomic and electronic structure of the bulk and thin-film morphologies of ZnO were modified using pulsed Bi-ion implantation (1x1017 cm-2 fluence, 70 min exposure under Bi-ion beam, EBi+ = 30 keV, pulsed ion-current density of not more than 0.8 mA/cm2 with a repetition rate of 12.5 Hz). The final samples were qualified by X-ray photoelectron core-level and valence band mapping spectroscopy applying ASTM materials science standard. The spectroscopy data obtained was discussed on the basis of DFT-models for Bi-embedding into ZnO host-matrices. It was established that in the case of direct Bi-impurities insertion into the employed ZnO-host for both studied morphologies neither the only "pure" Bi2O3-like phase nor the only "pure" Bi-metal will be preferable to appear as a secondary phase. An unfavorability of the large cluster agglomeration of Bi-impurities in ZnO-hosts has been shown and an oxygen 2s electronic states pleomorphizm was surely established., 20 pages, 8 figures, 2 tables, accepted to Appl. Surf. Sci

Corona discharge suppression for high-voltage direct-current (HVDC) transmission lines at line terminals such as converter stations is a subject that requires attention. In this paper, a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup. Compared with the bare conductor, the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device. The influences of film thickness and film material on the corona discharge suppression effect are investigated. The charge accumulation and dissipation characteristics of different film materials are also studied. The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge. The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength, and its ion current density is at the nA m−2 level. The corona threshold voltage can be promoted by increasing the film thickness, but the ability to inhibit corona discharge becomes weak. The larger the surface electric field strength, the more charge accumulated, but the faster the charge dissipation rate. Compared with polyvinyl chloride film, cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate, which can better restrain the corona discharge of HVDC transmission lines.

In this work, we present results of a study of low-energy (Е i < 200 eV) sputtering of Co and Mo nanometer thin films in high-density argon plasma of a low-pressure radio-frequency inductive discharge with a controlled incident ion energy and ion current density onto the sample. The average ion energy was determined by the negative self-bias potential, which arises when the RF bias power is applied to the substrate. The ion current density was determined from the ratio of the increments in the RF bias power and the self-bias potential. The sputtering rate was determined in situ by a refractometric method from a sharp change in the intensity of a reflected laser beam signal at the moment of a removal of a metal film. Precise control of sputtering made it possible to detect a formation of nanoscale structures at a stage near the end of sputtering of metal films. The experimentally determined sputtering yields of Co and Mo were in agreement with the results of semiempirical calculations. We demonstrate that for ion-plasma sputtering, removal of Co and Mo atoms occurs at ion energy lower than the sputtering threshold.

The paper presents a novel power supply device that provides a hybrid technique of dual magnetron sputtering. This power supply generates a sequence of bipolar pulses which provides both mid-frequency and high-power impulse magnetron sputtering. This allows using the advantages of both techniques, while numerous adjustable parameters considerably enhance the capabilities of the magnetron sputtering system. In the proposed power supply circuit, special attention is paid to the output pulse formers and the power switch control. The experimental results are obtained for superimposed mid-frequency and dual high-power impulse magnetron sputtering. During the aluminum film deposition, the deposition rate, the ion current density on the substrate and the ion-to-atom ratio are regulated by changing the power ratio between mid-frequency and high-power impulse magnetron sputtering.

The ICP plasma chemical reactor is studied by using the probe plasma diagnostic methods. The plasma density in the wafer region was evaluated at different parameters of the process. The automatic bias potential on the surface of glass wafers of different thickness and uniformity of the ion current density distribution over the plate diameter are measured. The deep silicon etching mode with a high uniformity over the whole plate is determined.

In der vorliegenden Arbeit wurde ein neuer reaktiver Magnetron Sputterprozess untersucht, bei welchem der beschichtende Sputterprozess durch eine zusatzliche Plasmaquelle unterstutzt wird. Die verwendete Plasmaquelle zeichnet sich durch eine hohe Ionenstromdichte bei moderater Ionenenergie aus. Zu Beginn der Arbeiten wurden umfangreiche Untersuchungen zur moglichen Wechselwirkung von Magnetron und Plasmaquelle im Beschichtungsprozess durchgefuhrt. Dazu gehort auch die Bestimmung von Plasmakenngrosen am Ort des Substrates. Es konnte gezeigt werden, dass durch die gewahlte Anordnung eine stabile, kontrollierbare Prozessfuhrung gewahrleistet ist. Anschliesend wurden mit dieser neuentwickelten Quellenanordnung bei reaktiver Prozessfuhrung oxidische Materialien wie Zirkon (ZrO2) und Titandioxid (TiO2) abgeschieden und untersucht. Es wird gezeigt, dass sich durch eine prazise Prozessfuhrung mit Einstellung des Ion-Teilchen-Verhaltnisses verschiedene optische und morphologische Schichteigenschaften gezielt beeinflussen lassen. Optical thin films with controlled properties by plasma enhanced magnetron puttering A new reactive magnetron sputter process was investigated in which an additional plasma source was implemented to support the magnetron sputter process. The plasma source is determined by high ion current density and moderate ion energy. At the beginning of the work, extensive investigations of the interaction of the magnetron with the plasma source during the deposition process were performed. Also, the plasma parameters in the region of the substrate were determined. A stable process which can be controlled very precicely was obtained with the set-up used here. In the following, different oxide materials such as zirconia (ZrO2) and titania (TiO2) were deposited and investigated. It shows that because of the precise process control, different optical and morphological properties can be directly influenced by tuning the ion-to neutral fraction of the process.

Ion beam etching based ultra precision surface finishing is a versatile technology with a high degree of predictability due to the high stability of state of the art ion sources and the acquired knowledge of the physics of beam surface interaction. The independent control of the ion energy and the ion current density over wide ranges and the possible additional use of chemical reactive species in combination with physical sputter removal allow solving tasks in a wide variety of applications. The paper summarizes the present status of more than 20 years of development of ion beam finishing technology in IOM. It gives an overview on the equipment and the components developed for production purposes and on the ion beam technologies developed to achieve nanometer and sub-nanometer depth accuracies over the entire spectrum of spatial surface wavelength from the full aperture size down to the microroughness level of only micrometer lateral feature size. Results of the finishing of high-end optical surfaces shown demonstrate the outstanding performances of the techniques with topography and roughness control on the atomic scale. Ultragenaue Oberflachen-Endbearbeitung mittels Ionenstrahltechniken Ionenstrahlatztechniken zur ultraprazisen Endbearbeitung von Oberflachen sind aufgrund der hohen Stabilitat gegenwartiger Ionenquellen und des physikalischen Verstandnisses der Strahlwechselwirkungen mit der Oberflache eine vielseitig einsetzbare Technologie. Die unabhangige Steuerung der Ionenenergie und der Ionenstromdichte sowie eine mogliche zusatzliche chemische Wirkung durch Reaktivgase zum physikalischen Zerstauben erlauben die Bearbeitung vielfaltiger Anwendungen. Die Publikation fasst den erreichten Stand von mehr als 20 Jahren Forschung und Entwicklung auf dem Gebiet der Ionenstrahl-Endbearbeitung von Oberflachen im IOM zusammen. Es wird ein Uberblick gegeben uber Anlagen und Komponenten, entwickelt bis zum Stadium fur einen Produktionseinsatz sowie uber Ionenstrahltechniken, die es erlauben, Oberflachen mit Nanometer- und Subnanometer-Tiefengenauigkeit uber das gesamte Spektrum der Ortswellenlangen von der vollen Apertur bis zu den Strukturen der Mikrorauheit effizient zu bearbeiten. Die vorgestellten Ergebnisse der Endbearbeitung von hochstgenauen optischen Oberflachen zeigen die hohe Leistungsfahigkeit der Techniken und demonstrieren die Bearbeitung von Oberflachentopografien und -rauheiten auf atomarer Skala.

This article reports on the effect of the energy delivered to a growing film by bombarding ions and fast neutrals on the macrostress σ and the structure of sputtered films. To demonstrate this effect, we selected Mo–Al–N films with a low (⩽20 at.%) Al content reactively sputtered using an unbalanced dc magnetron with a target of 100 mm diameter at a high total pressure p T = 3 Pa , low substrate bias U s = - 20 V and a high substrate ion current density i s = 1 mA / cm 2 . The main goal of this study was to show the reduction of σ in films sputtered at high pressures of several Pa. Under the conditions given above approximately 4 μm thick Mo–Al–N films with enhanced hardness H≈35 GPa and a very low (⩽−0.5 GPa) macrostress σ were successfully prepared. This result demonstrates that the enhanced hardness H of Mo–Al–N films is not caused by σ but is due to its nanostructure as shown in the XRD patterns of these films. The Mo–Al–N films with enhanced hardness are composed of a mixture of grains of different crystallographic orientations.

Biaxially textured CeO2 films were deposited on Hastelloy C276 substrates at room temperature using ion-beam-assisted e-beam evaporation with the ion beam directed at 55° to the normal of the film plane. The crystalline structure and in-plane orientation of films were investigated by x-ray diffraction 2θ-scan and -scan. The orientation of the films was studied as a function of ion-to-atom ratio and film thickness. The ion-to-atom ratio was varied by independently adjusting the deposition rate and the ion current density. Under optimum condition, (200) textured CeO2 films have been successfully grown on Hastelloy C276.

The exact equations of a radio frequency (rf) sheath driven by rf-biased voltage are solved numerically. All of the sheath characteristics for an arbitrary rf frequency are obtained, including the time-dependent ion density distributions, the ion current density, and ion kinetic energy at the electrode. Moreover, the ion energy distributions (IEDs) impinging on the rf-biased electrode are calculated, which match the experiment result [M. A. Sobolewski, J. K. Olthoff, and Y. C. Wang, J. Appl. Phys. 85, 3966 (1999)] exactly. The results show that the rf frequency is a crucial parameter for determining the spatiotemporal characteristic and the shape of IEDs.

The systematic Langmuir probe measurements for a weakly magnetized plasma have been carried out in the Linear Magnetized Plasma Device for different magnetic fields. By comparing the ion current density of probes with different sizes, the sheath thickness can be evaluated. It is found that while the ratio of cylindrical probe's dimension to ion Larmor radius is not more than 2, the model of probe for non-magnetized plasma is still applicable.

The moment and geometric aberrations of magnetoelectrostatic plasma lenses are studied by computer modeling. Conditions are determined such that these aberrations can be made substantially lower, in which case the cross-sectional area of a focused beam can be reduced by a factor of 105 and the ion current density at the focus of a lens can amount to 103 A/cm2.

GaN is implanted with 90 keV Mg-ions and afterwards annealed at 1150°C in a rapid thermal annealing furnace. In order to study the dependence of damage generation during implantation on the different implantation parameters, the dose is varied between 1×1014 and 5×1015 Mg+ cm−2, the substrate temperature during implantation is varied from 25 to 550°C and the ion current density is varied between 0.5 and 20 μA cm−2. The defect concentration is examined by Rutherford backscattering spectroscopy/channeling. Up to doses of 2.5×1015 Mg+ cm−2, the implantation-damage can readily be reduced by annealing. Variation of the ion current density has no influence on defect generation. Implantation at higher temperatures shows an unusual behaviour as it results in an increase in damage.

Accurate measurement of ion current density and ion energy distributions (IEDs) is often critical for plasma processes in both industrial and research settings. Retarding field energy analysers (RFEAs) have been used to measure IEDs because they are considered accurate, relatively simple and cost effective. However, their usage for critical measurement of ion current density is less common due to difficulties in estimating the proportion of incident ion current reaching the current collector through the RFEA retarding grids. In this paper an RFEA has been calibrated to measure ion current density from an ion beam at pressures ranging from 0.5 to 50.0 mTorr. A unique method is presented where the currents generated at each of the retarding grids and the RFEA upper face are measured separately, allowing the reduction in ion current to be monitored and accounted for at each stage of ion transit to the collector. From these I–V measurements a physical model is described. Subsequently, a mathematical description is extracted which includes parameters to account for grid transmissions, upper face secondary electron emission and collisionality. Pressure-dependent calibration factors can be calculated from least mean square best fits of the collector current to the model allowing quantitative measurement of ion current density.

The accurate modeling of surface and near-surface modifications under noble-gas ion sputter conditions requires a correct description of all the atom fluxes in the surface region, i.e. segregation, diffusion and sputter fluxes. A recently developed ternary segregation model was incorporated into existing sputter models and then used to calculate the surface concentration for model ternary alloys under sputtering. Several additional features to those discussed in the literature are identified. It is shown that (a) the surface concentration of preferentially sputtered ternary alloys depends on the diffusion coefficient and therefore on the temperature T , (b) the dominant species surface concentration of sequentially segregating systems is determined by the ion current density and (c) the surface state for attractive interacting species switches abruptly at a critical ion current density.

A model is presented explaining the formation of the carbonization in novolak based resists under intense ion bombardment (e.g. Ar+- or O2-RIE, Implantation). As an example for the carbonization the authors demonstrate sidewall passivation effects in a hole during a tri-level etching process. The influence of the ion current density, the neutrals, the dose and the radiation divergence on the passivation is discussed. plasma-enhanced chemical vapor deposited silicon oxide films.

The collective action of spherical elastic waves generated in atomic collision cascades under ion bombardment is shown to give rise to a random force similar to white noise in the dislocation glide plane. By way of example, the behaviour of radiation-produced perfect dislocation loops and dislocation structure segments under the action of this force is investigated. It is found that the loop depth distribution obeys the diffusion equation with a “diffusion coefficient” proportional to the ion current density J while dislocation generation due to Frank-Read source activation can be described in the framework of first-order phase transformation theory, with J in the role of temperature. Es wird gezeigt, das die kollektive Wirkung der elastischen Kugelwellen, die in den Atomstoskaskaden unter Bechus mit Ionen entstehen, eine weisem Rauschen ahnliche Zufallskraft in der Versetzungsgleitebene produziert. Beispielsweise wird das Verhalten der von der Bestrahlung produzierten vollstandigen Versetzungsringe und -struktursegmente unter der Wirkung dieser Kraft untersucht. Es wird gefunden, das die Tiefenverteilung der Ringe von der Diffusionsgleichung mit einer „Diffusionskonstante”, die zu der Ionenstromdichte J proportional ist, bestimmt wird und das die durch die Frank-Read-Quellenaktivierung verursachte Versetzungserzeugung im Rahmen der Theorie der Phasenumwandlungen 1. Ordnung, wo J die Rolle der Temperatur spielt, beschrieben werden kann.

The well‐known dc Bohm criterion is extended to rf discharges. Both low‐ (ωrf≪ωpi) and high‐(ωpi ≪ ωrf) frequency regimes are considered. For low frequencies, the dc Bohm criterion holds. This criterion states that the initial energy of the ions entering the sheath must exceed a limit in order to obtain a stable sheath. For high frequencies, a modified limit is derived, which is somewhat lower than that of the dc Bohm criterion. The resulting ion current density in a high‐frequency sheath is only a few percent lower than that for the dc case.

In preparing amorphous Gd–Co films by dc- and rf-bias sputtering, systematic variations are found of the composition both in the direction of the film normal and in the film plane. Therefore, the bias sputtering process is analyzed in terms of a simple mass balance model. The formation of a target surface layer whose composition depends on the sputtering yields of Co and Gd and on the bias voltage can lead to the growth of a Co-enriched initial layer in the film. The homogeneity in the film plane is determined by the radial variation of the transfer coefficient and of the ion current density at the substrate. The composition distribution in the plane is found to be different for dc- and rf-bias sputtering due to different influences of the bias voltage on the ion currents. Bei der Herstellung amorpher Gd–Co-Schichten mit der Methode des dc- oder rf-Bias-Sputterns werden systematische Zusammensetzungsvariationen sowohl in der Schichtebene als auch senkrecht dazu gefunden. Diese Erscheinungen werden im Rahmen eines einfachen Massenbilanz-Modells des Bias-Sputter-Prozesses gedeutet. Die Bildung einer Oberflachenschicht am Target, deren Zusammensetzung von den Sputterausbeuten von Co und Gd und von der Bias-Spannung abhangt, kann zum Wachstum einer Co-angereicherten Anfangsschicht im Film fuhren. Die Homogenitat in der Schichtebene wird durch die radiale Abhangigkeit des Transferkoeffizienten und der Ionenstromdichte am Substrat bestimmt. Die Zusammensetzungsverteilung ist unterschiedlich fur dc- und rf-Bias-Sputtern wegen des unterschiedlichen Einflusses der Bias-Spannung auf die Ionenstrome.

A series of depth profiles in Au 0.56 Cu 0.44 produced by bombarding at − 120°C with an argon ion beam of 2 keV energy and current densities of 4, 6, 12 and 24 μA/cm 2 , respectively, are presented. Gold is enriched in the top layer but the concentration rapidly decreases to a minimum at an average depth of about 2 A, then increases slowly and saturates at about 30 A. The change in the composition at this point is called a dip. The magnitude of the dip depends on the ion current density, but the depth is nearly independent of it. Segregation and diffusion effects in establishing the surface composition are stressed.

A broad-beam ion source of the Kaufman type was used to analyze the difference between the measured ion current density and etching flux of the sample. The discrepancy of these values is explained by a model of the charge exhange collisions which takes into account the different gas concentrations at the region near the discharge and at the etching chamber.