Showing papers on "Ion beam deposition published in 1996"

Tetrahedral bonding in amorphous carbon

Abstract: Electron configurations close to the tetrahedral hybridization are found in pure amorphous carbon at a concentration which depends on preparation conditions. Tetrahedral bonding at levels of approximately 80% is found in amorphous carbons formed from beams of carbon ions with energies in a `window' between 20 eV and approximately 500 eV. Suitable techniques for its formation include cathodic arc deposition, ion beam deposition and laser ablation. Similar material appears to be formed by pressure treatment of fullerene precursors and by displacement damage in diamond. Highly tetrahedral forms of amorphous carbon (ta-C) show electronic, optical and mechanical properties which approach those of diamond and are quite different from amorphous carbons with low content. Useful techniques for determining the content include electron energy loss spectroscopy, electron and neutron diffraction and Raman spectroscopy. Considerable progress has been made in the understanding of this material by simulating its structure in the computer with a range of techniques from empirical potentials to ab initio quantum mechanics. The structure shows departures from an idealized glassy state of diamond which would have a random tetrahedral network structure as used to describe amorphous silicon and germanium. A surprising feature of the structure simulated using ab initio methods is the presence of small rings containing three or four carbon atoms. The electronic and optical properties are strongly influenced by the residual of carbon. Applications to electronic devices are at an early stage with the demonstration of photoconductivity and some simple junction devices. Applications as a wear resistant coating are promising, since the theoretically predicted high values of elastic constants, comparable to but less than those of diamond, are achieved experimentally, together with low friction coefficients.

Properties of carbon ion deposited tetrahedral amorphous carbon films as a function of ion energy

Abstract: Ion energy, controlled by the substrate bias, is an important parameter in determining properties of films deposited by the filtered cathodic vacuum arc technique. The substrate bias determines the ion energy distribution of the growth species. The ion energy is varied, while keeping the other deposition conditions constant, in order to study the effect of ion energy on the film properties. The films were characterized by their optical and mechanical parameters using an ellipsometer, surface profilometer, optical spectrometer, and nanoindenter. Electron energy‐loss spectroscopy and Raman spectroscopy were used for structural analysis of the films.

Metal plasma immersion ion implantation and deposition: A review

Abstract: Metal Plasma Immersion Ion Implantation and Deposition (MePIIID) is a hybrid process combining cathodic arc deposition and plasma immersion ion implantation. The properties of metal plasma produced by vacuum arcs are reviewed and the consequences for MePIIID are discussed. Different version of MePIIID are described and compared with traditional methods of surface modification such as ion beam assisted deposition (IBAD). MePIIID is a very versatile approach because of the wide range of ion species and energies used. In one extreme case, films are deposited with ions in the energy range 20--50 eV, and at the other extreme, ions can be implanted with high energy (100 keV or more) without film deposition. Novel features of the technique include the use of improved macroparticle filters; the implementation of several plasma sources for multi-element surface modification; tuning of ion energy during implantation and deposition to tailor the substrate-film intermixed layer and structure of the growing film; simultaneous pulsing of the plasma potential (positive) and substrate bias (negative) with a modified Marx generator; and the use of high ion charge states.

Atomic beam alignment of liquid crystals

Abstract: We have found that liquid crystals can be aligned on a polyimide surface exposed to a low energy and neutral Argon ion beam. The energy of the incident ions were varied between 75 and 500 eV, the integrated current density from 100 μA/cm 2 to 500 mA/cm 2 , and the angle of incidence over which alignment was measured was between 10 and 20 degrees. The pretilt angle of the liquid crystals could be varied between 0 and 8 degrees, by controlling the processing conditions. Degradation of the polyimide, which leads to charge migration, can be avoided by operating at low accelerating voltages.

Ion beam process for deposition of highly wear-resistant optical coatings

Abstract: An ion beam deposition method is provided for manufacturing a coated substrate with improved wear-resistance, and improved lifetime. The substrate is first chemically cleaned to remove contaminants. Secondly, the substrate is inserted into a vacuum chamber onto a substrate holder, and the air therein is evacuated via pump. Then the substrate surface is bombarded with energetic ions from an ion beam source supplied from inert or reactive gas inlets to assist in removing residual hydrocarbons and surface oxides, and activating the surface. After sputter-etching the surface, a protective, wear-resistant coating is deposited by plasma ion beam deposition where a portion of the precursor gases are introduced into the ion beam downstream of the ion source, and hydrogen is introduced directly into the ion source plasma chamber. The plasma ion beam-deposited coating may contain one or more layers. Once the chosen coating thickness is achieved, deposition is terminated, vacuum chamber pressure is increased to atmospheric and the coated substrate products having wear-resistance greater than glass are removed from the chamber. These coated products may be ceramics, architectural glass, analytical instrument windows, automotive windshields, and laser bar code scanners for use in retail stores and supermarkets.

Process method and apparatus using focused ion beam generating means

Abstract: A processing method and a processing apparatus realizing the method use a focused ion beam generator. The apparatus includes a plasma or liquid metal ion source producing ions not influencing electric characteristics of a sample, an ion beam generator for extracting ions from the ion source into an ion beam, an ion beam focusing device for focusing the ion beam, an irradiator for irradiating the focused ion beam onto the sample, and a sample chamber in which the sample to be irradiated for processing is installed. The focused ion beam is irradiated onto a sample such as a silicon wafer or device to conduct on a particular position of the sample a fine machining work, a fine layer accumulation, and an analysis.

Highly durable and abrasion-resistant dielectric coatings for lenses

Abstract: An abrasion-resistant dielectric composite product is described comprising a substrate and an abrasion wear resistant coating material comprising carbon, hydrogen, silicon, and oxygen and a dielectric material. An improved method is provided for the deposition of highly durable and abrasion-resistant multilayer dielectric antireflective coatings and reflective colored mirror coatings onto plastic lenses such as ophthalmic lenses, safety lenses, sunglass lenses, and sports optics. An adhesion-enhancing polymer layer may be deposited onto the plastic substrate prior to deposition of the abrasion-resistant first coating layer. The multilayer dielectric coating structure consists of a transparent, highly abrasion-resistant first coating, and a second dielectric coating composed of at least one layer of dielectric material. The abrasion-resistant first coating layer is deposited by ion-assisted plasma deposition from mixtures of organosiloxane or organosilazane precursor gases and oxygen, and has the properties of Nanoindentation hardness in the range of about 2 GPa to about 5 GPa, a strain to microcracking greater than about 1.5% and less than about 3.5%, a transparency greater than 85% throughout the visible spectrum, and an abrasion resistance greater than or equal to the abrasion resistance of glass. The preferred method for deposition of the abrasion-resistant first coating layer is plasma ion beam deposition using an organosiloxane precursor gas and oxygen. Optimum abrasion-resistance is obtained when the first coating layer thickness is in the range of about 5 microns to about 20 microns. The thickness, refractive index, and number of the dielectric layers in the second coating are chosen to produce the desired optical effects of either antireflection, or reflected color. Optimum environmental durability and abrasion-resistance is obtained by producing highly dense dielectric coatings by ion beam assisted electron beam evaporation, magnetron sputtering, ion beam assisted magnetron sputtering, ion beam sputtering, and ion-assisted plasma deposition, including plasma ion beam deposition, from precursor gases.

The magnetic trapping mode of an electron beam ion trap: New opportunities for highly charged ion research

Abstract: Using x‐ray spectroscopic techniques, we have investigated the properties of an electron beam ion trap (EBIT) after the electron beam is switched off. In the absence of the electron beam, bare, and hydrogenlike Kr35+ and Kr36+ ions remain trapped due to externally applied magnetic and electric fields for at least 5 s; xenon ions with an open L shell, i.e., Xe45+–Xe52+, remain trapped at least as long as 20 s. The ion storage time in this ‘‘magnetic trapping mode’’ depends on the pressure of background atoms as well as on the value of the externally applied trapping potential, and even longer ion storage times appear possible. The magnetic trapping mode enables a variety of new opportunities for atomic physics research involving highly charged ions, which include the study of charge transfer reactions, Doppler‐shift‐free measurements of the Lamb shift, measurements of radiative lifetimes of long‐lived metastable levels, or ion‐ion collision studies, by x‐ray or laser spectroscopy, and mass spectrometry. Be...

High explosives vapor detection by glow discharge-ion trap mass spectrometry

Abstract: The combination of atmospheric sampling glow discharge ionization with quadrupole ion trap mass spectrometry for the detection of traces of high explosives is described. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass-selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass-selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment, thereby providing the capability for monitoring several targeted species simultaneously.

Surface processing by gas cluster ion beams at the atomic (molecular) level

Abstract: Gas cluster ion beam techniques have been developed for atomic and molecular level surface modification processing. Shallow implantation, high yield sputtering, surface smoothing, and low damage surface cleaning have been demonstrated experimentally. This article reports recent results concerning surface treatments that are distinctly different from those produced by conventional monomer ion irradiation. Possible applications of gas cluster ion beam processing to new areas of surface modifications are suggested.

Role of ion energy in determination of the sp3 fraction of ion beam deposited carbon films

Abstract: The role of ion energy over the range 5 eV≤E≤20 keV in the production of the dense diamondlike sp3‐bonded phase of carbon films deposited from ion beams has been investigated. Films with a significant sp3 component (≳40%), as determined by electron energy loss spectroscopy (EELS), can be formed over the wide energy region 30 eV≤E≤10 keV at room temperature. The sp3 fraction is completely suppressed only for E≤10 eV or E≥20 keV. For both cases, this suppression is associated with a sharp increase of the surface roughness, as determined by atomic force microscopy (AFM). The different nature of the mechanisms responsible for the suppression of sp3 bonding in both the low and high energy regions is discussed.

A universal ion-beam-sputtering device for diffusion studies

Abstract: An apparatus for ion-beam-sputtering is described which offers for the first time the possibility of measuring radiotracer diffusion profiles with mean diffusion length (D is the tracer diffusion coefficient and t is the diffusion time) in the nano- as well as in the micrometre range. It is also possible to use the device for ion milling, especially for the deposition of thin layers of radiotracer onto diffusion samples. Investigations of diffusion in pure metals, in a metallic glass, in a compound semiconductor and in intermetallic compounds are presented as examples.

New broad beam gas ion source for industrial application

Abstract: A source delivering a broad, high current ion beam compatible with both chemically active and inert gases has been developed which gives reliable, long term, maintenance‐free operation. It uses a glow discharge with a cold cathode in a magnetic field where a dense uniform plasma is generated in large volumes at low gas pressures. Optimal selection of the electrode configuration and magnetic field ensures operation at pressures lower than 0.1 Pa in pulse–periodic mode (1–10 A discharge current, 1 ms pulse length, 25–50 Hz frequency), and continuous mode (discharge current up to 2 A). The current density of a 15‐cm‐diam beam can reach 10 mA cm−2 in the former, and 1 mAcm−2 in the latter. Tests with a 50‐cm‐diam discharge chamber show the uniformity of the ion emission current to be better than ±10%, confirming that the technology is scaleable, and that beams of up to 2000 cm2 cross‐sectional area can be obtained without loss of beam uniformity through appropriate design of the extraction system. The source is completely reactive gas‐compatible, generating ion beams from oxygen, nitrogen, argon or ionized CH radicals (e.g., using C3H8). Mass‐charge beam analysis shows the beams generated to be of high purity (≳99%). Applications include low energy (1–3 keV) ion beam cleaning of glass, ceramic and metal surfaces prior to the deposition of protective and decorative coatings such as TiN and diamondlike carbon, ion beam assisted deposition, and high energy gas ion implantation using, e.g., pulse–periodic beams of ions with energies up to 50 keV.

Ion energy, ion flux, and ion mass effects on low-temperature silicon epitaxy using low-energy ion bombardment process

Abstract: In low‐temperature (300–350 °C) silicon epitaxy employing low‐energy inert‐gas ion bombardment on a growing film surface, the effects of ion bombardment energy and ion flux as well as that of ion species on the crystallinity of a grown silicon film have been experimentally investigated. It is shown that the energy dose determined by the product of ion energy and ion flux is a main factor for epitaxy that compensates for the reduction in the substrate temperature. Large‐mass, large‐radius ion bombardment using Xe has been demonstrated to be more effective in promoting epitaxy at low substrate temperatures than Ar ion bombardment. Thus, low‐energy, high‐flux, large‐mass ion bombardment is the direction to pursue for further reducing the processing temperature while preserving high crystallinity of grown films.

Investigations on the topology of structures milled and etched by focused ion beams

Abstract: For high precision micromachining of micro‐ and nanostructures by focused ion beams, the precision of the material removal process is of great importance. In this article, the topological properties of the ion beam generated structures like slope angles of trenches, surface roughness, and induced defects are investigated. The influence of the beam current and scanning strategy on the topological properties will be discussed. In addition, transmission electron microscopy analysis of thin lamellas generated by focused ion beams will be shown.

Recent Advances in Vacuum Arc Ion Sources

Abstract: Intense beams of metal ions can be formed from a vacuum arc ion source. This kind of source works well for most of the solid metals of the Periodic Table, and because the ions are, in general, multiply stripped with charge states as high as 4+ to 6+ , the mean energy of the ion beam produced can be 100–200 keV for an extractor voltage in the comfortable range of about 50–75 kV. Broad-beam extraction is convenient, and the time-averaged ion beam current delivered downstream can readily be in the tens of milliamperes range. The vacuum arc ion source has, for these reasons, found good application for metallurgical surface modification: it provides relatively simple and inexpensive access to high dose metal ion implantation. Several important source developments have been demonstrated recently, including very-broad-beam operation, macroparticle removal, charge state enhancement and the formation of gaseous beams. We have made a very-broad-beam source embodiment with beam formation electrodes 50 cm in diameter (area, 2000 cm 2 ), producing a beam with a width of approximately 35 cm for a nominal beam area of about 1000 cm 2 , and a pulsed Ti beam current of about 7 A was formed at a mean ion energy of approximately 100 keV. Separately, we have developed a high efficiency macroparticle-removing magnetic filter and have incorporated such a filter into a vacuum arc ion source so as to form macroparticle-free ion beams. Jointly with researchers at the High Current Electronics Institute, Tomsk, Russia and the Gesellschaft fur Schwerionenforschung, Darmstadt, Germany, we have developed a compact technique for increasing the charge states of ions produced in the vacuum arc plasma, thus providing a simple means of increasing the ion energy at fixed extractor voltage. Finally, operation with mixed metal and gaseous ion species has been demonstrated. In this paper, we briefly review the operation of vacuum arc ion sources and the typical beam and implantation parameters that can be obtained, and describe these source advances and their bearing on metal ion implantation applications.

Atomic level smoothing of CVD diamond films by gas cluster ion beam etching

Abstract: Chemical vapor deposited diamond films on silicon substrates were etched by a gas cluster ion beam. We found that a gas cluster ion beam of 10 17 ions/cm 2 would be effective to smooth the surface of the CVD diamond films. It was confirmed that atomic level smooth surfaces ( R a = 1.9 nm by AFM measurements) were formed by Ar gas cluster ion beam (Ar 3000 + ) etching. We believe that the gas cluster ion beam etching technique will be a key technology for diamond device fabrication.

Tetramethoxysilane as a precursor for focused ion beam and electron beam assisted insulator (SiOx) deposition

Abstract: Focused ion beams are intensively used for device modification by local material removal and ion beam induced metal deposition. With shrinking dimensions on modern multilayer devices, the need for ion beam induced insulator deposition is increasing. In this article, tetramethoxysilane as a precursor for ion beam induced deposition has been investigated. The influence of beam parameters dwell time and loop time on the material deposition rate will be discussed and compared to model calculations. For optimized scanning conditions, a maximum deposition rate of 0.33 μm3/nC was found. Insulating films were also deposited using an electron beam. The chemical composition and electrical properties of these films were compared with the films deposited by the ion beam. For electron beam deposition, the resistivity of the deposited films was 1×106 Ω cm which is two orders of magnitude higher than for ion beam deposited film.

Surface chemical reaction between polycarbonate and kilo-electron-volt energy Ar+ ion in oxygen environment

Abstract: In order to improve wettability of polycarbonate to triple distilled water, an Ar+ ion and an oxygen ion were irradiated on a polycarbonate (PC) surface under various oxygen flow rates. Doses of ions were changed from 5×1014 to 5×1016 ion/cm2 in a range from 500 eV to 1.5 keV energy by a broad ion beam source. Wetting angle of PC was not reduced much with only Ar+ irradiation, but the wetting angle was significantly decreased by Ar+ ion irradiation with flowing oxygen gas and had a minimum of 12° by 1 keV Ar+ ion irradiation at oxygen flow rate of 4 sccm. Change in wettability by O+2 ion irradiation shows the similar feature as compared with those of Ar+ ion irradiation. In atomic force microscopy study, root mean square of surface roughness was changed from 14 to 22–27 A by Ar+ ion irradiation, to 26–30 A by Ar+ ion irradiation with the oxygen flow, but did not depend on amounts of ion fluence which indicates that the wetting angle change was not influenced by surface morphology. Improved wettability of ...

New method of carbon nanotube growth by ion beam irradiation

Abstract: We report a new method of carbon nanotube growth by the argon ion beam irradiation of amorphous carbon under high vacuum conditions of 4×10−5 Torr. Earlier, carbon nanotubes have been produced at gas pressures above 100 Torr. The incident angle of the ion beam was normal to the target surface, and the acceleration ion energy was 3 keV. Nanotubes are produced outside the sputtering region on the target surface after ion irradiation. The tubes have multilayered walls, the distance between carbon layers is 0.34 nm, and wall thickness of tubes ranges from 10 to 15 sheets.

Effects of ion energy and arrival rate on the composition of zirconium oxide films prepared by ion‐beam assisted deposition

Abstract: Thin zirconium oxide films were grown using the ion‐beam assisted deposition method. Zirconium metal was evaporated by an electron beam and condensed on a Si substrate, while oxygen ions were directed simultaneously onto the substrate, allowing the fundamental deposition parameters of ion energy and arrival rate ratio ARR(O/Zr) to be measured and controlled easily. X‐ray photoelectron spectroscopy (XPS) was used to study the oxidation and the composition of the films. XPS analyses indicated the presence of four oxidation states of zirconium (Zr4+−Zr1+) in Zr 3d spectra and two peaks in O 1s spectra; Zr4+ is a predominant ion in all the films and the two peaks in O 1s spectra are related to the oxide and to hydroxyl groups and/or carbonates, respectively. Composition analyses of the films suggested that these oxygen‐associated species may be bound to zirconium. The variation of composition as a function of ion energy (from 2 to 20 keV) and ARR(O/Zr) (at 0.54 and 1.09) could be explained with the preferential sputtering of zirconium from the growing film by incoming oxygen ions and the incorporation of oxygen ions into the film.

Plasma chamber for controlling ion dosage in ion implantation

Abstract: An ion source for generating an ion beam of primary ions is disclosed that includes a plasma chamber and magnets positioned therein for separating the primary ions of the plasma from secondary ions within the plasma An electrode assembly extracts the primary ions through an extractor outlet port of the plasma chamber to form an ion beam, which preferentially is shaped as a ribbon beam The primary ions are accelerated in the form of a ribbon beam toward the target workpiece for doping the device The magnets are oriented in the chamber to produce a uniform current density of primary ions parallel to the elongated axis of the ribbon beam

Parallel ion optics and apparatus for high current low energy ion beams

Abstract: A device for the parallel processing of ions is provided. The device may be utilized for thin film deposition or ion implantation and may include the following: an ion source, ion capture and storage ion optics, mass selection ion optics, neutral trapping elements, extraction ion optics, beam neutralization mechanisms, and a substrate on which deposition and thin film growth occurs is provided. Ions are captured and stored within a closely packed array of parallel ion conducting channels. The ion conducting channels transport high current low energy ions from the ion source to irradiate the substrate target. During transport, ion species can be mass selected, merged with ions from multiple sources, and undergo gas phase charge exchange ion molecule reactions. Additionally, neutrals from the ion source, ion-molecule reaction reagent gases, residual background gas, or neutralization of ions may be eliminated from the processing stream by turbo pumping, cryo pumping, and cryocondensation on some of the ion optic elements. Different types of ion optic elements, including elements which are parallel or perpendicular to the ion path, and neutral trapping elements may be combined in different ways to achieve thin film ion deposition over a large homogenous substrate surface.

Development of a 500 keV, 22 A D− ion source for the neutral beam injector for JT‐60U

Abstract: The first results of the performance test of the large negative ion source for a JT‐60U negative‐ion‐based neutral beam injector (N‐NBI) are presented. The ion source consists of a cesium seeded multicusp plasma generator, where negative ions are produced via volume and surface processes, a 110 cm×45 cm multiaperture extractor, and a three‐stage electrostatic accelerator. After negative ion production and voltage holding tests in test stands, the ion source was installed in the N‐NBI system and the full power test began. Up to now, the ion source has produced 400 keV, 5.9 A (2.4 MW) D− ion beams, the world highest D− current and beam power, with a pulse duration of 0.1 s.

Effect of ion energy on the mechanical properties of ion beam assisted deposition (IBAD) wear resistant coatings

Abstract: Ion beam assisted physical vapor deposition offers a number of advantages over other surface modification methods with respect to the properties of wear resistant coatings. These properties include density, adhesion to the substrate, crystallographic orientation, durability and resistance to degradation by moisture. These improved film properties derive from the physical and chemical processes associated with the impingement of energetic ions onto the surface of a growing film. Such processes include sputtering and desorption of atoms from the substrate, implantation of atoms into the substrate, chemical reactions at the surface, cluster nucleation and dissociation, enhancement of surface diffusion, atomic displacements in the bulk, as well as energy and momentum transfer to the atoms in the growing film. A review of models for the influence of ion energy and momentum transfer to a growing film suggests that the effects of ion bombardment may be categorized according to the ion energy.

Fabrication of field emission array with filtered vacuum cathodic arc deposition

Abstract: A filtered cathodic vacuum arc is used as a source of metal to generate a highly directional beam of metal ions having substantially larger velocity parallel to the axis of the beam (perpendicular to the surface of the target) than perpendicular to the axis of the beam. This ion beam, with energies ranging up to 80 eV, is used to deposit metal into the bottom of high aspect (typically greater than 3 to 1) openings, for example, to deposit titanium in the bottom of deep contact holes in semiconductor devices or to deposit molybdenum to form tips for emitters for a field emission display. Gases can be introduced into the vacuum deposition chamber during deposition to change the nature of the deposit. The substrate or target bias can be adjusted to control the deposition rate.