Showing papers on "Ion beam deposition published in 1999"

Photodetachment photoelectron spectroscopy of multiply charged anions using electrospray ionization

Abstract: A magnetic-bottle time-of-flight (TOF) photoelectron spectrometer, coupled with an electrospray ionization source, has been developed for the investigation of multiply charged anions in the gas phase. Anions formed in the electrospray source are guided by a radio-frequency quadrupole ion guide into a quadrupole ion trap, where the ions are accumulated. A unique feature of this apparatus involves the coupling of a TOF mass spectrometer to the ion trap with perpendicular ion extraction. The ion trap significantly improves the duty cycle of the experiments and allows photodetachment experiments to be performed with low repetition-rate lasers (10–20 Hz). This novel combination makes the photodetachment photoelectron spectroscopy studies of multiply charged anions possible for the first time. Furthermore, the perpendicular extraction of ions, pulsed out of the ion trap, to the TOF mass spectrometer allows the ion energies to be conveniently referenced to ground, simplifying the configuration of the TOF mass sp...

A new high transmission infinite range mass selector for cluster and nanoparticle beams

Abstract: A new mass selection technique has been developed, which allows one to size-select charged particles from atoms to nanoparticles of almost unlimited size. It provides a mass resolution of m/Δm=20–50 and a transmission of about 50% for the selected size, both independent of mass. The technique is based on the time-of-flight principle, but differs fundamentally from time-of-flight mass selection normally used. The basic idea is to use time-limited high voltage pulses to displace laterally a preaccelerated ion beam, without changing its direction or shape. As the movement of the ions perpendicular to their original beam direction is independent of their forward velocity, mass resolution and calibration does not depend on the ion beam energy. A mass selector of this type has been implemented successfully into a cluster deposition experiment and has proven to be reliable and simple to operate.

Characterization of an improved electrodynamic ion funnel interface for electrospray ionization mass spectrometry.

Abstract: An improved electrodynamic ion funnel for ion focusing at high pressure (> 1 Torr) has been developed for a triple quadrupole mass spectrometer and its performance compared with that of an earlier prototype previously reported. The ion funnel consists of a series of ring electrodes of progressively smaller internal diameters to which rf and dc electric potentials are co-applied. The new design utilizes ring electrodes possessing larger internal diameters that taper down to a relatively larger exit aperture. In the 1-10 Torr pressure range, the new design provides significant improvement in low m/z ion transmission. Additionally, the overall ion transmission range is improved by linked scanning of the ion funnel's rf voltage concomitantly with the scanning of the quadrupole mass analyzer. Transmission of a noncovalent complex through the interface demonstrated that excessive ion heating was not problematic. Computer simulations of ion transport support the ion funnel design and help explain the relative performance of both designs. Both ion simulations and experimental results are in accord and indicate close to 100% ion transmission efficiency for electrosprayed biopolymer ions through the interface and into the mass analyzer.

Ion beam deposition of Mn-Ir spin valves

Abstract: Half-biased spin valves have been prepared by ion beam deposition. The magnetoresistance (MR) signal reaches 7.7% and the exchange field is 350 Oe with a coupling field of 15 Oe and a coercivity of the free layer equal to 4 Oe. The [111] texture induced by a very thin Ta buffer layer (thickness <10 /spl Aring/) has a strong effect in increasing the MR signal and coupling field, while decreasing the exchange field and coercivity. The blocking temperature of the MnIr-biased spin valves is 250/spl deg/C and a thermal stability study shows that the exchange field is constant up to 300/spl deg/C, under consecutive 5-h anneals at each temperature. After these anneals, the MR signal is still equal to 5%. These films show better thermal stability than equivalent samples prepared by sputtering.

Spectrometer provided with pulsed ion source and transmission device to damp ion motion and method of use

Abstract: A method and apparatus are provided for providing an ion transmission device or interface between an ion source and a spectrometer. The ion transmission device can include a multipole rod set and includes a damping gas, to damp spatial and energy spreads of ions generated by a pulsed ion source. The multipole rod set has the effect of guiding the ions along an ion path, so that they can be directed into the inlet of a mass spectrometer. The invention has particular application to MALDI (matrix-assisted laser desorption/ionization) ion sources, which produce a small supersonic jet of matrix molecules and ions, which is substantially non-directional, and can have ions travelling in all available directions from the source and having a wide range of energy spreads. The ion transmission device can have a number of effects, including: substantially spreading out the generated ions along an ion axis to generate a quasi-continuous beam; reducing the energy spread of ions emitted from the source; and at least partially suppressing unwanted fragmentation of analyte ions. Consequently, a number of pulses of ions can be delivered to the time-of-flight or other spectrometer, for each cycle of the ion generation.

Side-wall damage in a transmission electron microscopy specimen of crystalline si prepared by focused ion beam etching

Abstract: In focused ion beam (FIB) fabrication of cross-sectional transmission electron microscopy (X-TEM) specimens, highly accelerated ion beams sometimes cause serious damage. The damage can be induced in both the specimen surface and the side walls. We used the X-TEM technique to investigate the sidewall damage in crystalline Si. The damaged layer was found to be about 20 nm thick in the case of 30-keV-FIB etching. We evaluated several techniques for reducing the damage, such as gas-assisted etching (GAE) with iodine, low-energy FIB etching, and cleaning by broad argon ion milling or by wet etching. The damage depth was 19 nm for GAE and 10 nm for 10 keV FIB etching, and was reduced to 7 nm by 3 keV argon ion milling with a beam current of 20 μA and a tilt angle between the beam and the specimen of 4°. Wet etching using a mixture of nitric and hydrofluoric acid removed most of the damaged layer. The effect of the damaged layer on TEM observation was also investigated, and it was shown that removal of the damag...

Patterning a surface on the nanometric scale by ion sputtering

Abstract: Surface etching by ion sputtering, besides producing equilibrium-oriented patterns similar to those obtained by molecular beam epitaxy (MBE), can also be used to pattern the surface along nonequilibrium orientations, thus extending the possibilities of MBE. By tuning the competition between ion erosion at grazing angles and diffusion-induced surface reorganization, it is, for example, possible to pattern a substrate characterized by a square symmetry with a well-ordered ripple structure running along any desired direction.

Energy distribution of ions bombarding biased electrodes in high density plasma reactors

Abstract: A compact retarding field ion energy analyzer has been designed and built to measure the energy distribution of ions bombarding the wafer surfaces placed on radio frequency (rf) biased electrodes in high-density plasma reactors. The analyzer was used to measure the energy distribution of ions impinging on the rf-biased electrostatic chuck in a high-density transformer coupled plasma (TCP) reactor. The effects of TCP power, rf bias, gas composition, and ion mass on the ion energy distributions (IEDs) were demonstrated through Ar, Ne, Ar/Ne, O2 and CF4/O2 discharges. In the operating range studied, the average ion energy increased linearly with increasing rf bias while the ion flux remained constant indicating that independent control of ion flux and energy was achieved in the TCP reactor. Bimodal ion energy distributions resulting from ion energy modulation in the sheath were observed and multiple peaks in the IEDs measured in gas mixtures were identified as ions with different masses falling through the s...

Highly wear-resistant thermal print heads with silicon-doped diamond-like carbon protective coatings

Abstract: The invention provides a thermal print head with a protective coating of silicon-doped diamond-like carbon (Si-DLC) which imparts superior wear resistance, and improved lifetime. The Si-DLC is comprised of the elements C, H, Si and possibly O, N and Ar. The highly wear and abrasion-resistant Si-DLC diamond-like carbon coating is deposited by ion-assisted plasma deposition including direct ion beam deposition and capacitive radio frequency plasma deposition, from carbon-containing and silicon-containing precursor gases consisting of hydrocarbon, silane, organosilane, organosilazane and organo-oxysilicon compounds, or mixtures thereof. The resulting Si-DLC coating has the properties of Nanoindentation hardness in the range of approximately 10 to 35 GPa, thickness in the range of approximately 0.5 to 20 micrometers, dynamic friction coefficient of less than approximately 0.2, and a silicon concentration in the range of approximately 5 atomic % to approximately 40 atomic %. Optimum performance is obtained when the Si-DLC coating hardness is in the range of approximately 15 to 35 GPa, preferably in the range of about 15 GPa to about 19 GPa, and the Si-DLC layer thickness is in the range of approximately 2 micrometers to approximately 10 micrometers, dynamic friction coefficient of less than approximately 0.15, and a silicon concentration in the range of approximately 10 atomic % to 30 atomic %, preferably in the range of about 15 atomic percent to about 24 atomic percent.

Acceleration and analysis architecture for ion implanter

Abstract: An ion beam generator (10) includes an ion beam source (40) for generating an ion beam (12), an acceleration/deceleration column (44) for selectably accelerating or decelerating ions in the ion beam to desired energies, a source filter (42) positioned between the ion beam source and the acceleration/deceleration column for removing first undesired species from the ion beam, and a mass analyzer (50) positioned downstream of the acceleration/deceleration column for removing second undesired species from the ion beam. The ion beam generator supplies an energetic ion beam having a low level of energy and mass contaminants. The ion beam generator may be utilized in an ion implanter.

The Freiburg Electron Beam Ion Trap/Source Project FreEBIT

Abstract: An electron beam ion trap (EBIT) is under construction at the University of Freiburg. It will be operated both as an ion trap and as an ion source, and its design specifications will allow production of hydrogenic ions from even the heaviest elements. It will be possible to extract and accelerate the ions to energies up to 350 kV/q.

Amorphous tracks in insulators induced by monoatomic and cluster ions

Abstract: Amorphous tracks induced by monoatomic and cluster ion beams are compared in ${\mathrm{LiNbO}}_{3}$ and ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}.$ In agreement with the prediction of our model, at high energy deposition ${R}_{e}^{2}{/S}_{e}=\mathrm{const}$ (${R}_{e}$ is the effective track radius, ${S}_{e}$ is the electronic stopping power) for monoatomic and cluster ion irradiations. This indicates that the considerably higher energy density in the experiments with cluster ion beams does not modify the track formation. The analysis shows that the width of the thermal spike does not depend on the ion velocity in the range 0.02--20 MeV/nucleon. On the other hand, a strong variation of the efficiency of the energy deposition into the thermal spike g is observed around 2 and 4 MeV/nucleon for ${\mathrm{LiNbO}}_{3}$ and ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12},$ respectively. The results cannot be explained by the variation of the \ensuremath{\delta}-electron distribution with the specific ion energy E. The importance of the electron-lattice ion and ion-ion interactions are emphasized. The relative shift of the $g(E)$ curves is related to the different fraction of heavy elements in the two insulators.

Ion behavior and gas mixing in electron cyclotron resonance plasmas as sources of highly charged ions

Abstract: This article deals with ion behavior in small open-ended magnetic devices, the electron cyclotron resonance ion sources (ECRIS) that were developed for multicharged ion production. The ECRIS are basically ECR-heated plasma confinement machines with hot electrons and cold ions. The main parameters of the ion population in ECRIS plasmas are successively analyzed: temperature, collisions, losses, confinement times, followed by the gas mixing effect, a specific technique to improve the performance as an ion source. A series of experiments is described for the systematic analysis of this effect. It is experimentally shown that high charge state optimization by gas mixing results from an ion confinement time improvement due to ion cooling, and relies on a compromise between three criteria, ion losses, mass effect, and ionization rates.

Secondary electron emission coefficient of a MgO single crystal

Abstract: The secondary electron emission coefficient γ of different MgO single crystal has been measured by γ-focused ion beam system. It is found that the MgO single crystal with (111) orientation has the highest γ from 0.08 up to 0.21, while from 0.06 to 0.19 for (200) and from 0.05 to 0.15 for (220) orientation for operating Ne+ ions ranging from 50 to 300 eV throughout this experiment. It is also found that these observations can be explained by work functions, which are dependent on the crystal orientations of MgO.

Ion beam assisted deposition of niobium nitride thin films for vacuum microelectronics devices

Abstract: We have deposited niobium nitride thin films by ion beam assisted deposition and evaluated their properties from the viewpoint of a cathode material for vacuum microelectronics devices. Substrate temperature and ion–atom arrival rate ratio were selected as deposition parameters. The film properties of nitrogen composition, crystallinity, electric resistivity, work function and sputtering yield against a low-energy argon ion bombardment were investigated. It was found that polycrystalline films could be obtained at the substrate temperature higher than 500°C, and the composition could be controlled by the ion–atom arrival rate ratio. The results also showed that the stoichiometric nitride film exhibited superior properties of a lower work function and a lower partial sputtering yield of niobium. The electron emission test also demonstrated a lower current fluctuation for the stoichiometric films. In summary, ion beam assisted deposition provided a low temperature process which could control the film properties suitable to a cathode material.

Method for deposition of diamond-like carbon and silicon-doped diamond-like carbon coatings from a hall-current ion source

Abstract: A unique Hall-Current ion source apparatus is used for direct ion beam deposition of DLC coatings with hardness values greater than 10 GPa and at deposition rates greater than 10 Å per second. This ion source has a unique fluid-cooled anode with a shadowed gap through which ion sources feed gases are introduced while depositing gases are injected into the plasma beam. The shadowed gap provides a well maintained, electrically active area at the anode surface which stays relatively free of non-conductive deposits. The anode discharge region is insulatively sealed to prevent discharges from migrating into the interior of the ion source. A method is described in which a substrate is disposed within a vacuum chamber, coated with a coating of DLC or Si-DLC at a high deposition rate using a Hall-Current ion source operating on carbon-containing or carbon-containing and silicon-containing precursor gases, respectively. The method is particularly advantageous for producing thin, hard, wear resistant DLC and Si-DLC coatings for magnetic transducers and media used for magnetic data storage applications.

A distributed radiator, heavy ion target driven by Gaussian beams in a multibeam illumination geometry

Abstract: An inertial confinement fusion target driven by ion beams in a multibeam illumination geometry is presented. Two dimensional integrated LASNEX calculations (ion beam deposition to fusion burn in one computer simulation) predict a gain of greater than 65 for this target. Each beam has a Gaussian density profile and is focused to an elliptically shaped spot. Multiple beam ellipses are overlayed to form an annulus on the end of the cylindrical hohlraum. The beams enter at angles relative to the cylindrical axis of the hohlraum that are consistent with both liquid wall chamber protection and the space required for a final focusing system upstream. For an accelerator that is 25% efficient (η = 0.25), a gain G of 65 leads to ηG greater than 16; a reactor with a reasonably small recirculating power fraction requires ηG greater than 8-10.

Compact floating ion energy analyzer for measuring energy distributions of ions bombarding radio-frequency biased electrode surfaces

Abstract: A compact floating retarding-field ion energy analyzer and the accompanying electronics have been designed and built to measure the energy distribution of ions bombarding radio-frequency (rf) biased electrodes in high-density plasma reactors. The design consists of two main components, a compact retarding field vacuum probe and an integrated stack of floating electronics for providing output voltages, measuring currents and voltages and transmitting data to a computer. The operation and capabilities of the energy analyzer are demonstrated through ion energy distribution measurements conducted on a 4 MHz rf-biased electrostatic chuck in a 13.56 MHz high-density transformer coupled plasma (TCP) reactor. The analyzer is capable of operating while floating on several hundreds of volts of rf bias and at pressures up to 30 mTorr without differential pumping. The effects of pressure (2–30 mTorr), TCP power (500–1500 W), rf-bias power (0–800 W), gas composition, and ion mass on the ion energy distributions are de...

The Preparation, Characterization and Tribological Properties of TA-C : H Deposited Using an Electron Cyclotron Wave Resonance Plasma Beam Source

Abstract: A compact electron cyclotron wave resonance (ECWR) source has been developed for the high rate deposition of hydrogenated tetrahedral amorphous carbon (ta-C:H). The ECWR provides growth rates of up to 900 A/min over a 4 diameter and an independent control of the deposition rate and ion energy. The ta-C : H was deposited using acetylene as the source gas and was characterized in terms of its sp 3 content, mass density, intrinsic stress, hydrogen content, C-H bonding, Raman spectra, optical gap, surface roughness and friction coefficient. The results obtained indicated that the film properties were maximized at an ion energy of approximately 167 eV, corresponding to an energy per daughter carbon ion of 76 eV. The relationship between the incident ion energy and film densification was also explained in terms of the subsurface implantation of carbon ions into the growing film.

A new approach to nuclear microscopy: the ion–electron emission microscope

Abstract: A new multidimensional high lateral resolution ion beam analysis technique, ion–electron emission microscopy (IEEM) is described. Using MeV energy ions, IEEM is shown to be capable of ion beam induced charge collection (IBICC) measurements in semiconductors. IEEM should also be capable of microscopically and multidimensionally mapping the surface and bulk composition of solids. As such, IEEM has nearly identical capabilities as traditional nuclear microprobe analysis, with the advantage that the ion beam does not have to be focused. The technique is based on determining the position where an individual ion enters the surface of the sample by projection secondary electron emission microscopy. The x – y origination point of a secondary electron, and hence the impact coordinates of the corresponding incident ion, is recorded with a position sensitive detector connected to a standard photoemission electron microscope (PEEM). These signals are then used to establish coincidence with IBICC, atomic, or nuclear reaction induced ion beam analysis signals simultaneously caused by the incident ion.

Room temperature growth of cubic boron nitride

Abstract: Boron nitride thin films were deposited at room temperature with various ion energies by mass selected ion beam deposition on cubic boron nitride (c-BN) previously nucleated on Si (100) substrates at a higher temperature. Selective area diffraction, electron energy loss, and infrared spectroscopy results reveal continued growth of the cubic phase. The reported temperature threshold of about 150 °C for c-BN film formation is therefore unmistakably related to the initial nucleation of c-BN, whereas the growth of c-BN appears to be temperature independent. The latter is in accordance with predictions of the cylindrical thermal spike growth model recently proposed by our group.

Low-energy cluster ion beam modification of surfaces

Abstract: In cluster ion beam processes, multiple collisions during the impact of accelerated cluster ions upon the substrate surfaces produce fundamentally non-linear processes in a low-energy regime. The gas cluster ion beam process has been applied to produce ultra-shallow junctions (less than 7 nm in Si at 2 keV), very high-rate sputtering (more than two orders of magnitude higher than by monomer ions having the same energy), atomic scale smoothing of surfaces (to average roughness less than 0.2 nm) and reactive thin film formation at low substrate temperatures. This paper will review recent requirements for ion beam processing and the status of ion beam equipment development. Several characteristics of the gas-cluster ion beam processing are capable of meeting these recent requirements and will be demonstrated by our recent experimental and molecular dynamics simulation results.

Development of a triplasmatron ion source for the generation of SF5+ and F- primary ion beams on an ion microscope secondary ion mass spectrometry instrument

Abstract: A hot filament duoplasmatron ion source operating with argon has been modified by the addition of an enclosed expansion cup mounted to the extraction side of the duoplasmatron anode. Using sulfur hexafluoride (SF6) as a feed gas, this triplasmatron ion source has been used to generate SF5+ and F− primary ion beams for secondary ion mass spectrometry (SIMS). For positive primary ions, the current extracted from the source is composed of a series of SFx+ cluster ions (x=1–5) with the SF5+ ion being the most intense. SF5+ currents of ∼ 10–20 nA with a maximum of 40 nA are obtained at an extraction voltage of 10 kV. By applying a positive bias to the expansion cup, a localized secondary arc discharge is initiated giving 200 nA–300 nA of SF5+ with a current density of 0.5 mA/cm2. Depending on the operating parameters of the source, lifetimes of greater than 70 h have been achieved. For negative primary ions (with the cup removed), the current extracted from the source is primarily composed of F− ions with a ma...

Studies of ion bombardment in high density plasmas containing CF4

Abstract: We report ion energy distributions, relative ion intensities, and absolute total ion current densities at the grounded electrode of an inductively coupled Gaseous Electronics Conference radio-frequency reference cell for discharges generated in pure CF4, and in CF4:Ar and CF4:O2:Ar mixtures. Abundant ionic species, including secondary ions such as CO+ and COF+, were observed and their implications are discussed.

Position and size of the electron beam in the high-energy electron beam ion trap

Abstract: In the last decade, many spectroscopic studies have been performed using the electron beam ion trap. Often these measurements rely on the electron beam as an effective slit, yet until now, no systematic study of the position and size of the electron beam under various operating conditions has been made. Here, we present a thorough study of the electron beam's position and size (and thus the electron density) as affected by various operating parameters, and give optimal parameter ranges for operating the device as a spectroscopic source. It is shown that the diameter is constant as the energy is varied, which is important for accurate cross-section measurements.

Changes in chemical structure and optical properties of polyimide films induced by ion bombardment

Abstract: The effect of ion bombardment on the chemical structure and optical properties of polyimide films was investigated. Oxygen and nitrogen ion beams with energies in the range of 0.5–1.0 keV and doses between 1.7×1015 and 8.2×1016 ions/cm2 were irradiated on the films, and in situ x-ray photoelectron spectroscopy (XPS) and spectral transmittance analyses were carried out. The in situ XPS analyses showed that the addition reaction of oxygen and nitrogen atoms and desorption of components caused chemical structural changes in ion-bombarded polyimides. The in situ spectral analyses showed that the spectral transmittances of films were decreased by ion bombardment.