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The plasma-generating parts of ion sources including their power supplies are usually floated to high potential (ion extraction voltage), thus requiring great insulation efforts and causing high costs for high-energy ion beams. A new concept for pulsed ion sources is presented in which a single power supply is used to simultaneously produce the plasma and high extractor voltage via a modified Marx generator. Proof-of-principle experiments have been performed with high-current spark discharges in vacuum where multiply charged ions are produced with this Marx-generator-based ion source ("Magis"). Using "Magis", it has been demonstrated that pulsed ion beams of very high energies can be obtained with relatively low voltage. For copper, ions of charge states up to 7+ have been found whose energy was 112 keV for a charging voltage of only 10 kV.

A method for the plasma synthesis of metallic and composite thin films with atomically mixed interfaces is described. A large number of metal species can be applied and surface structures can be fabricated including films of metals and alloys, compounds including ceramics, and tailored multilayers. The added species can be energetically implanted below the surface or built up as a surface film with an atomically mixed interface with the substrate. A vacuum are produced metal plasma is used, and by adding a gas to the plasma region compound films can also be formed. The process parameters can be varied to fabricate a wide range of surface structures at the atomic level. We have demonstrated the method by synthesizing a number of metallic films as well as oxide and nitride films, including those described here: an yttrium film on silicon with an atomically mixed transition zone; a quarter-micron thick film of Pt on and mixed into Al; an Y/Ti multilayer structure in which the first and last layers were ion stitched to the material below; and an Al2O3 film on steel with a mixed bonding layer about 1000 A thick. Here we describe the background of the technique and the experimental results that we have obtained.

A novel high current metal ion implantation facility has been developed in which a metal vapor vacuum arc ion source is used. The source is operated in a pulsed mode, with pulse width 0.25 msec and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV and beam current up to several amperes peak and 10–20 mA time averaged delivered onto target. Implantation is done in a broad beam mode with a direct line of sight from ion source to target. Virtually all of the solid metals of the Periodic Table can be used. The facility has been used for a variety of different research applications, including metallurgical surface modification, high temperature oxidation resistance, ‘fine tuning’ of the composition of highT c superconducting thin films, formation of buried conducting layers in silicon, and other research purposes. Here we describe the implantation facility and some of the research programs carried out at our laboratory and collaboratively with others.

We have developed a high-current metal-ion implantation facility with which high-current beams of virtually all the solid metals of the periodic table can be produced. The facility makes use of a metal-vapor vacuum-arc ion source which is operated in a pulsed mode, with 0.25 ms pulse width and a repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge-state multiplicity; beam current is up to several amperes peak and around 10 mA time-averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the “seeding” of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III–V compounds.

A plasma immersion ion implanation (PIII) reactor compatible with integrated-circuit fabrication has been developed. Using this system, metallic impurity gettering with a noble gas plasma, sub-100-nm p+/n junction formation with SiF4 plasma for preamorphization and BF3 plasma for doping, trench conformal p+ doping, and Pd ion seeding implantation for selective Cu electroless plating were successfully carried out. The PIII system consists of an electron cyclotron resonance plasma source, a processing chamber with wafer bias supply, a sputtering target with bias supply, gas handling and plasma diagnostic tools. The apparatus is described in this paper. Plasma characterization and reactor performance are also presented.

A metal vapor vacuum arc (MEVVA) ion source has been used to implant Pd into SiO2 substrates. The ion implanted area formed a seeding layer on which a Cu film was successfully plated through an electroless plating process. It was found that the required Pd dose for Cu plating to occur is on the order of 3×1015 cm−2 when the implantation was performed with a 20 kV extraction voltage. Taking advantage of the large pulsed ion current capability (up to 1 A) of the MEVVA ion source, the needed Pd dose for seeding was achieved in minutes. With direct Pd implantation, an intermediate activation step using PdCl2 solution can be eliminated. The Cu plating rate was not a sensitive function of temperature and no incubation period was found in our experiments.

The ionization cooling of muons requires longitudinal acceleration of the muons after scattering in a hydrogen target. In order to maximize the accelerating voltage, we propose using linear accelerating structures with cells bounded by thin beryllium metal foils. This produces an on-axis field equivalent to the maximum surface field, whereas with beam-pipes the accelerating field is approximately half that of the peak surface field in the cavity. The muons interact only weakly with the thin foils. A /spl pi//2 interleaved cavity structure has been chosen, with alternate cells coupled together externally, and the two groups of cells fed in quadrature. At present we are considering an operating temperature of 77 K to gain a factor of at least two in Q-value over room temperature. We describe the design of the /spl pi//2 interleaved cavity structure, design of an alternative /spl pi/-mode open structure, preliminary experimental results from a low-power test cavity, and plans for high-power testing.

Triggering systems for vacuum arc plasma sources and ion sources have been developed that make use of a gaseous trigger discharge in a strong magnetic field. Two kinds of trigger discharge configurations have been explored, a Penning discharge and a magnetron discharge. The approach works reliably for low gas pressure in the vacuum arc environment and for long periods of operation between required maintenance: pressures in the mid 10/sup -6/ Torr range and for /spl sim/10/sup 6/ pulses.

Ion charge state distributions of vacuum arc plasma have been investigated using a time of flight method. It was found that the fraction of high charge components increased using an external strong magnetic field and high arc current. Compared with "conventional" low current arc parameters (zero magnetic field, arc current less then 300 A) in the parameters range investigated (magnetic field up to 10 kG, arc current up to 4 kA) the mean ion charge state increased by a factor 1.2-2.5 depending on the cathode materials and discharge external conditions. External magnetic field and a high arc current influence the charge state distribution in a similar way.

The quasi-linear constricted plasma source is a downstream plasma source with ten linearly aligned discharge cells. Each cell operates on the basis of a constricted glow discharge. The plasma output can easily be monitored by the plasma-emitted light. The information is not only intuitive but can also he used to operate on-line feedback control of the plasma source which is important for large-area plasma processing of materials.

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.

Summary form only given. A very broad beam version of a vacuum arc ion source has been used to carry out high-energy metal ion implantation of a particularly large substrate. A multiple-cathode vacuum arc plasma source was coupled to a 50-cm-diameter beam extractor (multiple aperture, accel-decel configuration) operated at a net extraction voltage of up to 50 kV. The metal ion species chosen were Ni and Ta. The ion source was operated in a repetitively pulsed mode with pulse length 250 /spl mu/s and repetition rate several pulses per second. The extracted beam had a Gaussian profile with FWHM of about 35 cm, giving a nominal beam area of about 100 cm/sup 2/. The current of Ni or Ta metal ions in the beam was up to several amperes. The targets for the ion implantation were a number of 24-inch long, highly polished Cu rails from an electromagnetic rail gun. The rails were located about 80 cm away from the ion source extractor grids, and were moved across a diameter of the vessel in such a way as to maximize the uniformity of the implant along the rail.

Metallic coatings can be fabricated using the intense plasma generated by the metal vapor vacuum arc. We have made and tested an embodiment of vacuum arc plasma source that operates in a pulsed mode, thereby acquiring precise control over the plasma flux and so also over the deposition rate, and that is in the form of a miniature plasma gun, thereby allowing deposition of metallic thin films to be carried out in confined spaces and also allowing a number of such guns to be clustered together. The plasma is created at the cathode spots on the metallic cathode surface, and is highly ionized and of directed energy a few tens of electron volts. Adhesion of the film to the substrate is thus good. Virtually all of the solid metals of the Periodic Table can be used, including highly refractory metals like tantalum and tungsten. Films, including multilayer thin films, can be fabricated of thickness from Angstroms to microns. We have carried out preliminary experiments using several different versions of miniature, pulsed, metal vapor vacuum arc plasma guns to fabricate metallic thin films and multilayers. Here we describe the plasma guns and their operation in this application, and present examples of some of the thin film structures we have fabricated, including yttrium and platinum films of thicknesses from a few hundred Angstroms up to 1 micron and an yttrium-cobalt multilayer structure of layer thickness about 100 Angstroms.

The metal vapor vacuum arc is a prolific generator of highly ionized metal plasma in which the ions are in general multiply stripped. We have utilized this plasma production mechanism to make a high current metal ion source. The metal vapor vacuum arc ion source is thus a laboratory tool for providing high quality, high current beams of a wide range of metal ion species. Charge state spectra have been measured using a time-of-flight diagnostic. In this paper we review the ion source development program, describe the various embodiments of the concept that have been made, and summarize those experimental results relating to the ion charge states that can be produced.

Metal implantation provides a powerful tool for the formation of non-equilibrium alloy layers for a wide variety of basic and applied materials applications, but the technique is fundamentally limited in two important ways: (i) the implanted species concentration is limited by sputtering of the modified layer by the incident ion beam itself, and the sputter-limited retained dose is often disappointingly low; (ii) the thickness of the modified layer is limited by the maximum ion energy available, and for practical reasons (implanter voltage) the layer thickness is often just a few hundred angstroms. We describe here a metal-plasma-immersion-based method for synthesizing non-equilibrium alloy layers of arbitrarily high dopant concentration and of arbitrary thickness. By repetitively pulse biasing the substrate to high negative voltage while it is immersed in the metal plasma from a vacuum arc plasma gun, a layer can be synthesized that is atomically mixed into the substrate with an interface width determined by the early-time bias voltage and with a thickness determined by the overall duration of the process. The species is that of the vacuum arc cathode material, which for this purpose can be a mixture of the substrate metal and the wanted dopant metal. We have used the method to form a high concentration Ta layer on the copper rails of an electromagnetic rail gun, with total surface area treated about 3000 cm2; the Ta depth profile was flat at about 50 at.% Ta in Cu to a depth of about 1000 A.

A vacuum arc triggering system based on the formation of cathode spots in E/spl times/B discharge plasmas have been used in the Mevva-V and Titan-2 ion sources. When a strong magnetic field is employed, significant improvements in triggering lifetime together with a decrease in the required background gas pressure can be obtained. The authors describe here the results of some further investigations of the triggering discharge and main vacuum arc plasma in a strong magnetic field and outline some of the physical processes responsible for the cathode spot ignition in this kind of configuration.