Platinum and rhenium monolayers and multilayers on Re(0001) and Pt(111) surfaces have been produced in ultrahigh vacuum using a pulsed metal vapor vacuum arc plasma gun technique. This new technique allows controlled deposition of the metals in a high vacuum environment without excessive heating, Auger electron spectroscopy results show that the growth of the metal thin film can be fabricated with the accuracy of one tenth of a monolayer.

The range and distribution of ions in matter is or major importance in the modification of materials by implantation. In this investigation the metal vapor vacuum arc (MEVVA) ion source was used as a versatile means of generating beams of metallic ions to implant 26 different species into carbon targets to a dose of 10(16) ions cm-2. Vitreous carbon was chosen as the target in order to provide an electrically conducting low Z value material in which no channeling can occur and redistribution of implanted atoms by diffusion is very unlikely. Range distributions were determined by Rutherford backscattering spectroscopy. The charge state distribution for each ion species was monitored and used in conjunction with PRAL and TRIM code calculations to arrive at the theoretically predicted ion ranges. Mean ion energies were between 78 and 192 keV.The results show significant anomalies in range which are not inconsistent with an oscillatory Z1 dependence. For ion species in the region around Z1 = 75, the ratio of measured to calculated ranges can rise as high as 1.28 +/- 0.08, while around Z1 = 41 this ratio is significantly lower than 1.O. These findings are discussed in relation to other experimental observations and current theoretical ideas.

Summary form only given. A high-current metal ion source has been developed in which a metal vapor vacuum arc is used as the plasma discharge mechanism, by means of which high-current beams of a wide range of multiply charged metal ions can be produced. Operating the source in a mode suitable for very-low-energy beam formation, in the approximate range of 100 eV to 2 keV, which might be useful for ion-beam-assisted deposition and other plasma processing applications, has been investigated. The beam formation electrodes (extractor grids) were reconfigured to work in an almost-symmetric accelerating-decelerating potential arrangement. In preliminary tests, an accelerating voltage that was limited to just 4 kV was used, and a titanium ion beam with a current of up to 100 mA at 1.5-kV net beam voltage was produced. It is anticipated that low-energy metal ion beams with current up to the 1-A level should be obtainable with an optimized grid spacing and an accelerating voltage of 10-20 kV

A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it.

ABSTRACTWe describe here a novel technique for surface modification in which a metal plasma is employed and by which various blends of plasma deposition and ion implantation can be obtained. The new technique is a variation of the plasma immersion technique described by Conrad and co-workers. When a substrate is immersed in a metal plasma, the plasma that condenses on the substrate remains there as a film, and when the substrate is then implanted, qualitatively different processes can follow, including ‘conventional’ high energy ion implantation, recoil implantation, ion beam mixing, ion beam assisted deposition, and metallic thin film and multilayer fabrication with or without species mixing. Multiple metal plasma guns can be used with different metal ion species, films can be bonded to the substrate through ion beam mixing at the interface, and multilayer structures can be tailored with graded or abrupt interfaces. We have fabricated several different kinds of modified surface layers in this way.

The MEVVA (metal vapor vacuum arc) ion source provides high current beams of multiply charged metal ions suitable for use in heavy ion synchrotrons as well as for metallurgical ion implantation. Pulsed beam currents of up to several amperes can be produced at ion energies of up to several hundred kiloelectronvolts. Operation has been demonstrated for 48 metallic ion species. The authors review the source performance when used for synchrotron injection.< >

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 describe a method for applying metal ions to the near-surface region of solid materials. 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; the metal ion species can be the same as the substrate species or different from it, and more than one kind of metal species can be applied, either simultaneously or sequentially. Surface structures can be fabricated, including coatings and thin films of single metals, tailored alloys, or metallic multilayers, and they can be implanted or added onto the surface and ion beam mixed. We report two simple demonstrations of the method: implantation of yttrium into a silicon substrate at a mean energy of 70 keV and a dose of 1×1016 atoms/cm2, and the formation of a titanium-yttrium multilayer structure with ion beam mixing to the substrate.

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.

We have measured vacuum arc ion charge-state spectra for a wide range of metallic cathode materials. The charge-state distributions were measured using a time-of-flight diagnostic to monitor the energetic ion beam produced by a metal vapor vacuum arc ion source. We have obtained data for 48 metallic cathode elements: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb, Hf, Ta, W, Ir, Pt, Au, Pb, Bi, Th, and U. The arc was operated in a pulsed mode with pulse length 0.25 ms; arc current was 100 A throughout. This array of elements extends and completes previous work by the authors. In this paper the measured distributions are cataloged and compared with their earlier results and those of other workers. We also make some observations about the performance of the various elements as suitable vacuum arc cathode materials.

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.

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.

We report on some studies we have made of the time evolution of the corrosion behavior of ion implanted samples of pure iron, medium carbon steel, and 18-8 Cr-Ni stainless steel. Ti, Cr, Ni, Cu, Mo and Yb were implanted at mean ion energies near 100 keV and at doses up to 1 {times} 10{sup 17} cm{sup {minus}2} using a Mevva metal ion implantation facility. A novel feature of this experiment was the simultaneous implantation with several different implanted species. The implanted samples were immersed in sulfuric acid solution at 40{degrees}C and the corrosion monitored as a function of time. The loss in mass was accurately measured using atomic absorption spectroscopy. The functional dependence of the corrosion behavior was established for all samples. The cumulative mass loss Q is given as a function of time t by Q = At{sup N}, where A and N are parameters; thus the corrosion rate V is given by V = ANt{sup N-1}. A is dominated by the initial mass loss and N reflects the long-time corrosion behavior. The values of the parameters A and N were obtained by a least-squares regression for all the samples investigated. We determined that for the samples investigatedmore » here, N > 1 always and V increases with time throughout the experimental duration. In this paper we summarize the experimental results and discuss the effect of A and N on corrosion rate and the relationship between the corrosion current density and the parameters A and N. 11 refs., 4 figs.« less