Michael R. Dickinson

Metal plasma immersion ion implantation and deposition using vacuum arc plasma sources

Plasma source ion implantation (PSII) with metal plasma results in a qualitatively different kind of surface modification than with gaseous plasma due to the condensable nature of the metal plasma, and a new, PSII‐related technique can be defined: metal plasma immersion ion implantation and deposition (MPI). Tailored, high‐quality films of any solid metal, metal alloy, or carbon (amorphous diamond) can be formed by MPI using filtered vacuum arc plasma sources, and compounds such as oxides or nitrides can be formed by adding a gas flow to the deposition. Here we describe the plasma formation at cathode spots, macroparticle filtering of the vacuum arc plasma by magnetic ducts, the underlying physics of MPI, and present some examples of MPI applications.

Streaming metal plasma generation by vacuum arc plasma guns

We have developed several different embodiments of repetitively pulsed vacuum arc metal plasma gun, including miniature versions, multicathode versions that can produce up to 18 different metal plasma species between which one can switch, and a compact high-duty cycle well-cooled version, as well as a larger dc gun. Plasma guns of this kind can be incorporated into a vacuum arc ion source for the production of high-energy metal ion beams, or used as a plasma source for thin film formation and for metal plasma immersion ion implantation and deposition. The source can also be viewed as a low-energy metal ion source with ion drift velocity in the range 20–200 eV depending on the metal species used. Here we describe the plasma sources that we have developed, the properties of the plasma generated, and summarize their performance and limitations.

S-shaped magnetic macroparticle filter for cathodic arc deposition

A new magnetic macroparticle filter design consisting of two 90/spl deg/ filters forming an S shape is described, The transport properties of this S filter are investigated using Langmuir and deposition probes. It is shown that the filter efficiency is the product of the efficiencies of two 90/spl deg/ filters, and the deposition rate is still acceptably high to perform thin-film deposition. Films of amorphous hard carbon have been deposited using a 90/spl deg/ filter and the S filter, and the macroparticle contents of the films are compared.

Recent advances in surface processing with metal plasma and ion beams

Abstract Surface processing by metal plasma and ion beams can be effected using the dense metal plasma formed in a vacuum arc discharge embodied either in a “metal plasma immersion” configuration or as a vacuum arc ion source, as well as by many other well-established methods. In the former case the substrate is immersed in the plasma and repetitively pulse-biased to accelerate the ions across the sheath and allow controlled ion energy implantation+deposition, and in the latter case a high energy metal ion beam is formed and ion implantation is done in a more-or-less conventional way. These methods have been used widely; here we limit consideration to work carried out at the Lawrence Berkeley National Laboratory. A number of advances have been made both in the plasma technology and in the surface modification procedures that enhance the effectiveness and versatility of the methods. Recent improvements in plasma technology include dual-source plasma mixing, ion charge state enhancement, and some scale-up of the hardware. We have made and explored some novel kinds of surface films and modified layers, including for example doped diamond-like carbon (DLC), novel multilayers, alumina and more complex ceramic materials such as mullite (3Al 2 O 3 .2SiO 2 ), high temperature superconducting films, and others. Recent research has included investigations of these and other surface materials for many different basic and applied applications, such as for high temperature tolerant protective coatings, biomedical compatibility, surface resistivity tailoring of ceramics, novel catalytic surfaces, corrosion resistance of battery electrodes, and more. Here we briefly review the fundamentals of the techniques, and describe some of the applications to which the methods have been put at the Lawrence Berkeley National Laboratory.

Metal ion implantation: Conventional versus immersion

Vacuum‐arc‐produced metal plasma can be used as the ion feedstock material in an ion source for doing conventional metal ion implantation, or as the immersing plasma for doing plasma immersion ion implantation. The basic plasma production method is the same in both cases; it is simple and efficient and can be used with a wide range of metals. Vacuum arc ion sources of different kinds have been developed by the authors and others and their suitability as a metal ion implantation tool has been well established. Metal plasma immersion surface processing is an emerging tool whose characteristics and applications are the subject of present research. There are a number of differences between the two techniques, both in the procedures used and in the modified surfaces created. For example, the condensibility of metal plasma results in thin film formation and subsequent energetic implantation is thus done through the deposited layer; in the usual scenario, this recoil implantation and the intermixing it produces ...

Hollow-anode plasma source for molecular beam epitaxy of gallium nitride

GaN films have been grown by molecular beam epitaxy (MBE) using a hollow‐anode nitrogen plasma source. The source was developed to minimize defect formation as a result of contamination and ion damage. The hollow‐anode discharge is a special form of glow discharge with very small anode area. A positive anode voltage drop of 30–40 V and an increased anode sheath thickness leads to ignition of a relatively dense plasma in front of the anode hole. Driven by the pressure gradient, the ‘‘anode’’ plasma forms a bright plasma jet streaming with supersonic velocity towards the substrate. Films of GaN have been grown on (0001) SiC and (0001) Al2O3 at 600–800 °C. The films were investigated by photoluminescence, cathodoluminescence, x‐ray diffraction, Rutherford backscattering, and particle‐induced x‐ray emission. The film with the highest structural quality had a rocking curve width of 5 arcmin, the lowest reported value for MBE growth to date.

Commissioning an EUV mask microscope for lithography generations reaching 8 nm

The SEMATECH High-NA Actinic Reticle review Project (SHARP) is a synchrotron-based, EUV-wavelength microscope, dedicated to photomask imaging, now being commissioned at Lawrence Berkeley National Laboratory. In terms of throughput, resolution, coherence control, stability and ease of use, SHARP represents a significant advance over its predecessor, the SEMATECH Berkeley Actinic Inspection Tool (AIT), which was decommissioned in September 2012. SHARP utilizes several advanced technologies to achieve its design goals: including the first Fouriersynthesis illuminator on a zoneplate microscope, EUV MEMS mirrors, and high-efficiency freestanding zoneplate lenses with numerical aperture values up to 0.625 (4×). In its first week of operation, SHARP demonstrated approximately 150 times higher light throughput than AIT and a spatial resolution down to 55-nm half-pitch with 0.42 4×NA (i.e. the smallest feature size on our test mask.) This paper describes the current status of the tool commissioning and the performance metrics available at this early stage.

High ion charge states in a high‐current, short‐pulse, vacuum arc ion source

Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1–4) depend on the cathode material and only a little on the discharge current as long as the current is low. Here we report on experiments with short pulses (several μs) and high currents (several kA); this regime of operation is thus approaching a more vacuum sparklike regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution.

Hybrid gas-metal co-implantation with a modified vacuum arc ion source

Energetic beams of mixed metal and gaseous ion species can be generated with a vacuum arc ion source by adding gas to the arc discharge region. This could be an important tool for ion implantation research by providing a method for forming buried layers of mixed composition such as e.g. metal oxides and nitrides. In work to date, we have formed a number of mixed metal-gas ion beams including Ti+N, Pt+N, Al+O, and Zr+O. The particle current fractions of the metal-gas ion components in the beam ranged from 100% metallic to about 80% gaseous, depending on operational parameters. We have used this new variant of the vacuum arc ion source to carry out some exploratory studies of the effect of Al+O and Zr+O co-implantation on tribology of stainless steel. Here we describe the ion source modifications, species and charge state of the hybrid beams produced, and results of preliminary studies of surface modification of stainless steel by co-implantation of mixed Al/O or Zr/O ion beams. 5 figs, 21 refs.

Cathodic arc deposition of copper oxide thin films

LBL-35678 UC-426 Submitted to Surface and Coatings Technology Cathodic Arc Deposition of Copper Oxide Thin Films R. A. MacGill, S. Anders, A. Anders, R. A. Castro, M. R. Dickinson, K. M. Yu and I. G. Brown Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 May 23,1994 This work was supported by the Electric Power Research Institute under Contract RP 8042-03, and the U.S. Department of Energy, Division of Advanced Energy Projects, under Contract No. DE-AC03-76SF00098.