Sputtering Source Research Articles

Spectroscopy of mass-selected VCo and VFe in argon matrices

We examine the resonance Raman spectroscopy of the heteronuclear dimers VCo and VFe, using a mass-selected cluster source. Cluster cations are produced in a sputtering source and mass filtered with a Wien filter, then neutralized and deposited in an Ar matrix at low temperatures. For VCo we obtain the resonance Raman spectra in Ar matrix excited with 457.9, 488.0, 496.5, 501.7, and 514.5 nm laser lines. We observe Raman shifts of 459 and 916 cm−1, and we assign these lines to the fundamental and first overtone of the ground state. The resulting force constant is ke=3.42 mdyne/Å. Resonance Raman spectra of VFe, obtained at the same five excitation wavelengths, display Raman shifts at 423 and 836 cm−1, and we assign these to the fundamental and first overtone of the ground-state vibration. The resulting force constant is ke=2.94 mdyne/Å. We compare these observed force constants and configurations with those of other V–X dimers (X=Ti–Ni), as well as related isoelectronic species. The value for VFe, with 13 valence electrons, is considerably lower than its neighbors. This molecule most likely has a Σ+2 ground state, stemming from a (3dσ)2(3dπ)4(3dδ)4(4sσ)2(4sσ*)1 configuration. The higher force constant for VCo with 14 valence electrons indicates either a (3dσ)2(3dπ)4(3dδ)4(3dδ*)2(4sσ)2 configuration with a Σ3 state, or a (3dσ)2(3dπ)4(3dδ)4(3dδ*)1(4sσ)2(4sσ*)1 configuration with a Δ3 state.

Gas-phase anions containing B and N

Mixed clusters of B and N have been produced by sputtering BN with Cs or Rb. The atom ordering in assumed linear species has been deduced from measurements of the mass distribution of both the positive and negative products from the fragmentation of the anionic clusters in a gas target. The existence of the anions BBN, BNN, BBBN, BBBBN, BBNN, and BBBNN has been demonstrated. The structural isomer with the largest electron affinity is usually the dominant species produced in the sputter source.

A modified ion sputter source with increased lifetime

The Cs sputter ion source HVEE 860-C has shown significant erosion of inner parts after an operation time of some thousand hours. This is caused by Cs ions generated at hot surfaces outside the spherical ioniser surface. The calculated trajectories of these ions and the erosion patterns show an excellent correspondence. The suppression of the disturbing ions has resulted in increased lifetimes of the ion source and an improved focus of the primary Cs ions on the sputter target.

Anti-bacterial silver coatings exhibiting enhanced activity through the addition of platinum

Anti-bacterial silver coatings were deposited on thermally sensitive polymeric substrates using a combination of magnetron sputtering and neutral atom beam (Saddle Field) plasma sources. The anti-bacterial activity of silver is dependent on the release of Ag+ ions, which act by displacing other essential metal ions such as Ca2+ or Zn+. This study evaluates the use of platinum to enhance the release of silver ions from the silver coating. In the galvanic series platinum is more active than silver and therefore Pt enhances Ag+ ion formation through galvanic action. In order to evaluate this, potential step (chronoamperometric) experiments were performed on silver/platinum alloys containing 0.5 and 3.0% Pt. The resulting current–time curves demonstrated that Ag+ formation increased with platinum addition by up to 100%. A magnetron sputtering target was fabricated consisting of 1% Pt in a Ag matrix. This was used to sputter Pt/Ag coatings with thicknesses in the range 5–12 nm onto silicone and polyurethane substrates. The bacterial adhesion and bactericidal effects of the coated polymers was assessed using Straphylococcus epidermidis and the cytotoxicity using fibroblast cells. The addition of 1% Pt was found to significantly enhance the anti-bacterial effectiveness of the Ag coatings. Up to a 2 log reduction in bacterial adhesion was achieved for 5 nm thick Ag/1% Pt coatings on silicone, which did not exhibit cytotoxicity.

Sputter deposition of crystalline alumina coatings

In the last years a variety of plasma sources have been developed for film deposition by magnetron sputtering. In addition to RF and DC sputter sources, pulsed DC and low-frequency plasma sources are gaining increased attention in sputter technology. This interest is driven by the wish of depositing coatings with superior properties as compared to those deposited by conventional techniques. One prominent example of coatings that are significantly enhanced by the usage of pulsed sputter deposition is alumina. Although crystalline α-alumina can be deposited by thermal CVD at temperatures above 1000 °C for two decades, no process for the deposition of crystalline alumina at low temperatures is commercially available up to now. In this paper, the results of a detailed study of the plasma parameters during bipolar pulsed magnetron sputtering and their effect on the properties of alumina hard coatings is reported. Langmuir type voltage measurements at the substrate position, optical emission spectroscopy as well as mass spectroscopy were used to monitor the effect of target poisoning on the reactive deposition of alumina. Those principal observations were connected to easily available process parameters like discharge voltage and oxygen partial pressure. Based on these measurements, the deposition of crystalline γ-alumina with high hardness and good adhesion under technical conditions was achieved.

Novel matching lens and spherical ionizer for a cesium sputter ion source

The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child’s law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally.

A high resolution AMS-injector for the Pelletron in Lund

A high resolution injector system has recently been installed at the Lund 3 MV tandem Pelletron accelerator. The new injector, designed mainly for 26Al ions, will increase the experimental potential of the Lund AMS facility considerably. High quality energy- and mass-resolution is obtained by using a 90° spherical electrostatic analyzer followed by a 90° magnetic analyzer. The injector is equipped with a high intensity sputtering source with a spherical ionizer.

Polycrystalline Si thin film growth on glass using pulsed d.c. magnetron sputtering

Crystalline poly-Si thin films were deposited on Corning glass substrates at a temperature of 500 °C using a pulsed d.c. magnetron sputtering source. The increased bias voltage causes an enhancement of the potential difference between the plasma and substrate. In case of the bipolar pulsed d.c. magnetron sputtering, V p shows higher value than that in the unipolar pulsed d.c. as the bias voltage increases. Therefore, the mobility of the sputtered adatoms increases by the surface heat accumulation of energetic sputtered particles with the increased bias voltage. Consequently, more higher mobility (41 cm 2 Vs −1) and crystallinity were obtained for the Si film grown with the bipolar-pulsed d.c. magnetron sputtering due to the energy incorporation by enhanced bombardment of Ar ions.

Beam optics optimization of a negative-ion sputter source

A negative-ion sputter source has been studied in order to increase the beam intensity delivered by the Vivitron tandem injector. The aim was to characterize the influence on the beam intensity of some factors related to the configuration of the source such as the shape of the target holder, the target surface topography and the anode/cathode voltage. The paper reports the results carried out by experimentation on a test facility and on the injector itself as well as the investigations performed with computer simulations.

Reactive sputter deposition of alumina thin films using a hollow cathode sputtering source

Reactive sputtering allows deposition of insulating compounds that cannot be easily prepared using conventional dc sputtering methods. However, this technique suffers from problems related to the poisoning of the target and associated hysteresis effects. In addition, the operating conditions that yield the highest growth rate are unstable, and feedback control is required to maintain the system at the optimal operating point. In order to address some of these issues, we have developed a new hollow cathode sputtering (HCS) source. In addition to the inherent advantages of high deposition rates and the capability for coating complex surfaces, we have found that the hollow cathode sputtering source does not exhibit the hysteresis behavior generally observed in planar reactive sputtering systems and is stable at all operating points without feedback control. We have characterized a HCS source for reactively depositing alumina thin films. The deposition rate increases on increasing the oxygen concentration. Pure alumina thin films can be deposited with high growth rates at very low-power densities.

Deposition of Thin Dye Coatings by Glow Discharge Induced Sublimation

A novel method for the vacuum deposition of thin fluorescent dye coatings by means of glow discharge induced sublimation (GDS) is disclosed. Powdered organic compound is put on a radio frequency plasma sputtering source and bombarded by low energy (<1 keV) noble gas ions and electrons. Ion bombardment gives rise to a local heating which induces sublimation of the dye molecules. The method has been successfully used for deposition of 3-hydroxyflavone (3-HF) coatings on silicon substrates. Plasma diagnostics, as performed by means of mass spectrometry and in situ optical emission spectroscopy, point out both the sublimation of integer 3-HF molecules and the presence of 3-HF molecular fragments in the glow discharge. The integer 3-HF molecules are positively ionized or protonated before reaching the substrate. Rutherford backscattering spectrometry and elastic recoil detection analysis confirm that the deposited film is stoichiometric within the experimental errors. FT-IR analysis points out all the main cha...

Properties of Ti1−xSixNy films deposited by concurrent cathodic arc evaporation and magnetron sputtering

A new technique is described in the synthesis of thin films of Ti1−xSixNy based on the concurrent reactive deposition of Ti produced by a cathodic arc source and Si produced by a d.c. magnetron sputter source. The technique permits the controllable doping of TiN with silicon over the range of 1–16 at.%. The films were found to have a microhardness of 70 GPa with a compressive stress of 5.5 GPa when deposited with a magnetron power of 220 W and a bias voltage of −150 V, and a maximum hardness of 58 GPa and stress values of approximately 3.3 GPa when deposited using 280 W magnetron power and −50 V bias. The hardness and stress of TiN was found to be 26 and 3.5 GPa, respectively, when deposited in the absence of the magnetron.

Off-line production of a 7Be radioactive ion beam

A 7Be ion beam of several particle pA at 8 MeV has been produced at the TTT3 tandem of the University “Federico II” in Naples. The 7Be nuclides were formed via the 7Li(p,n) 7Be reaction using a metallic Li target and an 11.4 MeV proton beam of 20 μA intensity, delivered by the cyclotron in Debrecen. Methods of hot chemistry were used to extract the 7Be nuclides from the Li matrix and to prepare the 7Be cathodes for the ion sputter source of the tandem. Examples of 7Be beam applications are given.

Absorption and Raman spectroscopy of mass-selected scandium tetramers in argon matrices

We examine the absorption and resonance Raman spectra of mass-selected Sc clusters, and obtain the spectra of tetramers of Sc. Tetramers are produced in a sputtering source and mass filtered with a Wien filter, then neutralized and deposited in an Ar matrix. The absorption spectrum indicates several new optical transitions at 350, 451, 538, and 563 nm. Raman resonances were excited at 488 nm with transitions at 222, 166, and 103 cm −1 . These indicate a tetrahedral (T d) geometry, and we assign the observed frequencies to a singly degenerate totally symmetric stretch ω 1(a 1), a triply degenerate mode ω 2(t) and a doubly degenerate ω 3(e) mode.

Phosphorous doping in beta-irondisilicide by co-sputtering method

We prepared phosphorous-doped n-type beta-irondisilicide (β-FeSi 2) thin films by co-sputtering followed by thermal annealing method using Si, Fe and Fe 3P as sputtering source. Phosphorous doping changed the conductivity of beta-irondisilicide films from p-type to n-type. In addition, the resistivity decreased with phosphorous doping by more than one order. However, the structure of the films changed to FeSi at the higher doping levels.

Comparative study on alloy cluster formation in Co-Al and Co-Pt systems

The formation of alloy clusters using a plasma-gas-aggregation technique is described for Co-Al and Co-Pt systems. This method employs two separate elemental sputtering sources and a growth chamber. Metallic vapors generated were cooled rapidly in an Ar atmosphere, and grown into alloy clusters. The composition of the clusters was controlled by adjusting the ratio of the applied sputtering power. We found that B2-CoAl clusters of about 12 nm in diameter were formed for a composition range wider than that predicted by the Co-Al phase diagram, and that high-temperature fcc-CoPt clusters were formed in the Co-Pt system. These findings suggest the nonequilibrium nature of the cluster formation. The size distribution of the clusters is highly monodispersive and does not follow commonly observed log-normal distribution. These results were discussed from the viewpoint of simple gas dynamics. We concluded that monomer absorption with discrete residence time is the dominant mechanism for monodispersive alloy cluster formation, and that the contrasting thermodynamical features between the Co-Al and Co-Pt systems are at the cause of the observed difference in average cluster size.

Rotatable magnetron sputtering of YBa 2Cu 3O 7− x thin films on single crystal substrates

The development of sputter deposition of YBa 2Cu 3O 7− x (YBCO) from rotatable targets is an important step in the realisation of a large scale deposition process for YBCO coated conductor. Rotatable magnetron sputter sources are standard equipment in large scale sputter industry and the power input in a rotatable magnetron can be much higher compared to a planar magnetron with the same race track area. This result in improved discharge characteristics and increased deposition speed. For this work a flame sprayed and a plasma sprayed cylindrical YBCO target was used to deposit YBCO thin films on single crystal MgO. c-Axis oriented YBCO thin films were obtained at lower pressure than is normally used for YBCO sputter deposition, resulting in a higher deposition speed. The influence of deposition parameters (such as sputter pressure, oxygen partial pressure, substrate temperature, etc.) on the properties of the YBCO layer was investigated and the possibilities for large scale deposition were explored.

ITO thin films deposited at low temperatures using a kinetic energy controlled sputter-deposition technique

Low-temperature deposition of tin (Sn)-doped indium oxide (ITO) thin films was attempted using a kinetic energy controlled particle deposition (KECD) technique in which the kinetic energies of sputtered particles along with their incidence angles to the substrate can be controlled in the film forming process. It was expected that this new sputter deposition technique would be able to deposit ITO thin film having a dense structure as well as extremely smooth surfaces even at low substrate temperatures, which would result in the formation of a film having low resistivity. It was found that this method can produce ITO thin films having resistivity as low as 3.5×10 −4 cm and smooth surfaces ( R a≦0.15 nm) even at temperatures below 50 °C. The sputtering must be performed at a voltage below −100 V, and the sputtering gas pressure in the sputtering source and the oxygen gas pressure during sputtering must be adjusted to an optimal value.

Surface improvements of industrial components treated by plasma immersion ion implantation (PIII): results and prospects

The major drive for PIII research in recent years has been the widespread use of plasma-based ion implantation in industries aiming at attaining high value-added components. After achieving the domain of the complete basic PIII cycle, we started to pursue the implementation of this process in various types of industrial components. A DC glow discharge source with a controlled plasma floating potential was used in a 100-l PIII system driven by a 30-kV peak voltage, 50 μs duration, up to 1.1 kHz pulse power source, in order to process the components which were provided by regional companies, spanning from machinery tools to prosthesis. The industrial components were set-up in the PIII chamber as received from the companies, after a simple cleaning procedure. In this phase, only nitrogen implantation was performed. The required processing times were typically from 60 to 120 min and the components were treated either individually or in batches. Fast steel drill bits, knife blades for wood cutting, tools for odontological applications, molds made of fast steel, a prosthesis made of Ti alloy, etc., have been three-dimensionally implanted successfully. Next, improvements in the PIII ongoing system included: a 10-kW pulser with up to 60 kV capability, turbo-pump, refrigerated walls, auxiliary heating of the components, a larger chamber and a magnetron sputtering source for hybrid treatments.

Comparison of plasma sprayed and flame sprayed YBa 2Cu 3O 7− x targets for rotatable magnetron sputtering

Rotatable magnetron sputter sources are standard equipment in large scale sputter industry for the deposition of metals and metal oxides. The power input in a rotatable magnetron can be much higher compared to a planar magnetron, resulting in improved discharge characteristics and increased deposition speed. In order to develop rotatable magnetron deposition of YBa 2Cu 3O 7− x (YBCO) on an industrial scale, the construction of large cylindrical YBCO targets using plasma and flame spraying was explored. Large cylindrical targets (∅ 13 cm×30 cm length) consisting of a stainless steel substrate coated with a 5 mm YBCO coating were fabricated. This paper describes the microstructure, mechanical, structural, thermal and electrical characterisation of the obtained coatings and the characteristics of the targets during magnetron sputtering.