Argon Target Research Articles

Influence of sputter deposition conditions on phase evolution in nitrogen-doped stainless steel films

In the present work, nitrogen-doped stainless steel (SS–N) films were deposited on Si (100) by reactive sputtering of an austenitic stainless steel target in argon and nitrogen gas mixtures under different conditions. The influence of several important parameters, such as nitrogen gas composition (%N 2), substrate temperature, sputtering power density and target–substrate distance, on phase evolution in the film was studied. The results showed that a range of phases can evolve in the SS–N films. These include crystalline ferrite, amorphous S phase, crystalline S phase, CrN and the new cubic MN phase. The conditions for the formation of each of these phases were identified. In particular, the effect of the various deposition parameters on the formation of crystalline S phase is discussed in detail in this paper.

Cluster-size dependence of ranges of 100 eV/atom Aun clusters

Using molecular-dynamics simulation, we determine the ranges of Aun clusters (n=1,13,43,87,201,402) at fixed energy per atom, 100eV/atom. We study three targets with different bonding properties and mass: a condensed amorphous argon sample, a gold crystal with a (100) surface and a graphite crystal with a (1000) surface. We find that the ranges follow a power law R∝nα, where α≅0.3 in a gold target and α≅0.4 in the graphite and argon targets.

Cross sections for charge change in argon and equilibrium charge states of 3.5 MeV/amu uranium ions passing through argon and carbon targets

Cross sections for single and multiple electron capture and loss were measured for 3.5MeV/amu uranium ions, traveling in argon gas, as a function of incident charge state. Multiple electron loss in single collisions was found to contribute significantly to the total loss cross section. The measured cross sections were used to determine the average equilibrium charge in argon by three different methods. The resulting charges were in good agreement with each other and with the effective charge calculated from stopping powers. In order to investigate the gas–solid (density) effect on the average equilibrium charge, the charge distributions of 3.5MeV/amu uranium ions emerging from carbon foils of different thicknesses were measured. It was found that the average equilibrium charge of the uranium ions emerging from the solid is 41% larger than that of the uranium ions emerging from the gas. The energy dependences of the average equilibrium charges for uranium ions exiting carbon and argon targets were examined by combining the present results with previous results of other investigators and compared with the predictions of a semiempirical formula developed recently by Schiwietz and Grande.

Physical vapor deposition route for production of Al–Cu–Fe–Cr and Al–Cu–Fe quasicrystalline and approximant coatings

A novel route for production of Al–Cu–Fe–Cr and Al–Cu–Fe quasicrystalline and approximant coatings by physical vapor deposition (PVD) methods is described. Powdered elemental stoichiometric mixtures were formed and vacuum pressed at 400 °C in a graphite die to produce ≈50% dense sputtering targets. X-ray diffraction analysis performed on the expended targets revealed elemental Al and Cu phases with significant quantities of intermetallic θ (Al 2Cu) and/or λ (Al 13Fe 4) phases also present. These targets were used to sputter thick (10 μm) precursor coatings onto alumina substrates. Predominantly O 1 approximant decagonal approximant coatings were produced by sputtering from the Al–Cu–Fe–Cr target and subsequent annealing in vacuum in flowing argon at 500 °C for 4 h. Icosohedral and rhombohedral approximant phases are produced by sputtering from the Al–Cu–Fe target and annealing in argon at 850 or 450 °C, respectively.

Formation of an MN-type cubic nitride phase in reactively sputtered stainless steel-nitrogen films

Stainless steel films doped with various amounts of nitrogen were deposited on (1 0 0) silicon wafers by radio frequency magnetron sputtering of an austenitic stainless steel target in argon and nitrogen gas mixtures, containing a range of nitrogen compositions. The evolution of phases as a function of nitrogen doping was studied by X-ray diffraction and transmission electron microscopy. It was found that with increasing nitrogen composition in the gas mixture, the crystalline structure of the films changed from bcc ferrite ( α), to expanded fcc austenite ( γ N) supersaturated with nitrogen, and finally to the MN type nitride (Fe 0.69Cr 0.2Ni 0.1Mo 0.01)N phase with ideal cubic symmetry and further enlarged lattice. This MN type phase has a fcc structure with a lattice parameter about 0.433 nm and possibly possesses the zinc blende type lattice structure. The morphological features of the single MN phase films produced are also discussed in this paper.

Optical measurement in carbon nanotubes formation by pulsed laser ablation

Carbon nanotubes (CNTs) were produced by laser ablation of a graphite composite target in argon and nitrogen ambient gas. To investigate the effect of nitrogen gas on CNTs formation, the plasma plume was examined using optical emission spectroscopy. The vibrational temperature of C 2 molecules was estimated by fitting of a Swan band spectrum. The temperature in N 2 ambient gas is lower than that in Ar ambient gas. In a nitrogen atmosphere, the spectrum intensity of C 2 Swan band was enhanced and CN violet system was also observed. Soot collected in the reaction tube was observed using FE-SEM and TEM. The soot deposited in the nitrogen gas contained more bundled CNTs than those in Ar ambience.

A study of capacitance–voltage characteristics of amorphous carbon multilayer nanostructures

Dark and illuminated capacitance–voltage ( C– V) characteristics and admittance measurements were carried out on multilayer carbon structures. The latter were produced by depositing ultrathin amorphous carbon layers with different optical band gaps on a monocrystalline boron-doped silicon substrate. The carbon layers were grown either by magnetron sputtering (MS) of a graphite target in argon or by plasma ion beam deposition (IBD) in cyclohexane. The structures were characterised by X-ray reflectivity (XRR). With respect to their electrical properties, it was shown that light strongly affects both the C– V-characteristics and the admittance. The results were interpreted in terms of the energy levels in these amorphous carbon multilayer structures.

Electrical Probe Measurements of the Late Stage of the Plasma Produced by Laser Irradiation in an Argon Gas-puff Target

The electron temperature and the expansion velocity of the late stage of an laser-induced argon plasma in an argon gas-puff target was measured using a Langmuir probe. The typical electron temperature at a distance of 100 mm from the laser focal point was found to be less than 1.0 eV and the expansion velocity of the plasma was about 1600 m/s.

Bond dissociation energy and Lewis acidity of the xenon fluoride cation.

This study focuses upon the Lewis acid reactivity of XeF(+) with various bases in the gas phase and the determination of the bond dissociation energy of XeF(+). The bond dissociation energy of XeF(+) has been measured by using energy-resolved collision-induced dissociation with neon, argon, and xenon target gases. Experiments with neon target yield a 298 K bond dissociation enthalpy of 2.81 +/- 0.09 eV, and those with argon target give a similar value at 2.83 +/- 0.12 eV. When using a xenon target, a significantly lower value of 1.95 +/- 0.16 eV was observed, which corresponds closely with previous measurements and theoretical predictions. It is proposed that the lighter target gases give inefficient excitation of the XeF(+) vibration leading to dissociation at energies higher than the BDE. Novel xenon-base adducts have been prepared in a flowing afterglow mass spectrometer by termolecular addition to XeF(+) and by reaction of base with XeF(+)(H(2)O). New species have been characterized qualitatively by CID, and it is found that the products formed reflect the relative ionization energies of the fragments. Among the new xenon-containing species that have been prepared are the first examples of xenon carbonyls.

Investigation and characterisation of silicon nitride and silicon carbide thin films

Thin films of silicon nitride (Si 3N 4) and silicon carbide (SiC) have been deposited by radio frequency (r.f.) magnetron sputtering of stoichiometric targets in non-reactive argon and in the case of Si 3N 4 additionally in reactive nitrogen–argon atmospheres. The influence of the sputtering atmosphere, the substrate temperature and the substrate bias on the composition and on the mechanical and microstructural properties of the thin films was investigated. FTIR and Raman spectroscopy was used to identify the chemical bonding configuration and to control the chemical composition. Raman investigation showed a change in the bonding configuration from amorphous silicon carbide to a crystalline structure and the incorporation of nitrogen in silicon nitride thin films with increasing substrate bias.

Corrosion behavior of NiCrMo Alloy 625 in high temperature, hydrogenated water

The corrosion behavior of NiCrMo Alloy 625 (UNS N06625) has been characterized in a 10,000 h test conducted in hydrogenated water at 260 °C. The corrosion kinetics were observed to be parabolic, the parabolic rate constant being determined by chemical descaling to be 0.074 mg dm −2 h −1/2. Characterizations of the corrosion oxide layer via grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy in combination with argon ion milling and target factor analysis, revealed the presence of two spinel oxide phases and significant amounts of recrystallized nickel. Based on the distribution of three oxidized alloying constituents (Ni, Cr, Fe) with respect to depth and oxidation state, it was concluded that: (a) corrosion occurs in a non-selective manner, but significant amounts of nickel(II) ions are released to the water, and (b) the spinel oxides exist as a chromite-rich inner layer (Ni 0.7Fe 0.3)(Cr 0.8Fe 0.2) 2O 4 underneath a coarser, ferrite-rich outer layer (Ni 0.9Fe 0.1)(Cr 0.1Fe 0.9) 2O 4. The trivalent cation distribution in each of these phases appears to represent a solvus in the immiscible NiCr 2O 4–NiFe 2O 4 binary.

Time-dependent independent-particle model calculation of multiple capture and ionization processes inp−Ar,p¯−Ar,andHe2+−Arcollisions

Previous work on multielectron transitions in proton, antiproton, and ${\mathrm{He}}^{2+}$-ion impact on neon is extended to the case of argon targets for collision energies in the 5--1000 keV/amu range. Global quantities such as net electron loss from the target, net capture, and net ionization are predicted within experimental errors using a spherically symmetric optimized effective target atom potential with dynamical screening effects based on the time-dependent net ionization probability. The inclusion of target response is crucial in order to obtain correct positions and heights for the peaks in the net ionization cross sections. Effects due to cascading following multiple outer-shell excitation are found to be appreciable at energies between 10 and 100 keV/amu, but are overestimated by the statistical model. L-shell vacancy production is reported to affect recoil charge state production at energies above 200 keV/amu for charge states $q>~3.$ At low and intermediate energies, the independent-particle model is shown to overestimate q-fold recoil ion production significantly for $q>~3$ for proton impact signaling the role of electronic correlations for these channels. For antiproton impact the $q=3$ cross section is consistent with the independent-particle model.

Photoprotective ceramic coatings on poly(ether ether ketone)

Zinc oxide and titanium dioxide coatings were deposited on poly(ether ether ketone) (PEEK) films by r.f. magnetron sputtering from ceramic targets in different argon–oxygen mixtures. PEEK and ceramic/polymer assemblies were irradiated with polychromatic light ( λ>300 nm). The structure modifications of the surface of irradiated PEEK films were studied by X-ray photoelectron and the rate of photoproducts formation was measured by infra-red and UV–visible spectroscopies. The ZnO coatings were found to protect more efficiently PEEK than TiO 2 coatings. The photoprotective efficiency was shown to depend on the thickness and structural properties of the ceramic coating. The sputtering parameters (total pressure, plasma composition, r.f. power) were optimised in order to limit the photodegradation of the polymer.

Corrosion behavior of 304 stainless steel in high temperature, hydrogenated water

The corrosion behavior of an austenitic stainless steel (UNS S30400) has been characterized in a 10,000 h test conducted in hydrogenated, ammoniated water at 260 °C. The corrosion kinetics were observed to be parabolic, the parabolic rate constant being determined by chemical descaling to be 1.16 mg dm −2 h −1/2. X-ray photoelectron spectroscopy, in combination with argon ion milling and target factor analysis, was applied to provide an independent estimate of the rate constant that agreed with the gravimetric result. Based on the distribution of the three oxidized alloying constituents (Fe, Cr, Ni) with respect to depth and elemental state, it was found that: (a) corrosion occurs in a non-selective manner, and (b) the corrosion film consists of two spinel oxide layers––a ferrite-based outer layer (Ni 0.2Fe 0.8)(Fe 0.95Cr 0.05) 2O 4 on top of a chromite-based inner layer (Ni 0.2Fe 0.8)(Cr 0.7Fe 0.3) 2O 4. These compositions agree closely with the solvi phases created by immiscibility in the Fe 3O 4–FeCr 2O 4 binary, implying that immiscibility plays an important role in the phase separation process.

The Effects of Nitrogen on Electrical and Structural Properties in TaSixNy/SiO2/p-Si MOS Capacitors

AbstractIn this work, we report the effects of nitrogen on electrical and structural properties in TaSixNy /SiO2/p-Si MOS capacitors. TaSixNy films with various compositions were deposited by reactive sputtering of TaSi2 or by co-sputtering of Ta and Si targets in argon and nitrogen ambient. TaSixNy films were characterized by Rutherford backscattering spectroscopy and Auger electron spectroscopy. It was found that the workfunction of TaSixNy (Si>Ta) with varying N contents ranges from 4.2 to 4.3 eV. Cross-sectional transmission electron microscopy shows no indication of interfacial reaction or crystallization in TaSixNy on SiO2, resulting in no significant increase of leakage current in the capacitor during annealing. It is believed that nitrogen retards reaction rates and improves the chemical-thermal stability of the gate-dielectric interface and oxygen diffusion barrier properties.

Measurements of the critical inclusion size for arcing and macroparticle ejection from aluminum sputtering targets

Arcing during sputtering is a significant cause of defect generation during sputter deposition of thin films. We studied the effect of dielectric inclusion size on the propensity for arcing while sputtering aluminum targets in argon at power densities ranging from 8 to near 60 W/cm2. We found that there is a critical inclusion size required for arcing to occur. The critical size for an Al2O3 inclusion in an aluminum-sputtering target in an argon plasma is 440±160 μm. Inclusions with sizes above this critical value readily induce arcing and macroparticle ejection during sputtering. Inclusions below this critical size do not cause arcing or macroparticle ejection. We also found that the inclusion critical size was not sensitive to the sputtering power density. When the inclusion size exceeds the critical value the plasma boundary over the inclusion is deformed by the charge accumulating on the dielectric inclusion and the plasma positive column diffuses toward the target leading to a bipolar arc. Inclusions below the critical size do not distort the dark space to an extent great enough to permit bipolar arc formation. Our proposed model predicts that the critical inclusion size depends upon the sheath thickness, which ranged between 300 and 600 μm for the experimental conditions used in this study.

Magnetron with gas injection through hollow cathodes machined in sputtered target

This article reports on a magnetron equipped with a target with holes. The holes machined in sputtered target can sustain hollow cathode discharges and/or inject the sputtering gas directly inside the magnetron discharge. This magnetron operates on the same principle as a gas-jet. It is shown that the size and number of holes can efficiently control I– V characteristics of the magnetron. The holes of large (≥2 mm) diameter can sustain hollow cathode discharges, which intensify the magnetron discharge. On the contrary, the holes of small (≤1 mm) diameter influences the I– V characteristics much less and allow: (i) to introduce the sputtering gas directly inside the discharge; and (ii) to compensate a gas density reduction in front of target when the magnetron is operated at high (≥100 W/cm 2) target power densities. Special attention is devoted to reactive sputtering. There is great difference in the deposition rate a D of films in the case when the sputtering gas is fed to the chamber or to the discharge through the holes. It is shown that for the gas feed to chamber, a D of the nitride films, sputtered from target with four holes of diameter 2 mm, is equal to that of pure metal films sputtered from a full target in argon. On the contrary, for the gas feed to discharge, a D of the oxide films, sputtered from target with four holes of diameter 2 mm, is very low, 40 times smaller compared to a D of metal films sputtered from a full target in argon. The magnetron discharge with an extremely low deposition rate is very suitable for cleaning and activation of surfaces prior to the film deposition.

Synthesis and properties of boron carbon nitride (BN:C) films by pulsed-DC magnetron sputtering

The ion-assisted, high-rate, reactive and pulsed-DC magnetron sputtering technique was used to deposit boron carbon nitride (BN:C) films by sputtering a boron carbide (B 4C) target in argon and nitrogen plasma. Various processing parameters were explored to grow BN:C films with high cubic boron nitride (c-BN) content. FTIR, SEM, TEM, AES, and Raman spectroscopy were used to characterize the phases, composition and surface morphology of the films. Significant influence of substrate bias voltage and temperature on phase composition of the films was found. The deposited BN:C films exhibit h-BN, wurtzite-BN (w-BN), c-BN phases and their mixed phases with the variation in substrate bias and temperature. A multi-stage deposition technique with variable substrate bias was exploited to obtain 90% c-BN film with clear grains and facets.

Degradation and stress evolution in a-C, a-C:H and Ti-C:H films

Presented in this contribution are some observations of the stress evolution and degradations of diamond-like a-C, a-C:H and Ti-C:H (10–20 at.% of Ti) films deposited by magnetron sputtering of the C or Ti target in the Ar or Ar+CH 4 gas mixture. The compressive stresses increased during several days for all the Ti-C:H films regardless of their structure (amorphous or a-C:H with TiC nanocrystalline inclusions) and composition (10–20 at.% of Ti). This phenomenon was not observed for a-C and was slightly displayed for a-C:H films having high hydrogen content. The growth of stress was accompanied by a decrease of optical constants, n and k. Simultaneously, Raman spectra and composition of Ti-C:H films remained unchanged. The degradation in ambient air during several hours or days takes place mostly for the films prepared by reactive sputtering in the Ar+CH 4 gas mixture, while a-C films, sputtered from the C target in argon, demonstrated stable behavior despite their high compressive stress level.

Optical characterization of TiN/SiO2(1000 nm)/Si system by spectroscopic ellipsometry and reflectometry

Titanium nitride (TiN) films are used as diffusion barrier layers in the semiconductor industry. There is a need for accurate data on optical properties, because film thickness are usually monitored by optical methods. There are further needs to characterize TiN/(interlayer dielectrics)/Si system simultaneously. Thus, TiN(35, 60, 90 and 105nm)/SiO2(1000nm)/Si samples were prepared using sputtering from a TiN target in argon and nitrogen atmosphere. Those samples were characterized using simultaneous fits of multiple angle of incidence spectroscopic ellipsometry and normal incidence spectroscopic reflectivity. TiN films partially transmit light that interferes in the thick thermal silicon oxide, which gives more detailed information on the optical properties of TiN. Consequently optical dielectric function of TiN as well as two thickness of TiN and SiO2 were successfully determined simultaneously.