Metal Vapor Vacuum Arc Implantation Research Articles

Growth and Characterization of Erbium Silicides Synthesized by Metal Vapor Vacuum Arc Ion Implantation

AbstractErbium atoms were implanted into p-type Si (111) wafers at an extraction voltage of 60 kV to doses ranging from 5×1016 to 2×1017 cm−2 using a metal vapour vacuum arc (MEVVA) ion source. The implantation was performed with beam current densities from 3 to 26 µA/cm2 corresponding to substrate temperatures ranging from 85 to 245°C. The characterization of the as-implanted and annealed samples was performed using Rutherford backscattering spectrometry, atomic force microscopy and x-ray diffraction. To determine the sputtering yield, masked implantation experiments were performed so that the thickness of the sputtered layer at different substrate temperatures can be obtained directly by an α-step surface profiler. The results showed that ErSi2-xwas directly formed by MEVVA implantation when the substrate temperature was higher than about 160°C. The effects of the implant dose and the beam current density on the retained dose, the sputtering yield and the surface morphology of the implanted samples were also studied.

Characterization and giant magnetoresistance effect in cobalt–silver granular films formed by MEVVA implantation

Cobalt–silver granular thin films exhibiting giant magnetoresistance (GMR) effect were formed by Co implantation into Ag using a metal vapor vacuum arc (MEVVA) ion source. The magnetic field dependence and the temperature variation of the GMR effect and their relation with the processing conditions were studied and discussed in conjunction with results of Rutherford backscattering spectrometry, atomic force microscopy and magnetic force microscopy (MFM). For the best sample obtained in this study, the magnitude of the GMR effect measured at a magnetic field strength of 7.6 kOe increases from about 1% at room temperature to over 7% at 20 K. The coercive field H C in the perpendicular-to-film direction determined from GMR measurements showed an anomalous temperature variation that shows a maximum value at around 240 K and decreases with decreasing temperature from 240 to 20 K. The domain structures of the implanted granular films revealed by MFM images exhibit a very different feature compared with those of sputter deposited Co–Ag granular films.

Percolation network of PdGe phase formed on Ge surface by high-current Pd-ion implantation

High-current Pd-ion implantation technique was employed to synthesize Pd germanide on Ge wafers, using a metal vapour vacuum arc (MEVVA) ion source. The implantation was conducted with an extracted voltage of 34 kV, beam current densities of 17.7 and 53 A and at a fixed dose of ions . It was found that implantation with a current density of 17.7 could directly synthesize the equilibrium PdGe phase on the Ge surface and that the formed germanide loosely dispersed on the surface. Interesting, in the case of implantation with the current density of 53 , the formed PdGe grains organized themselves in a fractal pattern with a dimension close to the percolation threshold of 1.90, and the sheet resistivity was therefore significantly reduced down to 59 . The formation of the PdGe phase as well as the percolation network under MEVVA implantation is also discussed.

Ion beam synthesized cobalt germanide alloy by metal vapor vacuum arc implantation

Germanide formation and evolution in Co-implanted germanium have been studied by θ–2 θ X-ray-diffraction (XRD), atomic force microscopy (AFM) and the Rutherford backscattering spectrometry (RBS). A metal vapor vacuum arc (MEVVA) ion source implanter operated at 60 kV was used to implant Co into Ge(1 0 0) wafers with doses ranging from 6 × 10 14 to 6 × 10 18 cm −2, and mean current density being either 15 or 210 μA cm −2. The sequence of phase formation was obtained by XRD. Dramatic cellular and columnar nanostructures were observed by AFM in the low and high mean current density samples, respectively. Information on the roughness was obtained. The degree of crystallinity and the thickness of the damaged layer were determined by RBS and ion channeling. The phase formation and evolution are discussed with respect to beam heating effect and the heat of formation.

Atomic force microscopy study of microcrystalline SiC fabricated by ion beam synthesis

Ion beam synthesis of silicon carbide (SiC) layers was performed by metal vapor vacuum arc implantation. Subsequent furnace annealing was carried out in nitrogen at various temperatures to form stoichiometric SiC layers. The implanted layers were characterized by various techniques. Rutherford backscattering spectrometry analysis revealed the carbon distribution and formation of the SiC layers. Fourier transform infrared spectroscopy spectra showed absorption peaks produced by the amorphous and β-phase crystalline SiC layers. The crystallinity was increased by high temperature annealing. The dependence of the surface morphology and dynamics of the crystallization on annealing temperature and time was studied by atomic force microscopy (AFM) for the first time. At about 900 °C, nanocrystalline SiC was formed on the sample surface and contained columnar grains with a full width of half maximum of tens of nanometers and a height of 10 nm. A conducting AFM was used to study the electrical properties of the formed SiC layer on the nanometer scale.

Flexural strength change of silicon nitride implanted by high dose titanium ions

Silicon nitride ceramics were modified by Ti-ion implantation in a MEVVA (MEtal Vapor Vacuum Arc) implanter. The influence of implantation parameters was studied by varying the ion dose over a wide range. The samples were implanted with 80 keV Ti ions with doses from 1 × 10 17 to 3 × 10 18 Ti/cm 2 at temperatures between 400 and 750 °C. The implantation dose strongly influences the flexural strength and microhardness of silicon nitride, increasing the flexural strength up to 14% relative to unimplanted silicon nitride.

Formation and Characteristics of CoSi2 Layers Synthesized by Mevva Implantation

AbstractIon beam synthesis of CoSi2 layers in Si by MEVVA (Metal Vapor Vacuum Arc) implantation has been performed under various conditions. The formation and characteristics of these CoSi2 layers have been studied by XTEM, RBS, AFM, X-ray diffraction, ellipsometry, electrical and Hall effect measurements. It was found that a higher substrate temperature during implantation results in an as-implanted Co distribution closer to the surface and hence the formation of a shallower CoSi2 layer after annealing. Buried CoSi2 layers of good crystal quality and low resistivity CoSi2 can be formed by MEVVA implantation and annealing under appropriate conditions. A strong temperature dependence of the Hall coefficient showing a large peak at around 100K was observed for the CoSi2 layers formed in p-type Si substrates but not in n-type substrates. The properties and their dependence on the processing conditions, in particular, the substrate temperature during implantation, are presented and discussed.

Ion Beam Synthesis of SiC/Si Heterostructures by Mevva Implantation

AbstractIon beam synthesis of SiC/Si heterostructures was performed by MEVVA (metal vapor vacuum arc) implantation under various implantation and annealing conditions. The implanted SiC/Si heterostructures were characterized by various techniques. Carbon redistribution in overstoichiometrically implanted samples during annealing to form a stoichiometric SiC layer has been observed for the first time. The FTIR spectra were found to be composed of two components, one attributed to amorphous SiC and the other to β-SiC. It was also found that there are critical dose and critical energy at which the crystalline fraction increases abruptly. Other results on electrical and optical characterization are also presented and discussed

Characterization of buried cobalt silicide layers in Si by MEVVA implantation

Buried cobalt silicide layers have been formed by high-dose Co implantation into Si with a metal vapor vacuum arc (MEVVA) ion source using an accelerating voltage of 70 kV. Annealing was performed by rapid thermal annealing at various temperatures for various time intervals. The structures of the implanted samples were studied by cross-section transmission electron microscopy and high-resolution electron microscopy observations and the electrical properties were studied by resistivity and Hall effect measurements. It is found that in the as-implanted sample a continuous CoSi 2 layer had not been formed but the surface layer contained a high density of CoSi 2 precipitates, either aligned A-type or twinned B-type. After rapid thermal annealing at 750 °C for 10 s and then at 1100 °C or 1200 °C for 5 s, a continuous buried single-crystalline CoSi 2 layer, about 60 nm thick, had been formed beneath a 40 nm Si layer. Both A-type and B-type CoSi 2 precipitates are present in the damaged layer below the buried CoSi 2 layer for the 1100 °C annealed sample. There were no precipitates in the damaged layer beneath the silicide layer for the 1200 °C annealed sample. However, some threading dislocations were observed. The temperature dependence of the resistivity of the CoSi 2 layer has been found to follow the Matthiessen's rule with similar magnitude to that reported by other researchers. However, in contrast to those reported in the literature, a surprisingly strong temperature dependence of the Hall coefficient has been observed with a large peak at about 100–110 K.

Electrical Characteristics of CoSi2 Layers Formed by Mevva Implantation of Co into Si

AbstractHigh dose Co implantation into Si has been performed with a metal vapor vacuum arc (MEVVA) ion source at an extraction voltage of 70 kV to doses from 8×1016 to 6×1017 ions cm−2 at substrate temperatures (Ts) in the range of 210°C to 700°C. Annealing was performed in nitrogen at various temperatures for various time intervals by either furnace annealing (FA) or rapid thermal annealing (RTA). The electrical properties of the CoSi2 layers formed were studied using resistivity and Hall effect measurements from 10 to 300K. We found that for all the samples prepared by MEVVA implantation, as long as a continuous CoSi2 layer was formed after annealing, a strong temperature dependence of the Hall coefficient was observed with a large peak at around 90 to 110K. The magnitude of the peak also varies depending on the substrate parameters and processing conditions. However, the temperature dependence of the resistivity for these CoSi2 layers follows the atthiessen's rule. We also found that it does not require high substrate temperature nor very high temperature annealing in order to form a CoSi2 layers with low resistivity by MEVVA implantation. Such low resistivity CoSi2 layers can be formed with a substrate temperature as low as 210°C after either RTA at high temperature for a few seconds or FA at a relatively low temperature of 750°C for one hour. The dependence of the electrical properties on Ts is also presented and discussed.