We have studied the silicide formation in Fe-implanted Si(100), with 1×1017-1×1018 Fe/cm2, using extended x-ray-absorption fine structure (EXAFS), x-ray diffraction and Rutherford backscattering spectrometry (RBS) methods. In the samples as-implanted at 350 °C, no silicide was observed at doses below 3×1017 Fe/cm2. At 5×1017 Fe/cm2, both α-FeSi2 and (β-FeSi2 form but α-FeSi2 appears to be the majority phase. As the dose increases to 7×1017 and above, ordered FeSi forms, but implantation damage is severe and a large number of Fe atoms are in very disordered environments. In addition to FeSi, Fe5Si3 was also observed in the 1×1018 Fe/cm2 sample. Upon post-implantation annealing at 700 °C or 900 °C, single phase P-FeSi2 was obtained independent of the dosage.

Buried FeSi2 layers have been fabricated by 200 keV Fe+ implantations into (111) and (100) Si substrates. By varying the dose from 0.4 to 7.1017 Fe+ cm−2 the dependence of the Fe concentration on ion dose was investigated systematically. The samples were characterized by Rutherford backscattering spectrometry, He+ ion channeling and secondary ion mass spectroscopy. In the as-implanted state the Fe peak concentration increases lineary with dose up to ≈2.4.1017 Fe+ cm−2. Above this dose a redistribution of Fe atoms was observed as indicated by comparison of measured depth profiles with Monte-Carlo simulations of high dose implantations. The Fe peak concentration shows an unusual dose dependence after rapid thermal annealing (RTA) at 1150°C for 10 s. A minimum dose of (2.4±0.1)1017 Fe+ cm−2 for (111) Si and a slightly higher dose of (2.7±0.1).1017 Fe+ cm−2 for (100) Si is necessary to form continuous metallic αFeSi2 layers.

Iridium has been implanted at 1MeV and 500keV in the dose range 1 to 3×1017/cm2 at 525°C to form a buried Ir-rich region ∼ 2500Å below the surface in (111)Si. Samples were annealed at temperatures in the range 600°C to 1200°C to form buried IrSi3 layers. Rutherford backscattering and channeling analysis in conjunction with transmission electron microscopy were used to study the formation and the alignment of the IrSi3 layer to the silicon host as a function of annealing. For a dose of 2×1017 Ir/cm2, stoichiometric IrSi3 formed beneath ∼ 2000Å of Si after annealing to 1100°C. The IrSi3 layer was aligned with the Si substrate with Xmin ∼12%, but a band of precipitates remained either side of the main layer.

We have investigated the dependence of electrical and material properties of buried CoSi2 layers on Co+ implantation and annealing conditions. The results indicated that the electrical resistivity and crystalline quality of the implanted buried CoSi2 layers depend strongly on the implantation temperature. CoSi2 layers with the lowest resistivity and best crystalline quality (Xmin as low as 3.6%) were obtained from samples implanted at 300°C-400°C. Implantation at higher temperatures (e.g., 580°C) produced cobalt disilicide layers with significantly higher electrical resistivity and a Xmin of about 10.7%.

We have synthesized single crystal Si1−xGex alloy layers in Si <100> crystals by high dose Ge ion implantation and solid phase epitaxy. The implantation was performed using the metal vapor vacuum arc (Mevva) ion source. Ge ions at mean energies of 70 and 100 keV and with doses ranging from 1×1016 to to 7×1016 ions/cm2 were implanted into Si <100> crystals at room temperature, resulting in the formation of Si1−xGex alloy layers with peak Ge concentrations of 4 to 13 atomic %. Epitaxial regrowth of the amorphous layers was initiated by thermal annealing at temperatures higher than 500°C. The solid phase epitaxy process, the crystal quality, microstructures, interface morphology and defect structures were characterized by ion channeling and transmission electron microscopy. Compositionally graded single crystal Si1−xGex layers with full width at half maximum ∼100nm were formed under a ∼30nm Si layer after annealing at 600°C for 15 min. A high density of defects was found in the layers as well as in the substrate Si just below the original amorphous/crystalline interface. The concentration of these defects was significantly reduced after annealing at 900°C. The kinetics of the regrowth process, the crystalline quality of the alloy layers, the annealing characteristics of the defects, and the strains due to the lattice mismatch between the alloy and the substrate are discussed.

The implantation of high doses of Co in Si1−xGex alloys is investigated for several Ge concentrations. The aim of this work is to monitor phase formation, layer formation and crystalline structure of the layers. The samples are evaluated by RBS, SIMS, TEM and sheet resistance measurements. Similar as for the implantation of high doses of Co in Si, buried layer formation of CoSi2 in the Si1−x Gex alloy is observed with a concommitant expulsion of Ge out of the silicide layer.

Experimental analysis and simulation of the formation and electrical characterization of TiSi2/+/p-Si shallow junctions are presented here. The formation of shallow n+-p junction, by ion implantation of As through Ti films evaporated on p-Si substrates followed by Rapid Thermal Annealing (RTA) and conventional furnace annealing has been performed in these experiments. Structural techniques such as Secondary Ion Mass Spec-troscopy (SIMS) and Rutherford Backscattering (RBS) experiments have been employed to characterize these devices. RUMP simulations were used to analyze and interpret the RBS data. Current-voltage characteristics have been simulated using PISCES simulator.

The interaction during low temperature thermal annealing of metal atoms from a Ni film evaporated on top of Si structures with a buried amorphous layer formed by ion implantation has been investigated. Rutherford Backscattering Spectrometry (RBS)/channeling, cross-sectional transmission electron microscopy (XTEM) and X-ray microanalysis were used to determine structures and compositions. It is shown that the combination of such silicon properties as the increased rate of silicidation reaction for amorphous silicon with respect to the crystalline one in combination with high metal atom diffusivity leads to formation of buried epitaxial Ni silicide islands at the interface between the amorphous and the top crystalline silicon layers. During thermal annealing at temperatures as low as 350° C, these islands move through the a-Si layer leaving behind epitaxially recrystallized Si.

The temperature dependence of 300 eV argon ion sputtering of CoSi2 thin films in the range 50–600°C has been investigated. At temperatures above 400°C, the etch rate of CoSi2 on Si is significantly reduced, while the underlying Si reacts with the Co atoms diffusing from the silicide surface. As a result, the silicide layer effectively moves into the substrate during Ar bombardment. During sputtering of CoSi2 on Sio2, the thickness of the silicide layer decreases almost linearly with bombarding time until all the silicide is removed. Similar behavior is observed in low temperature sputtering of CoSi2 on (100) Si and evaporated Si. However, at elevated temperatures (400°C< <600°C), sputtering of CoSi2 on Si undergoes two consecutive stages. During the initial stage, the thickness of the silicide layer decreases at the same rate as that of the silicide on SiO2, and is accompanied by an enrichment in Co concentration near the surface. During the second stage, the etch rate of the silicide is reduced to only one third of the rate during the initial stage.

We have studied the formation of platinum silicide layers by ion implantation and annealing, and have determined the dependence of platinum silicide phase formation on ion implantation conditions and substrate orientation. The results indicate that in most cases, the ion implanted layer consists of PtSi phase. However, depending on the implantation and annealing conditions and substrate orientation, other phases, including Pt2Si, Pt3Si, and Pt12Si5, as well as Si and Pt microcrystals, also form.

Effects of ion beam irradiation of five members of the (Mg, Fe)2SiO4 olivine series, from synthetic pure fayalite (Fe2SiO4) to naturally occurring (Mg0.88Fe0.12)2SiO4, have been studied by in situ transmission electron microscopy (TEM). Under 1.5 MeV Kr+ ion room temperature irradiations, all of the samples have been amorphized. The critical amorphization dose or the total collision energy loss required for amorphization increased rapidly with the increasing Mg:Fe ratio which coincides with an increasing melting temperature (bond strength) and an increasing average bond ionicity. A 400 keV He+ ion irradiation of (Mg0.88Fe0.12)2-SiO4, which mainly results in ionization energy loss in the sample, did not cause amorphization even at a much higher dose rate and a much higher final dose. This indicates nuclear interactions (collisions) are primarily responsible for ion beam induced amorphization. Also, high resolution electron microscopy (HREM) images of the defect structure at a low ion dose have been obtained and compared with the displacement cascade structure generated by computer modelling.

ABSTRACT:L: NiO surfaces have been the subject of numerous investigations using a wide variety of techniques, including transmission electron microscopy (TEM). The findings, however, remain inconclusive regarding the relative contributions of irradiation effects such as ballistic erosion, electron-stimulated desorption (ESD) and electron-stimulated reaction (ESR), especially at incident electron energies exceeding 100 keV. In earlier studies it was suggested that the surface environment played a significant role in the radiation damage process. In this study, the effect of the surface environment is further illustrated by in-situ experiments in controlled sample environments. NiO surfaces were irradiated with electrons, ranging in energy from 3 keV to 300 keV, and examined in-situ under ultra-high vacuum (UHV) conditions (10−10 Torr), as well as in controlled oxidizing (oxygen) and reducing (CO) atmospheres. The nature of the surface reactions and their contribution to the overall radiation damage process in the various energy regimes is examined.

During ion bombardment, polymethylmethacrylate (PMMA) shows degassing of polymer components with a fluence and energy dependent contraction of the material, which leads to a material modification.

The ion beam induced chemical modification of the implanted layers was examined by means of X-ray photoelectron spectroscopy (XPS). The dependence of the chemical modification on beam current, ion fluence and ion energy was investigated for nitrogen implantations at energies ranging from 50 keV to 400 keV for ion fluences between 7×1013 / cm2 and 7×1015/cm2. Compared with the C-spectrum of virgin PMMA, the spectra of the implanted layers exhibited an increase of intensity of the 284.5 eV peak and the 286.4 eV peak. The ion beam induced modification led basically to generation of new C-o-groups. These generations show drastical changes in the dependence of the beam current and the ion fluence. Nevertheless, at a constant dose of 2×1014/cm2 the concentrations of the new groups did not indicate any energy dependence.

Ion beam mixing of thin oxide films, Cr2O3 and ZiO2, on sapphire substrates has been studied. The systems were chosen according to their solubilities in α-Al2O3: Cr2O3 is completely soluble, while ZrO2 is insoluble. Mixing experiments were performed on 50 nm-thick Cr2O3 and ZrO2 films deposited on αAl2O3 by radio frequency (rf) sputter deposition. The specimens were bombarded with Cr+ at an energy of 160 keV to a fluence of 4×1016 ions-cm−2. Implantations were performed at 25 and 860°C. Rutherford backscattering spectroscopy was performed to analyze any interface modifications due to the bombardment. No detectable mixing was observed in either system for irradiations performed at 25°C, but a small amount of ballistic mixing was observed in both systems at 860°C.

Zirconia-yttria films containing 8.0wt% Y2O3 were prepared on a Si substrate with r.f. magnetron sputtering deposition followed by 170 KeV Ar+ ion irradiation at room temperature. The characterization of these zirconia-yttria films with different ion bombarding doses has been studied by XRD, XPS and AES. It was found that all the films consisted of three portions, the amorphous films deposited with r.f. magnetron-sputtering were partially crystallized and nontransformable tetragonal (T') phase was detected after Ar+ ion bombardment of a dose of 1×1016 ion/cm2, and the oxidized states of Zr3d, Y3d and Ols peaks of XPS were observed under the conditions of argon ion bombardment of different doses.

Analytical electron microscopy (AEM) and Rutherford backscattering spectroscopy-ion channeling (RBS-C) have been used to characterize single crystal α-silicon carbide implanted at room temperature with 160 keV 57Fe ions to fluences of 1, 3, and 6×1016 ions/cm2. Best correlations among AEM, RBS, and TRIM calculations were obtained assuming a density of the amorphized implanted regions equal to that of crystalline SiC. No iron-rich precipitates or clusters were detected by AEM. Inspection of the electron energy loss fine structure for iron in the implanted specimens suggests that the iron is not metallically-bonded, supporting conclusions from earlier conversion electron Mössbauer spectroscopy (CEMS) studies. In-situ annealing surprisingly resulted in crystallization at 600°C with some redistribution of the implanted iron.

Amorphisation of sintered SiC by bombardment with self (C, Si) ions has been studied. Ion doses ranged from 1×1015 to 1×1017 ions/cm2; and ion energy was varied from 0.09 to 5 MeV. Amorphisation was detected by micro-focus Raman scattering. Tribomechanical properties-friction and wear were studied with a high precision pin (steel ball) and disc (implanted) machine. Results show substantial improvements in friction and wear, which persist to a large number of cycles. Tribomechanical properties are shown to correlate with surface amorphisation and carburisation. Carbon ions are found to be much more effective than Si ions (with similar damage distributions) in reducing friction and wear.

The effect of ion implantation damage on energy transfer processes in Er-doped silica films prepared by MeV ion implantation is studied, using measurements of the luminescence decay of Er3+(4ƒ11) at 1.535 μm. Silica films implanted with Er and annealed at 900°C show a luminescence lifetime of 14.1 ms. Subsequent irradiation with MeV C, Si, or Ge ions at fluences as low as 1011 ions/cm2 decreases the lifetime, which eventually saturates at 6.6–7.8 ms for fluences larger than 1014 ions/cm2. The fluence required to saturate and the lifetime at saturation depend on the ion used. These results are interpreted in terms of non-radiative energy transfer processes caused by irradiation-induced defects in the silica. The ion damage effects are mainly caused by the electronic component of the energy loss along the ion trajectories.

Optical and infrared reflection spectra for Bi-implanted high-purity silica are reported as a function of dose and 5eV laser irradiation. The extinction coefficient per ion and the reflectance spectra are dose dependent. Subsequent effects of laser irradiation are dependent upon Bi content and total number of laser pulses. Changes reported are attributed to two photothermal processes. One involving diffusion and desorption of Bi ions and annealing of defects, while the second is dominated by annealing.

Formation of Au colloid particles and their optical property have been investigated in silica glasses implanted with Au+ ions at an acceleration energy of 1.5MeV and fluence levels of 1016-1017 ions/cm2. The Au colloid particles are formed in the as-implanted glasses. It is inferred that the average radius of Au colloid particles depends on the fluence level, although the fluence level does not affect the distribution of Au atomic concentration. The heat-treatment little affects the Au atomic distribution. The Au colloid particles grow to 4.3nm in average radius during heat treatment. It is revealed that the large nonlinear optical property of the Au+ -ion-implanted silica glass is attributed to the high concentration of the Au colloid particles in the narrow region.