Energy Nitrogen Ion Research Articles

CNx Films Deposited by Laser Ablation of Graphite Under Low Energy Nitrogen-Ion Beam Bombardment

Deposition of CNx thin films on Si(111) has been performed by laser ablation of graphite under a low-energy nitrogen ion beam bombardment. Films with a maximum N-concentration of 34% are obtained. The N species is found to be relatively constant along the depth of films. X-ray spectroscopy data confirm the existence of covalent C - N bonds. Nanocrystallites structure has been detected in the amorphous matrix of the films. Qualitative hardness tests indicate that the films are relatively hard and adhesive.

Reactive-ion-beam-sputtered WNx films on silicon: Growth mode and electrical properties

WN films were deposited on clean Si(100) substrates via reactive-ion-beam sputtering a W target by a nitrogen ion beam in an UHV system. The energy of the incident ions varied in the range of 0.250 to 3 keV. The growth mode dependence of the films on the nitrogen ion energy was studied by in situ Auger electron spectroscopy measured as a function of coverage. Nitridation of the Si at the first stage of deposition has been found. This nitridation was more pronounced for the lower N beam energies, and minimal for the 2 keV beam. A similar trend was observed for the bulk film composition. In a complementary way, the dependence of electrical properties of the WN/Si junctions on the nitrogen energy has been studied. A higher barrier height on p-type Si than on n-type Si was found, unlike the expectation for regular metallization of W and its compounds on Si. The electrical characteristics can be attributed to the deposition technique. For the low-energy beams, the formation of the interfacial layer was probably dominating, while at higher energies radiation damage and possibly also N implantation played a more important role.

Silicon nitride films prepared by high energy ion beam enhanced deposition

Amorphous silicon nitride films have been synthesized by a simultaneous electron beam evaporation of silicon and high energy nitrogen ion bombardment. Surface sensitive techniques, angular-resolved X-ray induced photoelectron spectroscopy (ARXPS) and Auger electron spectroscopy (AES), have been used for the surface characterization of air-exposed films and concentration depth profiling. Optical and photoelectrical properties have been investigated via infra-red (IR) transmission spectroscopy and photoconductivity measurements. A specific feature of high ion beam kinetic energies and high atomic arrival rate ratios of N/Si is that a part of the silicon nitride is grown inside the silicon substrates. It is suggested that ion beam bombardment enhanced diffusion of nitrogen from deeper regions can contribute to the silicon nitride growth.

Composition and Phase Control for Molybdenum Nitride thin Films

AbstractMolybdenum nitrides are active and selective hydrodenitrogenation (HDN) catalysts. The catalytic properties of molybdenum nitrides were found to be dependent on the structural properties. The purpose of research described in this paper was to synthesize molybdenum nitride thin films with well defined structures and stoichiometries using ion beam assisted deposition. The films were deposited by evaporating Mo metal, and simultaneously bombarding the growing film with low energy nitrogen ions. The phase constituents of the films were determined using x-ray diffraction and the film composition was obtained by Rutherford backscattering spectrometry.The film composition and phase constituents were strong functions of the ion-to-atom arrival rate ratio, ion energy and ion angle of incidence. Differences in the film composition for different arrival rate ratios and ion angles of incidence were interpreted based on reflection and sputtering effects. Our results suggest that phase formation was governed by the effective energy density per deposited atom. Evaluation of the effective energy density per deposited atom and its physical significance in ion beam assisted deposition is discussed.

低エネルギーイオンビーム照射によるＡｌＮ膜の低温形成

Aluminum nitride (AIN) is expected of useful electronic material because of properties of high temperature stability, chemical stability, high thermal conductivity, high sound velocity and so on. For purposes of fabrication and control of film crystallinity and orientation at low temperature, AIN film was prepared by dual ion beam deposition method. It was found that the bombardment of nitrogen ions was very important for reaction between aluminum and nitrogen, inc.1 that a good oriented AIN film could be formed at room temperature by the precision control of the bombardment of low nitrogen ion energy (100 eV). For stoichiometric AIN, the c-axis orientation depends on the nitrogen ion beam current density and becomes better with the increase of nitrogen ion beam current density. The c-axis orientation of AIN film by this method was independent of the kind of substrates and temperature.

Friction and wear of high speed steel doped with low energy nitrogen ions

The influence of low energy nitrogen implantation on the structure and mechanical properties of high speed steel was investigated. Ion implantation at low temperature led to the generation of metastable solid solutions only, but if the temperature was high enough Fe 2−2N and Fe 4N phases were also observed. Wear resistance of the steel increased by a factor of three compared with the virgin surface and residual compressive stresses in the surface layer were considered the main reason for the improvement in wear resistance.

Investigation of ZrN thin film prepared by dynamic mixing

ZrN films on steel substrates were fabricated by dynamic ion beam mixing (ion-beam-assisted deposition). Zirconium was deposited onto the substrate when the zirconium target was sputtered by a low energy argon ion beam. Meanwhile, the film was bombarded by a high energy nitrogen ion beam. The hardness, adhesion and crystal structure of the resulting film and the distribution, chemical state of the elements in the film were examined by X-ray diffraction. Auger electron spectroscopy and X-ray photoelectron spectroscopy. The experimental results showed that the film mainly consists of ZrN crystal as well as a small amount of ZrC, ZrC, ZrO 2, and carbon in the free state. The existence of a transitional area between the film and the substrate results in better adhesion of the film than is found for conventional coatings.

Surface modification of fluorozirconate glass by low energy nitrogen ion implantation

Fluorozirconate glass with the composition of 53ZrF4 20BaF2 4LaF3 3AlF3 20NaF (ZBLAN) was implanted with 5, 10 and 15 keV nitrogen ions to the doses of 2 × 1017 and 5 × 1017 ions/cm2. Optical transmission and electrical resistivity of implanted glasses are strongly dependent on implantation energies. The implanted glass surface showed good resistance to water corrosion. Characterizations by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that the surface compositional modifications were fluorine depletion, metallic Zr precipitation and nitride layer formation beneath the outermost glass surface. The nitride layers are responsible for excellent water resistance of the implanted glass surface.

Effects of Nitrogen Ion Energy on the Growth Mode of WN Films Deposited by Reactive Ion Beam Sputtering

ABSTRACTWN films were deposited on clean Si substrates by Reactive Ion Beam Sputtering in a UHV system. The growth mode of the films as a function of the nitrogen ion energy was investigated by in situ Auger Electron Spectrometry. The energy of the incident ions was varied from 250 eV to 3 keV. We observed a significant nitridation of the silicon at the very beginning of the deposition. This nitridation is more pronounced for the lower energy and is more reduced for 2 keV-ions. It seems to follow the trend of the film composition: 250 eV-ions and 2 keV-ions result in N-rich films (N/W≈1) and W-rich films (N/W≈0.5), respectively. All these results are discussed in terms of sputtering yield, backscattering and sticking coefficient and are explained by taking into account: first, the interaction between the incident ions and the target, and second, the interaction between the species emitted by the target and the growing film.

Nitrogen implantation for molecular beam deposited CuInSe2 thin films

We have implanted N+ ions at an accelerating voltage of 10 kV and a dose of 5×1017 ions cm−2 in molecular beam deposited stoichiometric CuInSe2 thin films at various substrate temperatures (380, 515, 600, and 720 K). The conduction type of the films changed from n to p type when the substrate temperature was below 515 K during implantation. The conduction type was n type when the film temperature during implantation was above 600 K. The resistivity measured at 300 K was 1.07×104, 0.417, 0.653, 160, and 121 Ω cm for the films before implantation, implanted at 380, 515, 600, and 720 K, respectively. Both the conduction type and the resistivity of the films could be changed by N+ doping. Fabrication of homojunction diodes may be achieved in n-type CuInSe2 films by using the low energy nitrogen ion implantation.

Characterization of TiN coatings prepared by ion-beam-enhanced deposition

Hard coatings of TiN were synthesized on M2 steel by ion-beam-enhanced deposition with various doses of nitrogen ions of energy 80 keV and beam current density 37 μA cm −2. The microhardnesses and wear resistances of the coatings for various ion doses are discussed. The chemical characteristics of the coatings were studied by Auger electron spectroscopy (AES) and AES profiling. In addition, the relation between the microchemical characteristics and the macrophysical properties is also studied in this paper.

Boron nitride film formation by means of dynamic mixing method

Boron nitride coating films are prepared by the dynamic mixing (IVD) method which has been developed by the present author and coworkers. In this method, boron is evaporated on a substrate and nitrogen ions of 200 eV–40 keV are simultaneously bombarded. Their properties are studied by a Transmission Electron muscope (TEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XD) and ir absorption spectroscopy. In most cases, the films consist of mixed phases of cubic (c-), wurtzite (w-), hexagonal (h-) boron nitride and amorphous phase. However, as the energy of nitrogen ions decreases, the ratio of c-BN in films increases. Films prepared by ions with lower energy than 5 keV show clearly a line due to c-BN in ir spectra. Moreover, XD patterns of films prepared at certain deposition rate by using 500 eV and 1 eV nitrogen ions show only a peak due to c-BN. Vickers hardness of films with about 1 μm thickness made at 3 and 10 kV is about a half to a third of that of c-BN.

Characterization of ion beam deposited refractory WNx films on GaAs

An ion beam assisted deposition (IBAD) technique has been explored for the growth of refractory W and WNx films on n-GaAs as candidate gate materials for GaAs integrated circuits. Tungsten was deposited by Ar-ion beam sputtering, and simultaneously low energy nitrogen ions were introduced directly onto the GaAs substrate, using a Kaufman-type ion gun, for nitridation of the W deposits. The deposited films were characterized by electrical resistivity measurements, x-ray diffraction, and x-ray photoelectron spectroscopy analyses. The results showed that the composition and the electrical resistivity could be controlled with the nitrogen-ion dose. Thermal stability of the WNx /GaAs interfaces was also investigated by examining Schottky diode characteristics and microstructures. The WNx contacts investigated in the composition range from x=0 to 0.47 were electrically stable up to 850 °C and showed remarkable enhancements in the Schottky barrier height through high temperature annealing. Such annealing induced barrier enhancements were attributed to the dissociation of a thin native oxide layer which was observed between the as-grown film and the GaAs substrate. Comparisons of our results with previous works on conventional sputter-deposited WNx films led to a conclusion that the IBAD technique generates much less ion damage in the substrate and the film, and therefore, is promising for growing refractory compounds on GaAs.

The structure and properties of ion-beam-synthesized boron nitride films

Films containing boron and nitrogen were prepared by electron-beam evaporation of boron and bombardment of the growing film with nitrogen ions of energy up to 1500 eV. Hard films of high transparency (extinction coefficient <0.01) were prepared with nitrogen-to-boron atomic arrival ratios greater than one. The optical constants in the visible part of the spectrum were determined as a function of B-to-N atomic ratio in the film and substrate temperature using optical photometry. Measurements of the optical constants were extended to 40 eV using a Kramers–Kronig analysis of electron-energy-loss spectra. Boron-to-nitrogen atomic arrival rates were determined and show that as ion energy and substrate temperature are increased ion flux must be increased to achieve the same stoichiometry. Film structure was imaged using high-resolution electron microscopy, and the radial distribution function (RDF) was determined. The RDF of stoichiometric films showed that high substrate temperatures increased the size of the ordered regions. The RDF and high-resolution imaging of all films were consistent with the presence of the hexagonal form of BN with substoichiometric films containing amorphous boron as the other constituent. This conclusion is consistent with the analysis derived from the sum rule obtained from the optical constants. No evidence could be found for the cubic form of BN.

The influence of the physicochemical characteristics of the substrate surface on the deposited TiN film properties

In this paper the properties of TiN films deposited by reactive r.f. sputtering on differently prepared high speed steel substrates have been investigated. The substrates surface could be bombarded before deposition with low energy argon and nitrogen ions at a fluence of around 4 mA cm -2. The aim was to investigate the influence of substrate preparation and the growth temperature on the structure of deposited TiN films, the microhardness and the adhesion. It was found that bombardment with Ar + increases the surface roughness and develops the structure, which influence the layer growth. Bombardment with nitrogen increases both the total surface hardness of the material and the adhesion of TiN layers to the substrate. The total increase in H μ, compared with the base material, is from 240% to 390% and the adhesion of layers increases from 4.5 to 21.5 MN m -2.

On the formation of BN films by ion beam and vapor deposition

Boron nitride films were prepared by using a low energy nitrogen ion beam and simultaneous vapor deposition of boron at room temperature. Films were analyzed by X-ray diffraction. Diffraction patterns show sharp peaks due to crystalline of the cubic boron nitride phase for every film formed with ion energies of 200–1000 eV. It is concluded that an ion beam in the low energy region is effective for forming the metastable cubic phase, c-BN.

XPS STUDY OF SURFACE NITROGEN ON PET ACTED BY LOW TEMPERATURE PLASMA AND LOW ENERGY IONS

ESCA analysis identifies that the different functional groups of nitrogen compounds have been conbined on the PET surfaces, when modified by the air plasma and the argon plasma. In particular, the double N15 peaks occur on the PET surface after 5 minutes treatment by the low temperature argon plasma. The second peak-N15 is considered as the contribution of nitrogen oxides. The double peaks PET-N15 structure does not result by bombardment with low energy nitrogen ions and argon ions, which indicates that the effect can not be attributed to the action of low energy ion alone.

Characterization of TiN Films Prepared by ion Beam Assisted Deposition

AbstractOne of the advantages of the ion beam assisted deposition process is its controllability of the processing parameters such as: ion-to-atom arrival ratio and the ion energy. In this study, the effects of the nitrogen ion energy (from 1 KV to 30KV) on the TiN film morphology and microstructures were systematically investigated as a function of ion-to-atom arrival ratios, using TEM, XTEM, SEM, ESCA and other analytical techniques.

Characterization of TiN Films Prepared by Ion Beam Assisted Deposition

ABSTRACTOne of the advantages of the ion beam assisted deposition process is its controllability of the processing parameters such as: ion-to-atom arrival ratio and the ion energy. In this study, the effects of the nitrogen ion energy (from 1 KV to 30KV) on the TiN film morphology and microstructures were systematically investigated as a function of ion-to-atom arrival ratios, using TEM, XTEM, SEM, ESCA and other analytical techniques.

Intrinsic stress in A1N prepared by dual-ion-beam sputtering

The intrinsic stress of AIN, prepared by dual-ion-beam sputtering, has been investigated as a function of deposition temperature and nitrogen ion energy. The results show that the stress is compressive over the temperature range 75–700°C with a maximum value of -28×10 9 dyn cm -2 at 75°C. The stress decreases gradually with increasing deposition temperature up to T d/ T m = 0.33 and then decreases sharply for higher temperatures. These results are similar to those reported for evaporated and r.f. sputtered metal films and appears to be a general result independent of the sign of the stress. The temperature dependence is interpreted in terms of the annealing of a strained layer and grain growth models. The results show that the compressive stress is due to the bombardment of the condensing film by energetic particles. Calculations indicate that the most energetic particles are of the order of 160 eV, originating as neutralized back-reflected argon neutrals. The nitrogen ions from the auxiliary gun do not appear to contribute materially to the intrinsic stress. Evaporation of aluminum, while simultaneously bombarding the film with an independent source, indicates that a saturation stress condition is established above a normalized energy of about 50 eV atom −1.