Dual Ion Beam Sputtering Deposition Research Articles

Initial study on the compositional and phase change of BaO/C/Mo under high temperature

In pulsed-controlled grid traveling wave tubes, electrons are emitted from the Mo grid heated by the hot cathode and contaminated by the evaporation material (i.e. BaO or Ba) from the cathode, which may cause the tubes to be unavailable. Some studies show that carbon film coated on a Mo grid can effectively suppress the grid emission. The reasons for it, however, have not been well understood. To study the effect of carbon film on the Mo grid contaminated with BaO or Ba under high temperature, carbon films were prepared on the Mo substrates at room temperature by dual ion beam sputtering deposition system and post-annealing was conducted to know their status under high temperature, and BaO layer was coated on the Mo and carbon-coated Mo substrates by the chemical method in our experiments. The compositional and phase change of BaO/C/Mo is investigated at two different temperatures of 973 and 1223 K. The results show that the BaO/C/Mo system changes into the C/Mo after the exhaustion of BaO in the case of 1223 K owing to the reaction of carbon with BaO, however, the BaO/C/Mo is almost invariable at 973 K. The mechanism that the addition of carbon film can effectively suppress the grid emission under its working conditions is discussed according to the experimental results and the calculation of the reaction free energy.

이중 이온빔 스퍼터링 방식을 사용한 보조 이온빔의 Ar/O2가스 유량에 따른 Ta2O5박막의 제조 및 특성분석

이중 이온빔 스퍼터링 방식을 사용한 보조 이온빔의 Ar/O₂가스 유량에 따른 Ta₂O₅박막의 제조 및 특성분석

Synthesis and properties of BN:C films deposited by a dual-ion beam sputtering method

Boron nitride films with carbon added (BN:C) were deposited on Si (1 0 0) substrates by a dual-ion beam sputtering deposition method. The BN:C films were analyzed by electron spectroscopy for chemical analysis and a Fourier transform infrared spectroscopy. In addition, a nano-indentation method was used to measure the hardness of the films. Internal stress was estimated by the bending-beam method. With an increase in the C content, the content of the cubic phase in BN:C films was reduced, and the structure of films changed from a cubic phase to a hexagonal phase at more than 13.1 at.% content of the carbon, while the compressive stress of 5.8 GPa and the hardness value of 60 GPa were reduced to 2 GPa and 10 GPa, respectively. Furthermore, the friction coefficient of the films was estimated in dry air, and the BN film with a content of 7.7 at.% carbon showed a lower value of 0.14 compared with 0.17 of the pure-cBN film.

The influence of ion mass and energy on the composition of IBAD oxide films

Dual ion-beam sputtering deposition is a very promising technique for fabricating optical coatings thanks to its very good control of the deposition parameters. Unfortunately, the different sputtering yields of the elements composing the films modify the stoichiometry and, consequently, may cause an increase of the absorption in the UV range and an undesirable variation of the refractive index . In this work we investigate the influence of ion-beam assistance on some oxide materials: SiO 2 , ZrO 2 , and HfO 2 . The sputtering yield has been measured by varying the mass (Ar, Xe) and energy (100–1000 eV) of the bombarding ions. The yield measurements were compared with the calculated yields using Sigmund's model. Different screening functions for different characteristic energy ranges were necessary to fit the experimental results.

Growth mechanism of cubic boron nitride thin films by ion beam assist sputter deposition

Cubic boron nitride (c-BN) thin films were successfully grown on Si(100) substrates by dual ion beam sputter deposition and the growth mechanism was studied with angle resolved in situ x-ray photoelectron spectroscopy (XPS) analysis. Boron was sputter deposited by 1 keV argon ions from a boron target and simultaneously bombarded with low energy nitrogen and argon ions mixture. Through Fourier transform infrared absorption spectroscopy (FTIR) and in situ XPS experiment, the optimum conditions for the c-BN growth such as the substrate temperature, the assist ion current density and the ion energy were determined to be 460 °C, 60 μA/cm2 and 350 eV, respectively. Angle resolved in situ XPS analysis showed that the 1.2±0.2 nm surface layer of the c-BN film is always in the hexagonal boron nitride (h-BN) phase, which clearly shows that c-BN phase grows by the transformation from the initially formed h-BN phase by low energy ion bombardment. Cross-sectional high resolution transmission electron microscopy (TEM) images show that the BN thin films on Si has a sequential layered structure which consists of an initial amorphous BN (a-BN) layer (∼4 nm), a transitional h-BN layer (∼5 nm), and a main c-BN layer. The transformation of the h-BN to the c-BN phase and the unusual sequential layered structure were discussed in view of the compressive stress model.

Observation of a hexagonal BN surface layer on the cubic BN film grown by dual ion beam sputter deposition

Cubic-boron nitride (c-BN) thin films were grown by dual ion beam sputter deposition and the growth mechanism was studied using angle resolved in-situ XPS (x-ray photoelectron spectroscopy) analysis. The π bond shake-up satellite of the B 1s peak, which is observed only in a hexagonal boron nitride (h-BN) phase, appeared in the XPS spectrum obtained for the surface layer of the c-BN film. This can be a clear evidence that the c-BN phase grows via the transformation of an initially formed h-BN phase and the transformation is induced by the compressive stress accumulated in the subsurface region during ion bombardment.

Ion-beam and dual-ion-beam sputter deposition of tantalum oxide films

Ion-beam sputter deposition (IBS) and dual-ion-beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. The optical properties, i.e., refractive index and extinction coefficient, of IBS films were determined in the 250- to 1100-nm range by transmission spectrophotometry and at λ=632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n=2.15 at λ=550 nm and the extinction coefficient of order k=2×10 -4 . Films deposited by e-gun deposition had refractive index n=2.06 at λ=550 nm. Films deposited using DIBS, i.e., deposition assisted by low energy Ar and O 2 ions (E a =0 to 300 eV) and low current density (J i =0 to 40 μA/cm 2 ), showed no improvement in the optical properties of the films. Preferential sputtering occurred at E a (Ar)=300 eV and J i =20 μA/cm 2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy, whereas composition of the film and contaminants were determined by Rutherford backscattering spectroscopy (RBS). Tantalum oxide films formed by IBS contained relatively high Ar content (2.5%) originating from the reflected argon neutrals from the sputtering target whereas assisted deposition slightly increased the Ar content. Stress in the IBS-deposited films was measured by the bending technique. IBS-deposited films showed compressive stress with a typical value of s=3.2×10 9 dyn/cm 2 . Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s5.6×10 9 dyn/cm 2 for E a =300 eV and J i =35 μA/cm 2 . All deposited films were amorphous as measured by the x-ray diffraction (XRD) method

Formation of the crystalline β- C3N4 phase by dual ion beam sputtering deposition

Preliminary investigations suggest that a crystalline carbon nitride compound corresponding to the new β- C 3 N 4 phase can be synthesized by a dual ion beam sputtering deposition technique. Two Kaufman ion sources have been used, one for sputtering a graphite target with 1.2 keV Ar + ions and a second one for bombarding the growing film with a 600 eV nitrogen ions beam at a temperature of 400 °C. Rutherford backscattering (RBS) analysis shows that the nitrogen content is very close to the value expected for the β- C 3 N 4 compound. The density of the films measured by X-ray reflectometry is found to be about 3.4 compared with a theoretical value of 3.47. The microstructural state of the films has been investigated by transmission electron microscopy (TEM) and our results indicate that the films are mainly formed of small crystallized grains of 50–100 nm although the presence of a second amorphous phase is also observed. The electron diffraction patterns are in good agreement with those predicted theoretically for the new β- C 3 N 4 phase.

Studies of diamond-like carbon films prepared by ion beam-assisted deposition

Ion beam-assisted deposition offers a novel and unique process to prepare diamond-like carbon (DLC) films at room temperature, with particularly good interface adhesion. This advantage was explored in this study to deposit highly wear-resistant coating on bearing 52100 steel. Both dual ion beam sputtering and ion beam deposition were employed. Various bombarding species and energy were investigated to optimize the process. Raman, X-ray photoelectron and Auger electron spectroscopy were used to characterize the bonding structure of DLC. Extensive experiments were carried out to examine the tribological behaviour of the DLC/52100 system. A metal intermediate layer can help tremendously in wear resistance. The results are optimistic and may lead to useful applications.

The effects of ion bombarding energy on the structure and properties of TiN films synthesized by dual ion beam sputtering

TiN films have been synthesized by dual ion beam sputtering (DIBS) deposition at the temperature below 100 °C. Ion bombardment influenced the metallographic morphology and crystalline orientation of TiN films. TiN film formed under N+ bombardment at low energy (<1 keV) consisted of fine crystal particles without texture. The film bombarded at 300 eV exhibited a hardness of 2750 kgf/mm2, which was an extremely high value for TiN films currently obtained by ion beam assisted deposition. The tribological tests demonstrated that TiN film synthesized by DIBS possessed good wear resistance.

Structural Characters and Tribological Properties of Diamondlike Carbon Films

ABSTRACTDiamond-like carbon films have been prepared by using dual ion beam sputtering deposition under CH++Ne+ bombardment with energies 50–800 eV. The obtained films possess a smooth surface and an amorphous structure containing some sp3 bondings. DLC films bombarded by low energy CH++Ne+ exhibit the relatively high binding energy and electrical resistivity which are approximate to those of diamond. It is believed that a Mo interlayer between AISI 52100 steel substrates and DLC films brings the films good adhesion. This offers promises to DLC films on bearing steel to perform a stable wearing in much lower friction coefficient (<0.1) under large wear loads (30–90N). Experimentally, low wear coefficients and high anti wear numbers obtained prove that the DLC films indeed possess excellent wear resistance. In addition, the speed or the momentum of friction motion was revealed to exert some serious effects upon the wear resistance of DLC films when the wearing was carried out under very high wear load (> 30 N).

Effects of Nitrogen on Formation and Properties of Diamondlike Films Synthesized by Dual Ion Beam Deposition

ABSTRACTDiamondlike carbon-nitrogen films on silicon (111) wafer and tungsten carbide plates have been prepared by using dual ion beam sputtering deposition and simultaneous bombardment by N+ with energies of 100-800 eV at room temperature. These films retain their diamondlike characteristics. However, as the nitrogen content increases from 10% at to 20% at., the Auger electron spectroscopy spectra of films change obviously in fine structure and the main Cls peak of carbon atoms in the X-ray photoelectron spectroscopy spectra shifts to 285.65 eV. The maximum hardness of these films on tungsten carbide plates is about 5260 kg/mm2. The films have an amorphous structure and smooth surface. The state of nitrogen in films and its influence on the structure and properties of films are discussed.

The irradiation effect of MeV protons on diamond-like carbon films

Diamond-like carbon films, prepared by dual-ion beam sputtering deposition on glass substrate, were irradiated by 1.5 MeV protons under doses ranging from 1 × 1013 to 1 × 1017 ions/cm2. The electrical resistivity, the infrared transmittance and the Raman spectrum were used to characterize the films. It was shown that the irradiation reduced both the film resistivity and the infrared optical transmittancy of specimens obviously and there existed a critical ion dose (1 × 1015 ions/cm2) for the onset of the reductions. The aging effect of the irradiated films in air was also studied at room temperature and it was found that higher increases in resistivity appeared for films irradiated by higher doses. It was concluded that the breaking of CC bonds, CH bonds and the release of hydrogen atoms are responsible for both the decreases in resistivity and in optical transmittancy. The critical ion dose is a threshold for the release of hydrogen. The aging effect of resistivity was caused by the passivation of dangling bonds in air.

Ion beam sputter deposited Permalloy thin films

Ni/sub 80/Fe/sub 20/ thin films were deposited using a wide range of process parameters in a dual source ion beam sputter deposition system. The films were characterized structurally, chemically, and magnetically. Two modes of deposition were investigated; the first permitted concurrent second source bombardment during film deposition but was limited in net deposition rate to about 300 AA/m; the second provided deposition rates in excess of 1000 AA/m, but did not allow for concurrent ion bombardment from the second ion source. Depending on specific conditions film stress varied from slightly tensile to highly compressive in both deposition modes. This, combined with small variations in magnetostriction, resulted in films with vertical anisotropy and stripe domain patterns as well as conditions where well-formed closure domain patterns were observed in yoke shaped structures. For monolithic films, easy axis coercivities >

Magnetic characterization of ion-beam sputter deposited permalloy thin films

Ni 80Fe 20 thin films were deposited using a wide range of process parameters in a dual source ion-beam sputter deposition system. The films were characterized magnetically, structurally and chemically. Depending on specific deposition conditions, film stress varied from slightly tensile to highly compressive in both deposition modes. This combined with small variations in magnetostriction resulted in films with vertical anisotropy and stripe domain patterns as well as conditions where well formed closure domain patterns were observed in yoke-shaped structures. For the monolithic films, easy-axis coercivities of < 0.7 Oe, anisotropy fields of ≅ 4 Oe and hard-axis coercivities of < 0.5 Oe were obtained.

Development of an automated dual ion beam assisted process for superconducting oxide film deposition

An automated dual ion beam sputter deposition system has been developed, in which individual targets of Y, Cu, and BaF 2 are sequentially sputtered to produce Y-Ba-Cu-O films with controlled composition. The dwell time of the ion beam on each target is determined by a computer controlled feedback loop using the signal of a quartz crystal resonator. Each individual target is exposed to the ion beam at the same spatial location, which optimizes compositional and thickness homogeneity across the substrate surface. As deposited superconducting Y-Ba-Cu-O films have been successfully grown at temperatures in the range 700–720°C using either an oxygen ion beam or an ozone jet directed at the substrate. Oxygenation effects by the two sources on film stoichiometry and microstructure are discussed.

Investigation on the DLC films prepared by dual-ion beam sputtering deposition

Investigation on the DLC films preparedby Dual-Ion beam sputtering depositionWang Tianmin Wang Weijie Liu GuidngDepartment of Materials Science, Lanzhou University,Lanzhou, Gansu, 730001, ChinaHuang Liangpu Luo Chuntai Liu DingquanXu Ming Yang YiminPhysics Research Institute of Lanzhou,Lanzhou, Gansu, ChinaABSTRACTThe diamond-like carbon films were successfully deposited onto Si,glass, No and stainless steel substrate at temperature less than 50°C

Modification of ZnO crystal orientation in dual ion beam sputtering deposition

The effect of ion irradiation on ZnO thin film's crystal orientation during dual ion beam sputtering deposition is studied. Glass and Si substrates are irradiated during depostion by oxygen and argon ions. The irradiating oxygen ions are swept away from the substrate by a cross-electric field to examine the effect of high energy neutral atoms on crystal orientation. Argon and oxygen positive ions prepared in a saddle field ion gun can effectively form c-axis orientation in ZnO film deposition. But oxygen high energy neutral atoms tend to deform the c-axis orientation of the films. ZnO film prepared by this method is useful in the production of devices with good piezoelectric and pyroelectric properties.

New fabrication technique and electronic tunneling studies of NbN

We have fabricated NbN films using a new dual ion-beam sputter deposition technique. In this technique, one ion beam sputters Nb from a target, while the second ion beam directly bombards the growing film. The T c of these NbN films is typically 11–12 K when deposited on near-room temperature substrates. Preliminary results on tunneling through a native oxide barrier yield a superconducting energy gap for NbN of 1.9 meV, for which 2 Δ/ kT c = 3.9. We have also studied oxidized overlayers of Al and Ta to produce an artificial oxide tunneling barrier. Conductance data indicate that the native oxide barrier is broad with a low barrier height (0.2–0.3 eV), whereas the oxidized Al overlayer has a higher (0.5–1.2 eV) and narrower barrier. The quality of the I–V curves for native oxide and for artificial oxide barriers is comparable.