Ion Beam Sputter Deposition Method Research Articles

Characterization of photoluminescence of β-FeSi 2 thin film fabricated on Si and SIMOX substrate by IBSD method

Fe is deposited on a single crystal bulk Si (1 0 0) and separated by implanted oxygen (SIMOX) substrate by the use of ion beam sputter deposition (IBSD) method to form β-FeSi 2 film. Photoluminescence (PL) is measured for these films, after the films on Si substrate are thermally annealed at 1153 K for 24 h. The PL intensity at around 0.83 eV dramatically increased. Such feature has not been seen on SIMOX substrate. To understand how the structural and compositional properties of the film and the substrate affect the PL characteristics, cross-sectional transmission electron microscopy (XTEM) has been applied. The results revealed that these films have quite different structures after thermal annealing due to aggregation of the film. In the bulk Si case, β-FeSi 2 has a particle size of about 200 nm, whereas on SIMOX, it has particle sizes of about 20–30 nm on insulator. Moreover, β-FeSi 2/Si interface remains in the former but not in the latter case. It is revealed that these structural properties are important for enhancement of PL intensity.

Composition spread metal thin film fabrication technique based on ion beam sputter deposition

A composition spread metal thin film fabrication technique based on ion beam sputter deposition method was developed. The technique enables us to fabricate any desired part or a complete binary/ternary composition spread metal thin films onto a single substrate by sequentially sputtering different target materials. Composition spread metal thin films can be deposited directly on a dielectric film in patterned electrode shape for C– V and I– V measurements. The system could be especially useful in the search for new multi-component metal gate materials.

Photoluminescence of β-FeSi2 thin film prepared by ion beam sputter deposition method

In this work, photoluminescence (PL) from β-FeSi2 thin film grown by ion beam sputter deposition (IBSD) method is investigated. For the first time, several small PL peaks are observed in the as-grown IBSD films at around 0.77 and 0.83eV below 100K. By thermal annealing at 1153K for more than 24h, these films showed a strong peak at around 0.81eV with increased intensity by more than an order of magnitude at 6K. These annealed samples showed luminescence up to room temperature, while no PL was observed above 100K for the as-grown films.

Material properties and growth control of undoped and Sn-doped In 2O 3 thin films prepared by using ion beam technologies

Undoped (IO) and Sn-doped In 2O 3 (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films ( R rms ≤ 1 nm and R p–v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed.

The role of sputter etching and annealing processes on the formation of β-FeSi 2 thin films

For formation of β-FeSi 2 using ion beam sputter deposition (IBSD) method, sputter etching (SE) followed by thermal annealing is effective substrate treatment to obtain highly (100)-oriented β-FeSi 2 on Si(100). However, the best condition of these treatments are not yet known. In this work, the effect of SE together with annealing process on the orientation of the film is investigated. Prior to the deposition of Fe, the substrate is irradiated by Ne + ions with various energy and fluence followed by thermal annealing at 1073 K for 60 min. The overall results show the most suitable SE condition using Ne + ion on IBSD method is the energy of 1 keV with the fluence of 3.0×10 19 ions /m 2.

The role of sputter etching and annealing processes on the formation of $beta;-FeSi2 thin films

For formation of β-FeSi2 using ion beam sputter deposition (IBSD) method, sputter etching (SE) followed by thermal annealing is effective substrate treatment to obtain highly (100)-oriented β-FeSi2 on Si(100). However, the best condition of these treatments are not yet known. In this work, the effect of SE together with annealing process on the orientation of the film is investigated. Prior to the deposition of Fe, the substrate is irradiated by Ne+ ions with various energy and fluence followed by thermal annealing at 1073 K for 60 min. The overall results show the most suitable SE condition using Ne+ ion on IBSD method is the energy of 1 keV with the fluence of 3.0×1019 ions /m2.

Effect of target compositions on the crystallinity of β-FeSi 2 prepared by ion beam sputter deposition method

Targets with the elemental composition of Fe, Fe 2Si and FeSi 2 were employed in the present study to grow β-FeSi 2 film on Si (100) substrate by means of ion beam sputter deposition (IBSD) method. The results revealed that when FeSi 2 target was employed, a Si-rich phase, α-FeSi 2 (Fe 2Si 5), was predominant at temperatures above 973 K, while β-FeSi 2 phase was observed only in the limited temperature range at around 873 K. In this case, Si was originated both from the sputtered target and the substrate, thus, the supply of Si was considered to be excessive to sustain β structure. On the other hand, the films prepared with Fe target became polycrystalline as they grow thicker than 100 nm. In order to optimize the supply of Fe and Si for epitaxial growth, Fe 2Si target was employed, where highly (100)-oriented β-FeSi 2 layer of 120 nm in thickness was obtained at 973 K.

Nanoscopic observation of structural and compositional changes for β-FeSi 2 thin film formation processes

For β-FeSi 2 formation, interdiffusion and silicidation are key processes in order to achieve better crystallinity, orientation and material properties. Transmission electron microscope (TEM) for the structural analysis and synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) for the diffusion process analysis are reviewed for the nanoscopic observation through the β-FeSi 2 formation. The TEM analysis provides nanostructure of interface region (β-FeSi 2/Si) obtained by ion beam sputter deposition (IBSD) method at 600–800 °C. The substrates were prepared by several methods, such as ordinary chemical etching of Si or ion beam sputtering, etc. Cross-sectional TEM images and electron diffraction patterns were obtained for the interface of silicide and Si substrate. The images showed that “damaged” surface produced by ion sputtering and subsequent thermal annealing provides quite smooth interface and epitaxially grown films compared with the chemically etched Si, which has atomically flat surface. The SR-XPS results provide compositional changes in the nm region non-destructively. Vapor deposited iron on Si substrate was measured after various annealing temperatures. The gradual changes of the composition from the topmost surface to the deeper region were clearly observed from the obtained results.

Effect of substrate temperature and deposited thickness on the formation of iron silicide prepared by ion beam sputter deposition

Ion beam sputter deposition (IBSD) method was employed to find optimum conditions for the formation of epitaxial β-FeSi 2 films on Si(100) substrate. It was found that crystal structure of the films as determined by X-ray diffraction (XRD) analysis is dependent on the substrate temperature as well as on the deposited thickness of sputtered Fe. The film with best crystal properties was obtained either at 873 K with the deposited Fe thickness of 15 nm, or at 973 K with the deposited Fe thickness of 30 nm. The obtained results indicate the importance of Fe and/or Si diffusion in determining the crystal properties of β-FeSi 2 film.

Characterization of air-exposed surface of β-FeSi 2 fabricated by ion beam sputter deposition method

The surface composition and chemical states of β-FeSi 2 on a Si(1 0 0) substrate after exposure to the ambient atmosphere was investigated by using X-ray photoelectron spectroscopy with synchrotron radiation (SR-XPS). The analysis revealed that about 70% of the Si substrate was covered with β-FeSi 2. In addition, it was found that a SiO 2 overlayer with a thickness of about 1 nm covered the whole surface of the sample. These results suggest that Si was segregated during the IBSD process and that the readily formed SiO 2 layer behaved as a protective layer against further oxidation of β-FeSi 2 surface.

Effect of surface treatment of Si substrate on the crystal structure of FeSi 2 thin film formed by ion beam sputter deposition method

Ion beam sputter deposition method under ultra-high vacuum conditions was employed to form β-FeSi 2 thin films on Si(1 0 0) substrate. We investigated the effect of three different kinds of surface treatment of Si on the crystal structure of FeSi 2 film, which was characterized by means of X-ray diffraction analysis and transmission electron microscopy (TEM) observation. The films formed on a substrate treated by thermal etching (TE) consisted of β-FeSi 2 with various crystal orientations. The films formed with sputter etching (SE) and wet etching methods also consisted of β-FeSi 2, but with comparatively strong (1 0 0) preferential orientation. From TEM observations, the films formed with TE method were composed of coalesced β-FeSi 2 islands, whereas those formed with SE method were almost continuous.

Surface chemical states and oxidation resistivity of ‘ecologically friendly’ semiconductor (β-FeSi 2) thin films

Surface chemical states and oxidation resistivity of the ‘ecologically friendly’ semiconductor β-FeSi 2 have been investigated. Previously, we studied β-FeSi 2 thin films prepared by the ion-beam sputter deposition method (IBSD) on an Si(100) substrate. Through these studies, it was observed that the oxidation of the formed FeSi 2 does not proceed so much even in the air atmosphere compared with elemental Si or Fe or other compound semiconductors. In the present study, the obtained films were analyzed by synchrotron–radiation X-ray photoelectron spectroscopy (SR-XPS) in order to obtain chemical states and depth profiles of films non-destructively. From the XPS spectra, the results indicated FeSi 2 films have strong oxidation resistivity. The XPS spectra reveal that oxidation resistivity is caused by a very thin SiO 2 layer covering the formed β-FeSi 2. The results of cross sectional observation by transmission electron microscope and surface morphological analysis by scanning electron microscope are consistent with the SR-XPS results.

β‐ＦｅＳｉ２薄膜の結晶構造におけるＳｉ基板処理効果

β-FeSi2 thin films on Si (100) substrate were prepared by ion beam sputter deposition (IBSD) method under ultra-high vacuum condition. We investigated the effect of surface treatments of Si on the crystal structure of β-FeSi2 film formed by IBSD method. Three kinds of conventional surface treatment methods were employed; namely, thermal etching (TE), sputter etching (SE) and wet etching (WE). After each etching, Fe was sputtered and deposited on heated Si in the temperature range between 873 K and 1073 K. In order to characterize the crystal structure of the formed films, X-ray diffraction (XRD) analysis was performed. From the XRD results, it was concluded that TE method is not appropriate to obtain an epitaxial β-FeSi2 on Si because the surface distortion is induced in Si. Little difference of the crystal structure was observed between SE and WE methods. These results suggest that a moderate disorder of the substrate surface may well enhance the mixing of Fe and Si atoms to form highly (100) -oriented β-FeSi2.

イオンビームスパッタ法を用いたマイクロアクチュエータ用ＴｉＮｉ形状記憶合金薄膜形成

TiNi shape memory alloy has been recently investigated for use in microactuators because of the high power to volume ratio. Conventional sputtering methods, such as RF and DC sputtering and magnetron sputtering, have previously been used by other workers in order to deposit TiNi thin films. As deposited films produced by these methods are amorphous, and are then crystallised typically by annealing at 500 °C for 1 hour in order to exhibit the shape memory effect. These deposition methods have invariably used alloyed targets to grow thin films. In this investigation, an Ion Beam Sputter Deposition (IBSD) method has been used by which argon ions are used to bombard non-alloyed targets. The thin films grown by this technique demonstrate the characteristics of the shape memory effect. Films have been characterised by electrical resistivity and change of resistance against heating and cooling temperature, giving physical properties in excellent agreement with those quoted in the literature. Compositional and density measurements were done by X-ray reflectometry and were consistent with equi-atomic composition and nominal density for TiNi.

Formation of ‘environmentally friendly’ semiconductor (β-FeSi 2) thin films prepared by ion beam sputter deposition (IBSD) method

‘Environmentally friendly’ semiconductor β-FeSi 2 thin films have been prepared by the ion beam sputter deposition (IBSD) method on Si(100) substrate. The difference in crystallinity of the FeSi 2 obtained has been investigated using Fe and Fe–Si targets at various substrate temperatures. When the Fe target was used, highly (100)-oriented β-FeSi 2 films with relatively smooth surfaces were formed at 700°C. On the other hand, such films were scarcely observed when the Fe–Si target was used. Sharp edge grains were observed, which consisted of a mixture of α and β phases or α single phase. In the latter case, α-FeSi 2 is formed at T s above 600°C, which is lower than the conventional transformation temperature for the β→α phase.

Bone apposition along thin Ca-P composite films prepared by the ion-beam assisted sputter deposition method

Bone apposition along thin Ca-P composite films prepared by the ion-beam assisted sputter deposition method

Control of electrical properties of ion beam sputter-deposited PZT-based heterostructure capacitors

Abstract Previous work on pulsed laser ablation-deposition (PLAD) and sol-gel synthesis has shown that the crystallographic orientation of ferroelectric Pb(ZrxTi1−x)O3 (PZT) films and electrical properties of PZT-based capacitors is controlled by the substrate and/or bottom electrode material type. Similar control is obtainable with the ion beam sputter deposition method. Also, a non-ferroelectric phase that is nucleated during processing on RuO2/MgO substrates can be reduced or eliminated by interposing a layer of PbTiO3 (PT) between the electrode and the PZT film. The use of the PT layer and other proprietary modifications made to the RuO2 bottom electrode result in a substantial reduction in the fatigue of these PZT-based capacitors. The fatigue resistance and low dc leakage current of these capacitors qualify their use in non-volatile ferroelectric random access (FRAM) and dynamic random access (DRAM) memory devices.

Giant magnetoresistance in Co/Cu, Co/sub 9/Fe/Cu, and Co/sub 7.5/Fe/sub 2.5//Cu multilayers

The authors report that giant magnetoresistance (MR) at room temperature up to 52% for a low field change of 0.9 kOe can be attained in (Co/sub 9/Fe/Cu)/sub n/, multilayers. A set of (Co/sub x/Fe/sub 1-x//Cu)/sub n/ multilayers (x=1.0, 0.9 and 0.75) was prepared by an ion-beam sputter deposition method on MgO [110] single-crystal substrates. The MR ratio was found to be quite sensitive to the argon acceleration voltage (V/sub B/) in ion-beam sputtering and have a maximum around V/sub B/=600 V. In the preparation condition for obtaining maximum MR ratio, strong antiferromagnetic coupling (J) for the Co/sub x/Fe/sub 1-x/ layers via thin Cu layers and the oscillation behavior for this indirect exchange coupling with a 12-A period were observed. It was found that the MR ratio for Co/sub x/Fe/sub 1-x/ multilayers is larger than that for Co/Cu multilayers in the higher Co-concentration range in the Co/sub x/Fe/sub 1-x/ alloy. It was also found that in-plane uniaxial anisotropy (K/sub u/), on the order of 10 degrees erg/c/sup 3/, was induced when this system was prepared on MgO [110]. Giant MR can be induced for a small external field change for film with magnetocrystalline anisotropy. MR curve behavior can be explained by metamagnetic transition when K/sub u/, J, and Zeeman terms are considered. >

ＣｏｘＦｅ１−ｘ／Ｃｕ）ｎ人工格子膜の巨大磁気抵抗効果

We report that giant magnetoresistance (MR) at room temperature up to 50% for low field of 0.9 kOe can be attained in (CoxFe1-x/Cu)n multilayers. A set of (CoxFe1-x/Cu)n multilayers was prepared by the ion beam sputter deposition method on MgO(110) single crystal substrates. All samples were confirmed to have hexagona1 structure of CoxFe1-x by X-ray diffraction measurements. The hexagonal c-axis is in the film plane, which induces in-plane uniaxial magnetic anisotropy of the order of 106 erg/cc. This anisotropy brings low saturation field in MR curves. We also investigated argon acceleration voltage (VB) dependence of the MR ratio, which is quite large and has a maximum around VB=600 V for [Co(10 A) /Cu (10A)]16 and [Co9Fe(10 A)/Cu(10 A)]16 multilayers. In the preparation condition of obtaining the maximum MR ratio, almost perfect antiferromagnetic coupling of the CoxFe1-x layers via thin Cu layes is realized. We found that the MR ratio of CoxFe1-x/Cu multilayers is larger than that of h/ Cu multilayers in the higher Co-concentration range of the CoxFe1-x alloy.

Two spin-freezing behavior in concentrated amorphous ferrite oxides

Amorphous CoFe2O4 with metal ions coordinated in a manner similar to the spinal crystal was prepared by the ion-beam sputter deposition method. The study of magnetic properties was carried out by dc- and ac-susceptibility measurements and Mössbauer spectroscopy. The strong spin-freezing behavior was observed in 80-Hz, 1-Oe ac susceptibility at two spin-freezing temperatures: 284 K (Tf1), which is considered to be caused by a random anisotropy of Co ions coordinated in distorted octahedral sites, and 86 K (Tf2), which might be caused by the frustration of antiferromagnetic interactions due to the amorphous structure. The dc susceptibility showed irreversibility below Tf1 which decreased with increasing applied field. However, a distinct change was not observed at Tf2. The Mössbauer spectrum revealed that some of the paramagnetic Fe ions were frozen below Tf1, with relaxation phenomena, and that the residual paramagnetic ions were frozen at Tf2. The time decay of the thermoremanent magnetization observed below Tf1 showed different behavior compared to that above and below Tf2.