Residual stress in obliquely deposited MgF2 thin films

MgF(2) films with a columnar microstructure are obliquely deposited on glass substrates by resistive heating evaporation. The columnar angles of the films increases with the deposition angle. Anisotropic stress does not develop in the films with tilted columns. The residual stresses in the films depend on the deposition and columnar angles in a columnar microstructure.     

Electron microscope structure and internal stress in thin silver and gold films deposited onto MgF2 and SiO substrates

In this work the internal stress of thin silver and gold films deposited onto MgF₂ and SiO substrate films was measured up to a mean thickness of about 1000 Å. The method used was based on the cantilever beam principle. The internal stress of the metal films was determined by subtracting the contributions due to momentum transfer and heat transfer. From parallel electron microscope investigations of films of various thicknesses it was seen that a close correlation exists between the internal stress generated in the films and their structure. On the basis of these results we propose a model which gives a qualitative explanation of the measured internal stress versus thickness curves and of their dependence on vacuum conditions, evaporation rate and the nature of the substrate.     

Microstructure of zi rcon is films deposited with ion assistance

Zirconia films were deposited in vacuum from an electron-beam hearth with simultaneous ion bombardment from a Kaufman source. The effects of argon, oxygen and nitrogen ions were investigated, together with those of temperature and substrate type. For amorphous substrates, without ions, X-ray and electron diffraction showed that amorphous films were produced at room temperature. Deposition on to 300°C amorphous substrates produced the monoclinic form. Ion assistance converted the structure to cubic. It was found that deposition on to KCI (100) substrates also produced the cubic form at elevated temperatures, with or without ions. High-resolution microscopy showed that these films were crystallographically oriented with either <100> or <110> normal to the KCI substrate. The Raman spectra of films on fused silica substrates were correlated with the X-ray diffraction scans and the conditions under which the Raman spectrum could be used as a reliable indicator of microstructure were found.     

Thermal expansion coefficients of obliquely deposited MgF2 thin films and their intrinsic stress

This study elucidates the effects of columnar angles and deposition angles on the thermal expansion coefficients and intrinsic stress behaviors of MgF2 films with columnar microstructures. The behaviors associated with temperature-dependent stresses in the MgF2 films are measured using a phase-shifting Twyman-Green interferometer with a heating stage and the application of a phase reduction algorithm. The thermal expansion coefficients of MgF2 films at various columnar angles were larger than those of glass substrates. The intrinsic stress in the MgF2 films with columnar microstructures was compressive, while the thermal stress was tensile. The thermal expansion coefficients of MgF2 films with columnar microstructures and their intrinsic stress evidently depended on the deposition angle and the columnar angle.     

Direct ion beam deposited carbon films and clusters

Carbon films and clusters have been formed by direct ion beam deposition. In all experiments crystalline n-Si 〈1 0 0〉 wafers with the 300 nm thermal SiO₂ film have been used as substrates. Effects of thermally microstructured Ni and substrate temperature were studied. Chemical structure of the carbon films was investigated using Raman spectroscopy. Surface morphology was studied by atomic force microscopy (AFM). Supplemental research on sheet resistance of the films has been performed. Rough diamond-like carbon film was grown onto the catalytic layer at 400 K temperature, and surface of the diamond-like carbon film deposited directly onto the SiO₂ layer at 400 K temperature was very smooth. At 750 K growth of the array of cylindrically shaped clusters was observed by AFM in the case of catalytically assisted deposition. Raman spectra of deposited films were typical for glassy carbon and/or carbon nanotubes with the carbonaceous deposits. Catalyticless deposition at 750 K temperature resulted in the formation of the conductive polymer-like carbon film with the graphite clusters in it.     

1.6 Composition and stress state of thin films deposited by ion beam sputtering

The ion beam sputtering technique offers several advantages over conventional sputtering systems. This technique operates at a lower pressure and substrate temperature than conventional sputtering. In addition, the angle of deposition which is easily varied with ion beam sputtering is essentially fixed in dc and rf diode sputtering. As a result of these advantages, many of the parameters which effect film stress, resistivity, and grain size can be varied independently.Several properties of ion beam sputtered Ni, Al, Ni₃Al and Au thin films have been evaluated as a function of ion beam current density, target material, and the angle and distance of the substrate from the target.The grain size and stress were found to vary with the angle of deposition. There is an apparent correlation between electrical resistivity and the oxygen content in the films. Both properties depend upon the grain size. The stress levels of the films are shown to be influenced by the oxygen content. These experimental results are discussed in light of models proposed to explain the origin of stress in thin films.     

Stress measurements and calculations for vacuum- deposited MgF2 films

Previous in situ measurements of the intrinsic stress in thin crystalline dielectric films have been interpreted in terms of a stress mechanism due to forces at the grain boundaries. The same stress interpretations were given for metal films by Hoffman and coworkers several years ago.In the present work it is shown that the tensile stress is a decreasing function of impurity concentration in the MgF₂ films. A similar decrease occurs through water vapour adsorption. Assuming that the impurity is located mainly on the crystallite surface, as with adsorbed water molecules, this effect can also be interpreted using the grain boundary model which predicts a decreasing tensile stress with increasing crystal size. The results of stress measurements of MgF₂ films deposited onto heated substrates support this prediction.     

双离子束溅射法制备铁氮薄膜

使用双离子束溅射法制得了铁氮薄膜,随着基片温度的变化,薄膜的成分是ε－Fe2-3N,γ′－Fe4N或是二相的混合物,薄膜的晶粒尺寸随基片温度的升高而增大。以振动样品磁强计（VSM）测定了薄膜的磁性能。另外,研究了在基片温度为160℃时,改变主源中通入N2／Ar的比例对薄膜成分的影响。     

Properties of amorphous carbon films deposited by ion beam methods

Amorphous carbon films were prepared by the ion beam sputtering of graphite, by the ion beam sputtering of graphite with simultaneous ion bombardment of the growing film, and by primary ion beam deposition using a beam from a methane- argon plasma. The films are semiconducting in nature, having band gaps of the order of 1 eV. A nuclear reaction involving an energetic (2 MeV) beam of ¹¹B⁺ was used to obtain hydrogen profiles of the films. It was found that the electrical, optical and mechanical properties of the films could be correlated with the hydrogen content. The observed properties are explained qualitatively in terms of amorphous semiconductor theory.     

Characterization and properties of GaN films deposited by middle-frequency magnetron sputtering with anode-layer ion source assistance

GaN films were deposited on Si (111) substrates at a high growth rate of 94 nm/min using middle-frequency (MF) magnetron sputtering method with anode-layer ion source assistance. XRD, TEM and PL experiments were used to investigate the structure and optical properties of the resulting films. GaN films produced under optimal conditions have an almost 1:1 N: Ga ratio. The O concentration decreased while the deposition rate increased with the increasing of bias voltages. Hexagonal polycrystal nature of the films was detected by the TEM and XRD measurements. Peaks located at 3.36 eV labeled as free-exciton were detected in the temperature dependence photoluminescence spectra. The binding energies of N 1s and Ga 3d were centered at 397.5 and 19.8 eV, respectively. The results show that the ion beam-assisted MF reactive magnetron sputtering method can be an encouraging method for deposition of polycrystalline GaN films at low temperatures.     

Characterization and properties of GaN films deposited by middle-frequency magnetron sputtering with anode-layer ion source assistance

GaN films were deposited on Si (111) substrates at a high growth rate of 94 nm/min using middle-frequency (MF) magnetron sputtering method with anode-layer ion source assistance. XRD, TEM and PL experiments were used to investigate the structure and optical properties of the resulting films. GaN films produced under optimal conditions have an almost 1:1 N: Ga ratio. The O concentration decreased while the deposition rate increased with the increasing of bias voltages. Hexagonal polycrystal nature of the films was detected by the TEM and XRD measurements. Peaks located at 3.36 eV labeled as free-exciton were detected in the temperature dependence photoluminescence spectra. The binding energies of N 1s and Ga 3d were centered at 397.5 and 19.8 eV, respectively. The results show that the ion beam-assisted MF reactive magnetron sputtering method can be an encouraging method for deposition of polycrystalline GaN films at low temperatures.     

Residual stress on nanocrystalline silicon thin films deposited under energetic ion bombardment by using internal ICP-CVD

Nano/microcrystalline silicon thin films were deposited using an internal-type, inductively coupled, plasma-chemical vapor deposition (ICP-CVD) at room temperature by varying the bias power to the substrate. The structural characteristics of the deposited thin film were investigated. The deposition rate was increased by the application of a small RF bias power of 30 W (12.56 MHz), but was then decreased as the bias power was increased above 30 W. In addition, the application of bias power generally increased the residual compressive stress, which was attributed to the increased defect formation in the thin film due to the formation of interstitial atoms. The crystalline volume fraction was also decreased with increasing bias power. However, in the low bias power range of 0-60 W, the compressive stress in the deposited thin film was in the range of − 34 to − 77 MPa, which was lower than the residual stress in the range of − 150 to − 1050 MPa that is observed for the nano/microcrystalline silicon thin films deposited by capacitively coupled plasma.     

Influence of ion assistance on LaF3 films deposited by molybdenum boat evaporation

LaF3 thin films at 193 nm were deposited by the molybdenum boat evaporation with ion-assisted deposition (IAD). Various optical characteristics, stress, and microstructures that formed under different ion-beam voltages of IAD deposition were investigated. The relation between these properties is also discussed. LaF3 films deposited with IAD exhibited small rough surfaces and large optical loss at 193 nm. The largest value of optical loss for films at 193 nm, which were prepared at an ion-beam voltage of 400 V, was 1.55% and the extinction coefficient was smaller than 0.0015. Microstructures and crystalline structures of films were influenced and changed by the ion-assisted deposition process. Tensile stress value of films increased as the ion-beam voltage rose. Refractive index, related to the packing density and microstructures, also increased as the ion-beam voltage rose.     

动态离子束混合沉积氧化钽薄膜的微观分析

用动态离子束混合技术在铁基材料表面上制备氧化钽薄膜.用Ar 束溅射沉积薄膜的同时,分别用100 keV,2×1017/cm2的O 离子或100 keV,8×1016/cm2的Ar 进行辐照.对两种工艺下生成的氧化钽薄膜进行了XPS、AES及RBS分析研究,结果发现,Ar 辐照下制备的氧化物薄膜主要由符合化学剂量比的Ta2O5化合物组成,引入的碳污染少.O 辐照下制备的薄膜生成了低价的氧化钽,引入了大量的碳污染.     

Growth and properties of the ion beam deposited SiOx containing DLC films

In the present study SiO_x containing diamond-like carbon (DLC) films were synthesized by the closed drift ion source from hexamethyldisiloxane vapor. Kinetics of the growth of DLC films was investigated using optical emission spectroscopy (OES). Structure, chemical composition, electrical and optical properties of the synthesized films were studied. The effects of ion beam energy were investigated. The main atomic hydrogen Balmer series lines and the intense broad CH group related peak were detected in the OES spectra registered in-situ during SiO_x containing diamond-like carbon film synthesis. The intensity ratio of H-β/CH peaks increased with the increase of applied ion beam energy. It was explained by activation of the dissociation of the hexamethyldisiloxane molecules. Changes of the structure of the diamond-like carbon films were observed for the films deposited under intense dissociation conditions.     

Magnetic and structural characteristics of ion beam sputter deposited Co-Cr thin films

-The magnetic and structural characteristics of ion beam sputter deposited Co82Cr18films were investigated. Films of between 1000A and 10,000A thickness were deposited on glass, titanium, chromium and amorphous Ta-W-Ni. The average angle of incidence of the sputtered species was normal to the substrate surface. Film orientation was determined by x-ray pole figure analysis. In films deposited on glass with thicknesses below 10,000A, the     

Semiconductor applications of thin films deposited by neutralized ion beam sputtering

Thin films deposited by sputtering with a neutralized ion beam source have shown promise for performance improvement in two distinct types of devices: insulating barriers on gallium arsenide and heterojunction solar cells. The source, first developed by NASA for space propulsion, accelerates positive argon ions to 100–800 eV and then neutralizes the beam with electrons from a hot filament. MIS structures formed from tantalum oxide, silicon oxide and silicon nitride on GaAs show very high resistivity and relatively low surface state densities. Indium tin oxides deposited on silicon produce respectable diodes and solar cells with efficiencies as high as 12%.     

Effect of assist ion beam voltage on intrinsic stress and optical properties of Ta2O5 thin films deposited by dual ion beam sputtering

The optical properties and intrinsic stress of Ta₂O₅ thin films deposited by dual ion beam sputtering (DIBS) were studied as a function of the assist ion beam voltage (250-650 V). When the assist ion beam voltage was in the range of 350-450 V, the transmittance at the quarter-wave point reached its highest value (lowest absorption). The refractive index increased to 2.185 as the assist ion beam voltage increased from 250 to 350 V, but decreased as the assist ion beam voltage was further increased from 350 to 650 V.     

Nanocrystalline diamond thin films deposited from C60 monoenergetic fullerene ion beam

Carbon films 250 division by 500 nm in thickness deposited on Si wafers from mass-selected flow of accelerated C60 ions with energies of 5.0 +/- 0.1 keV at temperatures of 300 K and 673 K are characterized by TEM and nanoindentation. On the TEM images of the films deposited at 673 K, nanocrystalline graphite with the typical grain size of -6 nm is observed. The films deposited at 300 K are transparent in visible light. TEM study of these films has revealed structural elements with lattice spacing close to that of diamond and the grain size of about 4 nm. Nanohardness and elastic modulus of the films prepared at a substrate temperature of 300 K were 23.1 +/- 0.2 GPa and 200 +/- 1 GPa, respectively. Possible mechanisms of the carbon films structure formation are suggested in the framework of a hydrodynamic shock wave model.     

Microstructural study of iron nitride thin films deposited by ion beam sputtering

An amorphous iron nitride thin film was deposited using reactive ion beam sputtering of iron by a beam of argon and nitrogen ions. Nitrogen content in the film as determined from conversion electron Mössbauer spectroscopy (CEMS) and X-ray photoelectron spectroscopy (XPS) was FeN_0.7. The mass density of the film was calculated using energy-dispersive X-ray reflectivity (EDXRR) measurements and is found to be 6.0 gm/cm³. CEMS shows that the film is nonmagnetic in nature. Morphology of the film is obtained from atomic force microscopy (AFM). The surface roughness of the film does not increase appreciably beyond that of the substrate even after a deposition of 131 nm of material with these qualities the film is a good candidate for the multilayer superstructure of a nuclear Bragg monochromator of the type ⁵⁶FeN_0.7/⁵⁷FeN_0.7.