Structure analysis of sputter-coated and ion-beam sputter-coated films: a comparative study

Gold, platinum and tungsten films were deposited by low energy input (7 mA, 450 V), or high deposition rate (80 mA, 1500 V), diode sputter coating and by ion beam sputter coating. Film structures on Formvar coated grids and on the surface of coated erythrocytes, resin embedded, sectioned, and recorded at high magnification in a TEM were compared using computer-assisted measurements and analysis of film thickness and grain size. The average grain size of the thinnest gold and platinum films was relatively independent of the mode or rate of deposition but as the film thickness increased, significant differences in grain size and film structure were observed. Thick platinum or gold films deposited by low energy input sputter coating contained large grain size and electron transparent cracks; however, more even films with narrower cracks but larger grain size were produced at high deposition rates. Ion beam sputter coated gold had relatively large grain size in 10 nm thick films, but beyond this thickness the grains coalesced to form a continuous film. Platinum films deposited by ion beam sputter coating were even and free of electron transparent cracks and had a very small grain size (1–2 nm), which was relatively independent of the film thickness. Tungsten deposition either by low energy input or ion beam sputter coating resulted in fine grained even films which were free of electron transparent cracks. Such films remained granular in substructure and had a grain size of about 1 nm which was relatively independent of film thickness. Tungsten films produced at high deposition rates were of poorer quality. We conclude that thick diode sputter coated platinum and gold films are best deposited at high deposition rates provided the specimens are not heat sensitive, the improvement in film structure being more significant than the slight increase in grain size. Thick diode or ion beam sputter coated gold films should be suitable for low resolution SEM, and thin discontinuous gold films for medium resolution SEM. Diode sputter coated platinum should be suitable for medium resolution SEM and ion beam sputter coated platinum for medium and some high resolution SEM. 1–5 nm thick tungsten films, deposited by low energy input or ion beam sputter coating should be suitable for high resolution SEM, particularly where contrast is of less importance than resolution.     

Ion beam-sputtered and magnetron-sputtered thin films on cytoskeletons: A high-resolution tem study

A comparison of ion beam-sputtered and magnetron-sputtered thin platinum (Pt) and tungsten (W) films was made. Cytoskeletons from detergent extracted glioma cells grown on gold grids were coated with Pt or W at thicknesses of 1, 1.5, and 2.5 nm. Transmission electron micrographs were taken at high magnification and the granularity of the metal films was evaluated both on the Formvar film and the filaments of the cytoskeleton. In order to make a comparison between the two deposition methods, the metal deposition rate must be equal when corresponding thicknesses are made. Since ion beam sputtering generally is a slower process than magnetron sputtering, an increased target to specimen distance was necessary with the latter technique. This resulted in a coarser granularity of the W films as compared with the ion beam sputtered. The Pt, however, showed no marked difference between the two techniques at equal deposition rates. The study also demonstrated that varying the deposition rate caused differences in the granularity of the magnetron-sputtered Pt and W films, even if the voltage of the target was kept constant. Decreasing the target to specimen distance which increased the deposition rate resulted in a finer granularity of both the Pt and the W films. At the highest deposition rate the granularity of both the Pt and W films was comparable with the granularity of the ion beam-sputtered films.     

高能离子束辅助沉积制备钛纳米膜

用离子束溅射沉积和高能离子束辅助沉积方法制备了具有择尤性的钛纳米薄膜,并采用原子力显微镜、X射线衍射仪和俄歇电子谱仪研究了试样表面预处理、离子束流和温度等离子束工艺参数对钛薄膜结构的影响。结果表明：离子束溅射沉积的钛膜在[002]和[102]晶向上呈现出明显的择尤生长现象,并分别在该两个晶向上表现出纳米晶型和非纳米晶型结构;当用高能离子束辅助沉积时,[102]晶向择尤生长现象消失,且钛膜的结构对束流变化较为敏感,束流较低时,钛膜为纳米结构且择尤生长现象减弱,而束流增加时晶粒长大,择尤生长现象叉增强。另外钛膜容易受到氧的污染,并随辅助离子强度增加而增强。     

Tribological properties of nickel-base nanocrystalline coatings sputter-deposited on austenitic stainless steel

500 nm-thick films are deposited on austenitic stainless steel by neutral (Ar⁺) or reactive (N⁺) ion beam sputtering of Ni or NiTi targets, with (or without) high energy 160 keV-Ar⁺ ion beam assistance. Most of the time the coatings are nanocrystalline and induce a large (excellent in some conditions) increase of the wear resistance. Only Ar⁺ ion beam sputtering of a NiTi target gives an amorphous deposit which does not improve the substrate tribological properties. The hardness and wear resistance of ion beam assisted films are larger than those obtained with non-ion beam assisted coatings. The presence of a hard TiN phase inside a ductile Ni phase, of grains with preferential orientation beneficial to slip, as well as film densification are the main factors which increase the wear resistance. The best results are obtained when the structure is composed of two phases, Ni and TiN. The TiN phase strengthens the already good tribological Ni properties and the Ni ductility induces mechanical accommodation during the friction process.     

基于离子束溅射Ta2O5薄膜的紫外吸收膜技术

为获得高性能紫外激光薄膜元件,急需研制紫外高反射吸收薄膜,实现吸收损耗的精确测量。本文采用离子束溅射技术,通过调控氧气流量实现了具有不同吸收的Ta_2O_5薄膜的制备。以Ta_2O_5薄膜作为高折射率材料,设计了355nm的紫外高反射吸收薄膜。采用离子束溅射沉积技术,在熔融石英基底上制备了355nm的吸收薄膜,对于A=5%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,95.0%和4.9%;对于A=12%的紫外吸收光谱,在355nm的透射率、反射率和吸收率分别为0.1%,87.4%和12.5%。实验结果表明,采用离子束溅射沉积技术,可以实现不同吸收率的355nm高反射吸收薄膜的制备,对于基于光热偏转测量技术的紫外光学薄膜弱吸收测量仪的定标具有重要的意义。     

Surface characteristics and tribology study of metal oxide thin films

Abstract

Microcrystalline high quality undoped ZnO thin films were deposited on Si(100) and Corning 1737F glass substrates by a dc magnetron sputtering system. Surface and mechanical properties of ZnO thin films deposited under different deposition conditions (thickness, deposition rate and plasma composition) were investigated. Atomic force microscopy, nanoindentation techniques and scratch tests have been carried out. The lateral grain radius was between 50 and 160 nm. Surface roughness was found to vary from 1·3 to 10·3. In order to measure the real hardness of ZnO thin films grown on Si(100) and glass Continuous Stiffness Measurement technique was used. The hardness was found to be between 11 and 13 GPa for the polycrystalline ZnO almost five times larger than for the corresponding single crystalline material, while scratch tests verified a film structure, thickness, and surface morphology dependency on the mechanical properties for these metal oxide thin films.     

Specimen coating for high resolution scanning electron microscopy

Thin conducting films, produced by evaporation or soft vacuum sputtering generally show cracks and grain formation, when examined under high resolution scanning electron microscopy (SEM). These artefacts can obscure surface features of coated specimens or cause confusion in the interpretation of micrographs. No such structures have been observed in films produced by ion beam deposition. Ion beam deposition equipment is described in which a cold cathode saddle field ion source, operating at low pressure (15mPa), produces a 2 mm diameter beam of energetic ions (5 keV) and neutrals. With the beam directed onto a target at 30° to glancing incidence, the sputtered material coats the specimens, which are held in a planetary system for good coverage. Conditions favouring fine grain growth are a high nucleation density and low energy transfer to the substrate by thermal conduction or radiation or by particle or photon radiation. These conditions are satisfied by ion beam deposition but evidently not by evaporation or soft vacuum sputtering. With the specimen stationary, sharp shadowing is obtained because the target acts almost as a point source, because of the small diameter of the beam and because there is little scatter at the operating pressure.     

Spin‐coated epoxy resin embedding technique enables facile SEM/FIB thickness determination of porous metal oxide ultra‐thin films

A facile nonsubjective method was designed to measure porous nonconductive iron oxide film thickness using a combination of a focused ion beam (FIB) and scanning electron microscopy. Iron oxide films are inherently nonconductive and porous, therefore the objective of this investigation was to optimize a methodology that would increase the conductivity of the film to facilitate high resolution imaging with a scanning electron microscopy and to preserve the porous nature of the film that could potentially be damaged by the energy of the FIB. Sputter coating the sample with a thin layer of iridium before creating the cross section with the FIB decreased sample charging and drifting, but differentiating the iron layer from the iridium coating with backscattered electron imaging was not definitive, making accurate assumptions of the delineation between the two metals difficult. Moreover, the porous nature of the film was lost due to beam damage following the FIB process. A thin layer plastication technique was therefore used to embed the porous film in epoxy resin that would provide support for the film during the FIB process. However, the thickness of the resin created using conventional thin layer plastication processing varied across the sample, making the measuring process only possible in areas where the resin layer was at its thinnest. Such variation required navigating the area for ideal milling areas, which increased the subjectivity of the process. We present a method to create uniform thin resin layers, of controlled thickness, that are ideal for quantifying the thickness of porous nonconductive films with FIB/scanning electron microscopy.     

Microstructure and Wear Properties Analysis of TiAlN Film Deposited on Cam Profile Using Ion Sputtering

In this study ion beam sputtering deposition was used as a new surface formation technology for strengthening cam surface during the manufacturing process of indexing cam mechanism. Phase exchanging deformation can be avoided in this manufacturing process. Compared to surface quenching processes, the shape accuracy and dimension accuracy can be improved using this method. The microstructure and properties of TiAlN composite film deposited on the profile surface of a cam (made of AISI 1045 steel) by ion beam sputtering deposition were discussed. The microstructural characterizations were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is shown that the fundamental Bragg peak of {111} in TiAlN coatings increased with a bias voltage reduction. The grain size is about 1 μm. The friction coefficient was tested by a rotating wear tester at different loads and speeds. The minimum friction coefficient can be achieved at 0.187.     

离子束辅助磁控溅射沉积铬-铜-氮薄膜的结构与性能

应用低能离子束辅助磁控溅射（IBAMS）沉积铬-铜-氮薄膜,研究了铜含量和轰击能量对薄膜结构、硬度和断裂韧度的影响。结果表明：在相同的轰击能量（400eV）下,铜含量对薄膜结构和硬度的影响不明显,但是铜的加入有利于提高薄膜的断裂韧度;离子辅助轰击能量从400eV增加到800eV时薄膜的结构发生了显著变化,断裂韧度和硬度均大幅度提高。     

ITO thin films prepared by electron beam evaporation with End-Hall ion source assisted without heating to the substrate

1Introduction ITO(indiumoxidedopedwithtin)trans parentconductingfilmshaveuniqueopticaland electricalpropertiesofhightransmittanceinthe visibleregionandstrongreflectanceintheinfra redregionaswellastheexcellentconductivity.Forthesecharacteristics,ITOfilmsplayanim portantroleinthefieldofoptoelectronicde vices,suchastransparentelectrodeforelectro magneticinterference(EMI)shielding,electro chromicwindow[1],liquidcrystaldisplays(LCD)[2],andarchitecturalapplications.Ava rietyofthinfilmdepositiont…     

Development of RF magnetron sputtering method to fabricate PZT thin film actuator

PZT piezoelectric very thin films suitable for a microactuator have been deposited onto Invar alloy substrate using a high-temperature RF magnetron sputtering technique. PZT thin films must be deposited onto conductive substrate for a monomorph or a bimorph actuator. The chemical composition and the crystalline structure of these films were measured by ESCA and XRD, respectively. The chemical composition of PZT deposited stoichiometrically was almost the same as commercially-produced bulk PZT. Crystal planes (1 1 0) and (1 1 1) of PZT perovskite structure were observed in XRD analysis. When the substrate was heated to above 600 °C, SEM revealed only a very small number of pinholes on the surface. A thin (500 nm) film actuator has been characterized by measuring the piezoelectric property using a Laser Doppler Vibrograph. It was confirmed that the piezoelectric property has a linear relationship with the grain size, which also increased with the substrate temperature. The piezoelectric property of deposited PZT thin films showed a good agreement with a quoted value of bulk PZT, when the substrates were heated to 600 °C.     

Imaging of fullerene-like structures in CNx thin films by electron microscopy; sample preparation artefacts due to ion-beam milling

The microstructure of CN(x) thin films, deposited by reactive magnetron sputtering, was investigated by transmission electron microscopy (TEM) at 200kV in plan-view and cross-sectional samples. Imaging artefacts arise in high-resolution TEM due to overlap of nm-sized fullerene-like features for specimen thickness above 5nm. The thinnest and apparently artefact-free areas were obtained at the fracture edges of plan-view specimens floated-off from NaCl substrates. Cross-sectional samples were prepared by ion-beam milling at low energy to minimize sample preparation artefacts. The depth of the ion-bombardment-induced surface amorphization was determined by TEM cross sections of ion-milled fullerene-like CN(x) surfaces. The thickness of the damaged surface layer at 5 degrees grazing incidence was 13 and 10nm at 3 and 0.8keV, respectively, which is approximately three times larger than that observed on Si prepared under the same conditions. The shallowest damage depth, observed for 0.25keV, was less than 1nm. Chemical changes due to N loss and graphitization were also observed by X-ray photoelectron spectroscopy. As a consequence of chemical effects, sputtering rates of CN(x) films were similar to that of Si, which enables relatively fast ion-milling procedure compared to carbon compounds. No electron beam damage of fullerene-like CN(x) was observed at 200kV.     

负偏压对DLC薄膜结构和摩擦学性能的影响

采用离子束溅射沉积镀膜法制备了DLC薄膜,研究了偏压对薄膜性能的影响。通过原子力显微镜(AFM)和拉曼光谱对DLC薄膜的表面形貌以及内部结构进行了分析表征。并用UTM-2摩擦磨损仪对其摩擦学性能进行了测试。结果表明,利用离子束溅射沉积制备的DLC薄膜具有良好的减摩抗磨性能。随着偏压的增加薄膜的摩擦因数先减小后增加,在-150 V偏压时,薄膜的摩擦学性能最好。     

磁控溅射法制备的五氧化二钒薄膜光电特性

利用射频磁控溅射方法,选取溅射时间为15,25,30和45min,在蓝宝石衬底上沉积了V2O5薄膜。研究了其他实验参量不变,溅射时间不同对薄膜结构、薄膜厚度、表面形貌、电学及光学性能的影响。实验结果表明,制备出的薄膜为单一组分的V2O5薄膜,其在(001)面有明显的择优取向。随着溅身时间的增加,结晶性能逐渐变强,晶粒尺寸也逐渐变大,而表面粗糙度值会逐渐降低;在晶体结构完整的基础上,随着溅射时间的增加,相变温度和经历的温度范围会逐渐增加,电学突变性能会降低。测试了薄膜在中红外波段的高低温透过率,结果显示:当膜厚为350nm,波长为5μm时,薄膜的透过率从25℃时的81%变为300℃的7%,变化幅度可达74%;所有薄膜相变前后透过率的比值均为9~13,表现出了非常突出的光学开关特性。     

Deposition and focused ion beam milling of anticorrosive CrC coatings on tool steel substrates

For micro replication, the base of a die should be ductile and the surface layer that will undergo processing should have a good machining response to various tool-making processes. At the same time, the resulting working surfaces of the tooling cavities should be hard; having low roughness, low wettability and high erosion resistance. To achieve such diverse properties, nano-crystalline CrC coatings deposited onto 12% Cr tool steel were investigated in this research. To verify the properties of such coatings various metallographic techniques were applied. In particular, the corrosion resistance was studied by means of potentiodynamic anodic polarisation. A scanning transmission electron microscopy analysis of the structure was performed on samples prepared with focused ion beam (FIB) machining. The mechanical properties and grain size distribution were determined and statistically analysed. In addition, X-ray diffraction, scanning electron microscopy and atomic force microscopy were used in studying the surface properties of these coatings. To investigate the response of the CrC coatings to micro- and nano-structuring technologies with high specific energy, a series of rectangular trenches were produced by FIB milling. The effects of the ion beam current, exposure time and ion fluence on the sputtering yield and roughness of the produced micro-structures were especially investigated. Some essential parameter windows for performing FIB milling with relatively high sputtering rates, higher than 1?µm/min, and at the same time achieving the best possible surface integrity were determined during the experiments.     

Ion beam sputtering: an improved method of metal coating SEM samples and shadowing CTEM samples

An apparatus to ion beam sputter-coat SEM samples has recently become available. The equipment uses a small saddle-field ion source to sputter deposit metals on to samples. This eliminates the surface artefacts seen at high magnifications on samples coated by diode sputtering. Ion beam sputtering has also been used to shadow samples for CTEM and has been found to result in a grain size of 1.2 nm. This technique isolates the specimens from the high-energy plasma and thus little or no heating of the sample occurs. The removal of the SEM samples from the high-energy plasma and the use of diffusion pump vacuum conditions to prevent contamination are suggested as reasons for the improved coating quality over diode sputtering.     

A comparative study of thin coatings of Au/Pd, Pt and Cr produced by magnetron sputtering for FE-SEM

Visualization of structural details of specimens in field emission scanning electron microscopy (FE-SEM) requires optimal conductivity. This paper reports on the differences in conductive layers of Au/Pd, Pt and Cr, with a thickness of 1.5–3.0 nm, deposited by planar magnetron sputtering devices. The coating units were used under standard conditions for source–substrate distance, current, HT and argon pressure. Carbon films, deposited by high-vacuum evaporation on small, freshly cleaved pieces of mica, were used as substrate and mounted on copper grids for TEM and SEM inspection. Au/Pd, Pt and, to a lesser extent, Cr coatings varied in particle density, size and shape. Au/Pd coatings have a slightly more granular appearance than Cr and Pt coatings, but this is strongly dependent on the type of sputtering device employed. In FE-SEM images there is almost no difference in contrast and particle size between the Au/Pd layer and the Pt layers of a similar thickness. The nuclei of Au/Pd are rather small with almost no growth to the sides or in height, making Au/Pd coatings a good alternative to chromium and platinum for FE-SEM of biological tissues because of its higher yield of secondary electrons.     

荷能离子束沉积的氧化物薄膜光学性质

报道在不加热的基底上,由双离子束溅射或离子辅助的电子束蒸发技术制造的ＺｒＯ２ 和ＴｉＯ２ 单层薄膜的光学性质,并提供了工艺参数和离子束设备的详情。这两种荷能离子束工艺已被用于光学多层膜,如减反射膜和短波通滤光片的制备。     

Thin multilayer aluminum structures for superconducting devices

Various aluminum-based thin-film structures were manufactured and investigated at temperatures of 50 mK–3 K. Multilayer films of Al and Si, Al and Cr, and Al in the presence of oxygen were deposited by the thermal evaporation technique. As the thickness of pure-Al films decreases from 20 to 3 nm, the temperature of the superconducting transition increases from 1.30 to 2.45 K. An increase in the oxygen pressure to 5 × 10⁻⁶ mbar during deposition of Al films results in an increase in the critical temperature to 2.4 K. The presence of a chromium sublayer with a thickness of <0.5 nm may lead to complete suppression of superconductivity, whereas a thicker layer, 1–4 nm, deposited at a higher temperature with preliminary sputtering reduces the critical current of Al/Cr two-layer films to a lower degree. An atomic-force microscope was used to study the surface morphology and granularity and the roughness of manufactured film structures. The smallest linear roughness having a size of 0.29 nm for a 3-nm-thick film shows the advantage of using thinner films for creating a homogeneous tunneling barrier.