Experimental approach on interfacial properties for Cr/Al double nanometer films under different temperature environment mode

In this paper, a typical interfacial structure sample between the materials Cr and Al was fabricated. To investigate the interfacial characteristics, the mechanical properties of the Cr/Al double interfacial structure were tested using the nanoindenter and the nanoscratch. The test results show that both of the values are easily influenced by the different depth h. In the nanoscratch experiment, the bilayer films are set off as two groups, one of which is tested after the thermal cycling load while the other is not. The test results show that the interface formation and the binding force in the interface can be easily influenced by the difference thermal characteristic of the each single film. The elastic modulus and the hardness of the bilayer films are investigated using the nanoindentation.     

Mechanical characteristics approach on W/Cr nano-interface structure

The objective of this article is to provide an experimental test and evaluation on mechanical characteristics of the W/Cr interface. The elastic modulus and hardness of the sample are measured by a nanoindentation tester. The test results show that the elastic modulus and hardness of the sample are nonlinear with respect to the depth h of the interface structure, unlike the usual approximate horizontal linear relationship as expected. To understand the bonding characteristics between W and Cr in nanoscale, the nano-scratch test is conducted considering the influence of thermal cycling load on the sample. The test results show that interfacial bonding strengths are different between samples under different thermal cycling loading conditions. It implies that the thermal loading has the potential probability to reduce the bonding reliability of the W/Cr interface. It builds a basis for future work of further investigations on mechanical properties of W/Cr interface structure.     

Experimental and numerical approach on interfacial properties of W/Al bilayer films for electronic devices manufacturing

The aim of this article is to provide a systematic method for performing experimental tests and theoretical evaluations on interfacial adhesion properties of the W/Al bilayer thin films interface. Samples W/Al bilayer thin films assembly is deposited on the quartz glass by using radio frequency magnetron sputtering. Based on the analysis of the experimental indentation data, the elastic modulus and hardness of the sample are investigated. The test results show that both of the values are easily influenced by the indentation depth. At the meantime, a finite element model is built to simulate the interface mechanical properties. The analysis shows that stress is mainly centralized close to the indenter and the maximum stress occurs in the lower layer Al film, not in the upper W film. The comparison between the experiment and the simulation shows the validity of the test and the modeling of each other to a certain extent. The investigation builds a basis for future work such as the fabrication of W/Al bilayer thin films for micro/nano manufacturing.     

Nano-indentation Test and Numerical Evaluation of Cu–Cr Interface Structure in Micro/Nano Manufacturing

Interface design is an important topic in micro/nano electronic manufacturing. Interfaces of dissimilar materials in micro/nano electronic manufacturing are prone to crack initiations, leading to delaminations. The objective of this paper is to provide a systematic investigation to design or evaluate a bilayer film structure between Cu and Cr in micro/nano electronic manufacturing. In this paper, the Cu/Cr bilayer film prototype was deposited on the quartz glass by using RF magnetron sputtering. The elastic modulus and the hardness of the bilayer film prototype can be tested by using a nano-indenter. The test results show that the elastic modulus and the hardness of the bilayer film prototype are different at the difference maximum depth, h _max. The elastic modulus and the hardness of the Cu/Cr interface are influenced by the nanometer indentation size effect and each single film. The elastic modulus of the bilayer film shows nonlinear characteristics which include increase at first and decrease on second stage. The change trend of the hardness also shows nonlinear characteristics which include a fast steady decline at first and a slow nonlinear decline on second stage. These results show that there are scale domino effects in micro/nano electronic manufacturing. Based on the test results, the mechanical properties of the interface are not the simple average of each composition film. There is very great difference in the interface. In the meantime, the finite element method is used to simulate the plastic property of the interface. The comparison between the simulation and the test shows that the modeling method is a valid investigating method to analyze mechanical properties for nano-interface structure. It builds a basis for a progressive study of the mechanical properties of a Cu/Cr interface structure.     

Nanoindentation Experimental Approach and Numerical Simulation of Al/Cr Bilayer Films

The Al/Cr double-layer film structure samples (thickness, 1200 nm) were prepared by the magnetron sputtering method. To investigate the mechanical properties, the samples were measured by using a nanoindentation instrument. The test results showed the nonlinearity and different modes of the main mechanical properties by comparing the macro-scale structure samples with other samples of similar materials. Based on the test, the elastic modulus and hardness of thin film structures can be calculated by considering different loads to conduct multi-point indentations. Meanwhile, the relationships between the mechanical parameters can be investigated based on these Al/Cr double-layer film structure samples. To validate the test, numerical analysis was developed using a finite element method to simulate the loading and unloading process of indentation. The simulation results were compared with the results of experiments to illustrate the validity of both the test and simulation to a certain extent. The investigation builds not only an experimental basis for practical applications for future study, but also supplies a complementary means of verification for theoretical analysis.     

Specific features of the Hall effect in Cr/Co bilayer films

The Hall effect and magnetoresistance in Cr(50 Å)/Co(200 Å) bilayer films prepared by ion sputtering on a silicon substrate are investigated at room temperature. The planar Hall effect revealed in the bilayer films differs from the planar Hall effect observed usually in that it is symmetric with respect to the sign of the change in the rotation angle of the magnetic moment in the film plane. Under conditions where the symmetric planar Hall effect is realized, the change in the Hall resistance is more than 10% and exceeds the anisotropic magnetoresistance by two orders of magnitude. The hysteresis loops are measured at different orientations of magnetic fields. The planar Hall effect is studied in a weak longitudinal magnetic field. The results obtained demonstrate that the symmetric planar Hall effect is associated with the multidomain structure of the cobalt film in Cr/Co bilayer composites.     

Fabrication and performance characterization of Al/Ni multilayer energetic films

Al/Ni multilayer bridge films, which were composed of alternate Al and Ni layers with bilayer thicknesses of 50, 100 and 200 nm, were prepared by RF magnetron sputtering. In each bilayer, the thickness ratio of Al to Ni was maintained at 3:2 to obtain an overall 1:1 atomic composition. The total thickness of Al/Ni multilayer films was 2 μm. XRD measurements show that the compound of AlNi is the final product of the exothermic reactions. DSC curves show that the values of heat release in Al/Ni multilayer films with bilayer thicknesses of 50, 100 and 200 nm are 389.43, 396.69 and 409.92 J?g^?1, respectively. The temperatures of Al/Ni multilayer films were obviously higher than those of Al bridge film and Ni bridge film. Al/Ni multilayer films with modulation of 50 nm had the highest electrical explosion temperature of 7000 K. The exothermic reaction in Al/Ni multilayer films leads to a more intense electric explosion. Al/Ni multilayer bridge films with modulation period of 50 nm explode more rapidly and intensely than other bridge films because decreasing the bilayer thickness results in an increased reaction velocity.     

Effect of Alumina and Chromium Interlayers on Microstructures and Optical Properties of Thin Ag Films on Glass Substrates

Effects of alumina and chromium interlayers on the microstructure and optical properties of thin Ag films are investigated by using spectrophotometry, x-ray diffraction and AFM. The characteristics of Ag films in Ag/glass, Ag/l2O3/glass and Ag/Cr/glass stacks are analysed. The results indicate that the insertion of an Al2O3 or Cr layer decreases the grains and influences the reflectance of Ag films. The reflectance of the Ag film can be increased by controlling the thickness of alumina interlayer. The stability of Ag films is improved and the adhesion of Ag films on glass substrates is enhanced by alumina as an interlayer.     

High-temperature oxidation resistant (Cr, Al)N films synthesized using pulsed bias arc ion plating

(Cr, Al)N films were deposited by pulsed bias arc ion plating on HSS and 316L stainless steel substrates. With pulsed substrate bias ranging from −100 V to −500 V, the effect of pulsed bias on film composition, phase structure, deposition rate and mechanical properties was investigated by EDX, XRD, SEM, nanoindentation and scratch measurements. The high-temperature (up to 900 °C) oxidation resistance of the films was also evaluated. The results show that Al contents and deposition rates decrease with increasing pulsed bias and the ratio of (Cr + Al)/N is almost constant at 0.95. The as-deposited (Cr, Al)N films crystallize in the pseudo-binary (Cr, Al)N and Al phases. The film hardness increases with increasing bias and reaches the maximum 21.5 GPa at −500 V. The films deposited at −500 V exhibit a high adhesion force, about 70 N, and more interestingly good oxidation resistance when annealed in air at 900 °C for 10 h.     

Modelling the energy gap in transition metal/aluminium bilayers

We present an application of the generalised proximity effect theory. The theory has been used to determine the energy gap (Δ_g) in proximised transition metal/aluminium bilayer structures such as Nb/Al, Ta/Al, V/Al and Mo/Al. These bilayers have different film thicknesses ranging from 5 to 260 nm. For the cases of Nb/Al, Ta/Al and V/Al bilayers, the interface parameters γ and γ_BN (here we define γ as the ratio of the products of normal state resistivity and coherence length in each film of the bilayer while γ_BN is the ratio of the boundary resistance between films 1 and 2 to the product of the resistivity and coherence length in the second film), which were used as input parameters to the model, were inferred experimentally from an existing bilayer of each kind and then suitably modified for different film thicknesses. This experimental assessment is therefore based on a comparison of measurements of the critical temperature and the energy gap at 300 mK with the predictions from the model for various values of γ, γ_BN. The energy gap of the bilayer was experimentally determined by using symmetrical superconducting tunnel junctions (STJs) of the form S–Al–AlO_x–Al–S, where each electrode corresponds to a proximised bilayer. However for the case of Mo/Al bilayers the interface parameters were determined theoretically since currently no STJ data for this configuration are available. The results for the Nb/Al, Ta/Al and V/Al bilayers have also then been compared to experimentally determined energy gaps found for a series of STJs with different film thicknesses. The correspondence between experiment and theory is very good.     

Influence of cycling electric polarization on multiferroic behaviors in heterostructural films composed of ferroelectric and ferromagnetic oxides

The CoFe₂O₄/Pb(Zr_0.52Ti_0.48)O₃ bilayer films were prepared by a sol–gel process, and the influence of cycling electric polarization on the multiferroic behaviors of the bilayer films was studied. The ferroelectric polarization hysteresis loops under various choices of magnetic bias were measured by an integrating current method. The results showed that after undergoing cycling electric polarization the ferroelectric polarization of the bilayer films enhanced and the suppression of ferroelectric polarization by external magnetic bias remarkably weakened. Based on the measurements of activation energy and leakage current, we confirmed that the oxygen vacancy migration in the bilayer films occurred during cycling electric polarization. Furthermore, we analyzed the mechanism of the influence of cycling electric polarization on the multiferroic behaviors of the bilayer films and attributed it to the oxygen vacancy migration, which could cause a part of ferroelectric domains to be unpinned from the oxygen vacancies and become more active under electric field and magnetic bias.     

金刚石/ZnSe结构中瞬态热栅场的有限元法分析

利用有限元法分析计算了脉冲激光激发瞬态热栅在金刚石薄膜/ZnSe衬底双层结构中的三维温度场分布及变化。通过比较不同厚度金刚石薄膜样品的温度场分布,结果显示金刚石薄膜的厚度对样品中温度场的分布有较大影响,随着薄膜厚度的增大,峰值温度提高并且二次加热现象更加明显。     

Polymerization of Langmuir–Blodgett films of diacetylenes

Monolayer and multilayer assemblies of Langmuir–Blodgett films of 10–12 pentacosadyinoic acid (12–8 diacetylene) were deposited on flat gold substrates. Micrometre-size features were patterned by polymerization of the films by using standard electron beam lithography. Polymerized areas on a monolayer and bilayer, as well as multilayer films, were examined by scanning electron microscopy, atomic force microscopy and resonant Raman spectroscopy. It was established that polymerized areas on a monolayer and bilayer LB film adhere onto the gold substrate after development. The exposure curve, sensitivity, contrast and resolution of the polymer have been determined by using atomic force microscopy and correlated with the deposition conditions and molecular parameters. Stresses induced in the organic film during polymerization lead to an in-plane buckling of the micrometre-size polymer structure. A simple self-consistent theory was developed to predict critical strain and critical length of buckling. The observed effect of buckling of polymers might open an avenue for a wide range of important practical applications in the area of nanomechanical engineering.     

条形畴结构的FeCoAlON薄膜磁性的研究

用磁控射频溅射法制备了FeCoAlON薄膜, 研究了Al-O和N元素的添加对FeCo合金薄膜的软磁性的影响. 研究结果表明: 随着Al, O, N元素添加量的增加, 薄膜微结构从多晶转化到纳米晶再转化到非晶态, 薄膜表现为软磁性; 在N的含量较高时, 薄膜呈现条形畴结构, 本文对条形畴结构出现的机理和条件作了详细讨论, 并发现具有条形畴结构的薄膜的磁导率频率特性具有多峰共振的特点. 关键词： 铁钴基合金 薄膜 条形畴     

Anomalous scaling in surface roughness evaluation of electrodeposited nanocrystalline Pt thin films

Atomic force microscopy (AFM) is used to measure the surface roughness of crystalline Pt thin films as a function of film thickness and growth rate. Our films were electrodeposited on Au/Cr/glass substrates, under galvanostatic control (constant current density), from a single electrolyte containing Pt⁴⁺ ions. Crystalline structure of the films was confirmed by X-ray diffraction (XRD) technique. The effect of growth rate (deposition current density) and film thickness (deposition time) on the kinetic roughening of the films were studied using AFM and roughness calculation. The data is consistent with a rather complex behaviour known as “anomalous scaling” where both local and large scale roughnesses show power law dependence on the film thickness.     

Elastic-plastic analyses on the residual stresses and curvature of the film/substrate bilayer system

During thermal cycling, the residual stresses are often generated in the film/substrate bilayer due to the material mismatch between the substrate and the film. If the thickness of the film is relatively high, the thermal residual stresses in it may be of different signs. When the film is subjected to elastic-plastic deformation, two plastic zones with different thicknesses may be generated in the film at a significantly high temperature difference. In this paper, a theoretical model which reflects the complete history of thermal residual stresses and curvatures in the elastoplastic film/substrate bilayer system is developed. Solutions are derived to estimate the residual stresses and curvature in the film as functions of temperature difference. The case of Al/Si system is used to illustrate the implementation of this model. Results show that the critical temperature difference at which the second plastic zone near the film surface is generated near the Al film surface is dependent on the film thickness. The strain hardening of the film has an obvious influence on the magnitude of residual stresses within the film at high temperature difference.     

Rapid initiation of reactions in Al/Ni multilayers with nanoscale layering

Research into nanoenergetic materials is enabling new capabilities for controlling exothermic reaction rates and energy output, as well as new methods for integrating these materials with conventional electronics fabrication techniques. Many reactions produce primarily heat, and in some cases it is desirable to increase the rate of heat release beyond what is typically observed. Here we investigate the Al-Ni intermetallic reaction, which normally propagates across films or foils at rates lower than 10 m/s. However, models and experiments indicate that local heating rates can be very high (10⁷ K/s), and uniform heating of such a multilayer film can lead to a rapid, thermally explosive type of reaction. With the hopes of using a device to transduce electrical energy to kinetic energy of a flyer plate in the timescale of 100's of nanoseconds, we have incorporated a Ni/Al nanolayer film that locally heats upon application of a large electrical current. We observed flyer plate velocities in the 2-6 km/s range, corresponding to 4-36 kJ/g in terms of specific kinetic energy. Several samples containing Ni/Al films with different bilayer thicknesses were tested, and many produced additional kinetic energy in the 1.1-2.3 kJ/g range, as would be expected from the Ni-Al intermetallic reaction. These results provide evidence that nanoscale Ni/Al layers reacted in the timescale necessary to contribute to device output.     

Fe/Al混合膜的PLD法制备及表面分析

 采用脉冲激光气相沉积（PLD）技术制备了Fe/Al混合膜,测量了该混合膜的光电子能谱（XPS）,并采用原子力显微镜（AFM）、扫描电子显微镜（SEM）对Fe/Al混合膜作了表面分析。结果表明：Fe/Al混合膜的表面粗糙度对衬底温度有明显的依赖性, 随着衬底温度的升高,薄膜的表面逐渐变得平滑,膜层变得致密,在200 ℃衬底温度下制得了均方根（rms）粗糙度为0.154 nm、具有原子尺度光滑性的Fe/Al混合膜, 膜中Fe和Al分布比较均匀,其成分比约为1∶3,同时XPS分析也表明Fe/Al混合膜暴露在空气中后表面形成了Al₂O₃和FeO氧化层。     

Self-propagating high-temperature synthesis and solid-phase reactions in bilayer thin films

Self-propagating high-temperature synthesis (SHS) in Al/Ni, Al/Fe, and Al/Co bilayer thin films is investigated. It is established that SHS is achieved in thin films at initiation temperatures 300–350° lower than in powders. The mechanism of SHS in thin films is similar to the process of explosive crystallization. It is shown that at the initial stage solid-phase reactions arising on the contact surface of condensate films can be self-propagating high-temperature synthesis. SHS could find application in different technologies for obtaining film components for microelectronics. Zh. Tekh. Fiz. 68, 58–62 (October 1998)     

Magneto-optical Kerr effect of amorphous TbFeCoTa film with a quadrilayer structure

The magneto-optical Kerr effect (MOKE) of a multilayered system has been described by using the characteristic matrix method of film optics. By using this method, the MOKE and read-out performance of an amorphous TbFeCoTa film with the quadrilayer structure of SiC/TbFeCoTa/SiC/metallic reflector/glass substrate, has been investigated in detail. Different from the MO/metallic bilayer structure, whose Kerr rotation can be strongly enhanced by the metallic reflector with low values of the optical constants n and , the Kerr rotation and the read-out figure of merit of the quadrilayer structure are strongly enhanced at wavelengths where the reflector layer has a high reflectivity, due to multiple reflection and optical interference. Among the Al, Ag, Cu, Cr and Au reflectors, Al and Ag reflectors result in the largest two increments in the Kerr rotation and the read-out figure of merit at short wavelengths, indicating that Al and Ag are the best reflector materials for the TbFeCoTa MO disk for short wavelength recording. The thickness dependencies of each layer on the MOKE, reflectivity and the figure of merit of the quadrilayer structure have been investigated. By employing this method, the optimum structure for the TbFeCoTa MO disk can be determined. PACS 78.20.Ls; 75.50.Ss; 75.50.Kj; 75.30.Gw; 42.79.Vb