Abstract: An original experimental approach is presented to test under compression ultra-thin films on compliant substrates. The sputtering chamber was modified to permit deposition of the film on an untreated polyimide substrate tensily stressed by a Deben (TM) device. Exploration of the compression response was made possible with the film being loaded, when unloading the polyimide dogbone substrates. The compression response of an ultra-thin film of gold (18.5 nm) deposited onto the elastically loaded substrate was investigated using synchrotron X-ray diffraction. In contrast to tensile loading reported in the literature, the elastic compression could be explored up to -0.5% (-440 MPa as compared to 290 MPa). (C) 2012 Elsevier B.V. All rights reserved.
Abstract: In this paper, we study the effect of mechanical stress on the domain configuration of a NiFe film obliquely deposited on a compliant polyimide substrate. To this end, we have developed a new method combining in situ mechanical tests with magnetic force microscopy (MFM) imaging. This approach allows changing the static magnetization structure of the film by controlling the stress-induced anisotropy. In the absence of applied stress and magnetic field, the sample shows stripe domains with an in-plane tilted direction with respect to the stress axis. After saturating the film, application of an increasing stress regenerates progressively a stripe domains structure with a modified in-plane magnetization direction. (C) 2012 American Institute of Physics. [doi:10.1063/1.3675613]
Abstract: We have studied the magnetic properties of thin epitaxial hexagonal Fe1.7Ge films grown on Ge(111) substrates by molecular beam epitaxy. For all samples, X-ray diffraction revealed an excellent epitaxy of the Fe1.7Ge films, with crystallographic [11 (2) over bar0] and [1 (1) over bar 00] axes lying in the sample plane. The static magnetic properties were studied by Magneto-Optical Kerr Effect (MOKE) at room temperature. The dynamic magnetic properties at room temperature were investigated by Micro-Strip Ferromagnetic Resonance (MS-FMR). The frequency dependence of the spectra versus the orientation of the applied in-plane magnetic field shows that the contribution of the in-plane anisotropy to the magnetic energy density consists in two distinct terms exhibiting a twofold and a sixfold symmetry, respectively. The amplitude of the sixfold anisotropy constant is an increasing function of the film thickness. The observed angular dependence of the MOKE reduced remanent magnetization is described using a coherent rotation model. A good agreement is observed between the in-plane anisotropy values derived from MS-FMR and those obtained with MOKE Transverse Bias Initial Inverse Susceptibility and Torque data. (C) 2012 American Institute of Physics. [doi:10.1063/1.3672396]
Abstract: A prototype X-ray pixel area detector (XPAD3.1) has been used for X-ray diffraction experiments with synchrotron radiation. The characteristics of this detector are very attractive in terms of fast readout time, high dynamic range and high signal-to-noise ratio. The prototype XPAD3.1 enabled various diffraction experiments to be performed at different energies, sample-to-detector distances and detector angles with respect to the direct beam, yet it was necessary to perform corrections on the diffraction images according to the type of experiment. This paper is focused on calibration and correction procedures to obtain high-quality scientific results specifically developed in the context of three different experiments, namely mechanical characterization of nanostructured multilayers, elasticplastic deformation of duplex steel and growth of carbon nanotubes.
Abstract: Synchrotron x-ray radiation was used for in situ strain measurements in gold films on polyimide substrate during uniaxial deformation tests. We have used an area detector that allows inspecting multiple directions in the polycrystalline thin film without serial sectioning during straining. We show in this paper the configuration used and the attainable orientations on a pole figure for which the x-ray strains are measured. Moreover, we show the effect on the x-ray strains of the onset on plasticity, which was not detected by optical (macroscopic) strain measurement. (C) 2011 Elsevier B.V. All rights reserved.
Abstract: The anisotropic elastic response of supported thin films with a 111 fiber texture has been studied using an in-situ micro-tensile tester and X-ray diffractometry. It is shown which specific X-ray diffraction measurement geometries can be used to analyze the elastic strains in thin films without requiring any assumptions regarding elastic interactions between grains. It is evidenced (theoretically and experimentally) that the combination of two specific geometries leads to a simple linear relationship between the measured strains and the geometrical variable sin2 epsilon, avoiding the transition scale models. The linear fit of the experimental data allows a direct determination of the relationship between the three single-crystal elastic compliances or a direct determination of the S (44) single-crystal elastic compliance and the combination of S (11) + 2S (12) if the macroscopic stress is known. This methodology has been applied to a model system, i.e. gold film for which no size effect is expected, deposited on polyimide substrate, and it was found that S (44) = 23.2 TPa-1 and S (11) + 2S (12) = 1.9 TPa-1, in good accordance with values for large crystals of gold.
Abstract: We have developed a new methodology to study the effect of mechanical stress on spin waves in thin films deposited onto compliant substrates. It is based on micro-tensile tests combined with Brillouin light-scattering spectroscopy, which allows in situ probing of the magnetization dynamics of the studied film upon deformation. This paper shows from both theoretical and experimental approaches that the magneto-elastic coupling in the saturation regime leads to a simple linear relationship between the spin waves’ frequency and the stress applied to the magnetic film. The linear part of the experimental data can be reproduced theoretically, assuming a complete strain transfer through the metallic film-compliant substrate interface.
Abstract: In situ biaxial tensile tests within the elastic domain were conducted with W/Cu nanocomposite thin films deposited on a polyimide cruciform substrate using a biaxial testing machine developed on the DiffAbs beamline at the Synchrotron SOLEIL. The mechanical behaviour of the nanocomposite was characterized at the micro- and macroscales using synchrotron X-ray diffraction and digital image-correlation techniques simultaneously. Strain analyses for equibiaxial and non-equibiaxial loading paths were carried out. The results show that the two strain measurements match to within 1 x 10(-4) in the elastic domain for strain levels less than 0.3% and for both loading paths.
Abstract: This paper illustrates the insights gained on the mechanical response of metal-coated soft polymer substrates using in-situ tensile testing under synchrotron x-rays. Progress made in external loading (uniaxial and biaxial) and detection capacities is reviewed since they allow scrutinizing multiphased specimens in a reasonable time frame. In general, the microstructure (grain morphology, preferential crystallographic orientation) has to be incorporated into the models used to interpret the experimental data.
Abstract: We have developed on the DIFFABS-SOLEIL beamline a biaxial tensile machine working in the synchrotron environment for in situ diffraction characterization of thin polycrystalline films mechanical response. The machine has been designed to test compliant substrates coated by the studied films under controlled, applied strain field. Technological challenges comprise the sample design including fixation of the substrate ends, the related generation of a uniform strain field in the studied (central) volume, and the operations from the beamline pilot. Preliminary tests on 150 nm thick W films deposited onto polyimide cruciform substrates are presented. The obtained results for applied strains using x-ray diffraction and digital image correlation methods clearly show the full potentialities of this new setup. (C) 2010 American Institute of Physics. [doi:10.1063/1.3488628]
Abstract: The deformation behaviour of 150 nm thick W/Cu nanocomposite deposited on polyimide substrates has been analysed under equi-biaxial tensile testing coupled to X-ray diffraction technique. The experiments were carried out using a biaxial device that has been developed for the DiffAbs beamline of SOLEIL synchrotron source. Finite element analysis has been performed to study the strain distribution into the cruciform shape substrate and define the homogeneous deformed volume. X-ray measured elastic strains in tungsten sub-layers could be carried out for both principal directions. The strain field was determined to be almost equi-biaxial as expected and compared to finite element calculations. (C) 2010 Elsevier B.V. All rights reserved.
Notes: 37th International Conference on Metallurgical Coatings and Thin Films, San Diego, CA, APR 26-30, 2010
Abstract: Elastic properties of non-textured and 1 1 1-fiber-textured gold thin films were investigated experimentally by several complementary techniques, namely in situ tensile testing under X-ray diffraction (XRD), nanoindentation and Brillouin light scattering (BLS). Specimens were probed along different directions to reveal the strong effects of elastic anisotropy at the (local) grain and (global) film scales. XRD allows the investigation of both local and global anisotropies, while BLS and nanoindentation are limited to global analyses. A micromechanical model, based on the self-consistent scheme, and accounting for the actual microstructure of the films, is applied to interpret experimental data. Although different types of elastic constants can be determined with the used experimental techniques (static/dynamic, local/global), a good agreement is obtained, showing that comparison of these techniques is feasible when carried out carefully. In particular, the use of a micromechanical model to estimate the effects of the local elastic anisotropy at the film scale is unavoidable. The presented results show that XRD, BLS and nanoindentation should capture anisotropic texture effects on elastic constants measurements for materials with a Zener anisotropy index larger than 2. Conversely, the actual texture of a given specimen should be taken into account for a proper analysis of elastic constants measurements using those three experimental techniques. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Abstract: Synchrotron x-ray radiation was used for in situ strain measurements during uniaxial tests on polymer substrates coated by a metallic gold film 400 nm thick deposited without interlayer or surface treatment. X-ray diffraction allowed capturing both components elastic strains and determining how these were partitioned between the metallic film and the polymeric substrate. For strains below 0.8%, deformation is continuous through the metal-polymer interface while above, the onset of plasticity in the metallic film induces a shift between film and substrate elastic strains.
Abstract: Magnetic properties of Co(2)MnGe thin films of different thicknesses (13, 34, 55, 83, 100, and 200 nm), grown by rf sputtering at 400 degrees C on single crystal sapphire substrates, were studied using vibrating sample magnetometry and conventional or microstrip line ferromagnetic resonance. Their behavior is described assuming a magnetic energy density showing twofold and fourfold in-plane anisotropies with some misalignment between their principal directions. For all the samples, the easy axis of the fourfold anisotropy is parallel to the c-axis of the substrate while the direction of the twofold anisotropy easy axis varies from sample to sample and seems to be strongly influenced by the growth conditions. Its direction is most probably monitored by the slight unavoidable miscut angle of the Al(2)O(3) substrate. The twofold in-plane anisotropy field H(u) is almost temperature independent, in contrast with the fourfold field H(4) which is a decreasing function of the temperature. Finally, we study the frequency dependence of the observed line-width of the resonant mode and we conclude to a typical Gilbert damping constant alpha value of 0.0065 for the 55-nm-thick film. (C) 2010 American Institute of Physics. [doi:10.1063/ 1.3475501]
Abstract: In situ tensile tests have been carried out under synchrotron radiation on supported gold (Au) thin films exhibiting a pronounced crystallographic texture. The 2 theta shift of X-ray diffraction lines has been recorded for different specimen orientations and several loading levels in the elastic domain. The data obtained demonstrate the large strain heterogeneities generated within the specimen because of the intergranular interactions associated with the large elastic anisotropy of Au grains. To interpret these results, the use of a multi-scale micromechanical approach is unavoidable. The theoretical background of such methods is described, and the points where exact results can be obtained and where approximations have to be introduced are highlighted. It is shown that the Vook-Witt model, for which a general formulation is provided, is the exact solution for polycrystals exhibiting a laminate microstructure, which is a significant departure from the standard thin-film microstructures. Among several standard models used in the field, the self-consistent model is the only one that reproduces the experimental data correctly. This is achieved by accounting for the actual crystallographic texture of the specimen, and assuming pancake-shaped two-point statistics for the morphological texture. A discussion of the limitations of this approach, originally developed for bulk materials, is given for the specific case of thin films.
Abstract: X-Ray diffraction (XRD) in combination with tensile testing is a very attractive tool for investigating the elastic behavior and further fracture or plasticity of metallic thin films and multilayers. Such studies are carried out with synchrotron X-ray sources allowing for several diffraction and loading conditions to be investigated and hence for great precision to be achieved. XRD is phase selective and allows for the study of individual layers or phase contributions. The method is based on a length scale change to relate in-grain elastic strains to tensile macrostresses. Hence, it requires the modeling of the grain interactions in view of the structure of the films (morphology, texture). The paper is illustrated with studies carried out on elastically isotropic tungsten (W) films, elastically anisotropic gold (Au) textured films, and nanometric tungsten/copper (W/Cu) multilayers.
Notes: 10th International Conference on Plasma Surface Engineering, Garmische-Partenkirchen, GERMANY, SEP 10-15, 2006
Abstract: The influence of texture on the elastic behavior of An thin films has been quantified experimentally and theoretically. The elastic behaviors of non-textured and 1 1 1 fiber-textured gold thin films were studied by in situ tensile testing using four-circle goniometers on a synchrotron beam line (LURE facility, France). The mechanical coupling of the substrate-thin film composite structure has been described and analytical solutions for diffraction strain analysis have been developed including texture and grain interaction models. These are applied to extract and compare elastic properties of the two types of gold films, and to quantify the effect of texture on the direction-dependent Young’s modulus. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Abstract: The elastic behavior of supported gold thin films has been studied using a framework in which the elastic interaction between grains and the actual structure of the film (i.e. preferential grain orientation and grain shape) are taken into account. Experiments were carried out using synchrotron X-ray diffraction combined with in-situ tensile testing and thereafter, no assumptions on the residual stress state and on the stress-free lattice parameter a(0) have to be made. Modeling of grain elastic interactions is based on the extension of Eshelby-Kroner model, which allows for estimating the elastic behavior of polycrystals considering the texture and the shape of the crystallites. Flat-disc shaped grains arrangement is shown to yield the best representation of the elastic behavior of the fiber-textured gold thin films composed of columnar grains. This non-intuitive representation results from free-surface effect. (c) 2006 Elsevier B.V All rights reserved.
Notes: 33rd International Conference on Metallurgical Coatings and Thin Films, San Diego, CA, MAY 01-05, 2006
Abstract: Synchrotron x-ray diffraction combined with in situ tensile testing is used to investigate the anisotropic elastic behavior of gold thin films exhibiting a fiber texture and columnar grains. Micromechanical modeling based on the self-consistent model and accounting for both crystallographic and morphological textures is applied. Flat-disk shaped inclusions must be used in the model to reproduce accurately experimental data, owing to the surface effects. (c) 2006 American Institute of Physics.
Abstract: The elastic behavior of gold thin films deposited onto Kapton substrate has been studied using in situ tensile tester in a four-circle goniometer on a synchrotron beam line (LURE facility, France). The mechanical description of the substrate-thin film composite structure has been developed to determine the stress tensor in the film while the strong 111 fiber texture was taken into account using the crystallite group method (CGM). CGM strain analysis allowed us to forecast the nonlinear relationship between strain and sin(2)psi obtained for the thin films due to the strong anisotropy of gold. A least-square method was used to fit the overall experimental data with good accuracy and allows determining all single-crystal elastic constants. (c) 2005 American Institute of Physics.
Abstract: The functionality and lifetime of thin film/substrate set depend mainly on its mechanical properties. Probing and improving the thermomechanical behaviour (stability) are then of utmost importance. Amorphous carbon thin films, 320 nm thick, have been deposited by a sputtering technique on silicon wafers, 500 and 200 mu m thick. The microstructure and the mechanical properties (hardness, indentation reduced modulus and average in-plane stresses) have been investigated using Raman and infrared spectroscopies, silicon curvature and nanoindentation experiments. In particular, the evolution of global stress in the film has been analysed in situ during an annealing treatment while the evolution of the mechanical response (elastic and plastic) induced by nitrogen post irradiations was surveyed by nanoindentation. We observed a rather good thermal stability of the film/substrate set and the presence of hydrogen in the film is discussed. Further, nitrogen irradiation and incorporation were observed to induce a dramatic decrease of the mechanical performance of the films. These behaviours are discussed in view of the thin film structure. (c) 2004 Elsevier B.V All rights reserved.
Notes: Symposium on Synthesis, Characterisation and Advanced Application of Amorphous Carbon Films, Strasbourg, FRANCE, MAY 24-28, 2004
Abstract: Uniaxial tensile testing on thin film/kapton composite specimens has been used to determine thin film elastic constants by X-ray diffraction. The method has been applied to a 140-nm-thick tungsten film which is elastically isotropic and to a 560-nm-thick gold film which is elastically anisotropic. The experimental a-vs.-sin 20 curves are linear for the polycrystalline isotropic tungsten film and nonlinear for the textured gold film. It is shown that a linear analysis of a-vs.-sin zip curves allows the direct determination of elastic constants of the tungsten film, while the use of the crystallite-group method is proposed to analyse the nonlinear behaviour of epsilon-vs.-sin(2)psi curves of the fibre-textured gold film. (C) 2004 Elsevier B.V All rights reserved.
Notes: 31st International Conference on Metallurgical Coatings and Thin Films, San Diego, CA, APR 19-23, 2004
Abstract: Au films of 8.9 nm thickness have been sputter deposited onto a (001) GaAs substrate at room temperature. An average grain size of 10 nm and no texture were obtained. Subsequent, nanoindentation tests were performed on the coated specimens and the mechanical response was compared to that of a bulk GaAs sample with the same crystallographic orientation. Furthermore, the loading-unloading curves were analysed in view of transmission electron microscopy plan-view images obtained on the deformed substrate-film specimens and compared to results previously reported in the literature for bulk sample. Constrained plasticity of the films was observed to occur for residual depth to thickness ratio below 0.67. Further, plastic deformation of the substrate happened on coated specimens at loads less than those required to plastically deform bare substrate. (C) 2004 Elsevier B.V. All rights reserved.
Abstract: The elastic constants (compliances s(ij)) of a textured anisotropic thin film deposited on a substrate have been determined. Using x-ray diffraction to measure the intragranular strain and a tensile machine to deform in situ the samples, an analytical method is described and has been developed for fiber textured thin films. The determination of thin film compliances only requires the knowledge of the substrate elastic constants. In the case of a 260-nm-thin gold film, the compliances were found to be slightly different from the corresponding bulk material ones. (C) 2003 American Institute of Physics.
Abstract: The objective of the present work is to study the elastic behaviour of composites exhibiting strong mechanical contrast components, namely, nanostructured metallic thin films deposited onto polymeric substrates. The stiff film/compliant substrate composites are submitted to complex stress fields during elaboration or applications and the use of a biaxial tensile device allows us mimicking the stress field of in-service thin films. The mechanical characterization of such structures and the relationship with the microstructure still require for further understanding both from fundamental and technological point of view. In such a way, the strain measurements at the macroscopic level have to be correlated with those at the microscopic level. In the present study, the applied strains were measured in situ both by X-ray diffraction (at the microscopic scale) and by digital image correlation (at the macroscopic scale). We used the biaxial testing machine dedicated to the DiffAbs beam line at the French synchrotron SOLEIL, which allows for controlling equi- or non-equi-biaxial loading on thin films supported by polymeric substrates. The metallic thin films were produced via Physical Vapour Deposition onto the centre of a cross-shaped polyimide substrate (Kapton (R)). The film-substrate composites were then deformed in the DiffAbs X-ray goniometer. Grain interaction models are very simple in the case of perfect local elastic isotropic materials such as tungsten. Such a material allows for directly comparing micro-strains (X-ray elastic strains) to macro-strains (DIC strains). The first results concerning W/Cu thin films deformed in situ with this biaxial testing machine are presented. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICM11
Notes: 11th International Conference on the Mechanical Behavior of Materials (ICM), Como, ITALY, 2011
Abstract: The mechanical behaviour of multilayered W/Cu thin films on polyimide substrate has been investigated at different scales and using complementary X-ray techniques and compared to finite element analysis. Mechanical testing has been carried out using a new biaxial tensile machine which allows for testing in controlled biaxial loading condition. This device has been developed for synchrotron measurements at DiffAbs beamline of the French synchrotron radiation facility (SOLEIL, Saint Aubin).
Notes: 14th International Conference on Experimental Mechanics (ICEM14), Poitiers, FRANCE, JUL 04-09, 2010
Abstract: Performing a complete in-situ strain measurement of polycrystalline thin films using X-ray diffraction is time consuming with most standard diffraction beamlines at synchrotron facilities and not realistic with laboratory diffractometers. Two dimensional detection is shown to enable relatively fast and reliable X-ray strain measurements during continuous in-situ tensile testing of metallic films deposited on polyimide substrates. We show in this paper the advantages to perform this kind of measurements as compared to those with punctual detection.
Notes: 14th International Conference on Experimental Mechanics (ICEM14), Poitiers, FRANCE, JUL 04-09, 2010
Abstract: We have shown a strong texture effect on elastic properties of gold thin films deposited by physical vapour deposition. Elastic properties of non-textured and 111 fiber textured gold thin films were investigated by x-ray diffraction combined with in-situ tensile testing and Brillouin light scattering. These static and dynamic methods allowed characterizing the local and macroscopic elastic behavior of gold films.
Notes: 12th International Conference on Phonon Scattering in Condensed Matter (PHONONS 2004), Paris, FRANCE, JUL 15-20, 2007
Abstract: X-ray diffraction is used in combination with tensile testing for measuring elastic properties of metallic thin films. Size effect, elastic anisotropy and grain morphologies are considered in all these experiments and supported by different kind of numerical simulations operating at different length scales. Such instrumental studies are time consuming even if synchrotron sources are used. New experiments are under progress for reducing acquisition data and improving precision on strain measurements. After introducing briefly the main principles and results of our techniques, first promising measurements on nanometric W/Cu multilayers using 2D CCD detectors and high monochromatic flux at the Advanced Light Source Berkeley (USA) on beam line 11.3.1 are presented. In addition, simulation experiments for analyzing elasticity in textured gold film are discussed.
Notes: 7th European Conference on Residual Stresses (ERCS 7), Berlin, GERMANY, SEP 13-15, 2006
Abstract: The elastic behavior of gold thin films deposited onto Kapton substrate has been studied using in-situ tensile tester in a four-circle goniometer at a synchrotron beam line (LURE facility, France). Knowing the stress tensor in the film, the strong 111 fibre texture was taken into account using the Crystallite Group Method (CGM). CGM strain analysis allows predicting a non linear relationship between strain and sin(2) Psi obtained for the thin films due to the strong anisotropy of gold. In contrast, the average of strains in longitudinal and transversal directions varies linearly with sin(2) Psi. The evolution of the slope of these curves as a function of the applied stresses in the film allowed determining the single-crystal elastic constant s(44) of thin gold films.
Notes: 11th Symposium on Thin Film - Stresses and Mechanical Properties held at the MRS Spring Meeting, San Francisco, CA, MAR 28-APR 01, 2005
Abstract: The mechanical behavior of W/Cu multilayers with periods ranging from 24 down to 3 nm prepared by ion beam sputtering was analyzed using a method combining X-ray diffraction and tensile testing, and instrumented indentation. Cracks perpendicular to the tensile axis observed by optical microscopy were generated in the films under the largest applied tensile stresses. These cracks may appear in the multilayer while W layers are still in a compressive stress state. Elastic modulus and hardness values were extracted from nano-indentation data. Crack initiation and elastic constants were observed to depend on the period of these multilayers.
Notes: 11th Symposium on Thin Film - Stresses and Mechanical Properties held at the MRS Spring Meeting, San Francisco, CA, MAR 28-APR 01, 2005
Abstract: Wear and corrosion behaviors of coated materials are tightly controlled by the coating structural and mechanical states and thus, the deposition process such as evaporation and sputtering. In this study, structural and mechanical characterization of stainless steel films have been done by X-ray diffraction and nanoindentation. A softening of the Young modulus is evidenced in the films with respect to the bulk state for both deposition processes. Using the measured elastic constants for X-ray residual stresses analysis, the stress value then obtained are equivalent to the mechanical one. There are found to be high - between 1 and 3 GPa - but of opposite sign considering either evaporation nor sputtering. A correlation with the film microstructure is observed.
Notes: 4th International Conference on Processing and Manufacturing of Advanced Materials, UNIV CARLOS III MADRID, MADRID, SPAIN, JUL 07-11, 2003
