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Laser annealing was employed to trigger the solid-state reaction of a thin Co film (2.5 nm) with undoped Si. A metastable disilicide layer was obtained after one laser pulse close to the melt threshold. Its diffraction pattern, relaxed lattice parameter, and residual resisitivity are consistent with the formation of the defective CsCl structure. The CoSi2 phase was found after prolonging the thermal treatment with additional pulses or rapid thermal annealing. Because CoSi is skipped in the phase sequence, CoSi2 layers are more uniform in thickness, have an increased superconductivity and a reduced formation temperature. This approach is compatible with the SALICIDE process and can be used to form smooth contacts in superconducting or regular transistors. [ABSTRACT FROM AUTHOR]

The reaction of a Ni 0.9 Pt 0.1 7 nm-thick thin film with the underlying Si(001) substrate as a function of the annealing temperature was studied using in situ XRD techniques as well as ex situ advanced XRD and TEM imaging on quenched samples. It was found that the Ni 0.9 Pt 0.1 /Si system initially evolves accordingly to diffusion controlled reactions via the development of nano-crystalline Ni-rich Ni 1 − x (Pt) Si x phases that combine the ability of fast kinetic growth and texture inheritance. The system remains then stable over some tens of degrees before Ni(Pt)Si nucleation occurs, once the related energetic barrier is overcome. It was additionally found that this newly observed phase sequence remains valid up to Ni 0.9 Pt 0.1 deposited layer thicknesses of about 16 nm, which is remarkable for such systems. [ABSTRACT FROM AUTHOR]

Improving the thermal stability of Ni/GeSn intermetallics is of great importance to avoid surface degradation and Sn segregation. For this purpose, we studied the effects of pre-amorphization by ion implantation (PAI) of GeSn layers prior to metallization. The impact of Si, Ge, C, or Ge + C PAI was evaluated in terms of phase sequence, morpohological, and electrical evolution during the solid-state reaction. The overall phase sequence, followed by in situ x-ray diffraction, was comparable with or without PAI and went as follows: the Ni 5 (GeSn) 3 hexagonal phase was obtained first, followed by the mono-stanogermanide phase: Ni(GeSn). Nevertheless, the threshold temperature for phase formation varied. These variations, depending on the nature of the implanted ions, can be related to kinetic and/or thermodynamic factors as supported by the analysis of bibliography for silicides and germanides. Additionally, it was reported that the use of Si or Ge implantation did not significantly impacted the surface morphology of the layers. On the other hand, the implantation of C positively impacts the surface morphology evolution by delaying Sn long-range diffusion and Ni(GeSn) agglomeration. This trend was then highly beneficial for preserving electrical stability in an enhanced process window. [ABSTRACT FROM AUTHOR]

Thin films of superconducting V 3 Si were prepared by means of RF sputtering from a compound V 3 Si target at room temperature onto sapphire and oxide-coated silicon wafers, followed by rapid thermal processing under secondary vacuum. The superconducting properties of the films thus produced are found to improve with annealing temperature, which is ascribed to a reduction in defects in the polycrystalline layer. Critical temperatures (T c ) up to 15.3 K were demonstrated after thermal processing, compared to less than 1 K after deposition. The T c was always found to be lower on the silicon wafers, by on average 1.9 ± 0.3 K for the annealed samples. This difference, as well as a broadening of the superconducting transitions, is nearly independent of the annealing conditions. In situ XRD measurements reveal that the silicide layer becomes strained upon heating due to a mismatch between the thermal expansion of the substrate and that of V 3 Si. Taking into account the volume reduction due to crystallization, this mismatch is initially larger on sapphire, though stress relaxation allows the silicide layer to be in a relatively unstrained state after cooling. On oxidized silicon, however, no clear evidence of relaxation upon cooling is observed, and V 3 Si ends up with an out-of-plane strain of 0.3% at room temperature. This strain increases as the sample is cooled down to cryogenic temperatures, though the deformation of the polycrystalline layer is expected to be highly inhomogeneous. Taking into account also the reported occurrence of a Martensitic transition just above the critical temperature, this extrapolated strain distribution is found to closely match an existing model of the strain dependence of A-15 superconducting compounds. [ABSTRACT FROM AUTHOR]

Ni-GeSn based materials are promising in order to obtain contacts in complementary metal oxide semiconductor and Si photonic devices. In this work, a systematic and comprehensive study of the solid-state reaction between NiPt thin films and Ge0.9Sn0.1 layers is carried out. A particular focus is given on the impact of the addition of 10 at. % of Pt in Ni thin films. In situ X-ray diffraction and in-plane reciprocal space map measurements reveal a sequential growth in which the first phase appearing corresponds to a Ni-rich phase: (Ni0.9Pt0.1)5(Ge0.9Sn0.1)3. Then, at 245 °C, the Ni-rich phase vanishes to the benefit of the mono-stanogermanide phase (Ni0.9Pt0.1)(Ge0.9Sn0.1), which is unstable. At 360 °C, a more stable (Ni1–yPty)(Ge1–xSnx) phase is obtained concomitantly to the formation of PtSnx compounds. Finally, Sn segregation occurs at even higher temperatures. Even if Pt addition in Ni thin films complicates the phase formation sequence, it positively impacts the surface morphology and roughness, delays film agglomeration and Sn segregation, and stabilizes the electrical properties of the stanogermanide in a wide range of temperatures. [ABSTRACT FROM AUTHOR]

A direct quantification of a structural in-depth composition in the lead zirconate titanate Pb(Zr,Ti)O3 thin films of morphotropic composition has been conducted using the newly available X-ray nano-pencil beam (i.e., beam size of 100 nm ×1 μm) diffraction approach. We tested two samples with different Zr/Ti chemical gradients. Here, we demonstrate the presence of a significant microstructural gradient between the rhombohedral and tetragonal phases through PbZrxTi1-xO3 (PZT) films with a 100 nm in-depth resolution. The phase gradient extends over around 350 nm, and it is repeated through the PZT film three times, which corresponds to the number of thermal annealings. Moreover, this microstructural gradient is in agreement with the Zr/Ti chemical gradient observed by the secondary ion mass spectroscopy (SIMS). Indeed, the quantity of tetragonal phases rises in the Ti-rich zones as revealed by SIMS, and the quantity of rhombohedral phases rises in the Zr-rich zones. We also demonstrated a huge difference in the in-depth phase variation between the two tested samples. The gradient free sample still contains 4.7% of phase variation through the film and the amplified gradient contains 9.6% of phase variation through the film. Knowing that the gradient free sample shows better electric and piezoelectric coefficients, one can draw a correlation between the chemical composition, crystallographic homogeneity, and electromechanical properties of the film. The more close the film is to the morphotropic composition and the more it is crystallographically homogeneous, the higher the piezoelectric coefficients of the PZT are. Finally, the adequate knowledge of phase variation and its relation to the fabrication technique are crucial for the enhancement of the PZT electro-mechanical properties. Our methodology and findings open up new perspectives in establishing a relevant quantitative feedback to reach an ultimate electro-mechanical coupling in the sol-gel PZT thin films. [ABSTRACT FROM AUTHOR]

Titanium-based contacts are envisioned for the integration of III–V device contacts on a 300-mm platform, such as photodetectors, semiconductor optical amplifiers (SOAs), and III–V silicon hybrid lasers. For the first time, the impact of the thermal budgets of process integration, back-end of line (BEOL), and long-term thermal stress on the electrical characteristics of the Ti/p-In0.53Ga0.47As and Ti/n-InP contacts has been investigated. Additional physical characterizations have been used to supplement the electrical properties on both systems. Results have indicated that, given a thermal budget between 350 °C and 450 °C during 60 s right after metal deposition, 1) Ti as a contact metal has led to contact resistivity in low 10−5 Ω ⋅ cm2 for p-contacts and in mid 10−5 Ω ⋅ cm2 for n-contacts, which is in accordance with the device requirements; and 2) process integration, BEOL, and long-term thermal stress will not induce any change of the electrical properties. In the scope of III–V silicon hybrid laser contact integration, Ti has hence been evidenced as a suitable candidate for both p- and n-contacts. [ABSTRACT FROM AUTHOR]

The local and average texture of thick polycrystalline CdTe films is determined before, upon, and after the coalescence of the initially isolated islands, using electron backscattered diffraction and x-ray powder diffraction. The coalescence and postcoalescence processes lead to a preferential texturation, initially along the <531> and <100> crystallographic directions and then along the <110> preferred orientation. The selection of grain orientation during the film growth is found to be driven by strain energy minimization. A model for the microyield stress is developed when plasticity is confined to each elemental grain and accounts for the <531> and <100> preferred orientations. On the contrary, when plastic deformation can propagate from one grain to its neighbors, the Hall–Petch model applies and leads to the <110> preferred orientation. Furthermore, at the end of growth, the stronger <111> preferred orientation is observed and arises because of kinetic limitations. [ABSTRACT FROM AUTHOR]

The structural evolution in fiber-textured Ti/Si thin films has been investigated by in situ x-ray diffraction, in a temperature range preceding the formation of silicide compounds. At low temperature, thermoelastic behavior of the metallic film was observed. Abnormal thermal behavior of both 002 and 101 diffraction profiles was observed at 360 and 450 °C, which could be understood in terms of Si diffusion, first in Ti grain boundaries, then, into the grains. By combining ex situ strain studies with analysis of the Si local environment in the whole Ti silicide family from Ti[sub 5]Si[sub 3] to TiSi[sub 2], it was possible to determine the stress-free lattice parameters of annealed films. They are significantly higher than the bulk parameters, and indicate that nearly 4.5 at. % Si is present in the Ti grains. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

By combining simultaneously in situ x-ray diffraction and curvature measurements, the stress evolution during silicide formation in thin Pd films deposited on Si substrates has been reliably investigated. The in-plane strain in the silicide is compressive. The combination method also permits the determination of the elastic constants and thermal expansion coefficient of Pd[sub 2]Si ([001] fiber texture): E[sub sil] = 86 ± 8 GPa, v[sub sil] = 0.34 ± 0.05, and α[sub sil] = 13.2 × 10[sup -6] K[sup -1]. It is shown that during growth the average compressive stress increases progressively up to a maximum temperature-dependent value (-1.5 GPa at 220 °C) and then vanishes for long annealing. This behavior is in reasonable agreement with the predictions of a model by Zhang and d'Heurle [S. L. Zhang and F. M. d'Heurle, Thin Solid Films 213, 34 (1992)]. A strain gradient in the growing silicide layer, which is predicted by the model, has been shown. [ABSTRACT FROM AUTHOR]

The force that a deposited film A exerts on its substrate B is usually written as the sum of volumetric and surface (and interface) contributions. In the simplest case (pseudomorphous film, absence of segregation), volumetric and surface contributions can be easily separated through simple force measurements. In this article, we show that, in the presence of segregation, only simultaneous in situ stress, strain, and composition measurements allow the proper analysis of stress establishment in thin films. For this purpose, we discuss how segregation influences both volumetric and surface stresses. More precisely, we show that (1) the separation between a surface and a volumetric stress can be meaningless when segregation occurs; (2) one should carefully distinguish between the true physical thickness and the deposited thickness; (3) surface strain should be accounted for in the analysis of the experimental diffraction data; and (4) when the elastic modulus misfit between film and substrate cannot be neglected the total stress depends explicitly on the shape of the concentration profile. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed the elastic strains in gold/nickel multilayer films using x-ray diffraction. Stress determination using x-ray diffraction; Results and discussion; Conclusions.

In 0.3 Ga 0.7 As quantum wells (QW) embedded in AlGaAs barriers and grown on oxidized patterned (001) silicon substrates by metalorganic chemical vapor deposition using the aspect ratio trapping method are studied. An appropriate method combining cathodoluminescence and high resolution scanning transmission electron microscopy characterization is performed to spatially correlate the optical and structural properties of the QW. A triple period (TP) ordering along the ⟨111⟩ direction induced by the temperature decrease during the growth to favor indium incorporation and aligned along the oxidized patterns is observed in the QW. Local ordering affects the band gap and contributes to the decrease of the optical emission efficiency. Using thermal annealing, we were able to remove the TP ordering and improve the QW optical emission by two orders of magnitude. [ABSTRACT FROM AUTHOR]

The composition and morphology of the product phase after the reaction of Ni thin film with In0.53Ga0.47As substrate at 350 °C were investigated by atom probe tomography, X-ray diffraction,and scanning electron microscopy. Results show the formation of a unique Ni3(In0.53 Ga0.47)As phase with a low concentration in-depth gradient of Ni and the decoration of the grain boundaries by In atoms. These analyses indicate that Ni is the main diffusing specie during the growth of Ni3(In0.53Ga0.47)As phase. The volume of the product phase is higher than the volume of the consumed Ni film as expected for the formation of Ni3(In0.53Ga0.47)As phase. [ABSTRACT FROM AUTHOR]

We take advantage of the zinc distribution of (211)B CdZnTe substrates to probe the lattice-mismatch-induced stress in long-wave infrared HgCdTe layers grown by molecular beam epitaxy. High-resolution x-ray diffraction is used to accurately determine the strain-free lattice parameters of both CdZnTe and HgCdTe, together with the in-plane components of the stress tensor. By using several wafers, the stress evolution is derived over a broad range of lattice mismatch. In particular, stress relaxation is evidenced for mismatch greater than 0.02% and 0.04% for tensile and compressively strained HgCdTe, respectively. In-plane strain anisotropy, expected for the (211) orientation, is only evidenced for the compressive configuration. Strain relaxation is correlated with substrate curvature and rocking-curve peak broadening, providing indirect evidence for plastic relaxation. [ABSTRACT FROM AUTHOR]

Tomography is a standard and invaluable technique that covers a large range of length scales. It gives access to the inner morphology of specimens and to the three-dimensional (3D) distribution of physical quantities such as elemental composition, crystalline phases, oxidation state, or strain. These data are necessary to determine the effective properties of investigated heterogeneous media. However, each tomographic technique relies on severe sampling conditions and physical principles that require the sample to be adequately shaped. For that purpose, a wide range of sample preparation techniques is used, including mechanical machining, polishing, sawing, ion milling, or chemical techniques. Here, we focus on the basics of tomography that justify such advanced sample preparation, before reviewing and illustrating the main techniques. Performances and limits are highlighted, and we identify the best preparation technique for a particular tomographic scale and application. The targeted tomography techniques include hard X-ray micro- and nanotomography, electron nanotomography, and atom probe tomography. The article mainly focuses on hard condensed matter, including porous materials, alloys, and microelectronics applications, but also includes, to a lesser extent, biological considerations. [ABSTRACT FROM PUBLISHER]

We present high-resolution diffraction measurements of the lattice parameters of HgCdTe and CdZnTe. These measurements were performed at various temperatures ranging from room temperature up to 300°C, enabling the determination of the coefficients of thermal expansion (CTE) and the evolution of the HgCdTe film stress during the thermal cycling. It is found that the CTE is linear with the zinc fraction for CdZnTe, while it can be described by a parabolic variation as a function of the cadmium fraction for HgCdTe. The temperature evolution of the stress is found to be dictated by the CTE difference between the substrate and epilayer up to a temperature of 150°C, for which the stress is partially relaxed. For the sample grown on CdTe/Ge, the HgCdTe lattice is found to be fully relaxed at room temperature and the thermoelastic evolution of the stress of HgCdTe is imposed by the coefficient of thermal expansion of the germanium substrate. [ABSTRACT FROM AUTHOR]

A white beam microdiffraction setup has been developed on the bending magnet source BM32 at the European Synchrotron Radiation Facility. The instrument allows routine submicrometer beam diffraction to perform orientation and strain mapping of polycrystalline samples. The setup features large source to optics distances allowing large demagnification ratios and small beam sizes. The optics of the beamline is used for beam conditioning upstream a secondary source, suppressing any possible interference of beam conditioning on beam size and position. The setup has been designed for an easy and efficient operation with position control tools embedded on the sample stage, a high magnification large aperture optical microscope, and fast readout detectors. Switching from the white beam mode to the monochromatic mode is made easy by an automatic procedure and allows the determination of both the deviatoric and hydrostatic strain tensors. [ABSTRACT FROM AUTHOR]

The electromigration threshold in copper interconnect is reported in this paper. The critical product (jL)c is first determined for copper oxide interconnects with temperature ranging from 250degC to 350degC from package-level experiments. It is shown that the product does not significantly change in this temperature range. Then, (jL)c was extracted for copper low-k dielectric (k=2.8) interconnects at 350degC. A larger value than that for oxide dielectric was found. Finally, a correlation between the n values from Black's model and with jL conditions was established for both dielectrics [ABSTRACT FROM PUBLISHER]

Al-0.5%Cu-1%Si thin films deposited onto oxidized Si substrates were subjected to both wafer curvature and in situ transmission electron microscopy thermal cycling experiments between room temperature and 450°C. The evolution of precipitates was monitored during cycling. Chemical analysis revealed that the precipitates are pure Si. Their average size increased from 80&ThickSpace;nm in the as-deposited state to 300&ThickSpace;nm after thermal cycling. The Si precipitates serve as anchoring points for dislocations and grain boundaries. Direct evidence for pipe-diffusion ripening was found in the vicinity of a dissolving precipitate. Real-time measurement of the radius of the precipitate allowed us to estimate the coefficient of pipe diffusion of Si in Al at this temperature. As expected, this coefficient is several orders of magnitude larger than the volume diffusion coefficient. The impact of precipitate ripening on the mechanical behavior of these alloyed Al films will also be discussed. [ABSTRACT FROM AUTHOR]

The diffraction of X-rays by a thin laver (of the order of a few nanometres) with a gradient in interplanar spacings is considered. It is shown that optical coherence over the film thickness leads to diffraction peak positions that no longer obey Bragg's law. Although a fitting of the diffracted intensity is indeed still possible, this has direct consequences on the applicability of more straightforward analysis methods, such as the sin²ψ method, which rely on diffraction peak positions. The intensity and peak position calculations are supported by a comparison with experimental data from a (001) Fe/GaAs thin (3 nm) epitaxic film. [ABSTRACT FROM AUTHOR]

A detailed investigation of the mechanisms related to the low temperature oxidation of nanocrystalline magnetite thin films into maghemite is presented. Despite strong differences in the functional properties of these two phases, structural similarities make it difficult to distinguish between them, and to quantify the oxidation process, particularly in the case of nanostructured polycrystalline layers. Contrary to the case of bulk materials or monocrystalline films and particles, the oxidation processes in nanocrystalline thin film have only scarcely been studied. In this work, structural and optical techniques, including X-ray diffraction (XRD), EXAFS/X-ray absorption near edge structure, FTIR, and Raman scattering, have been used to estimate the oxidation rate of magnetite. The overall oxidation reaction rates are discussed in the framework of two limiting cases corresponding to intra grain diffusion and to grain boundary diffusion. SIMS profiling and electrical measurements were also carried out to better assess the oxidation quantification in order to conclude on the predominant oxidation mechanisms in this heterogeneous material. We propose a qualitative model for the structure, in terms of insulating zone distribution, for partially oxidized films. [ABSTRACT FROM AUTHOR]