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Concurrent in-situ four-point probe resistivity and high resolution synchrotron x-ray diffraction measurements were used to characterize room temperature recrystallization in electroplated Cu thin films. The x-ray data were used to obtain the variation with time of the integrated intensities and the peak-breadth from the Cu 111 and 200 reflections of the transforming grains. The variation of the integrated intensity and resistivity data with time was analyzed using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. For both 111-textured and non-textured electroplated Cu films, four-point probe resistivity measurements yielded shorter transformation times than the values obtained from the integrated intensities of the corresponding Cu 111 reflections. In addition, the JMAK exponents fitted to the resistivity data were significantly smaller. These discrepancies could be explained by considering the different material volumes from which resistivity and diffraction signals originated, and the physical processes which linked these signals to the changes in the evolving microstructure. Based on these issues, calibration of the resistivity analysis with direct structural characterization techniques is recommended. [ABSTRACT FROM AUTHOR]

The microstructural evolution within plated Cu films has been investigated using high-resolution x-ray diffraction, revealing a change in strain state within the recrystallized grains and the surrounding matrix with time. By approximating the case of an isolated grain in a randomly textured material as an Eshelby inclusion in an elastically isotropic matrix, we can determine the elastic strain energy in addition to the interaction strains that develop within the grain due to the effects of elastic anisotropy. The elastic strain energy density generated by a grain possessing cubic symmetry with arbitrary orientation within an elastically isotropic matrix has been compared to that within a fiber-textured film, revealing that the former case possesses less strain energy. These results suggest that the recrystallization of Cu (111) grains from an electroplated film with a small, initial grain size is less energetically favorable for films exhibiting strong (111) texture than for a randomly textured film. Experimental results indicate a sequence that emerges during the recrystallization process: (111) grains grow first, suggesting that the decrease in surface energy provided by the (111) surfaces is larger than the increase in elastic strain energy created by (111) grains. For sufficiently thick films, (100) grains emerge, lowering the strain energy density in the film, after (111) grain growth has saturated because no further decrease in energy is supplied by (111) surface growth. By examining plated Cu films of different thicknesses, we correlate the appearance of recrystallized (100) grains with a threshold energy density based on the additional energy associated with (100) surfaces relative to (111) surfaces. [ABSTRACT FROM AUTHOR]

Sub-monolayer quantities of Mg are introduced in multilayer stacked ZnMgTe quantum dots (QDs) embedded in ZnSe barriers in order to reduce the hole confinement energy by controlling the bandgaps and band-offsets of ZnTe/ZnSe system having type-II band alignment. The photoluminescence (PL) emission from such ZnMgTe/ZnSe QD structure is found to be a broad band centered at 2.35 eV. The higher energy side of the PL band shows a larger blue-shift with increasing excitation intensity and a faster life-time decay due to a greater contribution of the emission from the smaller size dots and the isoelectronic bound excitons. It is found that the characteristic decay time of the PL evolves along the band with a value of 129 ns at 2.18 eV to 19 ns at 2.53 eV. The temperature dependent PL emission is controlled by two thermally activated processes: ionization of electrons away from QD state to the barrier (EA1 ∼ 3 meV) by breaking the type-II excitons and thermal escape of the holes from the ground state to the barrier (EA2 ∼ 114-116 meV). We propose a modified band diagram and energy levels for this ZnMgTe/ZnSe multilayer QD system by determining the composition of Mg inside the QDs and solving the 1-D Schrodinger's equation and show that Mg incorporation lowers the hole activation energy via modification of the valence band offset without changing the barrier significantly. [ABSTRACT FROM AUTHOR]

We report the structural properties and spatial ordering of multilayer ZnMgTe quantum dots (QDs) embedded in ZnSe, where sub-monolayer quantities of Mg were introduced periodically during growth in order to reduce the valence band offset of ZnTe QDs. The periodicity, period dispersion, individual layer thickness, and the composition of the multilayer structures were determined by comparing the experimental high resolution x-ray diffraction (HRXRD) spectra to simulated ones for the allowed (004) and quasi-forbidden (002) reflections in combination with transmission electron microscopy (TEM) results. Secondary ion mass spectroscopy (SIMS) profiles confirmed the incorporation of Mg inside the QD layers, and the HRXRD analysis revealed that there is approximately 32% Mg in the ZnMgTe QDs. The presence of Mg contributes to higher scattering intensity of the HRXRD, leading to the observation of higher order superlattice peaks in both the (004) and (002) reflections. The distribution of scattered intensity in the reciprocal space map (RSM) shows that the diffuse scattered intensity is elongated along the qx axis, indicating a vertical correlation of the dots, which is found to be less defined for the sample with larger periodicity. The diffuse scattered intensity is also found to be weakly correlated along the qz direction indicating a weak lateral correlation of the dots. [ABSTRACT FROM AUTHOR]

Rotation and strain fields were mapped across silicon-on-insulator (SOI) regions induced by overlying stressed Si3N4 features using x-ray nanobeam diffraction. The distribution in SOI tilt exhibited an antisymmetric distribution with a maximum magnitude of 7.9 milliradians, representing one of the first direct measurements of the lattice tilt conducted in situ within buried layers using a spot size of less than 100 nm. The measured rotation distribution corresponds to simulated values generated by boundary element method modeling, indicating that the strain transfer into the underlying SOI primarily induces elastic deformation. [ABSTRACT FROM AUTHOR]

Time-resolved in situ x-ray diffraction measurements were used to study the room-temperature recrystallization kinetics of electroplated copper thin films with thicknesses between 400 and 1000 nm. The thinnest films exhibited limited recrystallization and subsequent growth of grains, while recrystallized grains in the thicker films grew until all as-plated microstructure was consumed. For all films, recrystallized grains that belonged to the majority texture component, <111>, started growing after the shortest incubation time. These grains exhibited volumetric growth until they achieved the film thickness. After this point the growth mode became planar, with the <111>-type grains growing in the plane of the film. Grains with the <100> direction normal to the film surface started growing after the <111>-type grains switched to planar growth. However, the planar growth of this texture component finished at the same time as the growth of the <111> grains. Profile fitting of the 111 peak permitted the separation of the diffraction signals from recrystallized and as-plated grain populations. The average strains in these two populations, calculated from the peak position of the corresponding {111} reflections, were different, indicating a heterogeneous stress state within this texture component. The increasing volume fraction of recrystallized <111> grains with time was monitored via the variation in the diffracted intensity. This variation could be represented by the Johnson-Mehl-Avrami-Kolmogorov model. [ABSTRACT FROM AUTHOR]

We have used scanning microdiffraction topography to determine the mismatch strains and local strain distributions in silicon-on-insulator substrates with overlying thin film stressor features. Analysis of the data using the edge-force model and the Ewald–von Laue dynamical diffraction theory shows the presence of an exponential strain gradient in the vicinity of the buried SiO2/Si-substrate interface. We show that, for simple geometries, it is possible to deduce the sign of the mismatch strain simply by inspecting the microdiffraction topograph. [ABSTRACT FROM AUTHOR]

Strain distributions within a silicon-on-insulator (SOI) layer induced by overlying compressively stressed Si3N4 features were measured using x-ray microbeam diffraction. A comparison of analytical and numerical mechanical models of the depth-averaged strain distributions to the measured strain profiles in the SOI layer indicated a blanket film stress of -2.5 GPa in the Si3N4 features. A two-dimensional boundary element model, implemented to analyze thin film/substrate systems, reproduced the observed strain distributions better than an edge-force formulation due to the incorporation of loading along the Si3N4/Si interface. [ABSTRACT FROM AUTHOR]

We here report results of high resolution x-ray diffraction, x-ray reflectivity (XRR), as well as optical absorption and reflection measurements on ZnSe samples grown by molecular beam epitaxy, with insertion of planar (δ-) regions of both N as an acceptor dopant and Te as a “co-dopant” to facilitate a p-type doping. We note that to enhance the surface diffusion of Te, migration enhanced epitaxy was adopted in the growth of the “δ-layers;” i.e., Te is deposited in the absence of Zn flux. Structural parameters were extracted by simulating the experimental x-ray diffraction curves using a dynamical model. The results show that only the “δ-layers” (with submonolayer thickness) are rich in ZnTe, while the nominally undoped “spacers” have only a low Te concentration. Moreover, the morphology of the surface and interfaces are studied by XRR. Furthermore, the optical absorption and reflection results show that our samples largely preserve the optical properties of the host material (ZnSe). We note that our results, in particular those on the Te concentration, explain the observed good p-type doping of such samples. [ABSTRACT FROM AUTHOR]

Back-reflection images obtained from single-crystal semiconductor substrates using Laue microdiffraction with medium-to-high energy x rays (10–30 keV) may contain double spots, one strong and one weak, for the higher-energy reflections. Some of the weaker spots originate from the back surface of the sample and are due to dynamic diffraction from a finite crystal. Others may be due to epitaxial thin films on the substrate. The intensity and position of the back-surface peaks depend on the x-ray energy, sample characteristics, and diffraction geometry. We provide a set of simple equations that can be used to calculate the separation of such peak pairs. These equations can be used to identify the peaks from the back surface of the sample. [ABSTRACT FROM AUTHOR]

Heteroepitaxial thin-film features that are lattice matched to the underlying substrate undergo elastic relaxation at the free edges of the feature. To characterize the degree of elastic relaxation, we employed synchrotron-based x-ray diffraction techniques to map the change in lattice spacing in the thin film at a submicron resolution. Measurements were conducted on 0.24-μm thick, heteroepitaxially grown SiGe strips of various widths on Si (001). A comparison of the SiGe diffraction peak positions across the features provides a real-space mapping of the extent of elastic relaxation as a function of linewidth. The resultant in-plane normal film stress measurements were compared to calculated values from several elastic mechanical models to assess their validity in predicting stress distributions within the features. [ABSTRACT FROM AUTHOR]

We used hard x-ray fluorescence and soft x-ray transmission microscopy to quantitatively measure “in situ” Cu/SiO[sub 2] interconnect dimensions down to 0.3 μm dimensions. We describe methods and analysis techniques for measuring submicron linewidths, lengths, and thicknesses with accuracies of 30–60 nm precision. The dimensions and shape of submicron Cu vias, W lines, and a 20 nm Ta liner and an electromigration defect (void) were determined by these methods. These nondestructive techniques promise to be useful for nanometer precision metrology studies of a variety of materials systems. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present an analysis of Bragg-Brentano diffraction spectra from blanket thin (10-20 nm) films of polycrystalline Ir, sputter deposited on thermally oxidized Si wafers. We observed that postdeposition annealing sharpened the Ir diffraction peaks, produced enhanced texture, and resulted in the formation of well-defined thickness fringes that were symmetric around the 111 Ir reflection. Scanning electron microscopy confirmed that the fringes were caused by the increased coherence lengths of the annealed grains. Annealed samples subsequently subjected to reactive ion etching exhibited asymmetric fringe patterns, with lower intensity fringes on the high angle side of the 111 Ir peak. Reannealing these samples restored the symmetric fringes. Analysis of the fringe patterns using simple equations and modeling programs in the public domain yielded valuable structural information about the film and the changes caused by processing. These results were verified by x-ray reflectivity measurements and modeling. We conclude that thickness fringe analysis using standard x-ray systems and simple programs can provide cost-effective process diagnostics for high atomic number thin film structures. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Two regions of interest on a copper/tungsten integrated circuit interconnect are imaged using two techniques. Findings show that the two sets of images agree in their main features, but differ for finer features.