bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress Relaxation in Uniquely Oriented SiGe/Si Epitaxial Layers
Authors: Ware M. E. , Nemanich R. J. 
Published: April 2011

AbstractThis study explores stress relaxation of epitaxial SiGe layers grown on Si substrates with unique orientations. The crystallographic orientations of the Si substrates used were off-axis from the (001) plane towards the (111) plane by angles, θ = 0, 10, and 22 degrees. We have grown 100nm thick Si(1−x) Ge(x) epitaxial layers with x=0.3 on the Si substrates to examine the relaxation process. The as-deposited films are metastable to the formation of strain relaxing misfit dislocations, and thermal annealing is used to obtain highly relaxed films for comparison. Raman spectroscopy has been used to measure the strain relaxation, and atomic force microscopy has been used to explore the development of surface morphology. The Raman scattering indicated that the strain in the as-deposited films is dependent on the substrate orientation with strained layers grown on Si with 0 and 22 degree orientations while highly relaxed films were grown on the 10 degree substrate. The surface morphology also differed for the substrate orientations. The 10 degree surface is relatively smooth with hut shaped structures oriented at predicted angles relative to the step edges.
Coherent and Incoherent Relaxation in III-V Heterostructures
Authors: Rocher André , Snoeck Etienne 
Published: April 2011

AbstractThe relaxation for large lattice mismatch systems such as GaSb/GaAs and GaAs/InP has been studied by numerical analysis of HREM images. The GaSb/GaAs epitaxial system can be obtained with an interface constituted by a perfect square array of Lomer dislocations. GaSb appears to be coherently and homogeneously relaxed. For GaAs/InP grown at 450°C the GaAs layer becomes well relaxed at some distances from the interface by a network of randomly distributed partial and 60° dislocation segments with a limited length. At low temperature, the plastic relaxation appears directly at the growth front when the individual adatoms take a position different from the ideal pseudomorphic one. In this case, the relaxation mechanism is incoherent.
Wafer Scale Testing of MEMS Structural Films
Authors: Gally Brian J. , Abnet C. Cameron , Brown Stuart , Chui Clarence 
Published: April 2011

AbstractBiaxial modulus and residual stress of silicon-rich silicon nitride (Si3 + xN4−x) films on silicon substrates were measured at multiple discrete locations across wafer surfaces using a versatile bulge testing method. An array of 0.2 μm thick silicon nitride membranes were fabricated across the surface of 100 mm diameter wafers. The membranes were 1 mm square. Material properties of the film were extracted by measuring the deflection of the silicon nitride membranes under controlled pressure loading conditions. Pressures from 0 to 12 psi were applied across the membranes, while their deflected shapes were measured with a white light interferometer. Numerical analysis of the measured pressure-deflection behavior of the membranes enabled the biaxial modulus and residual stress of the film to be mapped over the wafer surface. These initial results indicated that the technique was able to determine biaxial modulus to within ±1 % and residual stress within ±4 %. Furthermore, the technique can be applied to composite membranes, enabling the determination of biaxial modulus and residual stress of an additional film subsequently deposited upon the membrane film.
Nanoindentation Probing of Environmental Effects on Polymer Coating Properties
Authors: Xia X. , Rowenhorst D. , Yoder K. B. , Scriven L. E. , Gerberich W. W. 
Published: April 2011

AbstractHumidity and temperature control accessories for Hysitron Triboscope have been developed to study the environmental influence on in situ properties of drying coatings. Mechanical properties of drying poly (vinyl alcohol) (PVOH) and poly (vinyl pyrrolidone) (PVP) coatings on silicon wafer were measured under different humidities. The modulus results were compared with outputs of elastic, plastic and viscoelastic theories of indentation testing.
Mechanical Properties and Toughening of a Polymethylsilsesquioxane Network
Authors: Zhu Bizhong , Katsoulis Dimitris E. , Zank Gregg A. , McGarry Frederick J. 
Published: April 2011

AbstractPolysilsesquioxanes are finding wider uses in microelectronics. However these materials are brittle and their mechanical behaviors need to be better understood. In this paper the mechanical properties of a cured methyl silsesquioxane network are studied and they are found to vary strongly with curing conditions. In the investigated curing temperature range there seems to be a correlation between the fracture toughness (KIc) and the viscoelastic transitions, which are affected by the network crosslink density. A higher crosslink density suppresses the cc and β transitions and reduces the KIc. A toughening approach is designed and its applicability is demonstrated by the increased fracture toughness.
Mechanical Stress Measurements in Damascene-Fabricated Aluminum Interconnect Lines
Authors: Besser Paul R. 
Published: April 2011

AbstractThe mechanical stress state of damascene-fabricated Al interconnect lines was determined on an array of lines on the product die of a logic technology device. Narrow, unpassivated, damascene Al lines have a purely hydrostatic stress (108 MPa). The hydrostatic stress of damascene Al lines (411 MPa) is much larger once the dielectric is deposited. However, the maximum shear stress remains small in magnitude, compared to RIE Al lines of similar thermal history and aspect ratio. The stress of damascene lines was measured as a function of linewidth. Unpassivated, wide lines, have compressive stresses along the length and width and zero along the line height. Passivated wide lines have a biaxial, tensile stress in-plane and zero along the line height.
Passivated Interconnect Lines: Thermomechanical Analysis and Curvature Measurements
Authors: Wikström A. , Gudmundson P. , Suresh S. 
Published: April 2011

AbstractIt is well known that curvature measurements may be used to obtain volume averaged stresses in thin continuous films and unpassivated lines without knowledge of the material properties of the film or lines. However, recently a method was presented which makes it possible to use curvature measurements also for the determination of volume averaged stresses in passivated lines. Since the problem is statically indeterminate the method requires knowledge of the material properties of the lines and passivation. The sensitivity of the method to uncertainties in material properties and curvature data is here investigated by utilizing the finite element method for anisotropic Cu or Al lines embedded in SiO2 passivation. Furthermore, the method is extended to cover the case of different stress-free temperatures for the lines and passivation respectively.
Quantitative Study of Nanoscale Contact and Pre-Contact Mechanics Using Force Modulation
Authors: Asif S. A. Syed , Wahl K. J. , Colton R. J. 
Published: April 2011

AbstractFor submicron-scale mechanical property measurements, depth sensing nanoindentation techniques are very successful and gaining much attention. However, for ultra-small volumes of materials below a length scale of 10 nm, measuring the quantitative mechanical properties of materials is still a problem. The atomic force microscope (AFM) has very good surface sensitivity and has been shown to measure nanomechanical properties. However cantilever instability, conventional force detection and displacement sensing make contact area measurement difficult, hence the measured mechanical properties are usually only qualitative. In this article, we show that combining force modulation with depth sensing nanoindentation allows measurement of the mechanical properties of materials on the nanometer scale. With this technique we have studied the role of oxide layers on the mechanical response of Si surfaces. We also present a novel quantitative stiffness imaging technique, which can be used to directly map the mechanical properties of materials with submicron lateral resolution.
Hardness and Elastic Modulus Measurements of AIN and TiN Sub-Micron Thin Films Using the Continuous Stiffness Measurement Technique with Fem Analysis
Authors: Rawdanowicz T. A. , Sankar J. , Narayan J. , Godbole V. 
Published: April 2011

AbstractThe hardnesses and elastic moduli of aluminum nitride (AIN) and titanium nitride (TiN) sub-micron thin films pulsed laser deposited (PLD) on silicon (111) were measured using nanoindentation based on a continuous stiffness measurement (CSM) technique. Thin film thicknesses, based on profile measurements of simultaneously grown step samples, are 210 nm and 180 nm with surface roughnesses of 12 nm and 2 nm for AlN and TiN, respectively. X-ray diffraction showed AlN as a highly textured polycrystalline AlN wurzite structure with a (0001) orientation and TiN as a cubic structure with a (111) orientation. The CSM technique provided hardness and elastic modulus as a function of depth. Finite element modeling (FEM) aided in determining the optimum indenter contact depth at which the thin films behaved as a semi-infinite solid with negligible substrate induced artifacts. Hardnesses of these AlN and TiN thin films were, determined analytically, 25 GPa and 33 GPa, as compared to FEM results of 24 GPa and 30 GPa, respectively. The elastic moduli measured 320 GPa and 370 GPa for these AlN and TiN thin films, respectively.
Structural Characterization and Raman Studies of SrBi2Ta0.8Nb1.2O9 Thin Films
Authors: Srinivas S. , Das R. R. , Mercoda J. , Fachini E. R. , Perez W. , Katiyar R. S. 
Published: April 2011

AbstractThe effect of growth conditions such as substrate temperature and oxygen partial pressure on the microstructure and properties of pulsed laser deposited SBTN thin films on Si(100) and MgO(100) substrates have been studied. Crystallization of films begins at room temperature but, the obtained phase was non-ferroelectric. The influence of oxygen pressure (150 to 450 mTorr) on crystallinity of the films deposited on Si(100) at 750°C is negligible. XPS studies of as-deposited films reveal that the oxygen vacancies are preferably present near the Bi ions at the Bi2O2 layers and vary with substrate temperature and oxygen partial pressure. Also, XPS studies of Sr 3d core level for SBTN films suggest that the oxygen ions in the Sr(Ta/Nb)2O7 perovskite layers are much more stable than those in the Bi2O2 layers. Micro-Raman studies of SBTN films deposited below 700°C show Raman modes of a non -ferroelectric phase.
Effect of Crystallographic Texture on Ferroelectric Performance of PZT Thin Films
Authors: Fox G. R. 
Published: April 2011

AbstractA large set of films with textures ranging from almost fully random to highly {111} textured were generated using an ULVAC ZX-1000 production sputter deposition machine. The PZT texture was altered by changing the {111} texture of the underlying Pt electrode, but the PZT thickness, composition, sputter deposition conditions, and crystallization anneals were held constant for all samples. X-ray diffraction peak intensities were used to calculate the volume fraction of {111}, {100}, and randomly oriented material composing the PZT films. All samples contained less than a 6% {100} textured volume fraction. It was found that the switchable polarization is linearly dependent on the {111} textured volume fraction. The voltage required to achieve 90% saturation of the switchable polarization also has a linear dependence on the {111} textured volume fraction. The rate of fatigue and degradation of the switchable polarization caused by same-state and opposite-state retention tests were independent of the {111} textured volume fraction.
Bottom Electrode Effects in Controlling Orientation of Lead Zirconate Titanate Films Deposited by Chemical Solution Deposition
Authors: Neumayer Deborah A. , Saenger Katherine L. , Laibowitz Robert B. , Shaw Thomas M. , Mih Rebecca , Grill Alfred 
Published: April 2011

AbstractThe microstructure and electrical properties of lead zirconate titanate Pb(Zr,Ti)O3 (PZT) films prepared by chemical solution deposition (CSD) with and without lead titanate (PT) seed layers were examined as a function of Ir/lr oxide electrode type. The novel PZT CSD solution was prepared from a mixture of zirconium and titanium butoxyethoxides and lead ethylhexanoate dissolved in butoxyethanol. The use of excess-lead (PbxsTi) and stoichiometric PT seed layers was found to promote PZT(111) orientation on Ir but not on Ir oxide. Ir substrate thickness was observed to influence orientation of PZT deposited on stoichiometric PT with greater PZT(111) texturing on thinner Ir(111) substrates. PZT with greater PZT(111) texturing tended to have greater remanent polarization (2Pr, μC/cm2). PZT deposited on stoichiometric PT seed layers on Ir(111) was of higher film quality than PZT deposited on PbxsTi seed layers on Ir(111). The PZT films deposited on stoichiometric PT on Ir(111) had enhanced PZT(111) orientation, a reduced pyrochlore content, and tended to saturate at lower coercive fields, have higher remanent polarization, squarer hysteresis loops with less tilt and greater fatigue endurance. The use of iridium oxide top electrode was demonstrated to significantly improve fatigue endurance compared to use of an iridium top electrode.
Stoichiometry and Interdiffusion in PZT Thin Films Studied by Transmission Electron Microscopy
Authors: Sagalowicz L. , Muralt P. , Hiboux S. , Maeder T. , Brooks K. , Kighelman Z. , Setter N. 
Published: April 2011

AbstractElectrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed.Diffusion mechanisms have been studied for Pt based electrode systems and RuO2-based electrode systems developed for direct integration onto silicon. The materials studied were composed of stacks of silicon-silicon oxide, an adhesion layer (Ti, Ta or TiOx), an electrode (Pt or RuG2) and PZT (45/55). The PZT was deposited by sol gel using the same parameters to allow for comparison of the different electrodes. Four different electrode / adhesion layer materials were compared (Pt/Ti, Pt/TiOx, Pt/Ta and RuO2 / TiO2). In the case of Pt, lead and oxygen diffusion through the electrode is observed. While the initial Ta layer transforms into a homogeneous pyrochlore phase, the Ti adhesion layer is heavily deformed. In the case of TiOx the lead is mainly incorporated at the interfaces with Pt and with SiO2. No lead diffusion to the adhesion layer is observed for the RuO2 electrode. In-situ sputtering and sol-gel deposition of PZT are also compared. The sol-gel films are close to the right stoichiometry for the perovskite while the sputtered films contained an excess of lead. No sign of second phase is found by X-ray diffraction (XRD), by EDS and by high resolution transmission electron microscopy (HRTEM) which suggests that the excess lead is accommodated in the perovskite lattice.
Phase Formation Studies and Structural Properties of Laser Ablated (Pb,La)(Zr, Ti)O3-Thin-Films on Stainless Steel
Authors: Klarmann R. , Kuhn M. , Schey B. , Lindner J. K. N. , Biegel W. , Stritzker B. 
Published: April 2011

AbstractIt is shown that high-quality La-doped PZT-films, (Pb,La)(Zr,Ti)O3, can be deposited by pulsed laser deposition (PLD) directly onto stainless steel substrates resulting in a very simple bicomponental system with high potential for sensor applications. This is an astonishing result, since there is quite a substantial lattice mismatch between the substrate and the PZT-film. Careful investigations revealed the existence of a thin oriented nickeloxide layer at the surface of the stainless steel. The formation of this interface layer leads to a reduction of the lattice mismatch thus affecting the subsequent phase formation of the perovskite PZT. The interface was examined by RBS, XRD, TEM / X-TEM studies and SIMS depth profiling. The phase formation and stoichiometry of the PZT films were investigated by XRD and EDX and their microstructure and texture by SEM and XRD pole figure measurements.
Measuring Bimodal Crystallographic Texture in Ferroelectric PbZrxTi1-x O3 Thin Films
Authors: Vaudin Mark D. , Fox Glen R. 
Published: April 2011

AbstractA powder x-ray diffraction method has been developed to quantify textured volume fractions in thin films. It has been applied to {111}, {100} and randomly oriented PbZrxTi1-xO3 in 200 nm thick films used for ferroelectric random access memory applications. The integrated and peak intensities of 100, 110, 200 and 222 Bragg peaks from an untextured PZT film were determined by applying a thickness correction to a θ–2θ scan obtained from random powder of the same composition as the film. X-ray scans were made on the same peaks from the PZT film specimens. The distributions of grain orientation for the {111} and {100} populations in the films were determined from ω scans which were obtained from the films using 100, 200 and 222 scattering angles and corrected for defocussing and absorption. To determine the total volume fraction of each population of grains, the ratios of the integrated film peak intensities to the corrected powder integrated peak intensities were multiplied by the integrals of the corrected ω scans.
Low-Voltage Pb(Zr,Ti)O3 Film Capacitors: Control of Charge Relaxation at the Interfaces
Authors: Stolichnov I. , Tagantsev A. , Gentil S. , Hiboux S. , Muralt P. , Setter N. , Cross J. S. , Tsukada M. 
Published: April 2011

AbstractIt is suggested that the processes of charge injection and entrapment at the interfacial layer of Pb(Zr,Ti)O3 (PZT) film capacitors are responsible for both polarization fatigue and size effects on ferroelectric switching. The study of the charge injection by analyzing the dependence of coercive field on maximum polarization shows that there is a direct relationship between the charge injection properties and fatigue performance. Based on our results, we conclude that enhancement of charge relaxation at the interfaces of PZT capacitors results in two positive effects: improvement of polarization fatigue performance and suppression of size effects on ferroelectric switching, which are detrimental for low-voltage PZT film capacitors.This idea has been implemented experimentally by introducing a thin RuO2 layer into the top-electrode interface of the Pt/PZT/Pt capacitor. PZT film capacitors of 100–170 nm thickness prepared in this way exhibited substantially improved fatigue in combination with weak size effects, which allows reduction of the operation voltage down to 0.8 V without degradation of the hysteresis properties. Our results show that the control of charge relaxation at the interface is a key issue for development of the low-voltage ferroelectric capacitors.
Ferroelectric and Piezoelectric Properties of MOCVD Pb(Mg1/3Nb2/3)O3-PbTiO3 Epitaxial Thin Films
Authors: Baumann P. K. , Bai G. R. , Streiffer S. K. , Auciello O. , Ghosh K. , Stemmer S. , Munkholm A. , Thompson Carol , Kim D.-J. , Maria J.-P. , Kingon A. I. 
Published: April 2011

AbstractWe have grown epitaxial Pb(Mg1/3Nb2/3)O3 (PMN) and (1-x)(Pb(Mg1/3Nb2/3)O3)- x(PbTiO3) (PMN-PT) thin films by metalorganic chemical vapor deposition at 700 - 780°C on (100) SrTiO3 and SrRuO3/SrTiO3 substrates. The zero-bias permittivity and loss measured at room temperature and 10 kHz for 220 nm thick pure PMN films were 900 and 1.5%, respectively. For PMN-PT films, the small-signal permittivity ranged from 1000 to 1500 depending on deposition conditions and Ti content; correspondingly low values for the zero-bias dielectric loss between 1 and 5% were determined for all specimens. For PMN-PT with x of approximately 0.30–0.35, polarization hysteresis with Pr,≈18μC/cm2 was obtained. Initial piezoresponse data are discussed.
Organic Light Emitting Diode Directly Fabricated on a Polymer Waveguide Device
Authors: Ohmori Yutaka , Ueta Hiroshi , Hikita Makoto , Yoshino Katsumi 
Published: April 2011

AbstractOrganic light emitting diodes (OLEDs) which consists of 8-hydroxyquinoline aluminum (Alq3) and diamine derivative (TPD) were directly fabricated on a polymer waveguide device. Polymer waveguide device consists of deuterated methacrylate polymer core and UV cured epoxy resin cladding. One of the edges of the polymer waveguide was cut in 45 degree, which was served as a mirror, in order to introduce the output light from OLED to the waveguide. Indium-tin oxide (ITO) or semi-transparent aluminum metal was deposited onto the polymer waveguide, which served as anode. The OLED was directly fabricated by evaporation technique at the edge of a waveguide, whose edge served as a mirror.Emission and transmission characteristics of the light from red-light-emitting OLED are also discussed as a light source for the polymer based waveguide with low transmission loss.
Enhanced Electrooptic Activity of Nlo Polymers Via the Use of Conductive Polymers
Authors: Grote J. G. , Drummond J. P. , Zetts J. S. , Nelson R. L. , Hopkins F. K. , Zhang C. , Dalton L. R. , Steier W. H. 
Published: April 2011

AbstractWe have demonstrated a 3 to 13 times increase in the effective electro-optic (EO) coefficient of electrode poled nonlinear optical polymers using a conductive polymer cladding, compared to using passive polymer claddings. We have also demonstrated the lowest poling voltage to date, 300 V, for a 2 μm thick NLO polymer film. Since the cladding material is more conductive than the core material, the majority of the applied poling voltage is dropped across the core, realizing a higher EO coefficient than for conventional devices using passive polymer claddings and has the potential for in-situ poling. These results show promise for shorter, lower operating voltage devices.
Dynamic Response of the Electro-Optic Effect in Epitaxial Ferroelectric Thin Films
Authors: Hoerman B. H. , Majewski J. C. , Nichols B. M. , Teren A. , Wessels B. W. 
Published: April 2011

AbstractThe dynamic response of the electro-optic coefficients and the electronic polarizability for epitaxial thin films of KnbO3 and BaTiO3 are measured. For these two systems a logarithmic dependence of the electro-optic response and the polarization on time was observed after removal of an applied electric field. The dynamic response of the electro-optic effect and the polarization of the films are attributed to the same physical mechanism, which we associate with the dynamic response of ferroelectric nanodomains.
Waveguiding and 1.54 μm Er3+ Photoluminescence Properties of Erbium Doped Silicon Rich Silicon Oxide
Authors: Seo Se-Young , Han Hak-Seung , Shin Jung H. 
Published: April 2011

AbstractThe waveguiding and 1.54 μm Er3+ photoluminescent properties of Er doped silicon-rich silicon oxide (SRSO) are investigated. Erbium-doped SRSO films, which consist of nanocrystalline Si clusters embedded inside Si0 2 matrix, were deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH4 and O2 with concurrent sputtering of erbium. The excess Si content of the SRSO films ranged from 0 to 10 at. %, and Er content ranged from 0.01 to 0.3 at. %. After deposition, films were rapid thermal annealed at temperatures between 750 and 1150°C for durations ranging from 2 to 20 min. to precipitate silicon nanoclusters. All films show strong room temperature 1.54 μm Er3+ photoluminescence. The luminescence lifetimes that can be > 6 msec. The refractive indices of the SRSO films range from 1.48 to 2.47, increasing with increasing excess Si content. Thus, waveguides can be formed easily by depositing erbium doped SRSO films on 1 μm thick SiO2 films. Furthermore, carrier-induced de-excitation mechanisms of excited erbium atoms in SRSO are nearly completely suppressed in such SRSO films, indicating that population inversion of Er3+ ions by carrier-mediated excitation is possible.