bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure Evolution of Al-1.5% Cu Alloy as a Function of Resistance Change Due to Isothermal DC Stressing
Authors: Lee T , Schade M , Merino A , Lee J , Christenson C , Varker C , Evans K 
Published: April 2011

AbstractThis paper investigates Cu segregation and void morphology along AlCu alloy metal lines as a function of resistance change resulting from isothermal DC stressing at 225°C and a current density of J=2×106 A/cm2. The Al-1.5wt.%Cu alloy was deposited via DC magnetron sputtering onto a Si substrate at 525°C with a 1500Å TiW barrier layer. NIST test structures (length = 800µm, thickness = 1.2µm, width = 5 and 10 µm) were utilized in this study. BPSG was used as the insulation layer between Si substrate and conductor. The surface passivation layer was composed of Si3N4/PSG. Various failure criteria were selected to explore the correlation between Cu segregation and void morphology along the metal line and the relative percent resistance change (ΔR/R). The log-normal plots, mean-times-to-failure, and sigmas at each ΔR/R ( -−%, 2%, 5%, 10%, 20%, 100%, 250%) were plotted and listed. The microstructural evolution in terms of void morphology was monitored using SEM. SEM-EDS was used to analyze the Cu concentrations along metal lines tested at various %ΔR criteria.
Modelling Electromigration and Stress Migration Damage in Advanced Interconnect Structures
Authors: Brown Dirk 
Published: April 2011

AbstractPhysical and statistical models have been used extensively to understand and improve electromigration and stress migration induced damage in narrow metal interconnects. As devices continue to shrink, and the interconnect delay becomes a more important fraction of overall circuit delay, the semiconductor industry has begun to make several important changes to the ‘standard’ Al-based interconnect technologies, including (i) a move from metal deposition and metal etch to metal deposition into damascene and dual-damascene structures, (ii) a move from Al-based to Cu-based metallizations, and (iii) a move from oxide to low-k dielectrics between the metal interconnects. The dominant electromigration and stress migration failure mechanisms associated with these advanced interconnect structures are typically different from the failure mechanisms associated with standard Al-based interconnects. In this work, physical and statistical models are used in conjunction with reliability data to compare the failure mechanisms in standard, Al-based interconnects with Cu-based, damascene interconnects. Methods are discussed for determining the dominant failure mechanisms and improving reliability in both types of interconnect.
Early Detection of the Metallization Quality Using Moderately Accelerated Electromigration Stress Conditions
Authors: Scorzoni A. , De Munari I. , Impronta M. , Balboni R. , Kelaidis N. , Foley S. , Forde M. 
Published: April 2011

AbstractIn this work we use a wafer-level, High Resolution Resistance Measuring Technique (HRRMT) to detect fabrication faults of Al-Cu interconnections. Experiments have been performed on two distinct sets of metal lines. The first set includes two lots of 4 μm wide lines which, once tested at moderately accelerated stress conditions, gave largely different life times. A microstructural analysis confirmed a major defectivity of the lot with shorter life time. An accurate examination of the early resistance variations revealed the presence of two distinct and subsequent phases, namely an initial pseudo-parabolic resistance increase followed by a linear resistance drop. Significant differences between the resistance behaviour of the two lots were detected during the first stage, lasting a few hours. Measurable differences could even be detected in the first few minutes. A second group of experiments was launched in order to assess the capability of HRRMT as in-line monitors. Samples from four wafers, one reference wafer and three wafers with intentional process variations, have been tested using our HRRMT at constant temperature and current, simulating an in-line production test. The standard life time of the four wafers have also been collected. Preliminary measurements highlight that a change of life time due to process variation corresponds to changes of the resistance behaviour in the first hours of test. These results pave the way for a new application of high resolution methods to assess the quality of a metallization system in a reasonable amount of time.
Model for Estimation of Metallization Lifetime Including Electromigration and Thermo-Mechanical Stress Relaxation
Authors: Roloff Herbert F. , Fellinger Johannes 
Published: April 2011

AbstractFuture semiconductor technologies with structural dimensions less than 0.35 µm and four or more metallization layers impede the realization of the reliability requirements due to their complexity and increasing operating conditions (>5 mA/µm2). Therefore it is necessary to provide reliability appraisal methods which ensure the operation lifetimes (up to 30 years) required by the market.
Electromigration Damage in Aluminum Alloys Studied by 1/f Noise
Authors: Kruelle C.A. , Ochs E. , Stoll H. , Seeger A. , Bloom I. 
Published: April 2011

AbstractThe electromigration damage in polycrystalline AlSiCu lines caused by dc current densities of the order of magnitude 1010 Am −2 at 500 K has been investigated by long-time high-resolution ac noise measurements over a wide range of temperatures. A multiple-probe setup allowed us to monitor the electrical resistance increase along the line and to show that sudden enhancements of the noise power and the resistance occurred in the same line segment. The peak in the distribution function N(E) of the activation energies E for the defect motion responsible for 1/f noise was found to shift from E0 = 0.7 eV with Gaussian width ΔE = 0.1 eV in the undamaged samples to E0 = 1.0 eV and ΔE = 0.2 eV in the damaged samples. The latter values are compatible with the Cu diffusivity along intermediate-misfit grain boundaries in Al, indicating that the damage process depends not only on the composition but also on the microstructure of the lines. It is proposed that electromigration causes Cu atoms to drift towards and get trapped in grain boundaries, that their thermally activated motion in the boundaries contributes substantially to the 1/f noise, and that eventually the Cu atoms assemble on the anode side of the sample. The dependence of the diffusivity on the grain-boundary mismatch may cause flux divergencies at boundary junctions and thus lead to void formation.
In-Situ X-ray Photoemission Spectromicroscopy of Electromigration in Patterned Al-Cu Lines With Maximum
Authors: Solak H.H. , Lorusso G.F. , Singh S. , Cerrina F. , Underwood J.H. , Batson P. 
Published: April 2011

AbstractWe report the application of a unique photoemission spectromicroscope (MAXIMUM) to the study of electromigration phenomena in Al-Cu interconnects. MAXIMUM is a scanning type photoemission microscope that uses multilayer-coated optics to focus 130 eV x-rays to a sub-0.1 µm spot. An electron energy analyzer collects photoelectrons in a chosen spectral region of interest to form an image of the sample that is sensitive to chemical states of elements on the sample surface. Al-Cu lines were characterized by spectromicroscopy techniques before and after electromigration stressing in the UHV environment of the microscope chamber. We present spectro-micrographs showing the chemical and structural changes on Al-Cu line surfaces as a result of the electromigration process.
Silicon Strength Testing for Mesoscale Structural Applications
Authors: Chen Kuo-Shen , Ayon Arturo A. , Spearing S. Mark 
Published: April 2011

AbstractThe development of power MEMS, such as the Microengine being developed at MIT, requires highly stressed structures to achieve high power densities. Material strength is, therefore, a critical issue for the design of such devices. Due to the stochastic nature of the strength of brittle materials, the length scales of the test specimens should be close to those of the structure in order to avoid excessive extrapolation of the test data. In this paper, strength characterization and supporting analysis of mesoscale biaxial flexure and radiused hub flexure single crystal silicon specimens are presented. The Weibull reference strength' of planar biaxial flexure specimens was found to lie in the range 1.2 to 4.6 GPa, depending on the surface quality. The local strength at stress concentrations was obtained by testing radiused hub flexure specimens. For the case of deep reactive ion etched (DRIE) specimens, the strength at fillet radii was found to be significantly lower than that measured from planar biaxial flexure specimens due to the inferior surface quality in such regions. It was found that strength could be significantly increased by the introduction of an additional isotropic etch after the DRIE step. The test results reported herein have important implications for the development of highly stressed microfabricated structures. The sensitivity of the mechanical strength to surface processing and etching techniques must be accounted for in the design cycle, particular with regard to the selection of the appropriate fabrication route. Furthermore, in the design of highly stressed MEMS devices, it is important to account for the stochastic nature of the material strength.
The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems
Authors: Lee Sang-Ho , Kwon Myong-Jong , Park Jin-Goo , Kim Yong-Kweon , Shin Hyung-Jae 
Published: April 2011

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.
Mechanical and Metallographic Characterization of Liga Fabricated Nickel and 80%Ni-20%Fe Permalloy
Authors: Christenson T.R. , Buchheit T.E. , Schmale D.T. , Bourcier R.J. 
Published: April 2011

AbstractA table top servohydraulic load frame equipped with a laser displacement measurement system was constructed for the mechanical characterization of LIGA fabricated electroforms. A drop-in tensile specimen geometry which includes a pattern to identify gauge length via laser scanning has proven to provide a convenient means to monitor and characterize mechanical property variations arising during processing. In addition to tensile properties, hardness and metallurgical data were obtained for nickel deposit specimens of current density varying between 20 and 80 mA/cm2 from a sulfamate based bath. Data from 80/20 nickel/iron deposits is also presented for comparison. As expected, substantial mechanical property differences from bulk metal properties are observed as well as a dependence of material strength on current density which is supported by grain size variation. While elastic modulus values of the nickel electrodeposit are near 160 GPa, yield stress values vary by over 60%. A strong orientation in the metal electrodeposits as well as variations in nucleating and growth morphology present a concern for anisotropic and geometry dependent mechanical properties within and between different LIGA components.
Heating Effects on The Young's Modulus of Films Sputtered onto Micromachined Resonators
Authors: Kahn H. , Huff M.A. , Heuer A.H. 
Published: April 2011

AbstractSurface-micromachined polysilicon lateral resonant structures were fabricated and used to determine the temperature dependence of the Young's modulus of the polysilicon. This is done by passing a dc current through the beams during resonance testing, resulting in Joule-heating. The temperatures are calibrated by increasing the dc current until the melting point of silicon is attained. The calculated Young's moduli agree well with reported values for single crystal silicon.In addition, metal films were sputter-deposited onto the polysilicon resonators, and similar experiments performed on the composite devices to determine the temperature dependence of the modulus of the sputtered films. Ni films demonstrate a linear decrease in Young's modulus with temperature. TiNi films demonstrate two distinct modulus values with an intermediate transition region, due to the temperature-induced reversible phase transformation exhibited by TiNi.
Observations of Low Cycle Fatigue of Al Thin Films for Mems Applications
Authors: Cornella G. , Vinci R.P. , Iyer R. Suryanarayanan , Dauskardt R.H. , Bravman J.C. 
Published: April 2011

AbstractThis paper addresses tension-tension (R=0) low cycle fatigue behavior of thin film Al structures released from a substrate. Al beam specimens 2 µm thick, 50 µm wide and 500 µm long (gauge length) were micromachined over a window in a Si substrate. Cyclic load-displacement behavior was investigated using a multiple step test method, in which each specimen was cycled with several blocks of constant maximum displacement amplitude. Load, displacement and temperature were recorded continuously. A load drop and a corresponding stabilized state were observed for each displacement block. Monotonic tension tests to failure were also performed for comparison. Evidence of cyclic creep was observed. SEM images revealed fatigue markings on cyclically loaded specimens but not on monotonically loaded beams.
Silicon Oxynitride Membrane for Chemical Sensor Application
Authors: Astle S. , Scheid E. , Gue A.M. , Guillemet J.P. , Lescouzeres L. 
Published: April 2011

AbstractTin oxide gas sensor can detect various gases by using the conductivity changes due to adsorption and desorption processes of gaseous molecules on its surface. The reduction of the power consumption especially for batteries back-up operation, is one of the challenge for SnO2 gas sensors. We propose a new solution using a silicon oxynitride membrane (SiOxNy) to reach this objective. Thin films of SiOxNy with different compositions have been studied. Their composition, residual stress, Young modulus and mechanical strength have been evaluated. As a result, we propose an optimized silicon oxynitride membrane with a low residual stress (-50 MPa), giving above 95% fabrication yield and low power consumption (65 mW / 450°C). A new sensors generation has been successfully fabricated and its mechanical strength and thermal performances have been evaluated. Moreover, an equation is derived, which describes the variation of the Young modulus as a function of the silicon oxynitride composition.
Characterization of Epoxy-Functionalized Silsesquioxanes as Potential Underfill Encapsulants
Authors: Lin E. K. , Snyder C. R. , Mopsik F. I. , Wallace W. E. , Wu W. L. , Zhang C. X. , Laine R. M. 
Published: April 2011

AbstractIn electronics packaging, underfill encapsulants are needed to improve package reliability in flip-chip devices. The underfill generally consists of an epoxy resin highly filled with silica particles and is designed to reduce the stress arising from the difference in the thermal expansion between the solder bumps and the substrate. Currently, concerns about the flow of the silica particles and surface phenomena are arising as electronics packages reduce in size. Newly developed epoxy-functionalized octameric silsesquioxanes provide an intriguing alternative to current formulations. These single-phase inorganic/organic hybrid materials may have properties similar to filled materials without the complications from the rheology of filled materials. The physical properties of the functionalized silsesquioxanes are measured with respect to the critical parameters for underfill materials. Measurements of properties such as the coefficient of thermal expansion and density are performed to evaluate the suitability of these materials as potential underfill encapsulants.
29Si Nmr Study of Hydrolyzed Teos-Rteos (R: Methyl, Ethyl, Phenyl) Systems
Authors: Mendez-Vivar J. , Mendoza-Bandala A. , Gutierrez A. , Cao G. 
Published: April 2011

AbstractSols composed of Tetraethoxysilane (TEOS) and RTEOS (R: methyl, ethyl, phenyl) catalyzed with HCl were prepared. The molar ratios TEOS :RTEOS:EtOH:H20:HC1 were (1.0-0.8947):(5.26×10−2-0.1579):0.95:1.0:7×10−4, respectively. The sols were analyzed by 29 Si NMR immediately after mixing the reagents in order to study the hydrolysis and condensation reactions. A predominant self-condensation was observed in the TEOS-ETEOS sol, compared to cross-condensation. This result was opposite to the behaviour of the TEOS-MTEOS and TEOS-PTEOS sols.
Processing of Inorganic-Organic Hybrids From Metal Alkoxides and Phenyltriethoxysilane
Authors: Yoshinaga Ikuko , Yamada Noriko , Katayama Shingo , Claflin B. , Lucovsky G. 
Published: April 2011

AbstractIn the synthesis of inorganic-organic hybrids from metal alkoxides and phenyltriethoxysilane (PTES), metal alkoxides were found to influence the phenyl siloxane network formation. The presence of metal alkoxides in the initial stage of hydrolysis and condensation of PTES promote the formation of phenyl siloxane networks to provide a dense hybrid. However, the presence of metal alkoxides in the stage of hydrolyzed PTES provide a loose structure of phenyl siloxane networks involving a number of silanol groups.
Barrier Properties of Inorganic-Organic Polymers
Authors: Hoffmann M. , Amberg-Schwab S. , Claflin B. , Lucovsky G. 
Published: April 2011

AbstractThe oxygen barrier properties of sol-gel derived inorganic-organic polymer coatings were investigated. By systematic variation of the ratios of the starting compounds and of the curing conditions, materials with different inorganic and organic network densities were obtained. The network densities were characterized using 29Si solid-state NMR and FT-Raman spectroscopy. It was found that the oxygen transmission rates decrease with increasing inorganic as well as organic network density.
Development of Some Promising Approaches for The Toughening of High-Temperature Polymers
Authors: Kumudinie C. , Premachandra J. K. , Mark J. E. , Dang T. D. , Unroe M. R. , Arnold F. E. , Claflin B. , Lucovsky G. , Claflin B. , Lucovsky G. 
Published: April 2011

AbstractHigh-temperature poly(arylene ether) and hydroxypolybenzoxazole polymers were toughened using dispersed rubbery phases. This rubbery phase was a hybrid material which was in-situ generated within the polymer matrix using mixtures of partially-hydrolyzable trialkoxy and dialkoxy organosilanes with a fully hydrolyzable tetraalkoxysilane. The resulting materials were characterized with regard to their structures, mechanical properties (modulus, ultimate strength, maximum extensibility, and toughness), thermal properties, optical properties, and tendencies to absorb water. Some of the results are presented here.
Synthesis and Characterization of Surface Protected Nanocrystalline Particles of Titania
Authors: Scolan E. , Sanchez C. 
Published: April 2011

AbstractMonodisperse non-aggregated nanoparticles of titania are obtained through hydrolysis at 60°C of titanium butoxide in the presence of acetylacetone and para-toluene sulfonic acid. After drying the resulting xerosols can be dispersed without aggregation in water-alcoholic or alcoholic solutions. The characterizations of the nanoparticles have been carried out by using quasi-elastic light scattering (QELS), 13C 1H in solution and X-ray diffraction, TEM, TG-DTA, 13C CP-MAS NMR in the solid state. The mean size of the anatase oxide core can be adjusted in the I to 5 nanometer range by a careful tuning of the synthetic conditions. The anatase particles are surrounded by acetylacetonato ligands, para-toluene sulfonate based species and water.
Structural and Rheological Properties of Zirconia-Pmma Sol-Gel System
Authors: Messaddeq S.H. , Pulcinelli S.H. , Santilli C.V. 
Published: April 2011

AbstractThe influence of polymethylmetacrylate on the rheological and structural characteristics of zirconia sols was analyzed by shear stress versus shear rate measurements, quasi elastic light scattering and infrared spectra. The thickness of coated film determined by profilometry increases linearly with the relative volume of PMMA. The addition of PMMA led to the polycondensation reaction and the formation and growth of zirconia particles.
Templating Nanoporosity in Organosilicates Using Well-Defined Branched Macromolecules
Authors: Hedrick L. , Hawker C. J. , Trollsås M. , Remenar J. , Yoon D. Y. , Miller R. D. 
Published: April 2011

AbstractA general route to organic-inorganic hybrids with nanophase morphologies has been elaborated with the objective of ultimately templating nanoporosity in organosilicates. A key feature of the hybrids is the preparation of well-defined macromolecules bearing significant functionality to interact with the organosilicates. The use of living polymerization methods allows the synthesis of polymers with accurate control of molecular weight, polydispersity, and chain ends. We have demonstrated living polymerizations from dendritic and hyperbranched initiators to produce controlled branched, star and hyperstar macromolecules. These polymers are used as structure directing agents to organize organosilicates into nanostructures. Once the macromolecular species has templated or organized the inorganic component, the organic polymer can be selectively removed by thermolysis to produce a nanoporous inorganic structure. The size and shape of the pores are similar to those of the initial hybrid morphology. A significant reduction in the dielectric constant of these insulating materials is achieved simply by replacing a portion of the glass matrix with air which has a dielectric constant of 1.
Amorphous Microporous Mixed Oxides of Tailored Polarity and their Application in Membrane Catalyzed Hydrogenation Reactions
Authors: Maier Wilhelm F. , Lange Christian 
Published: April 2011

AbstractAmorphous microporous mixed oxides (AMM) are materials characterized by a narrow micropore distribution, high porosity, definable surface polarity and homogeneous elemental distribution (absence of domains). They are prepared by a modified Sol-Gel procedure in a single preparation step. Membranes prepared from these materials are selective heterogeneous catalysts, whose microstructural properties can be adjusted to the reaction conditions. Here it is shown, how the surface polarity of the membrane affects the hydrogenation properties.