bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Interaction Between Indentation Cracks on Metallized Silicon
Authors: Manoharan M. , Muralidharan G. 
Published: April 2011

AbstractThe metallization of Si represents a important industrial process and produces a bi-layered composite of a ductile metal film on a brittle substrate. The mechanical properties of such a composite are determined by the properties of the two layers and the interface and influenced by the fact that the metallized layer, being a very thin film, possesses properties different from those of a bulk material. The fracture toughness is also influenced by the nature and distribution of defects which may be generated during use of these materials, even if the manufacturing process produces a reasonably defect free material. Indentation cracking has been extensively used for the measurement of fracture toughness due to its small sample size requirements as well as a relatively good correlation with values obtained from traditional fracture mechanics tests. The indentation process, with its associated cracks, produces permanent plastic deformation and also introduces a residual stress field. This field influences the crack pattern generated in an adjacent indent and can be used as a methodology to model the influence of multiple defect sources.The present study was aimed at understanding the effect of a thin Ti alloy metallization layer sputtered on a Si wafer on the sizes of the cracks associated with the indents. It was also aimed at studying the interaction between cracks emanating from sequentially placed indentations. The distance between the indents which generated these cracks was varied from a level comparable to the crack size to a level where interaction could be ignored. This paper discusses the changes in the nature as well as the sizes of cracks due to the presence of the metallization layer as well as the interaction between the stress fields of the indents in this ductile thin film – brittle substrate composite and possible methodologies for delineating these effects.
Interface Effect on the Transverse Thermal Conductivity of SiO2 Films Deposited on Silicon
Authors: Zhao W. , Brotzen F. R. , Hehn L. , Loos P. J. 
Published: April 2011

AbstractEarlier work revealed that the transverse thermal conductivity of thin films of amorphous SiO2 deposited on monocrystalline silicon decreased substantially when the film thickness was less than about 1 µm. When multiple interfaces were created by the intercalation of thin intermediate layers of polycrystalline silicon into the SiO2 film, the thickness effect was enhanced. This observation pointed to an interfacial effect. A model accounting for the interface effect is discussed.
Diffusion and Electromigration of Cu in Single Crystal Al Interconnects
Authors: Srikar V. T. , Thompson C. V. 
Published: April 2011

AbstractThe electromigration-induced transport properties of Cu in Al-Cu alloys, and their effect on electromigration lifetimes in interconnects with bamboo grain structures are not well understood. To isolate and study the mechanisms and kinetics of Cu diffusion and electromigration in interconnects for which grain boundary transport is not dominant, we have developed a test structure consisting of parallel Al single crystal lines, with every alternate line terminating in contact pads. Cu is locally added to the same regions in all the lines, and the effect of temperature and electric field can be simultaneously characterized by analyzing the Cu concentration profile measured using electron-probe microanalysis. Comparison of the calculated values of diffusivities with the diffusivity of Cu through the Al lattice, and through dislocation cores in Al, suggests that the path of diffusion of Cu in Al single crystals is along the Al/AlOx interface.
Grain Growth by Digm in Ni Thin Film Under High Tensile Stress
Authors: Jia Zhengyi , Pan G. Z. , Tu K. N. 
Published: April 2011

AbstractElectron beam evaporated Ni thin films are found to have tensile stress of 1.2 Gpa. The stress is relieved upon heating, accompanied by grain growth. The calculated stress matches the experimental result and a mechanism of grain growth is proposed.
A Novel Technique for the Fabrication of Free-Standing Adhesive Films Using a Polymer Template
Authors: Hansford D. J. , Lee L. P. , Ferrari M. 
Published: April 2011

AbstractA technique has been developed that allows the application of free-standing membranes of polymer adhesives used in microfabricated structures. The film is made free-standing by the application of the adhesive to a polymer template, followed by an adhesion step to a microfabricated substrate, and the final release of the film by the removal of the polymer template. It was found that the surface treatment used to treat the Teflon template made it adhere too strongly to the adhesive film for this application. The results show that Gel-Paks make a suitable template for the transference of polymer films over holes of at least micron size.
Adhesion of Polysilicon Microbeams in Controlled Humidity Ambients
Authors: de Boer M. P. , Clews P. J. , Smith B. K. , Michalske T. A. 
Published: April 2011

AbstractWe characterize in-situ the adhesion of surface micromachined polysilicon beams subject to controlled humidity ambients. Beams were freed by supercritical CO2drying. Consistent adhesion results were obtained using a post-treatment in an oxygen plasma which rendered the microbeams uniformly hydrophilic. Individual beam deformations were measured by optical interferometry after equilibration at a given relative humidity (RH). Validation of each adhesion measurement was accomplished by comparing the deformations with elasticity theory. The data indicates that adhesion increases exponentially with RH from 30% to 95%, with values from 1 mJ/m2 to 50 mJ/m2. Using the Kelvin equation, we show that the data should be independent of RH if a smooth interface is considered. By modeling a rough interface consistent with atomic force microscopy (AFM) data, the exponential trend is satisfactorily explained.
Buckling Evolution of Microelectromechanical Structures
Authors: Zhang Xin , Zhang Tong-Yi , Zohar Yitshak 
Published: April 2011

AbstractThis study reports in-situ observations of the buckling evolution of microelectromechanical structures during etching of their underneath sacrificial layers. As the etching went on, the buckling pattern evolved from mode I, the sinusoidal half-waves, to mode II, the constrained sinusoidal half-waves, to mode III, the conventional mode, and finally to mode IV, the blister- like local buckling. Closed formulae were derived from theoretical analysis, and the experimental results agreed well with the theoretical ones.
Silicon-Framed Tensile Specimens: Techniques and Results
Authors: Read D. T. 
Published: April 2011

AbstractThe silicon-framed tensile specimen design has been used in tensile tests of thin films of a variety of metals and epitaxial silicon. A piezo-actuated microtensile test device holds the specimen while the silicon frame is cut just before testing, imposes the tensile displacement, and provides voltages proportional to force and displacement. This technique is appropriate for films that are hundreds of micrometers long, tens to a few hundred micrometers wide, and from 0.3 to 15 micrometers thick. The specimen film must be amenable to lithographic patterning, must adhere well to the silicon substrate, and must resist a silicon etchant. The specimen fabrication is a bulk-micromachining process, because the silicon substrate is etched through underneath the specimen film. Uniaxial yield strength, ultimate tensile strength, and elongation to maximum load can be measured using the microtensile tester. The addition of laser illumination and digital photography allows implementation of electronic speckle pattern interferometry, for accurate measurement of local displacement. This addition allows evaluation of the tensile Young's modulus. Compared to bulk material, thin films of copper and aluminum have lower apparent Young's moduli, higher yield and ultimate tensile strengths because of their fine grain size, and lower elongation to failure. Correlation between properties measured by indentation and by tensile testing needs further study.
Internal Stress of ZnO thin Films Caused by Thickness Distribution and Crystallinity
Authors: Takeuchi M. , Inoue K. , Yoshino Y. , Ohwada K. 
Published: April 2011

AbstractThe improvement of thickness distribution and crystallinity in ZnO thin films prepared by radio frequency (rf) planer magnetron sputtering has been studied. Optimum thickness distribution of less than ± 2.2% in a 3-inch wafer is obtained by changing the substrate angle to the ZnO target and is in accordance with cosine law. The c-axis orientation perpendicular to the silicon substrate is confirmed by x-ray diffraction. The stress of ZnO thin films is larger than 0.3GPa and its distribution is independent of the substrate angle that is set at a slant to the optimum angle for thickness distribution. These results indicate that thickness distribution of ZnO thin films heavily depends on the substrate angle, while the stress and its distribution are independent of the setting angle of the substrate. Stress distribution is attributed to the distribution of argon ions and sputtered molecules impinging a wafer.
Mechanical Property Measurement of 0.5-µm CMOS Microstructures
Authors: Lu M. S.-C. , Zhu X. , Fedder G. K. 
Published: April 2011

AbstractMeasurements are reported on the mechanical properties of high-aspect-ratio micromechanical structures formed using a conventional 0.5-µm CMOS process. Composite structures are etched out of the CMOS dielectric, aluminum, and gate-polysilicon thin films using a post-CMOS CHF3:O2 reactive-ion etch and followed by a SF6 :O2silicon etch for release. Microstructures have a height of 5 µm and beam widths and gaps down to 1.2 µm. Properties are strongly dependent on the relative metal and dielectric content of the beams. Beams with three metal conductors and polysilicon have an effective Young's modulus of 62 GPa, residual stress of -29 MPa, and an average out-of-plane radius of curvature of 1.9 mm. Maximum Young's modulus variation is 3 GPa die-todie, and is 9 GPa between two runs. Die-to-die variation of stress and stress gradient is poor for many beam compositions, however local matching on a die is very good. Cracking is induced in a resonant fatigue structure at 620 MPa of repetitive stress after over 50 million cycles.
Synthesis of Sol-Gel Matrices for Encapsulation of Enzymes Using an Aqueous Route
Authors: Bhatia R.B. , Brinker C.J. , Ashley C.S. , Harris T.M. 
Published: April 2011

AbstractSol-gel matrices are promising host materials for potential chemical and biosensor applications. Previous studies have focused on modified sol-gel routes using alkoxides for encapsulation of enzymes. However the formation of alcohol as a byproduct during hydrolysis and condensation reactions poses limitations. We report the immobilization of glucose oxidase and peroxidase in silica prepared by an aqueous route which may provide a more favorable environment for the biomolecules. A two step aqueous sol-gel procedure using sodium silicate as the precursor was developed to encapsulate the enzymes and the dye precursor, o-dianisidine. Glucose oxidase catalyzes the oxidation of glucose to give gluconic acid and hydrogen peroxide. Peroxidase then catalyzes the reaction of the dye precursor with hydrogen peroxide to produce a colored product. The kinetics of the coupled enzymatic reactions were monitored by optical spectroscopy and compared to those occurring in tetramethyl orthosilicate (TMOS) derived silica matrices developed by Yamanaka et al. [1]. Enhanced kinetics in the aqueous silicate matrices were related to differences in the host microstructures as elucidated by microstructural comparisons of the corresponding aerogels.
Polymeric Based Conducting Nanocomposites: Controlling The Distribution of the Conducting Phase
Authors: Vaia Richard. A. , Lee Jar-Wha , Click William , Price Gary , Wang Chyi-Shan 
Published: April 2011

AbstractThe optimization of bulk properties of polymeric based nano– and mesoscale composites require the ability to spatially control phase distribution. In this study, electrical conductivity is introduced by incorporation of a metal precursor via infiltration into the polymer host and subsequent conversion in–situ by a reducing agent, templating the morphology of the polymer matrix. Distribution of nano– and mesoscale metal particles in isotropic and anisotropic swollen polymer hosts is discussed relative to metal precursor and reducing reagent diffusion and their in–situ bimolecular reduction reaction. The swelling and infiltration procedure employed to form the composites is generally applicable to rigid–rod, semi–flexible and flexible polymer matrices and not restricted to special synthesis of metal containing or complexing polymers. As an example, high–performance rigid–rod polymer fibers containing an interpenetrating network of polymer microfibrils and silver are produced with d.c. conductivities in excess of 104 S/cm and tensile
Organic-Inorganic Crystals for Optical Devices
Authors: Ibanez A. , Zaccaro J. , Baldeck P. L. , Masse R. 
Published: April 2011

AbstractTwo routes of crystal engineering and elaboration of optical materials are described. The former applied to the design of organic-inorganic crystals for quadratic nonlinear optics is supported by a strategy of deliberately engineered noncentrosymmetric structures built-up from herringbone motifs of 2-amino-5-nitropyridinium chromophore. The original crystal growth of a solid solution of a member of this family is presented and discussed. The latter is a simple and generic elaboration of stable organic nanocrystals embedded in sol-gel matrices. Several molecules and characterization techniques have been involved to demonstrate the validity of this preparation.
Carboxylate-Substituted Oxotitanium and Oxozirconium Clusters as Structural Models for Titania- and Zirconia-Based Inorganic-Organic Hybrid Materials
Authors: Kickelbick Guido , Schubert Ulrich 
Published: April 2011

AbstractReaction of Ti(OR)4 or Zr(OR)4 with carboxylic acids resulted in the formation of crystalline carboxylate-substituted oxotitanium and oxozirconium clusters with different Ti/Zr : carboxylate ratios. Structural investigations showed that the cluster cores are rutile- or zirconia-like if the carboxylate : metal ratio does not exceed 1.33 (for Ti) or 2 (for Zr), respectively. When the carboxylate : metal ratio is increased beyond these values, more open clusters and eventually polymeric structures are obtained.
Self-Organization in Nanoparticle Titanium Dioxide Thin Films
Authors: Burnside S.D. , Shklover V. , Barbe C.A. , Brooks K. , Comte P. , Arendse-Duriaux F. , Jirousek M. , Graetzel M. 
Published: April 2011

AbstractNanocrystalline titanium dioxide has been synthesized using a sol-gel technique followed by hydrothermal growth at temperatures in the range 190-270°C. Thin films of these colloids were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. Self-organization of the nanocrystalline particles in regular arrays was observed in films made from colloids autoclaved at lower temperatures. We present herein initial photovoltaic performance of these semiconducting films used as working electrodes in a dye-sensitized solar cell.
Characterization of Electrically Pulsed Chromium Disilicide Fusible Links
Authors: Domenicucci A.G. , Cunningham B. , Tsang P. 
Published: April 2011

AbstractFusible links, fabricated from silicon rich chromium disilicide thin films, were subjected to voltage pulses in the 3–6 volt range. An optimum voltage existed at which the fuses blew. Transmission electron microscopy (TEM) was used to study the microstructural characteristics of the fuses both before and after the application of the voltage pulses. The TEM characterization, coupled with electrical and physical measurements, revealed that the mechanism underlying the fuse blow was hole current induced Si electromigration. Below the optimum voltage, the amount of Si transported was insufficient to cause fuse rupture. Above the optimum voltage, the current- voltage characteristics of the fuses became nonlinear and a unique sequence of material phases was formed. The composition of the phases suggests that both thermomigration and electromigration processes were operating at voltages above the optimum voltage.
Aluminum Spiking Mechanism in Contact Holes Studied by High-Resolution Analytical TEM
Authors: Cerva H. , Klüppel V. , Barth H. J. , Helneder H. 
Published: April 2011

AbstractAl-spiking in contacts to Si were studied on a microscopic scale by a detailed cross sectional TEM analysis. Electron spectroscopic imaging and energy dispersive x-ray microanalysis with a I nm high-current electron probe formed by a field emission gun helped to identify the Al-diffusion paths and the reaction mechanisms which lead to contact failure. Combinations of advanced PVD-Ti/TiN barrier layers and cold/hot or high-pressure AlSiCu-fills revealed that the highly rugged TiN barrier sidewalls and thick Ti sidewall layers are the weak points which cause Al-spiking.
Electron Microscopic Studies of Co- and Ti-Germanosilicide Films Formed on SiGe Layers
Authors: Jin S. , Donaton R. A. , Bender H. , Maex K. 
Published: April 2011

AbstractCobalt films are sputter deposited on Si0.8Ge0.2 layers grown epitaxially on Si substrates. Compared with the silicidation on pure silicon, there is a retardation of the disilicide formation in the SiGe case. The conversion of the monosilicide into the disilicide strongly depends on the thickness of the initial SiGe layers. For the silicidation of titanium on poly-SiGe layers, the increase of the Ge content favours the nucleation of C54 titanium germanosilicide, hence helping the transition from the C49 to the C54 phase on the blanket layers. The thickness of the final C54 Ti-germanosilicide layers formed on narrow poly-Sil-×Gex runners is independent of the line width and the Ge concentration.
Tem Studies of Polysilicon Emitter Bipolar Materials & Devices: Increased Interfacial Oxide Break-Up and Polysilicon Regrowth and Decreased Emitter Resistance by Fluorine Implantation
Authors: Marsh C. D. , Moiseiwitsch N. E. , Schiz J. , Booker G. R. , Ashburn P. 
Published: April 2011

AbstractThe role of fluorine (F) in the break-up of the native oxide and the regrowth of As doped poly-Si layers on unpatterned Si wafers and on patterned regions of Si device wafers at temperatures of 900°C to 1000°C are investigated by TEM and by the fabrication of npn poly-Si emitter bipolar devices. Results for unpatterned wafers with F show i) a 950°C dopant drive-in anneal causes oxide break-up and regrowth after a time suitable for the fabrication of devices, ii) a pre-anneal, before the As implant, further enhances the break-up and regrowth and iii) there is an optimum F dose of 5×1015/cm2. Based on these results poly-Si emitter bipolar devices were fabricated using F=5×1015/cm2, a pre-anneal and a 900°C As drive-in anneal. The results establish quantitatively the relationship between the interface structures and the specific emitter resistance, i.e. with no F there is no break-up or regrowth and the emitter resistance is high (114Ωμm2) while with F there is break-up and regrowth and the emitter resistance is low (17Ωμm2).
Electron Microscopy, Electrical Activity, Artefacts and the Assessment of Semiconductor Epitaxial Growth
Authors: Brown Paul D. , Humphreys Colin J. 
Published: April 2011

AbstractThe characterisation of semiconductor thin films and device structures increasingly requires the use of a variety of complementary electron microscope-based techniques as feature sizes decrease. We illustrate how layer electrical and structural properties can be correlated: firstly averaged over the bulk and then on the individual defect scale, e.g. scanning transmission electron beam induced conductivity can be used to image the recombination activity of orthogonal <110> misfit dislocations within relaxed MBE grown Si/Si1-xGex/Si(001) heterostructures on the sub-micrometre scale. There is also need for improved understanding of sample preparation procedures and imaging conditions such that materials issues relevant to ULSI development can be addressed without hindrance from artefact structures. Hence, we consider how point defects interact under the imaging electron beam and the relative merits of argon ion milling, reactive ion beam etching, focused ion beam milling and plasma cleaning when used for TEM sample preparation. Advances in sample preparation procedures must also respect inherent problems such as thin foil surface relaxation effects, e.g. cleaved wedge geometries are more appropriate than conventional cross-sections for the quantitative characterisation of δ-doped layers. Choice of the right imaging technique for the problem to be addressed is illustrated through consideration of polySi/Si emitter interfaces within bipolar transistor structures. The development of microscopies for the rapid analysis of electronic materials requires wider consideration of non-destructive techniques of assessment, e.g. reflection high energy electron diffraction in a modified TEM is briefly described.
Applications of Plasma Cleaning for Electron Microscopy of Semiconducting Materials
Authors: Isabell T. C. , Fischione P. E. 
Published: April 2011

AbstractAs semiconductor device sizes continue to decrease, the degree of accuracy needed for electron microscopy and microanalyis of such materials increases. To achieve such accuracy, small electron probes with high beam currents are needed. The combination of these two factors results in an increase in the amount of carbonaceous contamination formed on the specimen under the electron beam. Recently, the use of low energy plasmas has been shown to be effective in preventing such contamination from occurring [1–7]. For TEM, the simultaneous placement of the specimen holder and specimen into such a plasma for short periods of time results in the ability to hold a converged probe on the specimen for analysis without contamination becoming an problem. Furthermore, in this presentation we show that existing contamination from prior TEM analysis can be removed from the specimen by plasma cleaning. The benefits of plasma cleaning are not solely limited to TEM. SEM specimens, as well as SEM specimen holders, aperture strips, tweezers and other electron microscopy accessories can readily be inserted into the plasma chamber for cleaning.
Application of Electron Microscopy Towards the Analysis of Submicron Particles and Microcorrosion
Authors: Rice Larry , Carpenter B. , Johnston L. , Chen Wei 
Published: April 2011

AbstractSmall particles in ULSI devices are one of the key causes for affecting device yield. This is especially true since modern devices are shrinking in all dimensions and the critical size for ‘killer’ particles is also shrinking. It is increasingly challenging to identify the root cause of particle contamination in terms of locating and identifying the particles. A precision cross section through the particles is required to be able to identify at which processing step the particles occurred and an energy dispersive spectroscopy (EDS) microanalysis usually helps identify the source. This paper focuses on the methodology for carrying out submicron defect and particle analysis. In addition to processing knowledge, it demonstrates the importance of techniques such as scanning electron microscopy (SEM), EDS, and focused ion beam (FIB). The analysis of microcorrosion observed after third metal deposition, and submicron titanium particles after metal etch are used as vehicles to illustrate the procedure of submicron particle analysis.