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Author: Han Sung Kim
Publisher:
ISBN:
Category : Finite element method
Languages : en
Pages : 139
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Book Description
Abstract: Simulation algorithms are developed for the prediction of effective elastic properties of NEMS (Nano-Electro Mechanical Systems) and MEMS (Micro-Electro Mechanical Systems) thin films. Finite Element Method (FEM) is used for micro-scale simulation while ab-initio Molecular Dynamics (MD) is employed for nano-scale. A lattice model is utilized in order to simulate microstructures of thin films. The proposed method can generate a statistically equivalent microstructure to any single phase micrograph in terms of the number of grains and the grain size distribution. A desired grain size distribution (GSD) is achieved by manipulating nucleation process. Analytical functions for GSD are obtained by taking into account of the domain size and the number of grains. It is believed that nucleation and growth can be controlled by temperature and pressure. The influence of temperature and pressure on the grain size as well as the grain size distribution is investigated. A quasi-3D mesh of the thin film is generated by employing prism elements. By applying specific boundary conditions to the quasi-3D meshed microstructure, the elastic properties of MEMS thin films are obtained through FEM analysis. The simulation results show that stochastic distributions of grain anisotropy have a significant influence on overall elastic properties at micro-scale. A fundamental statistical methodology is adopted to characterize elastic properties of thin films. For nano-scale simulations, the bulk modulus (and other elastic properties) can be influenced by grain boundary when grain boundary volume fraction is not negligible. Consequently, it is desirable to determine the size limit when the grain boundary begins to influence the bulk modulus significantly. The developed MD simulation algorithm found that 6nm is the critical grain size for polysilicon. Moreover, equations are derived from the simulation results for estimating bulk modulus by considering both grain and grain boundary. The developed MD simulation technique can be used to characterize bulk modulus of NEMS materials and to determine the size limit above which grain boundary can be ignored in bulk modulus simulation.
Author: Han Sung Kim
Publisher:
ISBN:
Category : Finite element method
Languages : en
Pages : 139
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Book Description
Abstract: Simulation algorithms are developed for the prediction of effective elastic properties of NEMS (Nano-Electro Mechanical Systems) and MEMS (Micro-Electro Mechanical Systems) thin films. Finite Element Method (FEM) is used for micro-scale simulation while ab-initio Molecular Dynamics (MD) is employed for nano-scale. A lattice model is utilized in order to simulate microstructures of thin films. The proposed method can generate a statistically equivalent microstructure to any single phase micrograph in terms of the number of grains and the grain size distribution. A desired grain size distribution (GSD) is achieved by manipulating nucleation process. Analytical functions for GSD are obtained by taking into account of the domain size and the number of grains. It is believed that nucleation and growth can be controlled by temperature and pressure. The influence of temperature and pressure on the grain size as well as the grain size distribution is investigated. A quasi-3D mesh of the thin film is generated by employing prism elements. By applying specific boundary conditions to the quasi-3D meshed microstructure, the elastic properties of MEMS thin films are obtained through FEM analysis. The simulation results show that stochastic distributions of grain anisotropy have a significant influence on overall elastic properties at micro-scale. A fundamental statistical methodology is adopted to characterize elastic properties of thin films. For nano-scale simulations, the bulk modulus (and other elastic properties) can be influenced by grain boundary when grain boundary volume fraction is not negligible. Consequently, it is desirable to determine the size limit when the grain boundary begins to influence the bulk modulus significantly. The developed MD simulation algorithm found that 6nm is the critical grain size for polysilicon. Moreover, equations are derived from the simulation results for estimating bulk modulus by considering both grain and grain boundary. The developed MD simulation technique can be used to characterize bulk modulus of NEMS materials and to determine the size limit above which grain boundary can be ignored in bulk modulus simulation.
Author: Raja Ramakanth Katta
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
With current demand for decreased size of micro/nanoscale systems, coupled with increased mobility, critical understanding of the ensuing contact or impact related behavior of thin solid films used in these systems is of paramount importance for improved design and reliability. In modern micro/nanodevice technologies significant emphasis has to be placed on the design of thin-films which can provide the required contact and scratch resistance. To aid this endeavor, scientific studies of the contact and scratch processes in these systems, both static and dynamic are needed to provide the tools necessary to help the advancement of these technologies. One such problem is the impact contact or quasi-static contact and scratch of the slider and disk in magnetic storage hard disk drives (HDD). Similar contact problems are encountered during the operation of other micromechanical systems like RF-MEMS switches where surface damage is observed after cyclic contact. One of the most critical elements of multilayer contact analysis is proper determination of the nanomechanical properties of each thin-film on the multilayer system. In the first part of this work the method of determining the mechanical properties using the Oliver and Pharr (O-P) nanoindentation technique is described. For nanometer sized thin-films where the O-P technique gives incorrect results, an improved method is used. Later a dimensional analysis-based method to obtain the mechanical properties from the nanoindentation data is implemented for magnetic storage films. A direct comparison of the properties obtained from conventional O-P nanoindentation technique to this new technique is presented. In the second part of this work, the effect of dynamic contact or impact on multilayer thin films specific to magnetic storage hard disk drives is presented. Since there are no impact models available for multilayer thin films in the literature, a new contact mechanics-based (CM) semi-analytical model of a rigid sphere (representing a slider corner) impacting an elastic-plastic (E-P) multilayer thin-film half-space was proposed for the first time to examine the potential damage to a magnetic storage head disk interface (HDI). A dynamic 3D finite element analysis (FEA) model was also developed to examine the impact damage in more detail and validate the impact model. To characterize the plastic deformation and frictional energy losses associated with the impact damage, a comprehensive oblique elastic impact coefficient of restitution (COR) model was proposed for elastic-plastic impacts for the first time and validated using FEA. A method to decouple the oblique impact parameters into normal impact COR and tangential impact COR was formulated. Since, in microsystems, the geometry of the impacting bodies is not limited to spherical bodies, a new contact mechanics-based (CM) model of a rigid cylinder with a finite length impacting an elastic-plastic homogeneous disk was also proposed and includes a novel method of estimating the residual depth after impact. Based on elastic unloading, an improved coefficient of restitution model was also proposed. This new impact model was applied to study a practical case of a cylindrical feature on the slider of a magnetic storage hard disk drive impacting the disk to predict various critical impact contact parameters. The CM model was validated using a plane strain FEA-based model and it was found that a cylindrical feature with longer length results in a substantial alleviation of impact damage. The final part of this work involved the investigation of the performance of thin-film multilayers while under the influence of much milder quasi-static contact scratch. A 2D plane strain FEA model of a rigid cylinder sliding over a multilayered thin-film half space was developed. The effects of different contact parameters such as applied normal load, friction coefficient and radius of curvature of the cylinder on the critical stresses in the multilayer system were analyzed. Later, for direct experimental comparison a full-blown 3D quasi-static FEA-based nanoscratch model of the multilayer thin-film system was also developed. The FEA scratch results were compared to nanoscratch experiments performed on actual magnetic disks. Consequently, the 3D FEA scratch model was used to quantitatively correlate the subsurface plastic deformation to the magnetic erasures typically found in HDDs due to scratch for the very first time.
Author: Jessica Torres
Publisher:
ISBN:
Category : Amorphous substances
Languages : en
Pages : 264
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Book Description
This dissertation provides a fundamental understanding of the impact of bulk polymer properties on the nanometer length scale modulus. The elastic modulus of amorphous organic thin films is examined using a surface wrinkling technique. Potential correlations between thin film behavior and intrinsic properties such as flexibility and chain length are explored. Thermal properties, glass transition temperature (Tg) and the coefficient of thermal expansion, are examined along with the moduli of these thin films. It is found that the nanometer length scale behavior of flexible polymers correlates to its bulk Tg and not the polymers intrinsic size. It is also found that decreases in the modulus of ultrathin flexible films is not correlated with the observed Tg decrease in films of the same thickness. Techniques to circumvent reductions from bulk modulus were also demonstrated. However, as chain flexibility is reduced the modulus becomes thickness independent down to 10 nm. Similarly for this series minor reductions in Tg were obtained. To further understand the impact of the intrinsic size and processing conditions; this wrinkling instability was also utilized to determine the modulus of small organic electronic materials at various deposition conditions. Lastly, this wrinkling instability is exploited for development of poly furfuryl alcohol wrinkles. A two-step wrinkling process is developed via an acid catalyzed polymerization of a drop cast solution of furfuryl alcohol and photo acid generator. The ability to control the surface topology and tune the wrinkle wavelength with processing parameters such as substrate temperature and photo acid generator concentration is also demonstrated. Well-ordered linear, circular, and curvilinear patterns are also obtained by selective ultraviolet exposure and polymerization of the furfuryl alcohol film. As a carbon precursor a thorough understanding of this wrinkling instability can have applications in a wide variety of technologies.
Author: Thomas E. Buchheit
Publisher: Cambridge University Press
ISBN: 9781558998292
Category : Technology & Engineering
Languages : en
Pages : 480
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Book Description
This book has a long tradition of representing current topics in thin-film properties and how they are related to the performance and reliability of thin-film structures. Several emerging and well-developed technologies rely on understanding the behavior of these structures. This book provides a forum for an exchange of ideas among researchers who are interested in the mechanical behavior of thin films, broadly applied to their materials choice or methodology. The book focuses on stress-related phenomena in thin films for a wide range of materials. Of particular interest are studies that explore the frontiers of thin-film materials science with regard to materials selection or size scale. Topics include: elasticity in thin films; characterizing thin films by nanoindentation; mechanical behavior of nanostructured films; mechanical properties of thin; thin-film plasticity; thin-film plasticity; thin-film plasticity; novel testing techniques; in situ characterization techniques; adhesion and fracture of thin films; fatigue and stress in interconnect and metallization; deformation, growth and microstructure in thin films and thin-film processing.
Author: Bharat Bhushan
Publisher: Springer Science & Business Media
ISBN: 364215283X
Category : Technology & Engineering
Languages : en
Pages : 633
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Book Description
The comprehensive reference and textbook serves as a timely, practical introduction to the principles of nanotribology and nanomechanics. Assuming some familiarity with macroscopic tribology, the book comprises chapters by internationally recognized experts, who integrate knowledge of the field from the mechanics and materials-science perspectives. They cover key measurement techniques, their applications, and theoretical modelling of interfaces, each beginning their contributions with macro- and progressing to microconcepts.
Author: Kenichi Takahata
Publisher: BoD – Books on Demand
ISBN: 9533070277
Category : Technology & Engineering
Languages : en
Pages : 528
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Book Description
This book discusses key aspects of MEMS technology areas, organized in twenty-seven chapters that present the latest research developments in micro electronic and mechanical systems. The book addresses a wide range of fundamental and practical issues related to MEMS, advanced metal-oxide-semiconductor (MOS) and complementary MOS (CMOS) devices, SoC technology, integrated circuit testing and verification, and other important topics in the field. ?Several chapters cover state-of-the-art microfabrication techniques and materials as enabling technologies for the microsystems. Reliability issues concerning both electronic and mechanical aspects of these devices and systems are also addressed in various chapters.
Author: Bharat Bhushan
Publisher: Springer Science & Business Media
ISBN: 3540282483
Category : Technology & Engineering
Languages : en
Pages : 1157
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Book Description
The recent emergence and proliferation of proximal probes, e.g. SPM and AFM, and computational techniques for simulating tip-surface interactions has enabled the systematic investigation of interfacial problems on ever smaller scales, as well as created means for modifying and manipulating nanostructures. In short, they have led to the appearance of the new, interdisciplinary fields of micro/nanotribology and micro/nanomechanics. This volume serves as a timely, practical introduction to the principles of nanotribology and nanomechanics and applications to magnetic storage systems and MEMS/NEMS. Assuming some familiarity with macrotribology/mechanics, the book comprises chapters by internationally recognized experts, who integrate knowledge of the field from the mechanics and materials-science perspectives. They cover key measurement techniques, their applications, and theoretical modelling of interfaces, each beginning their contributions with macro- and progressing to microconcepts. After reviewing the fundamental experimental and theoretical aspects in the first part, Nanotribology and Nanomechanics then treats applications. Three groups of readers are likely to find this text valuable: graduate students, research workers, and practicing engineers. It can serve as the basis for a comprehensive, one- or two-semester course in scanning probe microscopy; applied scanning probe techniques; or nanotribology/nanomechanics/nanotechnology, in departments such as mechanical engineering, materials science, and applied physics. With a Foreword by Physics Nobel Laureate Gerd Binnig Dr. Bharat Bhushan is an Ohio Eminent Scholar and The Howard D. Winbigler Professor in the Department of Mechanical Engineering, Graduate Research Faculty Advisor in the Department of Materials Science and Engineering, and the Director of the Nanotribology Laboratory for Information Storage & MEMS/NEMS (NLIM) at the Ohio State University, Columbus, Ohio. He is an internationally recognized expert of tribology and mechanics on the macro- to nanoscales, and is one of the most prolific authors. He is considered by some a pioneer of the tribology and mechanics of magnetic storage devices and a leading researcher in the fields of nanotribology and nanomechanics using scanning probe microscopy and applications to micro/nanotechnology. He is the recipient of various international fellowships including the Alexander von Humboldt Research Prize for Senior Scientists, Max Planck Foundation Research Award for Outstanding Foreign Scientists, and the Fulbright Senior Scholar Award.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 446
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Book Description
Author: K. N. Tu
Publisher: Elsevier
ISBN: 1483218295
Category : Technology & Engineering
Languages : en
Pages : 351
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Book Description
Treatise on Materials Science and Technology, Volume 24: Preparation and Properties of Thin Films covers the progress made in the preparation of thin films and the corresponding study of their properties. The book discusses the preparation and property correlations in thin film; the variation of microstructure of thin films; and the molecular beam epitaxy of superlattices in thin film. The text also describes the epitaxial growth of silicon structures (thermal-, laser-, and electron-beam-induced); the characterization of grain boundaries in bicrystalline thin films; and the mechanical properties of thin films on substrates. The ion beam modification of thin film; the use of thin alloy films for metallization in microelectronic devices; and the fabrication and physical properties of ultrasmall structures are also encompassed. Materials scientists and materials engineers will find the book invaluable.
Author: Jianguo Zhu
Publisher: World Scientific
ISBN: 9811224005
Category : Science
Languages : en
Pages : 706
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Book Description
Thin films have an extremely broad range of applications from electronics and optics to new materials and devices. Collaborative and multidisciplinary efforts from physicists, materials scientists, engineers and others have established and advanced a field with key pillars constituting (i) the synthesis and processing of thin films, (ii) the understanding of physical properties in relation to the nanometer scale, (iii) the design and fabrication of nano-devices or devices with thin film materials as building blocks, and (iv) the design and construction of novel tools for characterization of thin films.Against the backdrop of the increasingly interdisciplinary field, this book sets off to inform the basics of thin film physics and thin film devices. Readers are systematically introduced to the synthesis, processing and application of thin films; they will also study the formation of thin films, their structure and defects, and their various properties — mechanical, electrical, semiconducting, magnetic, and superconducting. With a primary focus on inorganic thin film materials, the book also ventures on organic materials such as self-assembled monolayers and Langmuir-Blodgett films.This book will be effective as a teaching or reference material in the various disciplines, ranging from Materials Science and Engineering, Electronic Science and Engineering, Electronic Materials and Components, Semiconductor Physics and Devices, to Applied Physics and more. The original Chinese publication has been instrumental in this purpose across many Chinese universities and colleges.
