Download or read book Electromigration Induced Interface Reaction in Cu wire Al pad Diffusion Couple written by Patricia Aracelly Rodriguez-Salazar and published by . This book was released on 2017 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents experimental observations that may assist the understanding of electromigration (EM) failure mechanism active in Cu wire and Al thin film pad (wire bond). This study is motivated by an ongoing industrial effort to adapt Cu as wire bonding material for interconnection. Traditional material used for the wire bond has been Au; however, its high cost combined with its susceptibility to reliability failure caused by excessive growth of IMCs (IMC) makes Cu to be an attractive replacement. Though, since an application of Cu to wire bond technology is relatively new, many of reliability failure mechanisms are unknown especially the ones related to EM reliability as it is increasingly serious in limiting useful life of wire bond. This makes the investigation on EM failure mechanism in Cu to be necessary. One of the most challenging difficulties of EM study is the isolation of the EM from any other effects on the failure process such as an increase in temperature by Joule heating. The Joule heat effect is of particular concern because it is expected to be considerable at wire bond configuration, making failure by EM to proceed concurrently with other failure mechanisms. Our investigation then begins with design of test structure that can prove that wire bond failure is indeed induced by EM, and progresses towards understanding microscopic mechanism by which wire bond becomes failure prone by EM. Therefore, this study proposes the use of a special configuration sample where two interfaces can be tested at the same temperature and current density conditions. The design of the sample includes a two-level interconnect structure pattern on Si substrate where a short strip conductor allows flow of test current from one pad to another. The short distance combined with heat-conduction through Si substrate assists the minimization of temperature gradient between the two interfaces. This design helps to isolate the EM effect over other factors that could contribute to the interface degradation such as Joule heating. The samples are then subjected to various testing conditions of temperature and current density and it is indeed found that there exists a difference in the failure kinetics when the interfaces are compared: the pad where current flows from pad to wire (mass flow is from the wire to pad) always fails faster than the opposite case. If it is considered that both interfaces have been tested at the same temperature and current density, the only factor contributing to this difference will be the EM because it is directional. The dependence of failure rate on the pad in respect to the direction of current flow is also found in Au-Al wire bond which is also tested for comparison purpose. This result indicates that the A-Al and Cu-Al wire bond shares the same failure mechanism when electric current is applied and provides further evidence that EM plays a critical role in inducing degradation in the interface integrity. When the EM failure kinetics of the first failing pad of samples are collected, and analyzed, they are found to follow the classic "Black's equation" that relates the failure rate to current density and test temperature; the failure rate shows current density dependence with exponent close to 2 for both Cu-Al and Au-Al wire bonds and temperature dependency with an activation energy of ~1.2eV for Cu-Al and 0.9eV for Au-Al. While Au-Al and Cu-Al wire bonds do not show typically different EM failure parameters, overall life of Cu-Al wire bond is notably higher (nearly one order of magnitude). This suggests that EM life enhancement in Cu-Al is mainly due to slower diffusion rate of species at the interface, which is consistent with other observations reporting slower IMC growth rate in Cu-Al than in Au-Al wire bond interface. In order to understand the EM mechanism leading to failure, microstructure of the interface is closely inspected after EM testing. This study shows that the growth of IMC is enhanced at the failing pad where EM forces IMC to grow into Al pad. Both Cu-Al and Au-Al shows the same trend, that is that the growth of IMC is substantially enhanced by EM when it is directed from the wire to the Al pad. This is consistent with a common expectation that the growth of IMC layers leads to the interface failure and EM makes the failure to be accelerated by speeding up their growth. However, it is noticed that there exists a distinctive difference in failure morphology between Au-Al and Cu-Al wire bond interface. The difference is that the damage at Au-Al interface appears as an extended voiding, while such voiding is absent in case of Cu-Al interface. Instead, it appears that the damage proceeds by the growth of cracks. It is believed that slow interdiffusion rate in Cu-Al interface makes the Kirkendall voiding to be suppressed from its formation while other factors like interface strain becomes primary factor responsible for interface failure. Although EM failure mechanism in Cu-Al wire bond interface is microscopically understood by the use of the theory that EM forces IMC growth to be accelerated when it directs atomic flux towards Al pads where short-circuit diffusion path is available, the difference in activation energy between EM failure and thermal growth rate of IMC phases appears to disagree with the theory. However, EM failure involves multiple processes such as crack initiation and growth in addition to IMC growth, it is possible that its activation energy may not necessarily be the same to that of thermal IMC growth. It is our belief that the cracking is delayed at higher temperature because of active stress relaxation process while such process is suppressed at lower temperature. This can make the activation of EM failure to be higher than that of IMC growth. On the other hand, the microscopic mechanism of EM failure established in this study also provides a reasonable explanation on an abnormal failure behavior at the interface. As is indicated, the failure always occurs faster at the pad where EM flux is directed toward Al pad. However, the rate of failure development is actually the opposite in the beginning EM testing. Initially, the failure rate measured by the interface resistance change is higher at the pad where EM flux is directed toward wire. With progressing of EM, its rate decreases and is eventually slower than the opposite case. This crossover in failure rate does not appear in case of Al-Au wire bond interface but is unmistakably existing in Cu-Al wire bond. This is found to be related to the interplay between the type of IMC phase forming at given time and its contribution to the interface resistance. In the pad where EM is directed toward Cu wire, the growth of high resistance [gamma]-- Cu9Al3 phase is initially more active because EM flux is against the direction of Cu diffusion. As EM progresses, with slow migration of Cu into Al pad, the growth of IMC phases in Al pad is generally suppressed, leading to slower increase in interface resistance. This agrees well with the microstructural mechanism found in our study. So as to better understand EM mechanism, the growth of IMC phases without EM load is investigated by subjecting the samples to only thermal condition. This study is done to compare IMC growth behaviors with and without EM, and also to determine the fundamental mechanism of IMC growth in Cu-Al; wire bond. This study leads to the conclusion that there are three IMC phases possible to grow at interface, and they are [alpha]2--Cu3Al,[gamma]-- Cu9Al4 and [theta] --CuAl2. Interdiffusion makes the CuAl2 phase to form first in Al pad because Al provides fast diffusion path for Cu due to abundant grain boundaries. This gradually consumes Al pad while a portion of CuAl2 is replaced for Cu9Al4. Finally, Cu rich phase, Cu3Al, forms at Cu wire side but its growth is very sluggish due to lack of diffusion short-circuit. As consequence, the three IMC layers form at the interface, mostly consuming Al pad with time. The growth rate of the total IMC layer thickness, all phases combined, follows an ideal diffusion controlled growth kinetics showing (t)1/2 dependence. The activation energy for the growth is observed to be ~0.5 eV, which is far lower than that of EM failure. While our investigation has yielded reasonably self-consistent EM failure mechanism active in Cu-Al wire bond, there still exists a number of subjects that await further investigation. Among many, the question as to the type of IMC phases possible to form at Cu-Al interface requires careful and extensive investigations. The source of stress that initiates the cracking and the type of IMC phase affecting such progress is an unanswered but critical question not only for understanding the fundamental mechanism of interface structure but also for finding ways to improving EM reliability of Cu/Al wire bonds.

Download or read book Interface Reaction Induced Stress Development in an Aluminum Thin Film Copper Bulk Plate Diffusion Couple written by Michael Codie Mishler and published by . This book was released on 2016 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the mechanism of the interface reaction induced intermetallic compound (IMC) phase formation and its impact on the interface reliability in the Al-Cu diffusion couple. This study is motivated by the accelerated failure experiments in lead frame to integrated circuit (IC) package wire-bonds using copper (Cu) wire and aluminum (Al) bond-pad that have shown failure most often occurs at the interface of the IMC [gammaa]2-phase (Cu9Al4). In a simulative investigation, we created a diffusion couple consisting of Cu bulk plate coated with pure Al thin film ~2 micrometer thick. This configuration resembles the microstructural configuration of a Cu wire / Al bond pad. In addition, we introduce two types of Cu plate as our samples, namely half-hard and fully annealed Cu plate. These samples are introduced in order to investigate the effect of microstructure, such as dislocation and grain boundaries and also residual stress on the interface reaction kinetics. Our experiment of Al thin film on bulk Cu has shown that the interface reaction creates a tensile stress in the Cu lattice. The stress generation is found to be closely associated with the formation of [gamma]2-phase. The expected initial formation of [theta]-phase (CuAl2) is never seen in our experiment as has been reported in thin-film / thin-film (TF/TF) and bulk / bulk (B/B) diffusion couples. While the principle mechanism of stress generation in Cu plate with the IMC formation remains the same for both half-hard and fully annealed Cu plate, X-ray diffraction data collected on aged samples revealed that the rate of IMC formation and thus the stress generation is smaller in half-hard Cu. This is the opposite of what is expected. The presence of finer grains and high dislocation density should promote short-circuit diffusion making the diffusion of Cu into Al faster. It is our conclusion that the enhancement in the short-circuit diffusion is outweighed by a suppression of diffusion by compressive residual stress in the half-hard Cu. Half-hard Cu plate is expected to have compressive residual stress and therefore likely to contain lower equilibrium concentration of vacancies. Our results of the stress generation during [gamma]2-phase formation and the suppression of diffusion in compressively strained lattices explains why it has been observed that IMC formation occurs first near the outer edges of the wire-bonds. The wire-bonding process creates a work hardened condition towards the center of the wire-bond, slowing IMC formation. The interface stress created by [gamma]2-phase formation expanding the Cu lattice presents favorable conditions for crack nucleation which has been observed in Cu- Al wire-bond failure.

Download or read book Copper Wire Bonding written by Preeti S Chauhan and published by Springer Science & Business Media. This book was released on 2013-09-20 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks. Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material. However, copper wire bonding has several process and reliability concerns due to its material properties. Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation. In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed. The book also discusses best practices and recommendations on the bond process, bond–pad metallurgies, and appropriate reliability tests for copper wire-bonded electronic components. In summary, this book: Introduces copper wire bonding technologies Presents copper wire bonding processes Discusses copper wire bonding metallurgies Covers recent advancements in copper wire bonding including the bonding process, equipment changes, bond–pad materials and surface finishes Covers the reliability tests and concerns Covers the current implementation of copper wire bonding in the electronics industry Features 120 figures and tables Copper Wire Bonding is an essential reference for industry professionals seeking detailed information on all facets of copper wire bonding technology.

Download or read book Electromigration in ULSI Interconnections written by Cher Ming Tan and published by World Scientific. This book was released on 2010 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromigration in ULSI Interconnections provides a comprehensive description of the electromigration in integrated circuits. It is intended for both beginner and advanced readers on electromigration in ULSI interconnections. It begins with the basic knowledge required for a detailed study on electromigration, and examines the various interconnected systems and their evolution employed in integrated circuit technology. The subsequent chapters provide a detailed description of the physics of electromigration in both Al- and Cu-based Interconnections, in the form of theoretical, experimental and numerical modeling studies. The differences in the electromigration of Al- and Cu-based interconnections and the corresponding underlying physical mechanisms for these differences are explained. The test structures, testing methodology, failure analysis methodology and statistical analysis of the test data for the experimental studies on electromigration are presented in a concise and rigorous manner. Methods of numerical modeling for the interconnect electromigration and their applications to the understanding of electromigration physics are described in detail with the aspects of material properties, interconnection design, and interconnect process parameters on the electromigration performances of interconnects in ULSI further elaborated upon. Finally, the extension of the studies to narrow interconnections is introduced, and future challenges on the study of electromigration are outlined and discussed.

Download or read book Interfacial Compatibility in Microelectronics written by Tomi Laurila and published by Springer Science & Business Media. This book was released on 2012-01-10 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interfaces between dissimilar materials are met everywhere in microelectronics and microsystems. In order to ensure faultless operation of these highly sophisticated structures, it is mandatory to have fundamental understanding of materials and their interactions in the system. In this difficult task, the “traditional” method of trial and error is not feasible anymore; it takes too much time and repeated efforts. In Interfacial Compatibility in Microelectronics, an alternative approach is introduced. In this revised method four fundamental disciplines are combined: i) thermodynamics of materials ii) reaction kinetics iii) theory of microstructures and iv) stress and strain analysis. The advantages of the method are illustrated in Interfacial Compatibility in Microelectronics which includes: solutions to several common reliability issues in microsystem technology, methods to understand and predict failure mechanisms at interfaces between dissimilar materials and an approach to DFR based on deep understanding in materials science, rather than on the use of mechanistic tools, such as FMEA. Interfacial Compatibility in Microelectronics provides a clear and methodical resource for graduates and postgraduates alike.

Download or read book Semiconductor Laser Engineering Reliability and Diagnostics written by Peter W. Epperlein and published by John Wiley & Sons. This book was released on 2013-01-25 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference book provides a fully integrated novel approach to the development of high-power, single-transverse mode, edge-emitting diode lasers by addressing the complementary topics of device engineering, reliability engineering and device diagnostics in the same book, and thus closes the gap in the current book literature. Diode laser fundamentals are discussed, followed by an elaborate discussion of problem-oriented design guidelines and techniques, and by a systematic treatment of the origins of laser degradation and a thorough exploration of the engineering means to enhance the optical strength of the laser. Stability criteria of critical laser characteristics and key laser robustness factors are discussed along with clear design considerations in the context of reliability engineering approaches and models, and typical programs for reliability tests and laser product qualifications. Novel, advanced diagnostic methods are reviewed to discuss, for the first time in detail in book literature, performance- and reliability-impacting factors such as temperature, stress and material instabilities. Further key features include: practical design guidelines that consider also reliability related effects, key laser robustness factors, basic laser fabrication and packaging issues; detailed discussion of diagnostic investigations of diode lasers, the fundamentals of the applied approaches and techniques, many of them pioneered by the author to be fit-for-purpose and novel in the application; systematic insight into laser degradation modes such as catastrophic optical damage, and a wide range of technologies to increase the optical strength of diode lasers; coverage of basic concepts and techniques of laser reliability engineering with details on a standard commercial high power laser reliability test program. Semiconductor Laser Engineering, Reliability and Diagnostics reflects the extensive expertise of the author in the diode laser field both as a top scientific researcher as well as a key developer of high-power highly reliable devices. With invaluable practical advice, this new reference book is suited to practising researchers in diode laser technologies, and to postgraduate engineering students.

Download or read book CRC Handbook of Metal Etchants written by Perrin Walker and published by CRC Press. This book was released on 1990-12-11 with total page 1434 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication presents cleaning and etching solutions, their applications, and results on inorganic materials. It is a comprehensive collection of etching and cleaning solutions in a single source. Chemical formulas are presented in one of three standard formats - general, electrolytic or ionized gas formats - to insure inclusion of all necessary operational data as shown in references that accompany each numbered formula. The book describes other applications of specific solutions, including their use on other metals or metallic compounds. Physical properties, association of natural and man-made minerals, and materials are shown in relationship to crystal structure, special processing techniques and solid state devices and assemblies fabricated. This publication also presents a number of organic materials which are widely used in handling and general processing...waxes, plastics, and lacquers for example. It is useful to individuals involved in study, development, and processing of metals and metallic compounds. It is invaluable for readers from the college level to industrial R & D and full-scale device fabrication, testing and sales. Scientific disciplines, work areas and individuals with great interest include: chemistry, physics, metallurgy, geology, solid state, ceramic and glass, research libraries, individuals dealing with chemical processing of inorganic materials, societies and schools.

Download or read book Semiconductor Packaging written by Andrea Chen and published by CRC Press. This book was released on 2016-04-19 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: In semiconductor manufacturing, understanding how various materials behave and interact is critical to making a reliable and robust semiconductor package. Semiconductor Packaging: Materials Interaction and Reliability provides a fundamental understanding of the underlying physical properties of the materials used in a semiconductor package. By tying together the disparate elements essential to a semiconductor package, the authors show how all the parts fit and work together to provide durable protection for the integrated circuit chip within as well as a means for the chip to communicate with the outside world. The text also covers packaging materials for MEMS, solar technology, and LEDs and explores future trends in semiconductor packages.

Download or read book CMOS written by R. Jacob Baker and published by John Wiley & Sons. This book was released on 2008 with total page 1074 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edition provides an important contemporary view of a wide range of analog/digital circuit blocks, the BSIM model, data converter architectures, and more. The authors develop design techniques for both long- and short-channel CMOS technologies and then compare the two.

Download or read book Advanced Flip Chip Packaging written by Ho-Ming Tong and published by Springer Science & Business Media. This book was released on 2013-03-20 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Flip Chip Packaging presents past, present and future advances and trends in areas such as substrate technology, material development, and assembly processes. Flip chip packaging is now in widespread use in computing, communications, consumer and automotive electronics, and the demand for flip chip technology is continuing to grow in order to meet the need for products that offer better performance, are smaller, and are environmentally sustainable.

Download or read book Mechanics of Microelectronics written by G.Q. Zhang and published by Springer Science & Business Media. This book was released on 2006-08-25 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written by leading experts with both profound knowledge and rich practical experience in advanced mechanics and the microelectronics industry essential for current and future development. It aims to provide the cutting edge knowledge and solutions for various mechanical related problems, in a systematic way. It contains important and detailed information about the state-of-the-art theories, methodologies, the way of working and real case studies.

Download or read book High Temperature Electronics written by F. Patrick McCluskey and published by CRC Press. This book was released on 1996-12-13 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of electronics that can operate at high temperatures has been identified as a critical technology for the next century. Increasingly, engineers will be called upon to design avionics, automotive, and geophysical electronic systems requiring components and packaging reliable to 200 °C and beyond. Until now, however, they have had no single resource on high temperature electronics to assist them. Such a resource is critically needed, since the design and manufacture of electronic components have now made it possible to design electronic systems that will operate reliably above the traditional temperature limit of 125 °C. However, successful system development efforts hinge on a firm understanding of the fundamentals of semiconductor physics and device processing, materials selection, package design, and thermal management, together with a knowledge of the intended application environments. High Temperature Electronics brings together this essential information and presents it for the first time in a unified way. Packaging and device engineers and technologists will find this book required reading for its coverage of the techniques and tradeoffs involved in materials selection, design, and thermal management and for its presentation of best design practices using actual fielded systems as examples. In addition, professors and students will find this book suitable for graduate-level courses because of its detailed level of explanation and its coverage of fundamental scientific concepts. Experts from the field of high temperature electronics have contributed to nine chapters covering topics ranging from semiconductor device selection to testing and final assembly.

Download or read book Science Abstracts written by and published by . This book was released on 1993 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capillary Electromigration Separation Methods written by Colin F. Poole and published by Elsevier. This book was released on 2018-04-13 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capillary Electromigration Separation Methods is a thorough, encompassing reference that not only defines the concept of contemporary practice, but also demonstrates its implementation in laboratory science. Chapters are authored by recognized experts in the field, ensuring that the content reflects the latest developments in research. Thorough, comprehensive coverage makes this the ideal reference for project planning, and extensive selected referencing facilitates identification of key information. The book defines the concept of contemporary practice in capillary electromigration separation methods, also discussing its applications in small mass ions, stereoisomers, and proteins. - Edited and authored by world-leading capillary electrophoresis experts - Presents comprehensive coverage on the subject - Includes extensive referencing that facilitates the identification of key research developments - Provides more than 50 figures and tables that aid in the retention of key concepts

Download or read book Materials for Advanced Packaging written by Daniel Lu and published by Springer. This book was released on 2016-11-18 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant progress has been made in advanced packaging in recent years. Several new packaging techniques have been developed and new packaging materials have been introduced. This book provides a comprehensive overview of the recent developments in this industry, particularly in the areas of microelectronics, optoelectronics, digital health, and bio-medical applications. The book discusses established techniques, as well as emerging technologies, in order to provide readers with the most up-to-date developments in advanced packaging.

Download or read book Metals Abstracts written by and published by . This book was released on 1994 with total page 1586 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Physics of Ultra High Density Magnetic Recording written by M.L. Plumer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Application-oriented book on magnetic recording, focussing on the underlying physical mechanisms that play crucial roles in medium and transducer development for high areal density disk drives.