Download or read book Investigation on the Mechanism of Interface Electromigration EM in Copper Cu Thin Films written by Jee Yong Kim and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study concerns the mechanism of the interface electromigration (EM) in copper (Cu) thin films. While EM in Cu is one of the most concerned reliability failure phenomena in Cu interconnects used microelectronic devices, its mechanism is not well understood yet. In order for better understanding of the EM mechanism, this study attempt to investigate the interface EM mechanism by examining the passivation effects on Cu EM using a cross-strip structure where Cu lines are cross-stripped with different passivation layers. From the observation of the marker polarity (hillocks and voids), the interface EM mechanism is determined whether the passivation layer increases or decreases the interface EM of Cu. A series of investigation finds that the surface/interface EM mechanism of Cu is different depending on both the passivation material and the thickness of passivation. Differing passivation materials and their thickness do induce change in the kinetics of the marker formation. In all cases, the results show that the mass transport along the metal passivation/Cu interfaces has slower EM rate than dielectric passivation/Cu interfaces. CoWP passivation provides interface with the slowest interface EM, and TaN passivation provides more stable interface with slower EM rate than Ta. In addition, Si3N 4 passivation seems to provide interface with slower interface EM than SiO2. On the other hand, when interface EM is compared to surface EM, it is found that the interface EM tends to be faster than the surface EM. This is somewhat unexpected result, but all systems inspected produced a consistent indication. It is found that the reason for higher rate of interface EM than the surface EM may be related to higher Z* at interface. The results of this investigation may bear importance both for scientific and engineering aspects. This is the first study that shows direct evidence for active interface EM in Cu. While the interface EM and also surface EM needs further investigation in order to understand how they occur, especially the mechanism, the results suggest that engineering the interface may be critical for reliability improvement of Cu interconnects.
Download or read book Electromigration in Thin Films and Electronic Devices written by Choong-Un Kim and published by Elsevier. This book was released on 2011-08-28 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding and limiting electromigration in thin films is essential to the continued development of advanced copper interconnects for integrated circuits. Electromigration in thin films and electronic devices provides an up-to-date review of key topics in this commercially important area.Part one consists of three introductory chapters, covering modelling of electromigration phenomena, modelling electromigration using the peridynamics approach and simulation and x-ray microbeam studies of electromigration. Part two deals with electromigration issues in copper interconnects, including x-ray microbeam analysis, voiding, microstructural evolution and electromigration failure. Finally, part three covers electromigration in solder, with chapters discussing topics such as electromigration-induced microstructural evolution and electromigration in flip-chip solder joints.With its distinguished editor and international team of contributors, Electromigration in thin films and electronic devices is an essential reference for materials scientists and engineers in the microelectronics, packaging and interconnects industries, as well as all those with an academic research interest in the field. - Provides up-to-date coverage of the continued development of advanced copper interconnects for integrated circuits - Comprehensively reviews modelling of electromigration phenomena, modelling electromigration using the peridynamics approach and simulation, and x-ray microbeam studies of electromigration - Deals with electromigration issues in copper interconnects, including x-ray microbeam analysis, voiding, microstructural evolution and electromigration failure
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 Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 902 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Electromigration Aware Integrated Circuit Design written by Jens Lienig and published by Springer. This book was released on 2018-02-23 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a comprehensive overview of electromigration and its effects on the reliability of electronic circuits. It introduces the physical process of electromigration, which gives the reader the requisite understanding and knowledge for adopting appropriate counter measures. A comprehensive set of options is presented for modifying the present IC design methodology to prevent electromigration. Finally, the authors show how specific effects can be exploited in present and future technologies to reduce electromigration’s negative impact on circuit reliability.
Download or read book Investigation of Electromigration Mechanisms in Silver Thin Films written by Christopher Joseph Waskiewicz and published by . This book was released on 1992 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electromigration in Metals written by Paul S. Ho and published by Cambridge University Press. This book was released on 2022-05-12 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn to assess electromigration reliability and design more resilient chips in this comprehensive and practical resource. Beginning with fundamental physics and building to advanced methodologies, this book enables the reader to develop highly reliable on-chip wiring stacks and power grids. Through a detailed review on the role of microstructure, interfaces and processing on electromigration reliability, as well as characterisation, testing and analysis, the book follows the development of on-chip interconnects from microscale to nanoscale. Practical modeling methodologies for statistical analysis, from simple 1D approximation to complex 3D description, can be used for step-by-step development of reliable on-chip wiring stacks and industrial-grade power/ground grids. This is an ideal resource for materials scientists and reliability and chip design engineers.
Download or read book Interconnect and Contact Metallization for ULSI written by G. S. Mathad and published by The Electrochemical Society. This book was released on 2000 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applications of Finite Element Methods for Reliability Studies on ULSI Interconnections written by Cher Ming Tan and published by Springer Science & Business Media. This book was released on 2011-03-28 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of Finite Element Methods for Reliability Studies on ULSI Interconnections provides a detailed description of the application of finite element methods (FEMs) to the study of ULSI interconnect reliability. Over the past two decades the application of FEMs has become widespread and continues to lead to a much better understanding of reliability physics. To help readers cope with the increasing sophistication of FEMs’ applications to interconnect reliability, Applications of Finite Element Methods for Reliability Studies on ULSI Interconnections will: introduce the principle of FEMs; review numerical modeling of ULSI interconnect reliability; describe the physical mechanism of ULSI interconnect reliability encountered in the electronics industry; and discuss in detail the use of FEMs to understand and improve ULSI interconnect reliability from both the physical and practical perspective, incorporating the Monte Carlo method. A full-scale review of the numerical modeling methodology used in the study of interconnect reliability highlights useful and noteworthy techniques that have been developed recently. Many illustrations are used throughout the book to improve the reader’s understanding of the methodology and its verification. Actual experimental results and micrographs on ULSI interconnects are also included. Applications of Finite Element Methods for Reliability Studies on ULSI Interconnections is a good reference for researchers who are working on interconnect reliability modeling, as well as for those who want to know more about FEMs for reliability applications. It gives readers a thorough understanding of the applications of FEM to reliability modeling and an appreciation of the strengths and weaknesses of various numerical models for interconnect reliability.
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 electro migration in integrated circuits. It is intended for both beginner and advanced readers on electro migration in ULSI interconnections. It begins with the basic knowledge required for a detailed study on electro migration, 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 electro migration in both Al- and Cu-based Interconnections, in the form of theoretical, experimental and numerical modeling studies. The differences in the electro migration 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 electro migration are presented in a concise and rigorous manner.Methods of numerical modeling for the interconnect electro migration and their applications to the understanding of electro migration physics are described in detail with the aspects of material properties, interconnection design, and interconnect process parameters on the electro migration 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 electro migration are outlined and discussed.
Download or read book Mechanism of Electromigration Failure in Al Thin Film Interconnects Containing Sc written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to understand the role of Sc on electromigration (EM) failure, Al interconnects with 0.1 and 0.3 wt.% Sc sere tested as a function of post-pattern annealing time. In response to the evolution of the line structure, the statistics of lifetime evolved. While the addition of Sc greatly reduces the rate of evolution of the failure statistics because the grain growth rate decreases, the MTF variation was found to be very similar to that of pure Al. These observations seem to show that Sc has little influence on the kinetics of Al EM; however, it has some influence on the EM resistance of the line since it is an efficient grain refiner. Unlike Cu in Al, Sc does not seem to migrate, which may explain its lack of influence on the kinetics of Al EM.
Download or read book Advanced Metallization Conference in written by and published by . This book was released on 2007 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Interconnects for ULSI Technology written by Mikhail Baklanov and published by John Wiley & Sons. This book was released on 2012-04-02 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finding new materials for copper/low-k interconnects is critical to the continuing development of computer chips. While copper/low-k interconnects have served well, allowing for the creation of Ultra Large Scale Integration (ULSI) devices which combine over a billion transistors onto a single chip, the increased resistance and RC-delay at the smaller scale has become a significant factor affecting chip performance. Advanced Interconnects for ULSI Technology is dedicated to the materials and methods which might be suitable replacements. It covers a broad range of topics, from physical principles to design, fabrication, characterization, and application of new materials for nano-interconnects, and discusses: Interconnect functions, characterisations, electrical properties and wiring requirements Low-k materials: fundamentals, advances and mechanical properties Conductive layers and barriers Integration and reliability including mechanical reliability, electromigration and electrical breakdown New approaches including 3D, optical, wireless interchip, and carbon-based interconnects Intended for postgraduate students and researchers, in academia and industry, this book provides a critical overview of the enabling technology at the heart of the future development of computer chips.
Download or read book Istc cstic 2009 cistc written by David Huang and published by The Electrochemical Society. This book was released on 2009-03 with total page 1124 pages. Available in PDF, EPUB and Kindle. Book excerpt: ISTC/CSTIC is an annual semiconductor technology conference covering all the aspects of semiconductor technology and manufacturing, including devices, design, lithography, integration, materials, processes, manufacturing as well as emerging semiconductor technologies and silicon material applications. ISTC/CSTIC 2009 was merged by ISTC (International Semiconductor Technology Conference) and CSTIC (China Semiconductor Technology International Conference), the two industry leading technical conferences in China, and consisted of one plenary session and nine technical symposia. This issue of ECS Transactions contains 159 papers from the conference.
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 Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
