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 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 Electromigration in Thin Film Aluminum Alloy Interconnects written by Lawrence Edward Felton and published by . This book was released on 1986 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Handbook of Semiconductor Interconnection Technology written by Geraldine Cogin Shwartz and published by CRC Press. This book was released on 1997-11-24 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering materials, processes, equipment, methodologies, characterization techniques, clean room practices, and ways to control contamination-related defects, this work offers up-to-date information on the application of interconnection technology to semiconductors. It offers an integration of technical, patent and industry literature.

Download or read book Materials Reliability in Microelectronics V Volume 391 written by Anthony S. Oates and published by . This book was released on 1995-10-24 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This long-standing proceedings series is highly regarded as a premier forum for the discussion of microelectronics reliability issues. In this fifth book, emphasis is on the fundamental understanding of failure phenomena in thin-film materials. Special attention is given to electromigration and mechanical stress effects. The reliability of thin dielectrics and hot carrier degradation of transistors are also featured. Topics include: modeling and simulation of failure mechanisms; reliability issues for submicron IC technologies and packaging; stresses in thin films/lines; gate oxides; barrier layers; electromigration mechanisms; reliability issues for Cu metallizations; electromigration and microstructure; electromigration and stress voiding in circuit interconnects; and resistance measurements of electromigration damage.

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 Effects of Microstructural Control on the Failure Kinetics and the Reliability Improvement of Al and Al alloy Interconnects written by and published by . This book was released on 1996 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reliability of microelectronic systems is often limited by electromigration failure in Al-based thin-film conducting lines which interconnect devices to form an integrated circuit. Under an applied electric field Al atoms migrate with the electron flow, causing a counterflow of vacancies that accumulate into voids, eventually leading to an open circuit failure. The work reported here is concerned with clarifying the microstructural mechanism of electromigration failure, and with developing a metallurgical method to improve the electromigration resistance of Al-based interconnects. Pure Al, Al-2Cu, and Al-2Cu-1Si lines with quasi-bamboo microstructures are explored as a function of heat treatment conditions and current density. The {open_quotes}weakest{close_quotes} microstructural unit that causes failure is identified by electron microscopy; with rare exceptions, failure occurs at the upstream end of the longest polygranular segment in a given line. This microstructural characteristic of electromigration failure is even observed in lines whose maximum segment lengths are less than a few microns. The time to failure appears to increase exponentially with decreasing longest polygranular segment length. A simple constitutive equation is reported to describe the failure kinetics as a function of the polygranular segment length that leads to failure. Given correct values of the kinetic constants included in the equation, this microstructure-based constitutive relation will provide a way to assess interconnect reliability. An effective metallurgical method that can eliminate relatively long polygranular segments is post-pattern annealing. This heat treatment particularly narrows the distribution of the longest polygranular segment lengths over a large set of lines. As a consequence, the time-to-failure distribution narrows as well, so that the time to first failure increases more substantially than the median time to failure.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling and Characterization of Electromigration Failures in IC Metallization Systems and Copper Metallization for ULSI Applications written by Jiang Tao and published by . This book was released on 1995 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.

Download or read book Guide to State of the Art Electron Devices written by Joachim N. Burghartz and published by John Wiley & Sons. This book was released on 2013-03-19 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: Winner, 2013 PROSE Award, Engineering and Technology Concise, high quality and comparative overview of state-of-the-art electron device development, manufacturing technologies and applications Guide to State-of-the-Art Electron Devices marks the 60th anniversary of the IRE electron devices committee and the 35th anniversary of the IEEE Electron Devices Society, as such it defines the state-of-the-art of electron devices, as well as future directions across the entire field. Spans full range of electron device types such as photovoltaic devices, semiconductor manufacturing and VLSI technology and circuits, covered by IEEE Electron and Devices Society Contributed by internationally respected members of the electron devices community A timely desk reference with fully-integrated colour and a unique lay-out with sidebars to highlight the key terms Discusses the historical developments and speculates on future trends to give a more rounded picture of the topics covered A valuable resource R&D managers; engineers in the semiconductor industry; applied scientists; circuit designers; Masters students in power electronics; and members of the IEEE Electron Device Society.

Download or read book Electromigration in Gold Interconnects written by Stephen Kilgore and published by . This book was released on 2013 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromigration in metal interconnects is the most pernicious failure mechanism in semiconductor integrated circuits (ICs). Early electromigration investigations were primarily focused on aluminum interconnects for silicon-based ICs. An alternative metallization compatible with gallium arsenide (GaAs) was required in the development of high-powered radio frequency (RF) compound semiconductor devices operating at higher current densities and elevated temperatures. Gold-based metallization was implemented on GaAs devices because it uniquely forms a very low resistance ohmic contact and gold interconnects have superior electrical and thermal conductivity properties. Gold (Au) was also believed to have improved resistance to electromigration due to its higher melting temperature, yet electromigration reliability data on passivated Au interconnects is scarce and inadequate in the literature. Therefore, the objective of this research was to characterize the electromigration lifetimes of passivated Au interconnects under precisely controlled stress conditions with statistically relevant quantities to obtain accurate model parameters essential for extrapolation to normal operational conditions. This research objective was accomplished through measurement of electromigration lifetimes of large quantities of passivated electroplated Au interconnects utilizing high-resolution in-situ resistance monitoring equipment. Application of moderate accelerated stress conditions with a current density limited to 2 MA/cm2 and oven temperatures in the range of 300°C to 375°C avoided electrical overstress and severe Joule-heated temperature gradients. Temperature coefficients of resistance (TCRs) were measured to determine accurate Joule-heated Au interconnect film temperatures. A failure criterion of 50% resistance degradation was selected to prevent thermal runaway and catastrophic metal ruptures that are problematic of open circuit failure tests. Test structure design was optimized to reduce resistance variation and facilitate failure analysis. Characterization of the Au microstructure yielded a median grain size of 0.91 ìm. All Au lifetime distributions followed log-normal distributions and Black's model was found to be applicable. An activation energy of 0.80 ± 0.05 eV was measured from constant current electromigration tests at multiple temperatures. A current density exponent of 1.91 was extracted from multiple current densities at a constant temperature. Electromigration-induced void morphology along with these model parameters indicated grain boundary diffusion is dominant and the void nucleation mechanism controlled the failure time.

Download or read book Materials Reliability in Microelectronics II Volume 265 written by C. V. Thompson and published by . This book was released on 1992-09-30 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners.

Download or read book Thin Film Interconnect Electromigration Reliability Determined by Abrupt Changes in Resistance written by Craig Carl Frank Fahrenkrug and published by . This book was released on 1998 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Materials Reliability in Microelectronics written by and published by . This book was released on 1992 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electromigration in Thin Films and Electronic Devices written by Choong-Un Kim and published by . This book was released on 2011 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: