Area Efficient Device Optimization For Esd Protection In High Speed Interface Ics

Electrostatic discharge (ESD) protection is considered as a vital step in integrated circuit (IC) manufacturing process. IC chips are unable to overcome the effects of transient events without adequate discharge protection. Recent trend in the industry has seen the incorporation of system level ESD protection within the IC chip. Incorporating system level on-chip ESD protection often increases cost, degrades circuit performance and consumes layout area which could otherwise be used for improving the circuit performance. These design challenges could be easily overcome if the parasitic components in a circuit were used for ESD protection. Despite the various design challenges, on-chip ESD protection is still desirable as it saves the area on the circuit board by eliminating the traditional ESD protection devices resulting in more compact circuits. Furthermore, using parasitic components while designing on-chip system level ESD protection can save layout area. In order to effectively implement this solution, a study on ESD events, protection circuits and high-speed ICs was carried out. Different types of ESD events and the different models pertaining to ESD events were studied and are discussed in detail. An overview of high-speed integrated circuits was also carried out with emphasis on the protection topologies that are commonly used. The ESD characteristics of parasitic PNP devices in rail-based ESD protection structure was then studied to summarize its viability as a protection circuit. The turn-on or breakdown voltage of the parasitic PNP is studied by technology computer aided design (TCAD) simulations performed in Silvaco software. The breakdown voltage, holding voltage, on resistance and failure current were studied and modeled to maximize ESD protection.

ESD Protection Device and Circuit Design for Advanced CMOS Technologies is intended for practicing engineers working in the areas of circuit design, VLSI reliability and testing domains. As the problems associated with ESD failures and yield losses become significant in the modern semiconductor industry, the demand for graduates with a basic knowledge of ESD is also increasing. Today, there is a significant demand to educate the circuits design and reliability teams on ESD issues. This book makes an attempt to address the ESD design and implementation in a systematic manner. A design procedure involving device simulators as well as circuit simulator is employed to optimize device and circuit parameters for optimal ESD as well as circuit performance. This methodology, described in ESD Protection Device and Circuit Design for Advanced CMOS Technologies has resulted in several successful ESD circuit design with excellent silicon results and demonstrates its strengths.

Electrostatic discharge (ESD) is defined as the transfer of charge between bodies at different potentials. The electrostatic discharge induced integrated circuit damages occur throughout the whole life of a product from the manufacturing, testing, shipping, handing, to end user operating stages. This is particularly true as microelectronics technology continues shrink to nano-metric dimensions. The ESD related failures is a major IC reliability concern and results in a loss of millions dollars to the semiconductor industry each year. Several ESD stress models and test methods have been developed to reproduce the real world ESD discharge events and quantify the sensitivity of ESD protection structures. The basic ESD models are: Human body model (HBM), Machine model (MM), and Charged device model (CDM). To avoid or reduce the IC failure due to ESD, the on-chip ESD protection structures and schemes have been implemented to discharge ESD current and clamp overstress voltage under different ESD stress events. Because of its simple structure and good performance, the junction diode is widely used in on-chip ESD protection applications. This is particularly true for ESD protection of low-voltage ICs where a relatively low trigger voltage for the ESD protection device is required. However, when the diode operates under the ESD stress, its current density and temperature are far beyond the normal conditions and the device is in danger of being damaged. For the design of effective ESD protection solution, the ESD robustness and low parasitic capacitance are two major concerns. The ESD robustness is usually defined after the failure current It2 and on-state resistance Ron. The transmission line pulsing (TLP) measurement is a very effective tool for evaluating the ESD robustness of a circuit or single element. This is particularly helpful in characterizing the effect of HBM stress where the ESD-induced damages are more likely due to thermal failures. Two types of diodes with different anode/cathode isolation technologies will be investigated for their ESD performance: one with a LOCOS (Local Oxidation of Silicon) oxide isolation called the LOCOS-bound diode, the other with a polysilicon gate isolation called the polysilicon-bound diode. We first examine the ESD performance of the LOCOS-bound diode. The effects of different diode geometries, metal connection patterns, dimensions and junction configurations on the ESD robustness and parasitic capacitance are investigated experimentally. The devices considered are N+/P-well junction LOCOS-bound diodes having different device widths, lengths and finger numbers, but the approach applies generally to the P+/N-well junction diode as well. The results provide useful insights into optimizing the diode for robust HBM ESD protection applications. Then, the current carrying and voltage clamping capabilities of LOCOS- and polysilicon-bound diodes are compared and investigated based on both TCAD simulation and experimental results. Comparison of these capabilities leads to the conclusion that the polysilicon-bound diode is more suited for ESD protection applications due to its higher performance. The effects of polysilicon-bound diode's design parameters, including the device width, anode/cathode length, finger number, poly-gate length, terminal connection and metal topology, on the ESD robustness are studied. Two figures of merits, FOM_It2 and FOM_Ron, are developed to better assess the effects of different parameters on polysilicon-bound diode's overall ESD performance. As latest generation package styles such as mBGAs, SOTs, SC70s, and CSPs are going to the millimeter-range dimensions, they are often effectively too small for people to handle with fingers. The recent industry data indicates the charged device model (CDM) ESD event becomes increasingly important in today's manufacturing environment and packaging technology. This event generates highly destructive pulses with a very short rise time and very small duration. TLP has been modified to probe CDM ESD protection effectiveness. The pulse width was reduced to the range of 1-10 ns to mimic the very fast transient of the CDM pulses. Such a very fast TLP (VFTLP) testing has been used frequently for CDM ESD characterization. The overshoot voltage and turn-on time are two key considerations for designing the CDM ESD protection devices. A relatively high overshoot voltage can cause failure of the protection devices as well as the protected devices, and a relatively long turn-on time may not switch on the protection device fast enough to effectively protect the core circuit against the CDM stress. The overshoot voltage and turn-on time of an ESD protection device can be observed and extracted from the voltage versus time waveforms measured from the VFTLP testing. Transient behaviors of polysilicon-bound diodes subject to pulses generated by the VFTLP tester are characterized for fast ESD events such as the charged device model. The effects of changing devices' dimension parameters on the transient behaviors and on the overshoot voltage and turn-on time are studied. The correlation between the diode failure and poly-gate configuration under the VFTLP stress is also investigated. Silicon-controlled rectifier (SCR) is another widely used ESD device for protecting the I/O pins and power supply rails of integrated circuits. Multiple fingers are often needed to achieve optimal ESD protection performance, but the uniformity of finger triggering and current flow is always a concern for multi-finger SCR devices operating under the post-snapback region. Without a proper understanding of the finger turn-on mechanism, design and realization of robust SCRs for ESD protection applications are not possible. Two two-finger SCRs with different combinations of anode/cathode regions are considered, and their finger turn-on uniformities are analyzed based on the I-V characteristics obtained from the transmission line pulsing (TLP) tester. The dV/dt effect of pulses with different rise times on the finger turn-on behavior of the SCRs are also investigated experimentally. In this work, unless noted otherwise, all the measurements are conducted using the Barth 4002 transmission line pulsing (TLP) and Barth 4012 very-fast transmission line pulsing (VFTLP) testers.

An authoritative single-volume reference on the design and analysis of ESD protection for ICs Electrostatic discharge (ESD) is a major reliability challenge to semiconductors, integrated circuits (ICs), and microelectronic systems. On-chip ESD protection is a vital to any electronic products, such as smartphones, laptops, tablets, and other electronic devices. Practical ESD Protection Design provides comprehensive and systematic guidance on all major aspects of designs of on-chip ESD protection for integrated circuits (ICs). Written for students and practicing engineers alike, this one-stop resource covers essential theories, hands-on design skills, computer-aided design (CAD) methods, characterization and analysis techniques, and more on ESD protection designs. Detailed chapters examine an array of topics ranging from fundamental to advanced, including ESD phenomena, ESD failure analysis, ESD testing models, ESD protection devices and circuits, ESD design layout and technology effects, ESD design flows and co-design methods, ESD modelling and CAD techniques, and future ESD protection concepts. Based on the author’s decades of design, research and teaching experiences, Practical ESD Protection Design: • Features numerous real-world ESD protection design examples • Emphasizes on ESD protection design techniques and procedures • Describes ESD-IC co-design methodology for high-performance mixed-signal ICs and broadband radio-frequency (RF) ICs • Discusses CAD-based ESD protection design optimization and prediction using both Technology and Electrical Computer-Aided Design (TCAD/ECAD) simulation • Addresses new ESD CAD algorithms and tools for full-chip ESD physical design verification • Explores the disruptive future outlook of ESD protection Practical ESD Protection Design is a valuable reference for industrial engineers and academic researchers in the field, and an excellent textbook for electronic engineering courses in semiconductor microelectronics and integrated circuit designs.

Simulation Methods for ESD Protection Development looks at the integration of new techniques into a comprehensive development flow, which is now available due advances made in the field during the recent years. These findings allow for an early, stable ESD concept at a very early stage of the technology development, which is essential now development cycles have been reduced. The book also offers ways of increasing the optimization and control of the technology concerning performance, thus making the process more cost effective and increasingly efficient. This title provides a guide through the latest research and technology presenting the ESD protection development methodology. This is based on a combination of process, device and circuit stimulation, and addresses the optimization of the industry critical issue, reduced development cycles.Written to address the needs of the ESD engineer, this text is required reading by all industry practitioners and researchers and students within this field. The FIRST Extensive overview on the subject of ESD simulation Addresses the industry critical issue of reduced development cycles, and provides solutions Presents the latest research in the field with high practical relevance and its results

An effective and cost efficient protection of electronic system against ESD stress pulses specified by IEC 61000-4-2 is paramount for any system design. This pioneering book presents the collective knowledge of system designers and system testing experts and state-of-the-art techniques for achieving efficient system-level ESD protection, with minimum impact on the system performance. All categories of system failures ranging from 'hard' to 'soft' types are considered to review simulation and tool applications that can be used. The principal focus of System Level ESD Co-Design is defining and establishing the importance of co-design efforts from both IC supplier and system builder perspectives. ESD designers often face challenges in meeting customers' system-level ESD requirements and, therefore, a clear understanding of the techniques presented here will facilitate effective simulation approaches leading to better solutions without compromising system performance. With contributions from Robert Ashton, Jeffrey Dunnihoo, Micheal Hopkins, Pratik Maheshwari, David Pomerenke, Wolfgang Reinprecht, and Matti Usumaki, readers benefit from hands-on experience and in-depth knowledge in topics ranging from ESD design and the physics of system ESD phenomena to tools and techniques to address soft failures and strategies to design ESD-robust systems that include mobile and automotive applications. The first dedicated resource to system-level ESD co-design, this is an essential reference for industry ESD designers, system builders, IC suppliers and customers and also Original Equipment Manufacturers (OEMs). Key features: Clarifies the concept of system level ESD protection. Introduces a co-design approach for ESD robust systems. Details soft and hard ESD fail mechanisms. Detailed protection strategies for both mobile and automotive applications. Explains simulation tools and methodology for system level ESD co-design and overviews available test methods and standards. Highlights economic benefits of system ESD co-design.

To enable predicting the ESD performance of IC's pins that are directly exposed to a system-level stress condition, a new the human metal model (HMM) test model has been introduced. In this work, a new testing methodology for product-level HMM characterization is introduced. This testing framework allows for consistently identifying ESD-induced failures in a product, substantially simplifying the testing process, and significantly reducing the product evaluation time during development cycle. It helps eliminates the potential inaccuracy provided by the conventional characterization methodology. For verification purposes, this method has been applied to detect the failures of two different products. Addition to the exploration of new characterization methodology that provides better accuracy, we also have looked into the protection devices itself. ICs for emerging high performance precision data acquisition and transceivers in industrial, automotive and wireless infrastructure applications require effective and ESD protection solutions. These circuits, with relatively high operating voltages at the Input/Output (I/O) pins, are increasingly being designed in low voltage Complementary Metal-Oxide-Semiconductor (CMOS) technologies to meet the requirements of low cost and large scale integration. A new dual-polarity SCR optimized for high bidirectional blocking voltages, high trigger current and low capacitance is realized in a sub 3-V, 180-nm CMOS process. This ESD device is designed for a specific application where the operating voltage at the I/O is larger than that of the core circuit. For instance, protecting high voltage swing I/Os in CMOS data acquisition system (DAS) applications.

For signal integrity reasons, the magnitude of the parasitics generated by electrostatic discharge (ESD) protection devices has become budgeted. Such budgets restrict the protection level and implementation options of the ESD protection circuit designer. In this work, the ESD protection on high-speed serial I/O link performance is investigated. Simulations are used to determine the effect of the parasitic ESD capacitance on the equalization required to maintain a specific bit error rate (BER). Then, the simulation results are converted into power estimates to demonstrate the power versus reliability trade-off. Essentially, rather than approaching the effect of ESD protection circuits as harmful, this work approaches the effect of ESD protection circuits as an engineering optimization problem which requires co-design between the printed circuit board (PCB) designer, transmitter and receiver circuit designer, and ESD protection circuit designer.

"This research proposal presents a methodology whereby a protection device can be modeled in SPICE compatible platforms with respect to the transient behaviors during Electrostatic Discharge (ESD) events. This methodology uses an exclusively "black-box" approach to characterize the parameters of the protection device, thereby allowing it to be implemented without intimate knowledge of the DUT. Results of this methodology can be used to predict the transient response (conductivity modulation and snapback delay) of the ESD protection devices, and thereby predicts how much current could flow into the device (typically a digital IO pin) under protection. The transient behavior modeling methodology for the ESD protection device is developed for the purpose of system level ESD design, and it is part of the study of System-level Effective ESD Design (SEED) methodology. During the work, the transient behavior modeling method and the SEED methodology have been applied to a high-speed USB3.x repeater IC circuit design. This article introduces a PCB test board working as USB3.x repeater, which allows to place various on-board protection devices and to measure the residual voltage and current at the IO pin accurately. In Section 2, the transient behavior modeling framework and the characterization method will be introduced. The validation results of three different types of protection devices are shown in the end of the section. In Section 3, the implementation of SEED methodology to a USB3.x system design will be introduced. The measurement setup is described in detail. Finally, the validation results for different scenarios will be shown"--Abstract, page iii.