Design, Characterization And Compact Modeling Of Novel Silicon Controlled Rectifier (scr)-based Devices For Electrostatic Discha

Electrostatic Discharge (ESD), an event of a sudden transfer of electrons between two bodies at different potentials, happens commonly throughout nature. When such even occurs on integrated circuits (ICs), ICs will be damaged and failures result. As the evolution of semiconductor technologies, increasing usage of automated equipments and the emerging of more and more complex circuit applications, ICs are more sensitive to ESD strikes. Main ESD events occurring in semiconductor industry have been standardized as human body model (HBM), machine model (MM), charged device model (CDM) and international electrotechnical commission model (IEC) for control, monitor and test. In additional to the environmental control of ESD events during manufacturing, shipping and assembly, incorporating on-chip ESD protection circuits inside ICs is another effective solution to reduce the ESD-induced damage. This dissertation presents design, characterization, integration and compact modeling of novel silicon controlled rectifier (SCR)-based devices for on-chip ESD protection. The SCR-based device with a snapback characteristic has long been used to form a VSS-based protection scheme for on-chip ESD protection over a broad rang of technologies because of its low on-resistance, high failure current and the best area efficiency. The ESD design window of the snapback device is defined by the maximum power supply voltage as the low edge and the minimum internal circuitry breakdown voltage as the high edge. The downscaling of semiconductor technology keeps on squeezing the design window of on-chip ESD protection. For the submicron process and below, the turn-on voltage and sustain voltage of ESD protection cell should be lower than 10 V and higher than 5 V, respectively, to avoid core circuit damages and latch-up issue. This presents a big challenge to device/circuit engineers. Meanwhile, the high voltage technologies push the design window to another tough range whose sustain voltage, 45 V for instance, is hard for most snapback ESD devices to reach. Based on the in-depth elaborating on the principle of SCR-based devices, this dissertation first presents a novel unassisted, low trigger- and high holding-voltage SCR (uSCR) which can fit into the aforesaid ESD design window without involving any extra assistant circuitry to realize an area-efficient on-chip ESD protection for low voltage applications. The on-chip integration case is studied to verify the protection effectiveness of the design. Subsequently, this dissertation illustrate the development of a new high holding current SCR (HHC-SCR) device for high voltage ESD protection with increasing the sustain current, not the sustain voltage, of the SCR device to the latchup-immune level to avoid sacrificing the ESD protection robustness of the device. The ESD protection cells have been designed either by using technology computer aided design (TCAD) tools or through trial-and-error iterations, which is cost- or time-consuming or both. Also, the interaction of ESD protection cells and core circuits need to be identified and minimized at pre-silicon stage. It is highly desired to design and evaluate the ESD protection cell using simulation program with integrated circuit emphasis (SPICE)-like circuit simulation by employing compact models in circuit simulators. And the compact model also need to predict the response of ESD protection cells to very fast transient ESD events such as CDM event since it is a major ESD failure mode. The compact model for SCR-based device is not widely available. This dissertation develops a macromodeling approach to build a comprehensive SCR compact model for CDM ESD simulation of complete I/O circuit. This modeling approach offers simplicity, wide availability and compatibility with most commercial simulators by taking advantage of using the advanced BJT model, Vertical Bipolar Inter-Company (VBIC) model. SPICE Gummel-Poon (SGP) model has served the ICs industry well for over 20 years while it is not sufficiently accurate when using SGP model to build a compact model for ESD protection SCR. This dissertation seeks to compare the difference of SCR compact model built by using VBIC and conventional SGP in order to point out the important features of VBIC model for building an accurate and easy-CAD implement SCR model and explain why from device physics and model theory perspectives

Design, Characterization And Analysis Of Electrostatic Discharge (esd) Protection Solutions In Emerging And Modern Technologies

Electrostatic Discharge (ESD) is a significant hazard to electronic components and systems. Based on a specific processing technology, a given circuit application requires a customized ESD consideration that includes the devices’ operating voltage, leakage current, breakdown constraints, and footprint. As new technology nodes mature every 3-5 years, design of effective ESD protection solutions has become more and more challenging due to the narrowed design window, elevated electric field and current density, as well as new failure mechanisms that are not well understood. The endeavor of this research is to develop novel, effective and robust ESD protection solutions for both emerging technologies and modern complementary metal–oxide–semiconductor (CMOS) technologies. The Si nanowire field-effect transistors are projected by the International Technology Roadmap for Semiconductors as promising next-generation CMOS devices due to their superior DC and RF performances, as well as ease of fabrication in existing Silicon processing. Aiming at proposing ESD protection solutions for nanowire based circuits, the dimension parameters, fabrication process, and layout dependency of such devices under Human Body Mode (HBM) ESD stresses are studied experimentally in company with failure analysis revealing the failure mechanism induced by ESD. The findings, including design methodologies, failure mechanism, and technology comparisons should provide practical knowhow of the development of ESD protection schemes for the nanowire based integrated circuits. Organic thin-film transistors (OTFTs) are the basic elements for the emerging flexible, printable, large-area, and low-cost organic electronic circuits. Although there are plentiful studies focusing on the DC stress induced reliability degradation, the operation mechanism of OTFTs iv subject to ESD is not yet available in the literature and are urgently needed before the organic technology can be pushed into consumer market. In this work, the ESD operation mechanism of OTFT depending on gate biasing condition and dimension parameters are investigated by extensive characterization and thorough evaluation. The device degradation evolution and failure mechanism under ESD are also investigated by specially designed experiments. In addition to the exploration of ESD protection solutions in emerging technologies, efforts have also been placed in the design and analysis of a major ESD protection device, diodetriggered-silicon-controlled-rectifier (DTSCR), in modern CMOS technology (90nm bulk). On the one hand, a new type DTSCR having bi-directional conduction capability, optimized design window, high HBM robustness and low parasitic capacitance are developed utilizing the combination of a bi-directional silicon-controlled-rectifier and bi-directional diode strings. On the other hand, the HBM and Charged Device Mode (CDM) ESD robustness of DTSCRs using four typical layout topologies are compared and analyzed in terms of trigger voltage, holding voltage, failure current density, turn-on time, and overshoot voltage. The advantages and drawbacks of each layout are summarized and those offering the best overall performance are suggested at the en

Design And Characterization Of Noveldevices For New Generation Of Electrostaticdischarge (esd) Protection Structures

The technology evolution and complexity of new circuit applications involve emerging reliability problems and even more sensitivity of integrated circuits (ICs) to electrostatic discharge (ESD)-induced damage. Regardless of the aggressive evolution in downscaling and subsequent improvement in applications\u27 performance, ICs still should comply with minimum standards of ESD robustness in order to be commercially viable. Although the topic of ESD has received attention industry-wide, the design of robust protection structures and circuits remains challenging because ESD failure mechanisms continue to become more acute and design windows less flexible. The sensitivity of smaller devices, along with a limited understanding of the ESD phenomena and the resulting empirical approach to solving the problem have yielded time consuming, costly and unpredictable design procedures. As turnaround design cycles in new technologies continue to decrease, the traditional trial-and-error design strategy is no longer acceptable, and better analysis capabilities and a systematic design approach are essential to accomplish the increasingly difficult task of adequate ESD protection-circuit design. This dissertation presents a comprehensive design methodology for implementing custom on-chip ESD protection structures in different commercial technologies. First, the ESD topic in the semiconductor industry is revised, as well as ESD standards and commonly used schemes to provide ESD protection in ICs. The general ESD protection approaches are illustrated and discussed using different types of protection components and the concept of the ESD design window. The problem of implementing and assessing ESD protection structures is addressed next, starting from the general discussion of two design methods. The first ESD design method follows an experimental approach, in which design requirements are obtained via fabrication, testing and failure analysis. The second method consists of the technology computer aided design (TCAD)-assisted ESD protection design. This method incorporates numerical simulations in different stages of the ESD design process, and thus results in a more predictable and systematic ESD development strategy. Physical models considered in the device simulation are discussed and subsequently utilized in different ESD designs along this study. The implementation of new custom ESD protection devices and a further integration strategy based on the concept of the high-holding, low-voltage-trigger, silicon controlled rectifier (SCR) (HH-LVTSCR) is demonstrated for implementing ESD solutions in commercial low-voltage digital and mixed-signal applications developed using complementary metal oxide semiconductor (CMOS) and bipolar CMOS (BiCMOS) technologies. This ESD protection concept proposed in this study is also successfully incorporated for implementing a tailored ESD protection solution for an emerging CMOS-based embedded MicroElectroMechanical (MEMS) sensor system-on-a-chip (SoC) technology. Circuit applications that are required to operate at relatively large input/output (I/O) voltage, above/below the VDD/VSS core circuit power supply, introduce further complications in the development and integration of ESD protection solutions. In these applications, the I/O operating voltage can extend over one order of magnitude larger than the safe operating voltage established in advanced technologies, while the IC is also required to comply with stringent ESD robustness requirements. A practical TCAD methodology based on a process- and device- simulation is demonstrated for assessment of the device physics, and subsequent design and implementation of custom P1N1-P2N2 and coupled P1N1-P2N2//N2P3-N3P1 silicon controlled rectifier (SCR)-type devices for ESD protection in different circuit applications, including those applications operating at I/O voltage considerably above/below the VDD/VSS. Results from the TCAD simulations are compared with measurements and used for developing technology- and circuit-adapted protection structures, capable of blocking large voltages and providing versatile dual-polarity symmetric/asymmetric S-type current-voltage characteristics for high ESD protection. The design guidelines introduced in this dissertation are used to optimize and extend the ESD protection capability in existing CMOS/BiCMOS technologies, by implementing smaller and more robust single- or dual-polarity ESD protection structures within the flexibility provided in the specific fabrication process. The ESD design methodologies and characteristics of the developed protection devices are demonstrated via ESD measurements obtained from fabricated stand-alone devices and on-chip ESD protections. The superior ESD protection performance of the devices developed in this study is also successfully verified in IC applications where the standard ESD protection approaches are not suitable to meet the stringent area constraint and performance requirement

Transient Safe Operating Area (tsoa) For Esd Applications

A methodology to obtain design guidelines for gate oxide input pin protection and high voltage output pin protection in Electrostatic Discharge (ESD) time frame is developed through measurements and Technology Computer Aided Design (TCAD). A set of parameters based on transient measurements are used to define Transient Safe Operating Area (TSOA). The parameters are then used to assess effectiveness of protection devices for output and input pins. The methodology for input pins includes establishing ESD design targets under Charged Device Model (CDM) type stress in low voltage MOS inputs. The methodology for output pins includes defining ESD design targets under Human Metal Model (HMM) type stress in high voltage Laterally Diffused MOS (LDMOS) outputs. First, the assessment of standalone LDMOS robustness is performed, followed by establishment of protection design guidelines. Secondly, standalone clamp HMM robustness is evaluated and a prediction methodology for HMM type stress is developed based on standardized testing. Finally, LDMOS and protection clamp parallel protection conditions are identifie

Advances in Solid State Circuit Technologies

This book brings together contributions from experts in the fields to describe the current status of important topics in solid-state circuit technologies. It consists of 20 chapters which are grouped under the following categories: general information, circuits and devices, materials, and characterization techniques. These chapters have been written by renowned experts in the respective fields making this book valuable to the integrated circuits and materials science communities. It is intended for a diverse readership including electrical engineers and material scientists in the industry and academic institutions. Readers will be able to familiarize themselves with the latest technologies in the various fields

Low-power switched capacitor voltage reference

Low-power analog design represents a developing technological trend as it emerges from a rather limited range of applications to a much wider arena affecting mainstream market segments. It especially affects portable electronics with respect to battery life, performance, and physical size. Meanwhile, low-power analog design enables technologies such as sensor networks and RFID. Research opportunities abound to exploit the potential of low power analog design, apply low-power to established fields, and explore new applications. The goal of this effort is to design a low-power reference circuit that delivers an accurate reference with very minimal power consumption. The circuit and device level low-power design techniques are suitable for a wide range of applications. To meet this goal, switched capacitor bandgap architecture was chosen. It is the most suitable for developing a systematic, and groundup, low-power design approach. In addition, the low-power analog cell library developed would facilitate building a more complex low-power system. A low-power switched capacitor bandgap was designed, fabricated, and fully tested. The bandgap generates a stable 0.6-V reference voltage, in both the discrete-time and continuous-time domain. The system was thoroughly tested and individual building blocks were characterized. The reference voltage is temperature stable, with less than a 100 ppm/°C drift, over a --60 dB power supply rejection, and below a 1 [Mu]A total supply current (excluding optional track-and-hold). Besides using it as a voltage reference, potential applications are also described using derivatives of this switched capacitor bandgap, specifically supply supervisory and on-chip thermal regulation

Design of Low-Capacitance Electrostatic Discharge (ESD) Protection Devices in Advanced Silicon Technologies.

Electrostatic discharge (ESD) related failure is a major IC reliability concern and this is particularly true as technology continues shrink to nano-metric dimensions. ESD design window research shows that ESD robustness of victim devices keep decreasing from 350nm bulk technology to 7nm FinFET technologies. In the meantime, parasitic capacitance of ESD diode with same It2 in FinFET technologies is approximately 3X compared with that in planar technologies. Thus transition from planar to FinFET technology requires more robust ESD protection however the large parasitic capacitance of ESD protection cell is problematic in high-speed interface design. To reduce the parasitic capacitance, a dual diode silicon controlled rectifier (DD-SCR) is presented in this dissertation. This design can exhibit good trade-offs between ESD robustness and parasitic capacitance characteristics. Besides, different bounding materials lead to performance variations in DD-SCRs are compared. Radio frequency (RF) technology is also demanded low capacitance ESD protection. To address this concern, a ?-network is presented, providing robust ESD protection for 10-60 GHz RF circuit. Like a low pass ? filter, the network can reflect high frequency RF signals and transmit low frequency ESD pulses. Given proper inductor value, networks can work as robust ESD solutions at a certain Giga Hertz frequency range, making this design suitable for broad band protection in RF input/outputs (I/Os). To increase the holding voltage and reduce snapback, a resistor assist triggering heterogeneous stacking structure is presented in this dissertation, which can increase the holding voltage and also keep the trigger voltage nearly as same as a single SCR device

Miniaturized Transistors

What is the future of CMOS? Sustaining increased transistor densities along the path of Moore's Law has become increasingly challenging with limited power budgets, interconnect bandwidths, and fabrication capabilities. In the last decade alone, transistors have undergone significant design makeovers; from planar transistors of ten years ago, technological advancements have accelerated to today's FinFETs, which hardly resemble their bulky ancestors. FinFETs could potentially take us to the 5-nm node, but what comes after it? From gate-all-around devices to single electron transistors and two-dimensional semiconductors, a torrent of research is being carried out in order to design the next transistor generation, engineer the optimal materials, improve the fabrication technology, and properly model future devices. We invite insight from investigators and scientists in the field to showcase their work in this Special Issue with research papers, short communications, and review articles that focus on trends in micro- and nanotechnology from fundamental research to applications

The 2018 GaN Power Electronics Roadmap

Gallium nitride (GaN) is a compound semiconductor that has tremendous potential to facilitate economic growth in a semiconductor industry that is silicon-based and currently faced with diminishing returns of performance versus cost of investment. At a material level, its high electric field strength and electron mobility have already shown tremendous potential for high frequency communications and photonic applications. Advances in growth on commercially viable large area substrates are now at the point where power conversion applications of GaN are at the cusp of commercialisation. The future for building on the work described here in ways driven by specific challenges emerging from entirely new markets and applications is very exciting. This collection of GaN technology developments is therefore not itself a road map but a valuable collection of global state-of-the-art GaN research that will inform the next phase of the technology as market driven requirements evolve. First generation production devices are igniting large new markets and applications that can only be achieved using the advantages of higher speed, low specific resistivity and low saturation switching transistors. Major investments are being made by industrial companies in a wide variety of markets exploring the use of the technology in new circuit topologies, packaging solutions and system architectures that are required to achieve and optimise the system advantages offered by GaN transistors. It is this momentum that will drive priorities for the next stages of device research gathered here