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

High-voltage ESD structures and ESD protection concepts in smart power technologies

Electro-static discharge (ESD) event can cause upset or permanent damage of integrated circuits (IC) and electrical systems. The risk of ESD fails needs to be mitigated or prevented. ESD robustness of IC products and electrical systems is specified, verified and qualified according to respective ESD standards. For high-voltage IC products based on smart power semiconductor technologies for industrial, power and automotive applications, design of effective and cost-efficient ESD protection is a big challenge, demanding wide and deep technical knowledge throughout high-frequency and high-power characterization techniques, semiconductor device physic, circuit design as well as modeling and simulation. The required measurement setups and tester components are developed and introduced. The characterization of ESD protection devices, IC and off-chip circuit elements is enabled and improved. The rise-time filters are important for the study of rise-time dependent ESD robustness. The human metal model (HMM) tester as an alternative to IEC ESD generators provides voltage waveform measurement with good quality in addition to current waveform measurement. It can be used for wafer-level or package-level device characterization. The measurement results of HMM tester and IEC ESD generator are compared. The on-chip ESD protection design relies on proper choice of different types of ESD protection devices and structures, depending on ESD specifications and IC applications. Typical on-chip ESD protection, whether snapback or non-snapback, single device or ESD circuit is introduced. The failure levels studies give a systematic benchmark of the ESD protection devices and structures, concerning device area, clamping voltage and other relevant parameters. The trade-off between those parameters and limitation of different ESD protection is discussed. Moreover, understanding of ESD failure modes is the key to implement effective ESD design. A unique ESD failure mode of smart power semiconductor device is discovered and investigated in detail. In the scope of finding ESD solutions, new active ESD clamps have been further developed in this work. The study of ESD protection is extended to the system-level involving on- and off-chip ESD protection elements. The characteristics of typical off-chip elements as well as the interaction between IC and off-chip protection elements plays essential role on the system robustness. A system-level ESD simulation incorporating IC and off-chip protection elements is desired for system efficient ESD design (SEED). A behavioral ESD model is developed which reproduces pulse-energy-dependent failure levels and self-heating effects. This modeling methodology can be used for assessment of system robustness even beyond ESD time-domain. The validation of the models is given by representative application examples. Several main challenges of high-voltage ESD design in smart power technologies have been addressed in this work, which can serve as guidance for ESD development and product support in future power semiconductor technologies

Modeling of reverse current effects in trench-based smart power technologies

The increase in complexity in todays automotive products is driven by the trend to implement new features in the area of safety, comfort and entertainment. This significantly raises the safety requirements of new ICs and the identification of possible sources of failures gains in priority. One of these failure sources is the injection of parasitic currents into the common substrate of a chip. This does not only occur during exceptions in the operation of the IC but also affects applications which require switching of inductive loads. The difficulty to handle substrate current injection originates from its nonlocality as it potentially influences the entire IC. In this thesis a point-to-point modeling scheme for Spice-based circuit simulation is proposed. It addresses parasitic coupling effects caused by minority carrier injection into the substrate of a deep-trench based BCD technology. Since minority carriers can diffuse over large distances in the common substrate and disturb circuits in their normal operation, a quantitative approach is necessary to address this parasitic effect early during design. An equivalent circuit based on the chip's design is extracted and the coupling effect between the perturbing devices and the susceptible nodes is represented by Verilog-AMS models. These models represent the three main components in the coupling path which are the forward biased diode at the perturbing device, the reverse biased diode at the susceptible node, and the intermediary common substrate of the chip. An automated layout extraction framework identifies the injectors of the minority carriers and the sensitive devices. Additionally, it determines the relevant parameters for the models. The curve fitting functions of the models are derived from calibrated TCAD simulations which are based on the measurement results of two dedicated test chips. The test chips were specifically designed to provide detailed analysis capabilities of this parasitic coupling effect. This led to a design which contains several different injector nodes and a large number of susceptible nodes spread over the entire area of the chip. Additionally, the chip incorporates the most commonly used layout-based guard structures to obtain an in-depth insight on their efficiency in recent BCD technologies. Based on the results obtained by measurements of the test chips the underlying physics of the coupling effect are discussed in detail. Minority carrier injection in the substrate is not much different to the operating principle of a bipolar transistor and the differences and similarities between them are presented. This forms the basis of the model development and explains how the equations of the Verilog-AMS models were derived. Finally, the entire simulation flow is evaluated and the simulation results are compared to measurements of the chip

Semiconductor Device Modeling, Simulation, and Failure Prediction for Electrostatic Discharge Conditions

Electrostatic Discharge (ESD) caused failures are major reliability issues in IC industry. Device modeling for ESD conditions is necessary to evaluate ESD robustness in simulation. Although SPICE model is accurate and efficient for circuit simulations in most cases, devices under ESD conditions operate in abnormal status. SPICE model cannot cover the device operating region beyond normal operation. Thermal failure is one of the main reasons to cause device failure under ESD conditions. A compact model is developed to predict thermal failure with circuit simulators. Instead of considering the detailed failure mechanisms, a failure temperature is introduced to indicate device failure. The developed model is implemented by a multiple-stage thermal network. P-N junction is the fundamental structure for ESD protection devices. An enhanced diode model is proposed and is used to simulate the device behaviors for ESD events. The model includes all physical effects for ESD conditions, which are voltage overshoot, self-heating effect, velocity saturation and thermal failure. The proposed model not only can fit the I-V and transient characteristics, but also can predict failure for different pulses. Safe Operating Area (SOA) is an important factor to evaluate the LDMOS performance. The transient SOA boundary is considered as power-defined. By placing the failure monitor under certain conditions, the developed modeling methodology can predict the boundary of transient SOA for any short pulse stress conditions. No matter failure happens before or after snapback phenomenon. Weibull distribution is popular to evaluate the dielectric lifetime for CVS. By using the transformative version of power law, the pulsing stresses are converted into CVS, and TDDB under ESD conditions for SiN MIMCAPs is analyzed. The thickness dependency and area independency of capacitor breakdown voltage is observed, which can be explained by the constant ?E model instead of conventional percolation model

Monolithic Integration of CMOS Charge Pumps for High Voltage Generation beyond 100 V

Monolithic integration of step-up DC-DC converters used to be one of the largest challenges in high voltage CMOS SoCs. Charge pumps are considered as the most promising solution regarding in- tegration levels compared to boost converter with bulky inductors. However, conventional charge pump architectures usually show significant drawbacks and reliability problems, when used as on- chip high voltage generators. Hence, innovative charge pump architectures are required to realize the monolithic integration of charge pumps in high voltage applications. In this dissertation, three 4-phase charge pump architectures with the dynamic body biasing tech- nique and clock schemes with dead time techniques were proposed to overcome drawbacks such as body effect and reverse current problem of traditional Pelliconi charge pump. The influences of high voltage CMOS sandwich capacitors on the voltage gain and power efficiency of charge pumps were extensively investigated. The most reasonable 4-phase charge pump architecture with a suitable configuration of high voltage sandwich capacitors regarding the voltage gain and power efficiency was chosen to implement two high voltage ASICs in an advanced 120 V 0.35 μm high voltage CMOS technology. The first test chip operates successfully and is able to generate up to 120 V from a 3.7 V low voltage DC supply, which shows the highest output voltage among all the reported fully integrated CMOS charge pumps. The measurement results confirmed the benefits of the proposed charge pump architectures and clock schemes. The second chip providing a similar output voltage has a reduced chip size mainly due to decreased capacitor areas by increased clock frequencies. Fur- thermore, the second chip with an on-chip clock generator works independently of external clock signals which shows the feasibility of integrated charge pumps as part of high voltage SoCs. Based on the successful implementation of those high voltage CMOS ASICs, further discussions on the stability of the output voltage, levels of integration and limitations in the negative high voltage generation of high voltage CMOS charge pumps are held with the aid of simulation or measurement results. Feed- back regulation by adjusting the clock frequency or DC power supply is able to stabilize the voltage performance effectively while being easily integrated on-chip. Increasing the clock frequency can significantly reduce the required capacitor values which results in reduced chip sizes. An application example demonstrates the importance of fully integrated high voltage charge pumps. Besides, a new design methodology for the on-chip high voltage generation using CMOS technolo- gies was proposed. It contains a general design flow focusing mainly on the feasibility and reliability of high voltage CMOS ASICs and design techniques for on-chip high voltage generators. In this dissertation, it is proven that CMOS charge pumps using suitable architectures regarding the required chip size and circuit reliability are able to be used as on-chip high voltage generators for voltages beyond 100 V . Several methods to improve the circuit performance and to extend the functionalities of high voltage charge pumps are suggested for future works

Design and Simulation of Device Failure Models for Electrostatic Discharge (ESD) Event

In this dissertation, the research mainly focused on discussing ESD failure event simulation and ESD modeling, seeking solutions for ESD issues by simulating ESD event and predict possible ESD reliability problem in IC design. The research involves failure phenomenon caused by ESD/ EOS stress, mainly on the thermal failure due to inevitable self-heating during an ESD stress. Standard Complementary Metal-Oxide-Semiconductor (CMOS) process and high voltage Doublediffusion Metal-Oxide-Semiconductor (DMOS) process are used for design of experiment. A multi-function test platform High Power Pulse Instrument (HPPI) is used for ESD event evaluation and device characterization. SPICE-like software ADICE is for back-end simulation. Electrostatic Discharges (ESD) is one of the hazard that may affect IC circuit function and cause serious damage to the chip. The importance of ESD protection has been raised since the CMOS technology advanced and the dimension of transistors scales down. On the other hand, the variety of applications of chips is also making corresponding ESD protection difficult to meet different design requirement. Aside from typical requirements such as core circuit operation voltage, maximum accepted leakage current, breakdown conditions for the process and overall device sizes, special applications like radio frequency and power electronic requires ESD to be low parasitic capacitance and can sustain high level energy. In that case, a proper ESD protection design demands not only a robust ESD protection scheme, but co-design with the inner circuit. For that purpose, it is necessary to simulate the results of ESD impact on IC and find out possible weak point of the circuit and improve it. The first step of the simulation is to have corresponding models available. Unfortunately, ESD models, especially there are lack of circuit-level ESD models that provide quick and accurate prediction of ESD event. In this dissertation paper, ESD models, especially ESD failure models for device thermal failure are introduced, with modeling methodology accordingly. First, an introduction for ESD event and typical ESD protection schemes are introduced. Its purpose is to give basic concept of ESD. For ESD failure models, two typical types can be categorized depends on the physical mechanisms that cause the ESD damage. One is the gate oxide breakdown, which is electric field related. The other is the thermal-related failure, which stems from the self-heating effect associated with the large current passing through the ESD protection structure. The first one has become increasingly challenging with the aggressive scaling of the gate dielectric in advanced processes and ESD protection for that need to be carefully designed. The second one, thermal failure widely exists in semiconductor devices as long as there is ESD current flow through the device and accumulate heat at junctions. Considering the universality of thermal failure in ESD device, it is imperative to establish a model to simulate ESD caused thermal failure. Several works related to ESD model can be done. One crucial part for a failure model is to define the failure criterion. As common solution for ESD simulation and failure prediction. The maximum current level or breakdown voltage is used to judge whether a device fails under ESD stresses. Such failure criteria based on measurable voltage or current values are straightforward and can be easy to implemented in simulation tools. However, the shortcoming of these failure criteria is each failure criterion is specifically designed for certain ESD stress condition. For example, the failure voltage level for Human Body Model and Charged Device Model are quite different, and it is hard to judge a device\u27s ESD capability under standard test conditions based on its transmission line pulse test result. So it is necessary to look deeper into the physical mechanism of device failure under ESD and find a more universal failure criterion for various stress conditions. As one of the major failure mechanisms, thermal failure evaluated by temperature is a more universal failure criterion for device failure under ESD stress. Whatever the stress model is, the device will fail if a critical temperature is reached at certain part inside the device and cause structural damage. Then finding out that critical temperature is crucial to define the failure point for device thermal failure. One chapter of this dissertation will focus on discussing this issue and propose a simple method to give close estimation of the real failure temperature for typical ESD devices. Combined these related works, a comprehensive diode model for ESD simulation is proposed. Using existing ESD models, diode I-V characteristic from low current turn-on to high current saturation can be simulated. By using temperature as the failure criterion, the last point of diode operation, or the second breakdown point, can be accurately predicted. Additional investigation of ESD capability of devices for special case like vertical GaN diode is discussed in Chapter IV. Due to the distinct material property of GaN, the vertical GaN diode exhibits unique and interesting quasi-static I-V curves quite different from conventional silicon semiconductor devices. And that I-V curve varies with different pulse width, indicating strong conductivity modulation of diode neutral region that will delay the complete turn-on of the vertical GaN diode

Structures MOS-IGBT sur technologie SOI en vue de l'amélioration des performances à haute température de composants de puissance et de protections ESD

Dans le cadre du projet FNRAE COTECH, nos travaux avaient pour objectifs d'améliorer le fonctionnement des structures électroniques à haute température d'une technologie SOI (200°C). La technologie choisie pour ce travail est une technologie de puissance intelligente comprenant une bibliothèque CMOS basse tension (5V), des transistors de puissance LDMOS (25V, 45V et 80V) et des transistors bipolaires NPN et PNP. Afin de caractériser cette technologie en température, dans un premier temps, nous avons conçu un véhicule de test en introduisant certaines règles de dessin bénéfiques pour le comportement en température, à la fois pour les composants basse et haute puissance. Nous avons également étudié une nouvelle architecture de composants combinant au sein d'un même composant un composant MOS et un composant IGBT, dans un objectif d'auto-compensation des effets négatifs de la température. Afin d'optimiser la conception de ces composants mixtes MOS-IGBT, la méthodologie que nous avons adoptée s'est appuyée sur des simulations 2D et 3D sur Sentaurus. Dans le cadre de ce travail, deux véhicules de test ont été réalisés et caractérisés. Ces structures mixtes MOS-IGBT ont été proposées en tant que structures de protection contre les décharges électrostatiques (ESD) pour remplacer une structure de protection de type "power clamp". En s'appuyant sur la simulation 3D, nous avons proposé plusieurs solutions, à la fois topologiques et d'architecture, permettant d'augmenter significativement le niveau de ce courant. Ces diverses solutions ont été validées expérimentalement. Enfin, les bonnes performances de ces structures mixtes ont motivé leur étude en tant que structures de puissance.Within the framework of COTECH FNRAE project, the objectives of our work were the improvement of the SOI electronic structures at high-temperature operation (200°C). The chosen technology in this work is a smart power technology including low voltage CMOS (5 V), LDMOS power transistors (25 V, 45 V and 80 V), NPN and PNP bipolar transistor. To characterize this technology at different temperatures, as a first step, we designed a test vehicle by introducing specific design rules beneficial for the temperature behavior, both for low and high power components. We also studied new components architecture by combining in a single component a MOS and an IGBT, with an objective of self-compensation of the negative effects of temperature. To optimize the performance of these components (mixed MOS-IGBT), our methodology was based on using 2D and 3D Sentaurus physical simulation. As part of this work, two test vehicles were produced and characterized. These mixed structures MOS-IGBT have been proposed as ESD protection structures (Electro Static Discharge protection structures), to replace the LDMOS of a power clamp circuit. Based on 3D simulation, we have proposed several solutions, both topological and architectural, to significantly increase the level of the holding current. These various solutions have been experimentally validated. Finally, the good performance of these mixed structures have motivated their study as power structures

Reliability Analysis of Power Electronic Devices

The thesis deals with the reliability of Power Electronic Devices to the purpose of evaluating the phenomena which mainly dictate the limiting conditions where a power device can safely operate. Reliability analyses are conducted by means of either simulations and experimental measurements

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