Soft Error Reliability Of Vlsi Circuits

This book is intended for readers who are interested in the design of robust and reliable electronic digital systems. The authors cover emerging trends in design of today’s reliable electronic systems which are applicable to safety-critical applications, such as automotive or healthcare electronic systems. The emphasis is on modeling approaches and algorithms for analysis and mitigation of soft errors in nano-scale CMOS digital circuits, using techniques that are the cornerstone of Computer Aided Design (CAD) of reliable VLSI circuits. The authors introduce software tools for analysis and mitigation of soft errors in electronic systems, which can be integrated easily with design flows. In addition to discussing soft error aware analysis techniques for combinational logic, the authors also describe new soft error mitigation strategies targeting commercial digital circuits. Coverage includes novel Soft Error Rate (SER) analysis techniques such as process variation aware SER estimation and GPU accelerated SER analysis techniques, in addition to SER reduction methods such as gate sizing and logic restructuring based SER techniques.

This monograph is motivated by the challenges faced in designing reliable VLSI systems in modern VLSI processes. The reliable operation of integrated circuits (ICs) has become increasingly dif?cult to achieve in the deep submicron (DSM) era. With continuouslydecreasing device feature sizes, combinedwith lower supply voltages and higher operating frequencies, the noise immunity of VLSI circuits is decreasing alarmingly. Thus, VLSI circuits are becoming more vulnerable to noise effects such as crosstalk, power supply variations, and radiation-inducedsoft errors. Among these noise sources, soft errors(or error caused by radiation particle strikes) have become an increasingly troublesome issue for memory arrays as well as c- binational logic circuits. Also, in the DSM era, process variations are increasing at a signi?cant rate, making it more dif?cult to design reliable VLSI circuits. Hence, it is important to ef?ciently design robust VLSI circuits that are resilient to radiation particle strikes and process variations. The work presented in this research mo- graph presents several analysis and design techniques with the goal of realizing VLSI circuits, which are radiation and process variation tolerant.

This book provides a comprehensive presentation of the most advanced research results and technological developments enabling understanding, qualifying and mitigating the soft errors effect in advanced electronics, including the fundamental physical mechanisms of radiation induced soft errors, the various steps that lead to a system failure, the modelling and simulation of soft error at various levels (including physical, electrical, netlist, event driven, RTL, and system level modelling and simulation), hardware fault injection, accelerated radiation testing and natural environment testing, soft error oriented test structures, process-level, device-level, cell-level, circuit-level, architectural-level, software level and system level soft error mitigation techniques. The book contains a comprehensive presentation of most recent advances on understanding, qualifying and mitigating the soft error effect in advanced electronic systems, presented by academia and industry experts in reliability, fault tolerance, EDA, processor, SoC and system design, and in particular, experts from industries that have faced the soft error impact in terms of product reliability and related business issues and were in the forefront of the countermeasures taken by these companies at multiple levels in order to mitigate the soft error effects at a cost acceptable for commercial products. In a fast moving field, where the impact on ground level electronics is very recent and its severity is steadily increasing at each new process node, impacting one after another various industry sectors (as an example, the Automotive Electronics Council comes to publish qualification requirements on soft errors), research and technology developments and industrial practices have evolve very fast, outdating the most recent books edited at 2004.

Soft errors are a multifaceted issue at the crossroads of applied physics and engineering sciences. Soft errors are by nature multiscale and multiphysics problems that combine not only nuclear and semiconductor physics, material sciences, circuit design, and chip architecture and operation, but also cosmic-ray physics, natural radioactivity issues, particle detection, and related instrumentation. Soft Errors: From Particles to Circuits addresses the problem of soft errors in digital integrated circuits subjected to the terrestrial natural radiation environment—one of the most important primary limits for modern digital electronic reliability. Covering the fundamentals of soft errors as well as engineering considerations and technological aspects, this robust text: Discusses the basics of the natural radiation environment, particle interactions with matter, and soft-error mechanisms Details instrumentation developments in the fields of environment characterization, particle detection, and real-time and accelerated tests Describes the latest computational developments, modeling, and simulation strategies for the soft error-rate estimation in digital circuits Explores trends for future technological nodes and emerging devices Soft Errors: From Particles to Circuits presents the state of the art of this complex subject, providing comprehensive knowledge of the complete chain of the physics of soft errors. The book makes an ideal text for introductory graduate-level courses, offers academic researchers a specialized overview, and serves as a practical guide for semiconductor industry engineers or application engineers.

Reliability is a key concern in VLSI systems and transient/intermittent faults, often caused by soft errors, require designers to create special mitigation techniques. This book describes such techniques, spanning all levels of the design flow, to reduce systematically the vulnerability of VLSI systems to soft errors. Readers will be enabled to address soft error issues early in their design flow, allowing them to weigh the implications of dedicating more resources for soft error detection and prevention, against the correlating impact on delay, power and area.

ABSTRACT: The occurrence of transient faults like soft errors in computer circuits poses a significant challenge to the reliability of computer systems. Soft error, which occurs when the energetic neutrons coming from space or the alpha particles arising out of packaging materials hit the transistors, may manifest themselves as a bit flip in the memory element or as a transient glitch generated at any internal node of combinational logic, which may subsequently propagate to and be captured in a latch. Although the problem of soft errors was earlier only a concern for space applications, aggressive technology scaling trends have exacerbated the problem to modern VLSI systems even for terrestrial applications. In this dissertation, we explore techniques at all levels of the design flow to reduce the vulnerability of VLSI systems against soft errors without compromising on other design metrics like delay, area and power. We propose new models for estimating soft errors for storage structures and combinational logic. While soft errors in caches are estimated using the vulnerability metric, soft errors in logic circuits are estimated using two new metrics called the glitch enabling probability (GEP) and the cumulative probability of observability (CPO). These metrics, based on signal probabilities of nets, accurately model soft errors in radiation-aware synthesis algorithms and helps in efficient exploration of the design solution space during optimization. At the physical design level, we leverage the use of larger netlengths to provide larger RC ladders for effectively filtering out the transient glitches. Towards this, a new heuristic has been developed to selectively assign larger wirelengths to certain critical nets. This reduces the delay and area overhead while improving the immunity to soft errors. Based on this, we propose two placement algorithms based on simulated annealing and quadratic programming which significantly reduce the soft error rates of circuits. At the circuit level, we develop techniques for hardening circuit nodes using a novel radiation jammer technique. The proposed technique is based on the principles of a RC differentiator and is used to isolate the driven cell from the driving cell which is being hit by a radiation strike. Since the blind insertion of radiation blocker cells on all circuit nodes is expensive, candidate nodes are selected for insertion of these cells using a new metric called the probability of radiation blocker circuit insertion (PRI). We investigate a gate sizing algorithm, at the logic level, in which we simultaneously optimize both the soft error rate (SER) and the crosstalk noise besides the power and performance of circuits while considering the effect of process variations. The reliability centric gate sizing technique has been formulated as a mathematical program and is efficiently solved. At the architectural level, we develop solutions for the correction of multi-bit errors in large L2 caches by controlling or mining the redundancy in the memory hierarchy and methods to increase the amount of redundancy in the memory hierarchy by employing a redundancy-based replacement policy, in which the amount of redundancy is controlled using a user defined redundancy threshold. The novel architectures and the new reliability-centric synthesis algorithms proposed for the various design abstraction levels have been shown to achieve significant reduction of soft error rates in current nanometer circuits. The design techniques, algorithms and architectures can be integrated into existing design flows. A VLSI system implementation can leverage on the architectural solutions for the reliability of the caches while the custom hardware synthesized for the VLSI system can be protected against radiation strikes by utilizing the circuit level, logic level and layout level optimization algorithms that have been developed.

This book provides a detailed treatment of radiation effects in electronic devices, including effects at the material, device, and circuit levels. The emphasis is on transient effects caused by single ionizing particles (single-event effects and soft errors) and effects produced by the cumulative energy deposited by the radiation (total ionizing dose effects). Bipolar (Si and SiGe), metal-oxide-semiconductor (MOS), and compound semiconductor technologies are discussed. In addition to considering the specific issues associated with high-performance devices and technologies, the book includes the background material necessary for understanding radiation effects at a more general level.

In 2007 The Design, Automation and Test in Europe (DATE) conference celebrated its tenth anniversary. As a tribute to the chip and system-level design and design technology community, this book presents a compilation of the three most influential papers of each year. This provides an excellent historical overview of the evolution of a domain that contributed substantially to the growth and competitiveness of the circuit electronics and systems industry.

This book contains extended and revised versions of the best papers presented during the fourteenth IFIP TC 10/WG 10.5 International Conference on Very Large Scale Integration. This conference provides a forum to exchange ideas and show industrial and academic research results in microelectronics design. The current trend toward increasing chip integration and technology process advancements brings about stimulating new challenges both at the physical and system-design levels.

Several techniques at the architectural level to detect soft errors with minimal performance overhead, that make use of data, information, temporal and spatial redundancy are proposed. The techniques are designed in such a way that much of their latency overhead can be hidden by the latency of other functional operations. It is shown that the proposed methodologies can be implemented with negligible or minimal performance overhead hidden by critical path operations in the datapath. In designs with large peak power values, high current spikes cause noise within the power supply creating timing issues in the circuit which affect its functionality. A path clustering algorithm is proposed which attempts to normalize the current draw in the circuit over the circuit's clock period by delaying the start times of certain paths. By reducing the number of paths starting at a time instance, we reduce the amount of current drawn from the power supply is reduced. Experimental results indicate a reduction of up to 72\% in peak power values when tested on the ISCAS '85 and OpenCores benchmarks. Variations in VLSI designs come from process, voltage supply, and Temperature (PVT). These variations in the design cause non-ideal behavior at random internal nodes which impacts the timing of the design. A variation aware circuit level design methodology is presented in this dissertation in which the architecture dynamically stretches the clock when the effect of an variation effects are observed within the circuit during computations. While previous research efforts found are directed towards reducing variation effects, this technique offers an alternative approach to adapt dynamically to variation effects. The design technique is shown to increase in timing yield on ITC '99 benchmark circuits by an average of 41\% with negligible area overhead.