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.

As the complexity and the density of VLSI chips increase with shrinking design rules, the evaluation of long-term reliability of MOS VLSI circuits is becoming an important problem. The assessment and improvement of reliability on the circuit level should be based on both the failure mode analysis and the basic understanding of the physical failure mechanisms observed in integrated circuits. Hot-carrier induced degrada tion of MOS transistor characteristics is one of the primary mechanisms affecting the long-term reliability of MOS VLSI circuits. It is likely to become even more important in future generation chips, since the down ward scaling of transistor dimensions without proportional scaling of the operating voltage aggravates this problem. A thorough understanding of the physical mechanisms leading to hot-carrier related degradation of MOS transistors is a prerequisite for accurate circuit reliability evaluation. It is also being recognized that important reliability concerns other than the post-manufacture reliability qualification need to be addressed rigorously early in the design phase. The development and use of accurate reliability simulation tools are therefore crucial for early assessment and improvement of circuit reliability : Once the long-term reliability of the circuit is estimated through simulation, the results can be compared with predetermined reliability specifications or limits. If the predicted reliability does not satisfy the requirements, appropriate design modifications may be carried out to improve the resistance of the devices to degradation.

Only two decades ago most electronic circuits were designed with a slide-rule, and the designs were verified using breadboard techniques. Simulation tools were a research curiosity and in general were mistrusted by most designers and test engineers. In those days the programs were not user friendly, models were inadequate, and the algorithms were not very robust. The demand for simulation tools has been driven by the increasing complexity of integrated circuits and systems, and it has been aided by the rapid decrease in the cost of com puting that has occurred over the past several decades. Today a wide range of tools exist for analYSiS, deSign, and verification, and expert systems and synthesis tools are rapidly emerging. In this book only one aspect of the analysis and design process is examined. but it is a very important aspect that has received much attention over the years. It is the problem of accurate circuit and timing simulation.

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.