Cross-Layer Resiliency Modeling and Optimization: A Device to Circuit Approach

The never ending demand for higher performance and lower power consumption pushes the VLSI industry to further scale the technology down. However, further downscaling of technology at nano-scale leads to major challenges. Reduced reliability is one of them, arising from multiple sources e.g. runtime variations, process variation, and transient errors. The objective of this thesis is to tackle unreliability with a cross layer approach from device up to circuit level

Area-Energy Tradeoffs Of Logic Wear-Leveling For Bti-Induced Aging

Ensuring operational reliability in the presence of Bias Temperature Instability (BTI) effects often results in a compromise either in the form of lower performance and/or higher energy-consumption. This is due to the performance degradation over time caused by BTI effects which needs to be compensated through frequency, voltage, or area margining to meet the circuit\u27s timing specification till end of operational lifetime. In this paper, a circuit-level approach referred to as Logic-Wear-Leveling (LWL) utilizes Dark-Silicon to mitigate BTI effects in logic datapaths. LWL introduces fine-grained spatial redundancy in timing vulnerable logic components, and leverages it at runtime to enable post-Silicon adaptability. The activation interval of redundant datapaths allows for controlled stress and recovery phases. This produces a wear-leveling effect which helps to reduce the BTI induced performance degradation over time, which in turn helps to reduce the design margins. This approach demonstrates a significant reduction in energy consumption of up to 31.98% at 10 years as compared to conventional voltage guardbanding approach. The benefit of energy reduction is also assessed against the area overheads of spatial redundancy

Long-term reliability of nanometer VLSI systems: modeling, analysis and optimization

This book provides readers with a detailed reference regarding two of the most important long-term reliability and aging effects on nanometer integrated systems, electromigrations (EM) for interconnect and biased temperature instability (BTI) for CMOS devices. The authors discuss in detail recent developments in the modeling, analysis and optimization of the reliability effects from EM and BTI induced failures at the circuit, architecture and system levels of abstraction. Readers will benefit from a focus on topics such as recently developed, physics-based EM modeling, EM modeling for multi-segment wires, new EM-aware power grid analysis, and system level EM-induced reliability optimization and management techniques. Reviews classic Electromigration (EM) models, as well as existing EM failure models and discusses the limitations of those models; Introduces a dynamic EM model to address transient stress evolution, in which wires are stressed under time-varying current flows, and the EM recovery effects. Also includes new, parameterized equivalent DC current based EM models to address the recovery and transient effects; Presents a cross-layer approach to transistor aging modeling, analysis and mitigation, spanning multiple abstraction levels; Equips readers for EM-induced dynamic reliability management and energy or lifetime optimization techniques, for many-core dark silicon microprocessors, embedded systems, lower power many-core processors and datacenters

Contemporary Cmos Aging Mitigation Techniques: Survey, Taxonomy, And Methods

The proposed paper addresses the overarching reliability issue of transistor aging in nanometer-scaled circuits. Specifically, a comprehensive survey and taxonomy of techniques used to model, monitor and mitigate Bias Temperature Instability (BTI) effects in logic circuits are presented. The challenges and overheads of these techniques are covered through the course of this paper. Important metrics of area overhead, power and energy overhead, performance overhead, and lifetime extension are discussed. Furthermore, the techniques are assessed with regards to ease of implementation and the ability to cope with challenges such as increase in manufacturing induced process variations. Finally, a taxonomy of the surveyed techniques is presented to facilitate generalization of the discussed approaches and to foster new inspiring techniques for this important reliability phenomenon leading to advancements in the design of defect-tolerant digital circuits

Aging effects in FPGAs: an experimental analysis

International audienceModern Field Programmable Gate Arrays (FP-GAs) are built using the most advanced technology nodes to meet performance and power demands. This makes them susceptible to various reliability challenges at nano-scale, and in particular to transistor aging. In this paper, an experimental analysis is made to identify the main parameters and phenomena influencing the performance degradation of FPGAs. For that purpose, a set of controlled ring-oscillator-based sensors with different frequencies and tunable activity control are implemented on a Spartan-6 FPGA. Thus, the internal switching activities (SAs) and signal probabilities (SPs) of the sensors can be varied. We performed accelerated-lifetime conditions using elevated temperatures and voltages in a controlled setting to stress the FPGA. A novel monitoring method based on measuring the electromagnetic emissions of the FPGA is used to accurately monitor the performance of the sensors before and after the stress. The experiments reveal the extent of performance degradations, the impact of SPs and SAs, and the relative impacts of BTI and HCI aging factors