Vlsi Interconnect Performance Optimization And Planning

Introduction The exponential scaling of feature sizes in semiconductor technologies has side-effects on layout optimization, related to effects such as inter connect delay, noise and crosstalk, signal integrity, parasitics effects, and power dissipation, that invalidate the assumptions that form the basis of previous design methodologies and tools. This book is intended to sample the most important, contemporary, and advanced layout opti mization problems emerging with the advent of very deep submicron technologies in semiconductor processing. We hope that it will stimulate more people to perform research that leads to advances in the design and development of more efficient, effective, and elegant algorithms and design tools. Organization of the Book The book is organized as follows. A multi-stage simulated annealing algorithm that integrates floorplanning and interconnect planning is pre sented in Chapter 1. To reduce the run time, different interconnect plan ning approaches are applied in different ranges of temperatures. Chapter 2 introduces a new design methodology - the interconnect-centric design methodology and its centerpiece, interconnect planning, which consists of physical hierarchy generation, floorplanning with interconnect planning, and interconnect architecture planning. Chapter 3 investigates a net-cut minimization based placement tool, Dragon, which integrates the state of the art partitioning and placement techniques.

This book covers layout design and layout migration methodologies for optimizing multi-net wire structures in advanced VLSI interconnects. Scaling-dependent models for interconnect power, interconnect delay and crosstalk noise are covered in depth, and several design optimization problems are addressed, such as minimization of interconnect power under delay constraints, or design for minimal delay in wire bundles within a given routing area. A handy reference or a guide for design methodologies and layout automation techniques, this book provides a foundation for physical design challenges of interconnect in advanced integrated circuits.

As prevailing copper interconnect technology advances to its fundamental physical limit, interconnect delay due to ever-increasing wire resistivity has greatly limited the circuit miniaturization. Carbon nanotube (CNT) interconnects have emerged as promising replacement materials for copper interconnects due to their superior conductivity. Buffer insertion for CNT interconnects is capable of improving circuit timing of signal nets with limited buffer deployment. However, due to the imperfection of fabricating long straight CNT, there exist significant unidimensional-spatially correlated variations on the critical CNT geometric parameters such as the diameter and density, which will act the circuit performance. This dissertation develops a novel timing driven buffer insertion technique considering unidimensional correlations of variations of CNT. Although the fabrication variations of CNTs are not desired for the circuit designs targeting performance optimization and reliability, these inherent imperfections make them natural candidates for building highly secure physical unclonable function (PUF), which is an advanced hardware security technology. A novel CNT PUF design through leveraging Lorenz chaotic system is developed and we show that it is resistant to many machine learning modeling attacks. In summary, the studies in this dissertation demonstrate that CNT technology is highly promising for performance and security optimizations in advanced VLSI circuit design.

The book provides a detailed analysis of issues related to sub-threshold interconnect performance from the perspective of analytical approach and design techniques. Particular emphasis is laid on the performance analysis of coupling noise and variability issues in sub-threshold domain to develop efficient compact models. The proposed analytical approach gives physical insight of the parameters affecting the transient behavior of coupled interconnects. Remedial design techniques are also suggested to mitigate the effect of coupling noise. The effects of wire width, spacing between the wires, wire length are thoroughly investigated. In addition, the effect of parameters like driver strength on peak coupling noise has also been analyzed. Process, voltage and temperature variations are prominent factors affecting sub-threshold design and have also been investigated. The process variability analysis has been carried out using parametric analysis, process corner analysis and Monte Carlo technique. The book also provides a qualitative summary of the work reported in the literature by various researchers in the design of digital sub-threshold circuits. This book should be of interest for researchers and graduate students with deeper insights into sub-threshold interconnect models in particular. In this sense, this book will best fit as a text book and/or a reference book for students who are initiated in the area of research and advanced courses in nanotechnology, interconnect design and modeling.

This volume provides a complete understanding of the fundamental causes of routing congestion in present-day and next-generation VLSI circuits, offers techniques for estimating and relieving congestion, and provides a critical analysis of the accuracy and effectiveness of these techniques. The book includes metrics and optimization techniques for routing congestion at various stages of the VLSI design flow. The subjects covered include an explanation of why the problem of congestion is important and how it will trend, plus definitions of metrics that are appropriate for measuring congestion, and descriptions of techniques for estimating and optimizing routing congestion issues in cell-/library-based VLSI circuits.