Physical Design Methodologies for the More-than-Moore Era PDF Download

Author: Wei-Ting Chan
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ISBN:
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Languages : en
Pages : 212

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Book Description
In the past decades, device scaling along the Moore's Law trajectory has been the major focus of technology innovation in the semiconductor industry. However, this scaling has in recent years slowed down due to power limits, lithography complexity, and other physics limitations. The semiconductor industry has identified several looming technology challenges and expected new design paradigms that demand new "design-based equivalent scaling" approaches to enable continuation of Moore's Law. This thesis addresses several aspects of these challenges, for both the "More-Moore" and "More-than-Moore" domains. Interconnect reliability increases the design uncertainty in advanced node technologies. Electromigration is a growing concern in sub-22nm technology. To close a costly "chicken-egg" loop that spans library characterization and signoff in the presence of design adaptivity, we study the interlock among front-end (device) aging, voltage scaling, and electromigration; we furthermore quantify timing and power costs of meeting lifetime requirements. Based on this, we provide new signoff guidelines and demonstrate that suboptimal choice of voltage step size and scheduling strategy can result in decreased product lifetime. As semiconductor technology advances, leading-edge product companies must rapidly improve yield for designs that seek to reach mass production while still early in the adoption of a new technology node. We study the possible mitigation of yield loss by opportunistic, last-stage redundant logic insertion in early advanced-node production. We describe a yield estimation methodology, and propose an integer linear programming-based optimization of redundant logic insertion for opportunistic yield optimization. In sub-14nm processes, routability challenges arise from multiple patterning and pin access constraints that drastically weaken the correlation between global-route congestion and detailed-routing design rule violations. We present a method that applies machine learning techniques to effectively predict detailed-routing design rule violations after global routing, as well as detailed placement techniques to effectively reduce detailed-routing design rule violations. Beyond conventional design paradigms, three-dimensional integrated circuits (3DICs) with multiple tiers are expected to achieve large benefits (e.g., in terms of power and area) as compared to conventional two-dimensional designs. However, upper bounds on the potential power and area benefits from 3DIC integration with multiple tiers are not well-explored. We use the concept of implementation with infinite dimension to estimate upper bounds on power and area benefits achievable by 3DICs versus 2DICs. We observe that design power sensitivity to implementation with different dimensions correlates well with placement-based Rent parameter of the netlist. We show that the quality of netlist synthesis and optimization benefits from awareness of the target implementation dimension (e.g., 2D versus 3D). Last, aggressive requirements for low power and high performance in VLSI designs have led to increased interest in non-conventional computation paradigms. Approximate and stochastic hardware can achieve improved energy efficiency compared to accurate, traditional hardware modules. To exploit any benefits of approximate and stochastic hardware modules, design tools should be able to quickly and accurately estimate the output quality of composed approximate designs. We propose new accuracy estimation methodologies for approximate hardware and stochastic hardware, respectively. For stochastic circuits, we further investigate opportunities to optimize circuits under aggressive voltage scaling. We find that logical and physical design techniques can be combined to significantly expand the already powerful accuracy-energy tradeoff possibilities of stochastic circuits.