Practical Redundant-Via Insertion Method Considering Manufacturing Variability and Reliability

Kazuyuki OOYA

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A    No.12    pp.2962-2970
Publication Date: 2009/12/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.2962
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Physical Level Desing
redundant via,  manufacturing variability,  reliability,  

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As the integrated circuit technology has undergone continuous downscaling to improve the LSI performance and reduce chip size, design for manufacturability (DFM) and design for yield (DFY) have become very important. As one of the DFM/DFY methods, a redundant via insertion technique uses as many vias as possible to connect the metal wires between different layers. In this paper, we focus on redundant vias and propose an effective redundant via insertion method for practical use to address the manufacturing variability and reliability concerns. First, the results of statistical analysis for via resistance and via capacitance in some real physical layouts are shown, and the impact on circuit delay of the resistance variation of vias caused by manufacturing variability is clarified. Then, the valuation functions of delay variation, electro-migration (EM), and stress-migration (SM) are defined and a practical method concerning redundant via insertion is proposed. Experimental results show that LSI with redundant vias inserted by our method robust against manufacturing variability and reliability problems.