Critical area extraction for soft fault estimation

Abstract

Algorithms are presented for extracting the critical area associated with extra and missing material soft faults of an integrated circuit from the mask layout. These algorithms have been implemented within the Edinburgh Yield Estimator (EYE) tool which permits efficient extraction of the critical area from an arbitrary mask layout. Accurate estimates of device critical area of even the largest devices can be obtained in a reasonable time using the sampling version of the tool. The application of these algorithms to defect related reliability is explored and results reported that compare the susceptibility to soft faults before and after layout modifications intended to enhance manufacturing yield. These results suggest that yield enhancement techniques can have a significant impact on defect-related device reliability.

Efficient Fault Localization and Failure Analysis Techniques for Improving IC Yield

“…In case of complementary metal oxide semiconductor (CMOS) processes, one of the greatest loss factors of the yield is that the defect causes the electrical faults. The modeling of real defect outlines that exhibit a great variety of defect shapes is usually modeled as a circle, which causes error of critical area simulation [6][7][8]. Various new models have been experimented which can predict real defects in a much better way than the usual circular model does [9,10].…”

Reliability and yield: a joint defect-oriented approach

“…Allan and Walton in [8] define soft faults as those generated by defects that do not connect separate electrical nodes but reduce the distance between them (or reduce the width of a wire but do not cause an open); they show that extra material soft faults may result in device failure due to eventual dielectric breakdown, and apply the EYE tool to estimate the yield considering those faults. However, the algorithm developed in [8] does not simply apply to electromigrationdependent yield because it does not consider the different currents in different wires. Number of works, summarized in [9] use catastrophic yield data and statistics about process at waferfab to assess EFR -Early Failure Rate -a measure of reliability.…”