Metal-only ECO is prevalent at design houses to perform incremental design changes to resolve last found functional and/or timing failures. However, it is hard to perform mixed functional and timing changes manually. Prior endeavors focus on functional or timing ECO alone, but we observe that separating them may fail to fix all timing violations. Consequently, this paper presents the first work to perform simultaneous functional and timing ECO. We use an augmented bipartite graph to model both types of ECO. In addition, through comprehensive constant insertion and bridging, the functional capability of each spare cell is enhanced, thus facilitating spare cell selection. Experimental results show that our simultaneous functional and timing ECO engine can successfully resolve mixed functional and timing ECO that is unsolvable by the sequential scheme. Moreover, our engine outperforms the state-of-the-art works for timing ECO with a 117X speedup, and for functional ECO with 6-15% wirelength reductions.
Abstract-Due to excessive current densities, electromigration (EM) may trigger a permanent open-or short-circuit failure in signal wires or power networks in analog or mixed-signal circuits. As the feature size keeps shrinking, this effect becomes a key reliability concern. Hence, in this paper, we focus on wiring topology generation for avoiding EM at the routing stage. Prior works tended towards heuristics; on the contrary, we first claim this problem belongs to class P instead of class NP-hard. Our breakthrough is, via the proof of the greedy-choice property, we successfully model this problem on a multi-source multi-sink flow network and then solve it by a strongly polynomial time algorithm. Experimental results prove the effectiveness and efficiency of our algorithm.
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