Incremental Layer Assignment for Timing Optimization.

With VLSI technology nodes scaling into the nanometer regime, interconnect delay plays an increasingly critical role in timing. For layer assignment, most works deal with via counts or total net delays, ignoring critical paths of each net and resulting in potential timing issues. In this article, we propose an incremental layer assignment framework targeting delay optimization in timing the critical path of each net. A set of novel techniques are presented: self-adaptive quadruple partition based on K × K division benefits the runtime; semidefinite programming is utilized for each partition; and the sequential mapping algorithm guarantees integer solutions while satisfying edge capacities; additionally, concurrent mapping offers a global view of assignment and post delay optimization reduces the path timing violations. The effectiveness of our work is verified by ISPD’08 benchmarks.