Incremental layer assignment for critical path timing.

With VLSI technology nodes scaling into 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 paper we propose an incremental layer assignment framework targeting at delay optimization for critical path of each net. A set of novel techniques are presented: self-adaptive quadruple partition based on KxK division benefits the run-time; semidefinite programming is utilized for each partition; post mapping algorithm guarantees integer solutions while satisfying edge capacities. The effectiveness of our work is verified by ISPD'08 benchmarks.