DRC-aware Pin Access Planning for Detailed Routing

Detailed routing is one of the key steps in integrated circuit physical design. Pin access planning is a key factor affecting the quality of detailed routing result and reducing design rule check(DRC) violations. A pin access planning algorithm based on minimum cost maximum flow(MCMF) and taking DRC violations into account is proposed. Firstly, it constructed detailed routing graph and corresponding grid graph. Then, all the pin access positions were assigned by searching MCMF of the routing area on the grid graph. On the basis of the above pin access planning algorithm, a rip-up and rerouting algorithm is proposed. New pin access positions were reassigned for the unreasonable ones when ripping-up and rerouting. DRC violation was taken into account as well. Algorithm was optimized with three aspects:the definition of cost function, the order of ripping-up and rerouting and the routing method. Experimental results show that DRC violations are decreased by 24% in average after using the algorithm.