Analyses of Power Staple Inserting Methodologies for Mitigating IR-Drops

As the process technology scales down and the supply voltage is getting low, meeting the IR-drop constraint becomes much more difficult. Inserting power staples, i.e., connecting adjacent power rails (called vertical staples) or stacking metal segments on a power rail (called horizontal staples) is a well known technique for IR-drop mitigation. However, so far no analyses have been performed regarding the following two issues: (1) which type of staple insertion outperforms the other? (2) how much the staple insertion applied at the pre-placement and the post-routing (relatively) impacts on the IR-drop mitigation. In addition, based on the analyses, we propose a power staple insertion flow that is able to effectively minimize the maximal IR-drop while controlling the number of routing failures.