A new triple-layer OTC channel router

We propose a new algorithm for triple-layer over-the-cell (OTC) routing in irregular cell area. While other over-the-cell routers assume the cell structure to be restricted to certain type, our channel router accepts most standard cells and custom cells. In this paper, the channel routing problem is decomposed into five steps: (i) 2-layer routing, (ii) track-to-metal1 transformation, (iii) segment-to-metal3 transformation, (iv) segment-to-metal1 transformation, and (v) 3-layer routing. We prove that the transformation steps can be executed in linear time. The effectiveness of our algorithm is demonstrated through physical layout of fully customized cells. Our algorithm is applied to MCNC benchmark circuits to generate compact layouts