A multiple layer contour-based gridless channel router

With the continuing advances of VLSI-technology, multiple layer channel routing has become increasingly important. A new n-layer gridless channel router is presented. Instead of the commonly employed grid it uses a set of contours as routing framework. The contours together with a set of reserved areas prevent short circuits and ensure routability of all nets. A compact routing can he expected since the framework is a very adequate model of the physical channel. We will show that it is also versatile enough to handle the classic vertical constraint problem. The inherent flexibility enables a design rule driven tradeoff between the number of vias, the wire length, and the channel height. The behavior of the algorithm has been investigated for many different channels, among which the well-known “difficult example” and its recent derivatives. Very competitive results have been achieved for channel height as well as the via count.