US Patent 7340711 Method and apparatus for local preferred direction routing

Some embodiments of the invention provide a method for defining routes in a design layout. The method defines at least one particular wiring layer that has at least two regions with different local preferred wiring directions. The method then uses the differing local preferred wiring directions to define a detailed route on the wiring layer. In some embodiments, the method defines a first route that traverse first and second regions between two layers by using a first via that has a first pad in the second region. The method also defines a second route that traverses the second region and a third region in the two layers by using a second via that has a second pad in the second region, where the first and second pads have different shapes.