Some embodiments of the invention provide a method for identifying locations
of potential via between two layers of a design layout. The method identifies on
one layer a first non-rectangular polygonal region for containing the via, and
identifies on the other layer a second non-rectangular polygonal region for containing
the via. It then determines whether an intersection of the first and second regions
is sufficiently large to contain a via. If the intersection is sufficiently large,
the method identifies the intersection of the two regions as a region for containing
a via.
