Some embodiments of the invention provide a method of identifying routes for
net in a region of a design layout. The method identifies a first route for a first
net without using a routing grid. It then updates at least one previously defined
route for another net to account for spacing constraints relating to the first
route. In some embodiments, the method further (1) identifies previously defined
routes that might need to be modified to account for spacing constraints relating
to the first route; (2) examines the identified routes to determine whether the
identified routes need to be modified to account for spacing constraints relating
to the first route; and (3) updates several previously defined routes to account
for spacing constraints relating to the first route.
