Based on non-crossing relations, vertical constraint relations and net-geom
etry relations in one T-type junction region, two kinds of routability cros
sing distributions are proposed to improve routing performance in one T-typ
e junction region. For routability crossing distribution in one T-type junc
tion region, a routability-ordering graph is built to decide a net ordering
in O(n(2)) time. For routability quota crossing distribution in one T-type
junction region, if the number of net crossings in base channel is more th
an a given quota, this net ordering in routability crossing distribution wi
ll be further adjusted to satisfy the quota requirement by using a net inte
rchange operation in O(n) time. For floating pin;assignment in one;T-type j
unction region, global nets are assigned on the boundary between top channe
l and base channel by interleaving vacant pins in O(n) time according to a
net ordering in routability crossing distribution.