minimal changes to resolve DRC.

KEY Wire spreading only pushes wires off-track when space allows; it does not change layers.

Wire Spreading and Antenna Violations

• The antenna ratio depends on antenna length, which may change slightly during wire spreading.
• In most cases wire spreading should not introduce new antenna violations.

KEY Wire spreading changes antenna length only slightly and usually does not create new antenna violations.

Double Via Insertion

Voids in vias are a serious manufacturing problem. To address this, two approaches are used.

• Reduce the via count by using via optimization techniques during route_opt.
• Add backup vias, also known as redundant or double vias, so a defective contact still has a working parallel via.

A good double-via rate is about 95% on the top-level layers and around 70% on via1. Double vias are rolled back to single vias where they would cause antenna violations.

One drawback is that double vias can introduce DRC violations in congested designs.

KEY Double via insertion adds redundant vias to survive void defects, with rollback where they cause antenna or DRC issues.

Double Vias and Critical Area

Yes - any addition of metal on the routing or cut layers in the layout inevitably introduces some critical area, but the increase is very small.

KEY Double vias add a small amount of critical area, but the increase is minor.