Redundant vias (via doubling)

Redundant vias (via doubling). This is a DFM (Design for Manufacturability) step, a recommended rule rather than a hard one. A single via between two metal layers is a yield risk: if that one cut voids or breaks, the net opens. Doubling a via into a redundant pair means a single cut failure does not open the connection.

• Double every via that has room beside it for a second cut (click it).
• Leave single any via that is boxed in by neighbouring metal: a second cut there would break the spacing rule.

Doubling a blocked via creates a spacing violation; leaving a via single where there was room misses the yield improvement. Double all the feasible vias and no others, then Submit vias.