Electromigration can be reduced in a copper-based metallization of an integrated circuit that includes a first copper-containing via that electrically connects an underlying conductive line and an overlying copper-containing line through an intervening insulating layer. Electromigration can be reduced...http://www.google.com/patents/US7078817?utm_source=gb-gplus-sharePatent US7078817 - Multiple copper vias for integrated circuit metallization
