Optimal anneal technology for micro-voiding control and self-annealing management of electroplated copper

The present invention generally provides for a two step annealing process for a deposited metal layer (18). More particularly, the two step annealing process provides for annealing a metal layer, preferably electroplated copper, at less than about 300°C for less than about 30 seconds, followed by annealing the layer at between about 300°C and about 450°C for less than about 90 seconds. The annealing process occurs in a processing gas preferably with an oxygen content less than about 100 parts per million (ppm) and an hydrogen content less than about 4% by volume. The invention has the advantages of increased substrate throughput rates, improved self-annealing micro-void control, and improved grain growth management.