COPPER ELECTROFILL ON NON-COPPER LINER LAYERS

Void-free bottom-up fill of copper in features is achieved on non-copper liner layers. A non-copper liner layer has a higher resistivity than copper. An electroplating solution for plating copper on a non-copper liner layer includes a low copper concentration, high pH, organic additives, and bromide ions as a copper complexing agent. The high pH and the bromide ions do not interfere with the activity of the organic additives. In some implementations, the concentration of copper ions is between about 0.2 g/L and about 10 g/L, a concentration of sulfuric acid is between about 0.1 g/L and about 10 g/L, and a concentration of the bromide ions is between about 20 mg/L and about 240 mg/L. In some implementations, the electroplating solution further includes chloride ions as an additional copper complexing agent at a concentration between about 0.1 mg/L and about 100 mg/L.