Metal interconnect structures are reworked to address possible voids or other defects. Etching of initially deposited interconnect metal to open voids is followed by reflow to accumulate interconnect metal at the bottoms of trenches. Additional interconnect metal is deposited over the initially deposited interconnect metal by electroplating and/or electroless plating. Additional diffusion barrier material may be deposited and patterned prior to deposition of the additional interconnect material.