Methods for making copper (Cu) interconnects in semiconductor devices for interconnect dimensions less than 50 nm are described. The processes form Cu interconnects using a sequence of barrier layer, liner layer, and Cu deposition layer depositions, followed by a thermally assisted Cu reflow of the Cu deposition layer, and then a chemical mechanical polish (CMP) to removed excess portions of the reflowed Cu. The liner layer comprises noble metals such as Ru, Ir, Os, Rh, Re, Pd, Pt, and Au. Such processes avoids the formation of voids in copper interconnects with dimensions less than 50 nm.