Novel electro-chemical mechanical planarization using carbon polishing pad to achieve robust ultra low-k/Cu integration

We developed a novel electro-chemical mechanical planarization (e-CMP) method that uses a conductive carbon pad for polishing 300-mm wafers. More than one hundred electro-cells were fabricated into the carbon pad, and the method resolved issues with conventional e-CMP, such as scratching caused by metal electrodes, copper residues, and process complexity of cathode regeneration. By using an e-CMP process followed by TaN-CMP, porous low-k/Cu interconnects were successfully fabricated.