Preparation of Porous Au electrode used for additives investigation in copper filling

In three-dimensional integration technology, through-silicon vias(TSV) are potential to meet the demand for a higher packing density. Copper filling makes up nearly 40% of the overall TSV cost. To achieve the superconformal mode in TSV copper filling, additives are added to the electroplating bath. Porous Au electrode is prepared by geometric replica of the Nickel microcone arrays. Holes with a diameter of 350nm and a depth of 1µm are evenly distributed. The porous electrode is used as working electrode in the three-electrode system and can be repeatedly used. By comparing the linear sweep voltammetry curves measured using porous Au electrode and flat Au electrode as working electrode, and further analysis on the current inside and outside the holes, it is found that the suppressor PEG can suppress the copper deposition, lengthen the hole close time as to attain more time for the copper deposition inside the holes. The porous Au electrode can be effectively used as working electrode to investigate the additive performance in TSV copper filling.