Synergistic Effect of Additives on Filling of Tapered TGV Vias by Copper Electroplating

Through Glass Vias (TGV) interconnection has important application and development in 2.5D package, especially for interposers. Compared with through silicon vias (TSV), the coefficient of thermal expansion is well matched to wafer. Also, TGV interposer has less dielectric loss when transmitting high-frequency signals. The electrodeposition of through-holes (THs) is a key step, especially at a fast speed. In this research, typical tapered THs with double-sided seed layers were filled by copper electroplating, which has an aspect ratio of 3: 1 and diameter of 50 μm. Double anode plating method is used to achieve void-free filling under different current densities. The test results of scanning electron microscopy confirm the surface and cross section quality of electroplating. With the synergistic effect of particular inhibitor A, accelerator B and leveler C which ratio is 60:1:1, we can fill the THs without voids at a current density of 1.5ASD in 1.5 hours, along with smoother coating surfaces and uniformity of two coating surfaces.