Fabrication and Characterization of Annular Copper Through-Silicon via for Passive Interposer Applications

This paper develops an annular copper through silicon via (TSV) integration process. Additives, including accelerator, suppressor, and leveler, with different concentrations are employed in the methanesulfonic-based electrolyte. Besides, other influence factors, including current density, forced convection, and environment temperature, are also taken into consideration for the sake of annular TSV filling. A same number of samples with annular and fully filled copper TSV, in the same structure parameters and technological conditions, are fabricated, respectively. Electroplating experiment, X-ray inspection, electrical testing as well as reliability testing are performed in order to compare the characterization of the two integration processes. All test results support this proposed annular TSV integration approach has great application prospect for passive interposer applications.