The key role of suppressor diffusion in defect-free filling of the through-silicon-via with high depth

Defect-free filling of through-silicon-via (TSV) with high depth is still a challenge to obtain in the industry. Herein, physical quantities, i.e. deposited copper morphology, local current density, local coverage of additives and local concentrations of additives, were investigated in the filling process of TSV with high depth. It was found that the local current density was controlled by the local coverage of accelerator. And the competitive adsorption process of additives was dominated by the suppressor. Therefore, the limited diffusion of the suppressor gave rise to the pinch-off defect of the TSV with high depth. Moreover, ultrasonic vibration was used to promote the diffusion of the suppressor, and defect-free filling of the TSV with high depth was implemented.