Copper Deep Via Filling with Selective Accelerator Deactivation by Polyethyleneimine

Abstract

Obvious bottom-up copper superfilling of through silicon vias (TSV) was demonstrated by deactivating accelerator selectively on top field and via opening. Generally, superfilling of TSVs are achieved by addition of levelers in the plating bath or additional suppression on the top surface. We previously demonstrated the superfilling of TSV by three step plating with a reverse pulse. The reverse pulse deactivated accelerator preferentially on top field and via opening, and accelerator rich condition on via bottoms was realized. In this study, we attempted to deactivate the accelerator by dipping a chip into polyethyleneimine (PEI) solution, which is thought as one of basic components of levelers, instead of applying a reverse pulse. PEI showed obvious accelerator deactivation, and extreme bottom-up was demonstrated by the three step plating, which consists of initial accelerator adsorption, second accelerator deactivation, and final main plating without accelerator bath steps.