Periodic Pulse Reverse Cu Plating for Through-Hole Filling

Abstract

A copper electroplating formula, composed of a single organic additive, nitrotetrazolium blue chloride monohydrate, is developedfor the direct filling of the through holes (THs) of a printed circuit board (PCB) and the through-silicon holes (TSHs) of a wafer.Two plating modes, direct current (DC) and periodic pulse reverse (PPR) current, are employed to perform the filling plating. DCplating requires an extended time period and results in void formation at high current density. In contrast, PPR plating requires ashorter time and results in a very thin copper layer on the wafer surface after the TSH is fully filled