Via Filling Electrodeposotion of 4μm Diameter Via by Periodical Reverse Current

Abstract

To enable low power consumption and the access speed increase, three dimensional packaging of semiconductor chips has been proposed. In particular, a high-aspect ratio through silicon via(TSV) allows short chip to chip interconnection. 4 μm diameter and aspect ratio of 7.5 via TSV has filled. The perfect via filling was achieved within 25 minutes with the increasing i rev /|i on | ratios of periodic reverse pulse current waveform. In addition, we evaluated produced cuprous ion concentration during electrodeposition by using rotating ring disk electrode(RRDE). From the electrochemical measurement by RRDE, cuprous ion concentration on the reactive surface was markedly increasing with the increasing i rev /|i on | ratios. At i rev /|i on | ratio of large(i rev /|i on | = 6.0), a large amount of cuprous ion concentration produces during copper dissolution by reverse current and cuprous ion remain at the via bottom. High cuprous ion concentration at the via bottom accelerate deposition at the via bottom and achieve bottom up filling.