Linear Sweep Voltammetric Study on the Copper Electrodeposition of Though-Silicon-Vias

Abstract

Fast copper electroplating with void free via filling is required in though-silicon-via (TSV) manufacture. Copper electrodeposition in methanesulfonic acid (MSA) bath with additives is considered to be more effective and efficient than that in sulfuric acid used in Damascene. In this paper, a novel evaluation method is proposed for specific additives (sodium 3,3'-dithiodipropane sulfonate and polyethylene glycol) used in Cu electroplating of TSV in MSA bath based on their acceleration and inhibition at different potential region of liner sweep voltammetry (LSV) curve. The peak and valley of the LSV curve are closely related to the thickness of the deposited copper inside the via. Relatively lower potential region of the LSV curve corresponds to deeper positions inside the via during electroplating. Combined with the analysis of the LSV curve, the mechanism of void formation is proposed, which is further confirmed by the wafer-segment plating of TSV with three particular potentials.