A comparison of copper sulfate and methanesulfonate electrolytes in the copper plating process for through silicon via metallization

Abstract

In this study, authors studied and compared the behaviors of the additives in copper sulfate and cupric methanesulfonate electrolytes by means of electrochemical measurement method with a rotary electrode. The electrochemical parameters including exchange current density and cathodic transfer coefficient of the electrolytes were successfully determined utilizing linear sweep voltammetry. Chronoamperometry (CA) was conducted to verify the diffusion time of additives to the surface of electrodes and the corresponding diffusion constants were characterized. Copper plating of 50/200 μm TSVs was achieved with copper sulfate and cupric methanesulfonate electrolytes respectively. The plated surface morphologies were studied using Scanning Electron Microscopy (SEM).