Analysis of interface impurities in electroplated Cu layers by using GD‐OES and TOF‐SIMS

Abstract

Abstract Electrochemically deposited (ECD) copper layers used as interconnect metallizations exhibit incorporated impurities in the form of H, S, C, O, N, and Cl originating from additives in the electrolyte solution. These impurities were observed in the whole layer and especially at the interface to the underlying Cu seed layer due to an increased adsorption at the beginning of the electroplating process. Time‐of‐flight (TOF)‐SIMS and glow discharge optical emission spectroscopy (GD‐OES) were carried out for interface analysis of 100‐nmECD thin Cu films plated on a 50‐nm Cu seed layer deposited by physical vapor deposition (PVD). This reveals the respective advantages and disadvantages of both techniques for thin film analysis. Also the effect of a modification of the electroplating procedure is shown. This so‐called Hot Start Plating inhibits the additive adsorption and decreases the undesirable incorporation of impurities. Copyright © 2008 John Wiley & Sons, Ltd.