Journal of The Electrochemical Society, 161 (5) D269-D276 (2014) D269 0013-4651/2014/161(5)/D269/8/$31.00 © The Electrochemical Society Stochastic Modeling of Polyethylene Glycol as a Suppressor

The desorption / adsorption of suppressor additive during Cu electroplating plays a critical role in the void-free filling of recessed features such as through-silicon vias (TSVs) used in 3-dimensional integration. A stochastic model was proposed for Polyethylene Glycol (PEG) as a suppressor additive in Cu electroplating. Using the proposed model, a program capable of simulating transient processes such as cyclic voltammograms (CVs) was developed. The steep change of current density due to suppressor desorption, as well as the characteristic hysteresis, observed in the CVs was shown in simulation. The dependency of PEG desorption / adsorption on various factors, including the bath composition, scan rate and molecular weight, was simulated. The simulation results were confronted side-by-side with the corresponding experimental measurements. An overall good qualitative match was shown. © 2014 The Electrochemical Society. [DOI: 10.1149/2.072405jes] All rights reserved. Manuscript submitted January 17, 2014; revised manuscript received March 5, 2014. Published April 1, 2014. Cu electroplating has been widely employed in the fabrication of interconnects in integrated circuits. Various organic and inorganic additives are added to the plating bath to improve the feature-filling performance. The organic additives are generally categorized accord-ing to their effect on Cu plating. The additives that act as “suppressors” reduce the Cu plating rate on Cu surface when adsorbed. Polyethy