Evaluating the filling performance of a copper plating formula using a simple galvanostat method

This work presents a feasible galvanostat method using a copper working electrode that was individually operated at two different rotation speeds to accurately predict the filling performance of a copper plating formula for microvia filling. This approach is based on the convection-dependent adsorption (CDA) of additives. Of six copper-plating formulas, formulated to examine the applicability of this method, four were effective for bottom-up filling and two were ineffective. In contrast with the microvia cross sections, it was demonstrated that this approach is effective to evaluate the workability of a plating formula in microvia filling. A relationship between the filling performance and the leveler concentration of a plating formula that was composed of polyethylene glycol, bis(3-sulfopropyl) disulfide, and Janus Green B was also examined by using the galvanostatic measurement. The final results showed that the variation trend of the filling performance with the leveler concentration coincided with that of the potential difference obtained from the galvanostatic measurement. (c) 2006 The Electrochemical Society.