Bottom-up Filling of Damascene Trenches with Gold in a Sulfite Electrolyte
Daniel Josell, Thomas P. Moffat
Superconformal Au deposition is demonstrated in a Na3Au(SO3)2 + Na2SO3 electrolyte including Bi3+. Micromolar additions of the Bi3+ to the electrolyte catalyze the reduction of Au(SO3)23- based on hysteretic voltammetry and rising chronoamperometric transients indicating accelerated Au deposition rates. Void-free bottom-up filling of Damascene trenches is achieved for a range of Bi3+ concentrations. In the presence of significant convection the bottom-up filling is accompanied by near-perfect passivation of the field, resulting in deposition that resembles through-mask plating in the recessed features. The observed behavior is discussed in the context of previously described mechanisms for superconformal electrodeposition.