Superconformal film growth: Mechanism and quantification
by T. P. Moffat, D. Wheeler, M. D. Edelstein, D. Josell
Superconformal electrodeposition of copper is explained by the recently developed curvature-enhanced-accelerator coverage (CEAC) model, which is based on the assumptions that 1) the local growth velocity is proportional to the surface coverage of the accelerator, or catalyst, and 2) the catalyst remains segregated at the metal/electrolyte interface during copper deposition. For growth on nonplanar geometries, this leads to enrichment of the catalyst on advancing concave surfaces and dilution on advancing convex sections, thereby giving rise to bottom-up superfilling of submicrometer trenches and vias. In this paper the robustness of the CEAC model is demonstrated by characterizing the kinetics of catalyst accumulation and consumption in a series of electroanalytical experiments on planar electrodes. The model is then used to successfully predict interface shape evolution during feature filling in a variety of experiments, without using adjustable parameters.