Effect of intermolecular and intramolecular synergism on the inhibition from hybrid additives in damascene copper electrodeposition

Additives are crucial in the electroplating metallization for damascene features, among which hybrid additives with both superfilling and leveling capabilities have attracted much attention, yet their inhibition mechanism remains to be further explored. In this work, hybrid additives named IDZ-PEs, which comprise imidazole and polyethers with varying degrees of polymerization, were designed and prepared to reveal the inter- and intramolecular synergism between superfilling and leveling inhibitors. In addition, mixtures of imidazole and polyether were applied for comparison. Electrochemical tests and quantum calculations demonstrated that IDZ-PEs exhibited both superfilling and leveling capabilities. The intermolecular synergism between independent imidazole and polyether weakens the inhibition of polyether by changing its active adsorption sites. In contrast, the intramolecular synergism between imidazole and polyether enhances the inhibition from both components, and the enhancement reduces with the increasing polyether polymerization. Furthermore, the void-free filling of damascene features was achieved with IDZ-PEs, demonstrating that IDZ-PEs were effective suppressors for damascene copper electrodeposition. The explanation of the synergism between superfilling and leveling inhibitors provides further insights into the mechanism of hybrid additives.