The Impact of Adsorbates on Metal Deposition through the Curvature Enhanced Accelerator Coverage Mechanism

Abstract

Superconformal electrodeposition utilizing deposition accelerating additives enabled the implementation of damascene interconnects in microelectronics using copper “superfill” in the late 1990’s. The underlying Curvature Enhanced Accelerator Coverage (CEAC) mechanism was defined in 2001. Since then, superconformal deposition of copper, silver and gold in fine features as well as the formation of optically smooth, soft deposits has been successfully predicted by CEAC-based models that capture the interplay of deposition-rate accelerating adsorbate coverage and metal deposition through area change on nonplanar surfaces. Void-free filling of high aspect ratio, submicrometer trenches and vias with silver and gold has been quantitatively predicted and demonstrated using additives selected from the literature on catalysis of metal deposition by additive adsorption. These additives also provide, through the same CEAC mechanism, a means of obtaining optically smooth deposits without relying on deposit-hardening grain refinement through additive incorporation. I will summarize results to date, including what we believe we understand as well as what we don’t.