Curvature Enhanced Adsorbate Coverage Mechanism for Bottom-Up Superfilling and Bump Control in Damascene Processing

Published

October 16, 2008

Author(s)

Thomas P. Moffat, Daniel Wheeler, Soo K. Kim, Daniel Josell

Abstract

Superconformal electrodeposition is explained by the recently developed curvature enhanced adsorbate coverage (CEAC) mechanism. The model is used to quantitatively explain shape evolution during trench and via filling. The bottom-up filling dynamic is a consequence of competitive adsorption between a rate suppressing polyethylene glycol-chloride layer (PEG-C1) and a depassivating or rate accelerating species comprised of sulfonate-terminated propane thiol/disulfide and chloride (SPS-C1). SPS is the stronger surfactant and its adsorption occurs concurrently with displacement of the more rapidly formed PEG-C1 layer. The metal deposition rate is proportional to the local accelerator (SPS-C1) surface coverage. For growth on non-planar geometries this leads to enrichment of SPS on advancing concave surfaces, and dilution on convex sections. The resulting positive feedback naturally gives rise to the desired bottom-up superfilling. The accelerating action of SPS may be quenched by the addition of a cationic surfactant (LEV). Additive concentrations can be optimized to allow SPS derived bottom-up superfilling followed by LEV induced SPS deactivation that inhibits overshoot that otherwise would result in bump formation above the features. This paper presents a summary of simulations of electroanalytical and feature filling behavior during copper deposition in the PEG-C1-SPS-LEV system.

Citation

Electrochimica Acta

Pub Type

Journals

Citation

Moffat, T. , Wheeler, D. , Kim, S. and Josell, D. (2008), Curvature Enhanced Adsorbate Coverage Mechanism for Bottom-Up Superfilling and Bump Control in Damascene Processing, Electrochimica Acta (Accessed March 10, 2025)