Effect of Cleaning Chemistries on Cobalt: Surface Chemistries and Electrical Characterization

Abstract:

The etching characteristics of ECD cobalt in different cleaning solutions were characterized using four-point probe, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. 0.05% HF solution with saturated dissolved oxygen concentration was found to result in a substantial etch of ECD cobalt (~5 nm/min). In contrast, cleaning in the SC1 1:4:100 mixture and the formulated mixture led to a significantly lower etch amount, which could be explained by the formation of a passivation layer at the surface. XPS characterization indicated the formation of a cobalt hydroxide at the surface. The electrical evaluation of the DD structure carried out after cleaning using the formulated chemical mixture and subsequent metallization showed good yield for the 22 nm Kelvin vias, testifying an efficient cleaning of the Co surface at the via bottom.

• Periodical: Solid State Phenomena (Volume 282)
• Pages: 263-267
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.282.263
• Online since: August 2018
• Authors: Quoc Toan Le*, Els Kesters, Yuya Akanishi, Marleen H. van der Veen, Atsushi Mizutani, Frank Holsteyns
• Keywords: Cobalt, Dual Damascene Clean, Metal Clean, Metal Etch, Post-Etch Residue Removal (PERR), Pre-Metallization Clean

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