Dependence of Cu electromigration resistance on selectively deposited CVD Co cap thickness

Co films with various thicknesses were selectively deposited as Cu capping layers by chemical vapor deposition technique. Selectivity of the Co deposition between Cu and dielectric surfaces was improved by both raising the deposition pressure and adopting a pre-clean process prior to the Co deposition. Degree of electromigration resistance enhancement was observed to be dependent on the deposited Co thickness. Compared to the no-Co control, significant EM lifetime enhancement was observed when the Co cap is thicker than 6 nm.

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► Co films were selectively deposited as Cu capping layers by a chemical vapor deposition technique.
► Further selectivity enhancement up to 9 nm Co on Cu was achieved through deposition process optimizations.
► Observed electromigration (EM) enhancement confirms the Co/Cu interfacial property.
► Degree of the EM enhancements shows dependence on the deposited Co cap thickness.
► Compared to the no-Co control, significant EM lifetime enhancement is observed when the Co thickness is >6 nm.