Co capping layers for Cu/low-k interconnects

Co films were selectively deposited as Cu capping layers by chemical vapor deposition technique. X-ray fluorescence spectroscopy determined the Co deposition selectivity as a function of the deposition temperature and substrate materials. Co/Cu interfacial property was characterized and revealed no detectable oxygen at the interface. In addition to electrical resistance measurements of the resulted Cu/low-k interconnects, selectivity of the Co deposition process and property of the resulted Co/Cu interface were further confirmed with time-dependent-dielectric-breakdown and electromigration tests.

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► Co films were selectively deposited as Cu capping layers by a chemical vapor deposition (CVD) technique.
► Compared with Cu/porous-dielectric, the CVD Co process shows higher selectivity between Cu and dense-dielectric.
► Comparable time-dependent-dielectric-breakdown resistance to the control further confirms selectivity of the Co deposition process.
► Electromigration enhancement observed from the selective Co deposition process confirms the Co/Cu interfacial property.