Through-Cobalt Self Forming Barrier (tCoSFB) for Cu/ULK BEOL: A novel concept for advanced technology nodes

Abstract

Through-Co self-forming-barrier (tCoSFB) metallization scheme is introduced, with Cu gap-fill capability down to 7 nm-node dimensions. Mn atoms from doped-seedlayer diffuse through CVD-Co wetting layer, to form TaMnxOy barrier, with integrity proven by vertical-trench triangular-voltage-sweep and barrier-oxidation tests. tCoSFB scheme enables 32% and 45% lower line and via resistance, respectively at 10 nm node dimensions, while achieving superior EM performance to competitive TaN/Co and TaN/Ru-based barriers.