Cu passivation for integration of gap-filling ultralow-k dielectrics

For Cu/low-k interconnects, the reversed damascene is an alternative integration approach where the metal wires are patterned first and then the spacing filled with a flowabledielectric. In this paper, the replacement of a sacrificial template by gap-filling ultralow-kdielectrics is studied, focusing on yield and transport performance ( “replacement dielectric” scheme). On non-passivatedcopper, the low-k curing processes induce severe damage to the metal lines, leading to the degraded electrical properties. This is confirmed by chemical inspection on the blanketCu films and morphological inspection on patterned structures. In order to avoidCu oxidation and out-diffusion at elevated temperature,Cupassivation by plasma-enhanced chemical vapor deposition SiCN is proposed and studied in detail. The inter-metal dielectric properties of replacement low-k are evaluated byresistance-capacitance and IV measurements using a Meander-Fork structure. By tuning thepassivation layer thickness andultraviolet curing time, high electrical yield is obtained with integrated porous low-k showing promising effective k-values (keff) and breakdown voltages (Ebd), confirming the interest of this specific integration scheme.

Source: Applied Physics Letters - December 5, 2016 Category: Physics Authors: Liping Zhang, Jean-Francois de Marneffe, Alicja Lesniewska, Patrick Verdonck, Nancy Heylen, Gayle Murdoch, Kristof Croes, Juergen Boemmels, Zsolt Tokei, Stefan De Gendt and Mikhail R. Baklanov Source Type: research