Organosiloxane nanolayer as diffusion barrier for Cu metallization on Si

Abstract

Development of emerging technologies such as artificial intelligence, big data, and smart vehicles brings increasing demands on high-performance integrated circuits (ICs). To achieve this goal, ultra-miniaturization of Cu interconnects as well as diffusion barrier layer to increase the integration density is imperative. In this study, we demonstrate that an ultrathin organosiloxane nanolayer exhibits excellent barrier efficacy against the active diffusion of Cu towards Si. The organosiloxane nanolayer is constructed on the SiO2 surface using dehydration to covalently tether the hydrolyzed organosilane molecules. The amine termini of organosilanes are used to adsorb catalytic Pd nanocluster to accomplish the Cu metallization on Si. Rapid thermal annealing is performed with respect to the Si/SiO2/organosiloxane/Cu junctions to evaluate the efficacy of diffusion barrier. Based on microstructural and crystallographic examinations, the organosiloxane nanolayer with a shorter alkyl chain performs better with a higher breakdown temperature of 923 K at which the Cu diffusion and the Cu silicide formation at the junctions occur. The grafting conformations of organosilane molecules with various alkyl chain lengths on the SiO2 surface are constructed based on energy minimization calculations to rationalize the diffusion barrier efficacy.