title: Mass transport mechanism of cu species at the metal/dielectric interfaces with a graphene barrier.
abstract: The interface between the metal and dielectric is an indispensable part in various electronic devices. The migration of metallic species into the dielectric can adversely affect the reliability of the insulating dielectric and can also form a functional solid-state electrolyte device. In this work, we insert graphene between Cu and SiO2 as a barrier layer and investigate the mass transport mechanism of Cu species through the graphene barrier using density functional theory calculations, second-ion mass spectroscopy (SIMS), capacitance-voltage measurement, and cyclic voltammetry. Our theoretical calculations suggest that the major migration path for Cu species to penetrate through the multiple-layered graphene is the overlapped defects larger than 0.25 nm2. The depth-profile SIMS characterizations indicate that the "critical" thickness of the graphene barrier for completely blocking the Cu migration is 5 times smaller than that of the conventional TaN barrier. Capacitance-voltage and cyclic voltammetry measurement reveal that the electrochemical reactions at the Cu/SiO2 interface become a rate-limiting factor during the bias-temperature stressing process with the use of a graphene barrier. These studies provide a distinct roadmap for designing controllable mass transport in solid-state electrolyte devices with the use of a graphene barrier.
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hung Hom, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Yuda
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Liu
authors.forename: Tieyu
authors.initials: T
authors.lastname: Sun
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.forename: Wenjing
authors.initials: W
authors.lastname: Jie
authors.forename: Xinsheng
authors.initials: X
authors.lastname: Wang
authors.forename: Yizhu
authors.initials: Y
authors.lastname: Xie
authors.forename: Yuen Hong
authors.initials: YH
authors.lastname: Tsang
authors.forename: Hui
authors.initials: H
authors.lastname: Long
authors.forename: Yang
authors.initials: Y
authors.lastname: Chai
keywords: Cu interconnect; barrier; graphene; mass transport