Shinde Prashant P, Adiga Shashishekar P, Pandian Shanthi, Mayya K Subramanya, Shin Hyeon-Jin, Park Seongjun
Materials Simulation (SAIT-India), Samsung R&D Institute, Bangalore, India.
Inorganic Material Lab, Samsung Advanced Institute of Technology, Suwon, 433-803, Republic of Korea.
Sci Rep. 2019 Mar 5;9(1):3488. doi: 10.1038/s41598-019-40193-6.
The stiff compromise between reliability and conductivity of copper interconnects used in sub-nanometer nodes has brought into focus the choice of encapsulation material. While reliability was the primary driver so far, herein, we investigate how electronic conductivity of Cu(111) thin films is influenced by the encapsulation material using density functional theory and Boltzmann transport equation. Atomically thin 2D materials, namely conducting graphene and insulating graphane both retain the conductivity of Cu films whereas partially hydrogenated graphene (HGr) results in reduction of surface density of states and a reduction in Cu film conductivity. Among transition metal elements, we find that atoms in Co encapsulation layer, which essentially act as magnetic impurities, serve as electron scattering centres resulting in a decrease in conductivity by at least 15% for 11 nm thick Cu film. On the other hand, Mo, Ta, and Ru have more favorable effect on conductivity when compared to Co. The cause of decrease in conductivity for Co and HGr is discussed by investigating the electronic band structure and density of states. Our DFT calculations suggest that pristine graphene sheet is a good encapsulation material for advanced Cu interconnects both from chemical protection and conductivity point of view.
亚纳米节点中使用的铜互连在可靠性和导电性之间的艰难折衷，使封装材料的选择成为焦点。到目前为止，可靠性一直是主要驱动因素，在此，我们使用密度泛函理论和玻尔兹曼输运方程研究封装材料如何影响Cu(111)薄膜的电子导电性。原子级薄的二维材料，即导电的石墨烯和绝缘的石墨烷，都能保持铜膜的导电性，而部分氢化的石墨烯（HGr）会导致态密度表面降低和铜膜导电性降低。在过渡金属元素中，我们发现钴封装层中的原子，本质上充当磁性杂质，作为电子散射中心，导致11纳米厚的铜膜导电性至少降低15%。另一方面，与钴相比，钼、钽和钌对导电性有更有利的影响。通过研究电子能带结构和态密度，讨论了钴和HGr导电性降低的原因。我们的密度泛函理论计算表明，从化学保护和导电性的角度来看，原始石墨烯片是先进铜互连的良好封装材料。
