Integration of multilayer graphene wires onto tungsten plugs for carbon/metal hybrid interconnects

We have successfully integrated multilayer graphene (MLG) wires connected to tungsten (W) plugs with contact metal layers for carbon wire and metal plug/via hybrid interconnects for the first time. Generally, owing to the high temperature associated with the growth of high-quality MLG films, it is necessary to develop effective transfer and connection processes for MLG for back-end-of-line (BEOL) processing in LSI. In this study, using MLG formed by annealing sputtered amorphous carbon with a cobalt (Co) catalyst layer, we have successfully performed the transfer of MLG without any electrical open failures and resistance changes in the wires, despite the use of a simple transfer method without any support layers. Moreover, the connections between the transferred MLG wires and the W plugs were drastically improved using TiN/Ti as contact metal layers, as compared with the case of not using any contact metal layers. This study will be of great importance for developing contact structures not only in MLG wire and metal plug/via hybrid interconnects without carbon nanotubes (CNTs) but also in all carbon interconnects using CNT plug/via.