Imaging and nanoprobing of graphene layers on Ni damascene interconnects by conductive atomic force microscopy

Graphene is a promising material to replace copper interconnect metallization under 10 nm in width. We report a method for evaluating graphene interconnect wiring structure by conductive atomic force microscopy (C-AFM), which enables direct measurement of the 2D-resistance distribution and coverage evaluation of multilayer graphene (MLG) grown on Ni interconnects using a 300 mm damascene process. It is demonstrated that the coverage of MLG upon Ni can be estimated more precisely by C-AFM than that by back-scattered electron scanning electron microscopy (BSE-SEM) observation. We also measured the resistance of the MLG/Ni conductor and confirmed conduction paths of the MLG/Ni interconnect. Process dependence of MLG shows that lower local resistance corresponds to higher G band and D band intensity ratio (G/D ratio) in Raman spectra. C-AFM is demonstrated to be a potential technique for local conductance evaluation of next generation interconnects.