Design, fabrication and Helium Ion Microscope patterning of suspended nanomechanical graphene structures for NEMS applications

This paper investigates the potential uses of graphene nanomechanical devices for NEMS applications fabricated using Helium Ion Microscope (HIM). Suspended nanomechanical graphene drum structures of diameter (~2 - 3 μm) and thickness ranging from few atomic layers (~10 Å) to about 11 nm have been fabricated and characterized using Atomic Force Microscopy (AFM). The initial suspension profile and the thickness of the fabricated structures have been obtained using AFM. FEM results suggest that these structures can vibrate in the range of several MHz. Their small size and the higher operating frequencies make them well suitable for mass sensing applications with sensitivities greater than 10^-21 g Hz^-1 which is more than three orders of magnitude improvement over silicon based structures. The initial suspended graphene membranes have been patterned using HIM to obtain multiple z-axis flexures with sub-10nm feature sizes.