Pyrolyzed Photoresist Thin Film: Effect of Electron Beam Patterning on Dc and Thz Conductivity

Pyrolyzed photoresist films (PPFs), which are formed via vacuum annealing of a photoresist without a catalyst, allow the development of graphitic nanostructures employing conventional lithographic techniques. We perform comparative study of the PPF structures fabricated by pre- and postprocessing via electron beam lithography (EBL). In the first approach, the structures are defined by pre-patterning the photoresist followed by pyrolysis, while in the latter, we pyrolyzed a continuous photoresist film and employed the reactive ion etching through another resist mask. We also fabricated PPF nano-gratings with a lateral dimension down to 250 nm to demonstrate feasibility of suggested approach. By comparing charge transport properties in the structures of two types, we found that both pre-and post-processing of PPF demonstrate the same values of dc and high frequency conductivities obtained in the frequency range from 0.2 to 1.5 THz. Moreover, the sheet resistance of PPF with a thickness below 200 nm is of 1000 Ohm/square, value of which is comparable to that of commercially available CVD graphene. Our finding opens a path for simple, reproducible, and scalable fabrication of graphitic-film-based high frequency nanocircuits.