Optimization of graphene dry etching conditions via combined microscopic and spectroscopic analysis

Abstract

Single-layer graphene structures and devices are commonly defined using reactive ion etching and plasma etching with O 2 or Ar as the gaseous etchants. Although optical microscopy and Raman spectroscopy are widely used to determine the appropriate duration of dry etching, additional characterization with atomic force microscopy (AFM) reveals that residual graphene and/or etching byproducts persist beyond the point where the aforementioned methods suggest complete graphene etching. Recognizing that incomplete etching may have deleterious effects on devices and/or downstream processing, AFM characterization is used here to determine optimal etching conditions that eliminate graphene dry etching residues.

Engineering of Bi-/Mono-layer Graphene Film Using Reactive Ion Etching

“…Achieving single layer graphene was confirmed by Raman spectroscopy after 6 s of the RIE process and using the oxygen at a flow rate of 10 sccm, RF power density of 0.0015 W/cm 2 and working pressure of 200 mTorr. In this study, the achieved etching time for a single layer graphene film grown by CVD was significantly smaller than reported values (15 s) for a graphene flake [14].…”

“…The processing parameters were fixed as: O 2 (etchant gas) with a flow rate of 10 sccm (standard cubic centimeters per minute unit), a working pressure of 200 mTorr and an RF power density of 0.015 W/ cm 2 for both graphene films that were covered by conventional PR and PS polymers. The etching process parameters, such as etchant gas flow rate, RF power density and working pressure were optimized after a series of experiments based on the reported parameters in the literature [3,9,14]. Raman spectroscopy is a powerful technique in characterizing the quality of the graphene films and investigating the number of layers [21,22] in engineered graphene based devices.…”

“…Although high quality graphene films can be grown using epitaxial synthesis and chemical vapor deposition (CVD) [9][10][11][12][13], the fabrication of specific structures, such as graphene ribbons, graphene pads or graphene electrodes, still remain a challenge due to the engineering challenge of controlling the number of graphene layers in a multi-layered graphene film. The graphene based nanodecive performance can be significantly altered by the presence of fabrication residue [14]. Hence, the fabrication of the high quality and high uniformity of nanoscale structures using single/ bi-layer graphene is still a major challenge in advanced nanofabrication.…”

“…Prado et.al [14] employed the RIE process and plasma cleaning to remove the monolayer of graphene. Based on their observation the graphene layers can be etched using O 2 or Ar as etchant gas.…”

The effect of residual gas scattering on Ga ion beam patterning of graphene

“…12 At this ion dose, it is possible that there are still some carbon species remaining below the detection limit of Raman. 22 The electrical conductance through the milled area is however already negligible at a lower ion dose, as shown in the supplementary material. 23 The ratio between the D and G peak intensities (I D /I G ratio) is typically used as a measure of the defect density in graphene.…”