Surface morphology and structural analysis of fluorocarbon nano-rings formation through EBL and SiO2 plasma etching

This paper reports the formation of nano-scale ring-shaped fluorocarbon macromolecules during silicon dioxide SiO2 reactive ion etching (RIE). This nanostructure was created on a SiO2 substrate with poly methyl methacrylate (PMMA) mask during the RIE process, using trifluoromethane (CHF3) and oxygen etchants. Variation in etching time results in the creation of square, double concentric, and flower-shaped nano-rings around SiO2 micro-pits. In addition, increasing the etching times leads to an increase in ring width. The formation of these nano-rings is shown by a deposition of passivation layer, consisting of silicon oxide, SixOy and fluorocarbon, CxFy, on sidewalls during SiO2 etching in fluorocarbon plasma. Field Emission Scanning Electron Microscopy (FESEM) and Energy-dispersive X-ray (EDX) were utilized to investigate the morphology and the structure of the nano-rings. Results show that the flower-shaped nano-rings were created on the surface of silicon for 8 min of etching time. These fluorocarbon nano-rings could be used as nano-scale templates.

► Fluorocarbon nano-rings are formed during SiO2 reactive ion etching.
► For 5 min etching time, square-shape and for 8 min etching time flower-shape ring formed.
► Redeposition of etching products is the main mechanism for creation of the nano-rings.
► The etching time is an important factor in fabrication of nano-rings.
► These fluorocarbon nanostructures pattern can be used as a nano-template.