A non-lithographic plasma nanoassembly technology for polymeric nanodot and silicon nanopillar fabrication

Abstract

In this work, we present plasma etching alone as a directed assembly method to both create the nanodot pattern on an etched polymeric (PMMA) film and transfer it to a silicon substrate for the fabrication of silicon nanopillars or cone-like nanostructuring. By using a shield to control sputtering from inside the plasma reactor, the size and shape of the resulting nanodots can be better controlled by varying plasma parameters as the bias power. The effect of the shield on inhibitor deposition on the etched surfaces was investigated by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) measurements. The fabrication of quasi-ordered PMMA nanodots of a diameter of 25 nm and period of 54 nm is demonstrated. Pattern transfer to the silicon substrate using the same plasma reactor was performed in two ways: (a) a mixed fluorine-fluorocarbon-oxygen nanoscale etch plasma process was employed to fabricate silicon nanopillars with a diameter of 25 nm and an aspect ratio of 5.6, which show the same periodicity as the nanodot pattern, and (b) high etch rate cryogenic plasma process was used for pattern transfer. The result is the nanostructuring of Si by high aspect ratio nanotip or nanocone-like features that show excellent antireflective properties.

Key words： plasma; nanoassembly; etching; nanodots; nanopillars; nanofabrication

Acknowledgements

The authors would like to thank Dr. Dimitrios Kontziampasis for his contribution in the AFM measurements and his important work on the development of the plasma directed assembly process. This work was supported by (a) the Research Excellence Project ‘Plasma Directed Assembly and Organization—PlasmaNanoFactory’ which is implemented under the ‘Aristeia I’ Action of the ‘Operational Programme Education and Lifelong Learning’ (Project ID 695) and is co-funded by the European Social Fund (ESF) and National Resources, (b) the Ph.D. fellowship programme of NCSR Demokritos which supported Dr. A. Smyrnakis, and (c) the M. Smoluchowski Krakow Research Consortium (in the framework of the KNOW project).

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