Plasma Directed Assembly and Organization: Formation of polymeric nanodots and silicon nanopillars

Periodic, well-defined, features in the nano-scale (dots, pillars, pores etc) are essential in several science and technology fields (photonics, hard disk drives, catalysis, biology). Top-down nano-lithographic processes, as well as self-assembly processes (block copolymer, colloidal particles) are used for the fabrication of such features. Here, we demonstrate an assembly-organization method to both create the nanodot pattern on any non-specialty commercial polymer, and then transfer it to the subsequent silicon substrate [1,2]. First we perform a simple, fast, low ion-energy oxygen plasma etching step in a helicon plasma source. This creates polymer nanodots on the polymer film, due to simultaneous co-deposition of etch inhibitors from the reactor walls. Pattern transfer of the polymer nanodots on silicon has been subsequently performed by either SF6/O2 based high-density plasma at cryogenic temperatures, or a gas mixture of SF6, C4F8 and O2 at room temperature, leading to the fabrication of high aspect ratio silicon nanopillars. Possible applications are discussed. [1] E. Gogolides et al., Patent Appl. no.PCT/GR2009/000039, [2] N. Vourdas et al., Nanotechnology 21 (2010) 085302