Controlled fabrication of periodically high-aspect ratio CVD-diamond nanopillar arrays by pure oxygen etching process

Abstract

The CVD (Chemical Vapor Deposition) diamond nanopatterning has been a great challenge due to its superhard property and chemical stability as well as rough surface, especially for fabricating high aspect ratio nanostructures such as nanowires and nanopillars. In this work, we report an approach to fabricate directly periodic high-aspect-ratio nanopillar arrays on the rough CVD-diamond film by e-beam lithography (EBL) and inductively coupled plasma (ICP) etching method. The as-fabricated diamond nanopillar arrays have a controllable aspect ratio and tunable period with good repeatability and uniformity, and the highest aspect ratio of above 10 with 200nm in diameter can be obtained. This result relies on reduced grain size of CVD-diamond and a special treatment process of the mask-patterning and then effective etching control. The fabrication process does not rely on a thick hard mask layer, but uses a just few nanometers of metal to improve mask adhesion. Masking is also improved by adjusting the growth process of diamond film to make its surface as smooth as possible. Such development of CVD-diamond nanopillar fabrication process, especially having ultrahigh aspect ratio, will likely impact the application of CVD-diamond nanostructure based nanoscale sensors, nanoelectronic devices, and NEMS/MEMS manufacturing.