Open Access Nano Express

Large-scale fabrication of nanopatterned sapphire substrates by annealing of patterned Al thin films by soft UV-nanoimprint lithography

Lin Cui1*, Jie-Cai Han12, Gui-Gen Wang1*, Hua-Yu Zhang1, Rui Sun1 and Ling-Hua Li1

Author Affiliations

1 Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, People's Republic of China

2 Center for Composite Materials, Harbin Institute of Technology, Harbin 150080, People's Republic of China

For all author emails, please log on.

Nanoscale Research Letters 2013, 8:472  doi:10.1186/1556-276X-8-472

Published: 11 November 2013

Abstract

Large-scale nanopatterned sapphire substrates were fabricated by annealing of patterned Al thin films. Patterned Al thin films were obtained by soft UV-nanoimprint lithography and reactive ion etching. The soft mold with 550-nm-wide lines separated by 250-nm space was composed of the toluene-diluted polydimethylsiloxane (PDMS) layer supported by the soft PDMS. Patterned Al thin films were subsequently subjected to dual-stage annealing due to the melting temperature of Al thin films (660°C). The first comprised a low-temperature oxidation anneal at 450°C for 24 h. This was followed by a high-temperature annealing in the range of 1,000°C and 1,200°C for 1 h to induce growth of the underlying sapphire single crystal to consume the oxide layer. The SEM results indicate that the patterns were retained on sapphire substrates after high-temperature annealing at less than 1,200°C. Finally, large-scale nanopatterned sapphire substrates were successfully fabricated by annealing of patterned Al thin films for 24 h at 450°C and 1 h at 1,000°C by soft UV-nanoimprint lithography.

Keywords:
Al; Annealing; Patterned sapphire substrates; UV-nanoimprint lithography; Reactive ion etching