Authors: A. Chen, S.J. Chua and P. Chen
Affilation: Singapore-MIT Alliance, National University of Singapore (NUS), Singapore
Pages: 258 - 261
Keywords: nanodot, electron-beam lithography
We report on the fabrication process of SiO2 templates with periodic sub-100nm air hole patterns using electron beam (e-beam) lithography followed by reactive ion etching (RIE). Two-dimensional periodic air holes with sub-100nm dimensions were defined in 350-nm PMMA resist using a single-pixel exposure scheme by e-beam writing. Both square and hexagonal hole arrays can be achieved by exposing the pixels of one rectangle or the combination of two rectangles. Periodic holes with the diameters from 100nm to 45nm and the minimum period of 150nm were obtained by exposure at various pixel distances and various doses. After e-beam lithography the patterns were transferred into a 100-nm SiO2 layer coated on GaAs or GaN/sapphire substrate by RIE. The etching time was optimized to ensure a reliable pattern transfer, and at the same time to cause the minimum damage to the substrate surface. After the etching the periodic sub-100nm patterns were precisely transferred to the SiO2 template, with a slight increase of the hole size less than 5%. The SiO2 template fabricated is very promising for the growth of periodic III-V semiconductor nanodots.