Generally Applicable Self-Masked Dry Etching Technique for Nanotip Array Fabrication

Well-aligned nanotip arrays were fabricated by electron cyclotron resonance (ECR) plasma process using gas mixtures of silane, methane, argon, and hydrogen. The resultant tips have nanoscale apexes (∼1 nm) with high aspect ratios (∼50), which were achieved by simultaneous SiC nanomask formation and dry etching during ECR plasma process. This technique was applied to a variety of substrates such as silicon, polycrystalline silicon, gallium nitride, gallium phosphide, sapphire, and aluminum, indicating its general applicability. High-resolution transmission electron microscopy and Auger depth profile analyses revealed that the SiC cap, with Si:C ratio of 1:1, exhibited 3C−SiC and 2H−SiC structure on Si and GaP, respectively, with heteroepitaxial relationship. This one-step self-masked dry etching technique enables the fabrication of uniform nanotip arrays on various substrates over large area at low process temperatures, thereby demonstrating a high potential for practical industrial application.