Fabrication of photonic crystals using a spin-coated hydrogen silsesquioxane hard mask

Abstract

We present a method for creating a hard mask for the dry etching of microphotonic structures and devices. We demonstrate that spin-on glass [hydrogen silsesquioxane (HSQ)] has sufficient dry etch resistance to allow the creation of high-quality, deeply etched photonic crystals. Furthermore, HSQ is a more favorable hard mask for the creation of active devices than plasma-enhanced chemical-vapor deposition (PECVD) silica, as less damage is incurred. It is also an economic and convenient replacement for PEVCD in photonic crystal fabrication. We examine this method and show that it can create photonic crystals of equivalent quality to those created using PEVCD masking.