Realization of sub-micron patterns on GaAs using a HSQ etching mask

Hydrogen SilSesQuioxane is now known for its possibilities as negative tone e-beam resist. Good quality patterning can be obtained with low roughness. We report here the transfer of this pattern to a GaAs layer. Our aim is to fabricate nano-photonic structures with the lowest roughness and the most vertical walled profiles by means of GaAs reactive ion etching technique using SiCl4/Ar chemistry. To do so, the etching resistance of the HSQ mask needs to be strenghten and an optimization of the etching step is necessary.