A simple technique using hybrid organic-inorganic sol-gel films for compound semiconductor processing is proposed and demonstrated. The dual organic and inorganic nature of the hybrid sol-gel films allows high quality photopatternability and robust masking for the dry-etching process. The sol-gel channels on GaAs and InP are fabricated and high-aspect-ratio dry etching of semiconductors is shown. In addition, the potential of the hybrid sol-gel as a planarizing layer on deep-etched InP with overcut and undercut profiles is demonstrated.