Characterization of chemically assisted ion beam etching of InP

Abstract

Chemically assisted ion beam etching involving an Ar ion beam and a Cl2 ambient was investigated for the etching of high quality facets in InP. Detailed investigations on how the etch anisotropy as well as surface morphology could be optimized under different etch conditions were performed. It was necessary to elevate the substrate temperature above 150 °C to obtain smooth surfaces and above 225 °C to achieve good anisotropy. At these elevated temperatures, very high etch rates in excess of 2 μm/min were obtained. The choice of mask material was found to have a strong influence on the surface quality due to micromasking effects. Hard baked photoresist and Ti masks were used to obtain surfaces free of ‘‘grasslike’’ roughness. Free standing InP wires of various widths were fabricated to estimate the extent of sidewall damage under different etch conditions.