A three-level masking technique is used to improve the aspect ratio of InP-based photonic crystals. The masking consists of a ZEP/Cr/SiOx stack where the ZEP layer is used to open the Cr which on its turn is a good mask for opening the 500 nm thick SiOx layer. Subsequently InP is etched in an ICP process using Cl2:O2. Very high aspect ratios could be achieved in holes ranging from 130 up to 270 nm in diameter. A maximum aspect ratio of >20 is obtained with the narrowest holes having diameters of 180 and 130 nm.
|Title of host publication||20th International Conference on Indium Phosphide and Related Materials, 2008. IPRM 2008, 25-29 May 2008|
|Place of Publication||Piscataway|
|Publisher||Institute of Electrical and Electronics Engineers|
|Publication status||Published - 2008|