Excimer laser direct etching of GaAs

Abstract

The direct etching of GaAs substrates by excimer laser light has been studied at wavelengths of 193 nm (ArF). 248 nm (KrF) and 351 nm (XeF). For absorbed laser fluences greater than the direct etching fluence thresholds of 23 mJ cm-2 for ArF, 33 mJ cm-2 for KrF and 80 mJ cm-2 for XeF, the authors observe direct etching in air to depths of order one nanometre per pulse. For low-fluence exposures in either vacuum (10-2 Torr) or N2 (1 atm) environments the etch depth per pulse is less than a quarter of that observed when exposure takes place in air. For higher fluence exposures ( approximately 250 mJ cm-2) the etched regions show signs of melting. Using a line-narrowed KrF excimer laser and holographic interference techniques gratings of period 1.5 mu m were directly etched in GaAs substrates.