LASER-ASSISTED ETCHING OF GALLIUM-ARSENIDE IN CHLORINE AT 308 NM

Xenon chloride (308 nm) excimer laser-assisted etching of GaAs (100) in Cl2 was demonstrated and characterized with respect to laser and gas parameters. The etch rate increased linearly with laser fluence from thresholds in the range of 50 to 75 mJ/cm2 to the highest fluence studied, 650 mJ/cm2. For a laser fluence of 370 mJ/cm2, the etch rate varied with Cl2 pressure reaching a maximum at a Cl2 pressure of about 2 Torr. The etch rate decreased monotonically with Ar buffer gas pressure because of redeposition of GaCl3 products into the etched channel. The redeposited GaCl3 affected the etch rate and the etch morphology. The etch rate and morphology also varied with laser repetition rate. The mobility of chlorine on the surface also plays an important role in the etching mechanism.