Patterned, photon-driven cryoetching of GaAs and AlGaAs

Abstract

We present a high-resolution, damage-free etching technique for GaAs and related compound semiconductors which utilizes surface-specific photochemistry at 193 nm to excite a physisorbed layer of Cl2 on a cryogenically cooled (∼140 K) sample. Etch rates as high as 0.25 Å/pulse (corresponding to 0.09 μm/min) have been achieved. Etching is anisotropic, and etched features of 0.2–0.3 μm linewidth have been routinely obtained. The etch rate has been characterized as a function of several ‘‘system’’ parameters including Cl2-partial pressure, substrate-temperature, laser repetition rate and fluence, and the addition of rare gases. A phenomenological model of this cryoetching has been developed which agrees well with the experimental data. The etch damage and contamination have been studied with Auger electron spectroscopy, photoluminescence, and Schottky-barrier measurements. All results indicate that there is minimal if any damage induced by the cryoetching process.