Excimer laser induced etching of InP

Abstract

We report 193 nm ArF excimer laser induced etching of InP in Cl2. Etching occurs by desorption of an In-chloride layer, as evidenced by an etch rate which increases linearly with laser repetition rate and is nearly pressure independent between 2 and 50 mTorr Cl2. At substrate temperatures near 150 °C, the etch rate increases above a ‘‘threshold’’ fluence of 0.02 J/cm2 and saturates at 2.3 Å/pulse by ∼0.12 J/cm2, corresponding to nearly one monolayer of InP removed per laser pulse. On samples masked with SiO2 stripes, etched surfaces were smooth, with little or no undercutting of the mask edge. Sidewalls on etched features slope out at a ∼45° angle. Etching mechanisms and implications for in situ processing are discussed.