Material system using HBr gas and a 172 nm excimer lamp

The photochemical etching (PCE) behavior of InGaAs in HBr gas has been characterized by studying the temperature dependence of etch rate, etched surface observation and analysis with SEM, AFM, XPS and AES. At room temperature, the etching is hampered by the formation of arsenic compounds and liquid phase etch products at the surface. At temperatures between 50°C to 100°C, the etch rate increase with temperature linearly. In this region, the surface is smooth and fine. At temperatures above 100°C, the etching rate decreases and surface becomes grainy and rough. XPS and AES analysis suggest that oxide formation at the surface during etching in this temperature range slows down the etch rate. Schottky diodes were fabricated to compare the electrical properties of the diodes after PCE and the commonly used wet etching. The diode fabricated by PCE was superior in terms of less leakage current, smaller n factor and higher barrier height. This improvement in Schottky diode performance was found to be due to superior surface quality after PCE compared to wet etching