Efficient 193 nm-laser assisted cryogenic etching of GaN with Cl/sub 2//CH/sub 4/

Summary form only given. Cryo-etching provides a unique etching mechanism which combines cryogenic cooling of the substrate with laser-assisted excitation to enhance the anisotropy of the etching without causing damage to the etched surface. For etching GaN, by lowering the substrate temperature in a chlorine/methane ambient, a layer of Cl/sub 2//CH/sub 4/ is physisorbed on the GaN surface. Excimer laser radiation at 193 nm dissociates the condensed phase chlorine and methane molecules to form reactive Cl, H, CH/sub x/ and HCl radicals, which are confined to the illuminated zone and react with the GaN surface. The etching products (GaCl/sub x/ and NH/sub x/), are then desorbed with the assistance of laser irradiation, resulting in etching. The confinement of the reactive species and etching product desorption to the laser illuminated zone lead to laser defined etching pattern. Also, the etching results from low energy reactive species minimize substrate damage which is often produced due to momentum transfer of high energy reactive ion species in ion beam techniques.