FABRICATION OF STEP-EDGE STRUCTURES ON R-PLANE SAPPHIRE USING A SELECTIVE WET ETCH PROCESS

With the aim of using some well established techniques in the planar t ecnology of silicon for the fabrication of high-T-c grain boundary bas ed junctions, we investigated a process suitable for the realisation o f step-edge on R-plane sapphire substrates. Step-edges were prepared b y exposing a photolitographically defined area to Ar+ ion implantation . The damaged area was selectively removed by different wet etching pr ocesses. With this technique we were able to produce 150 nm height ste ps, 30 degrees-45 degrees slope. The surface roughness on both sides o f the step was the same as that of the virgin sustrate. The influences of dose, angle of implant, etch rate and related main feature of the process are discussed.