A computer controlled chemical bevel etching apparatus: applications to Auger analysis of multi-layered structures

Abstract

Analysis of thin layer structures can be achieved by chemically etching a bevel and subsequently analysing the surface. However non-linear bevels often result due to differing etch rates of the materials leading to incorrect analysis results. We report on a computer controlled stepper motor reactor whereby the specimen is lowered into the etchant at a rate which compensates for the different etch rates of the various layers constituting the sample. The apparatus is used to produce linear bevels of various magnifications on GaAs/AlGaAs heterostructures. The etchant of H 3PO 4/H 2O 2/H 2O is used for bevel preparation capped by a water layer to suppress the meniscus. Application of the technique to Multi Quantum Wells (MQW) and Bragg diffraction layers is shown. The depth resolution of the bevelled samples are analysed by AES and a comparison is made to conventional ion sputtering techniques.