Monitoring ion etching of GaAs/AlGaAs heterostructures by real time spectroscopic ellipsometry: Determination of layer thicknesses, compositions, and surface temperature

Abstract

A real time spectroscopic ellipsometry (RTSE) study of the GaAs/AlGaAs/GaAs heterostructure, performed during Ar ion beam etching, provides the instantaneous GaAs and AlGaAs layer thicknesses and etch rates, the Al composition for the alloy layer, the evolution of the thickness and composition of the surface damage layer, and the near-surface temperature. In addition, combined effects of ion-induced atomic intermixing and etching inhomogeneity can be assessed as the interfaces are crossed. These results demonstrate the extensive capabilities of the RTSE technique for monitoring semiconductor structures during processing.