Microstructural evaluation of reactive ion etched - regrown GaAs

Abstract

Reactive ion etching (RIE) is a preferred dry process step for fabrication of submicron III-V semiconductor device structures. This kinetically assisted chemical dry etch process offers several important advantages over other etching methods, namely etch anisotropy, etch rate control, selectively, accuracy, uniformity across the wafer and reproducibility. As a result of these desirable characteristics, a number of semiconductor device designs involve REE in their device fabrication process. Some of the more novel designs involve lateral quantum well arrays, whereby fabrication requires molecular beam epitaxial (MBE) regrowth on RIE semiconductors.A major drawback of RIE is the potential lattice damage introduced by energetic ion bombardment and contamination. This material damage may lead to deterioration of device performance. It is important to identify and understand this RIE induced damage in order to develop and refine the RIE process, i.e. minimize crystal damage and thus optimize device performance. This study identifies and analyzes the damage associated with various RIE parameters used for quantum well fabrication. Microstructural characterization via TEM is used to identify the nature of lattice defects, their distribution, and density. Optical methods, Photoluminescence and Raman spectroscopy are used to evaluate the crystal damage and serve as a reliable comparators for the TEM results.