Characterization and Control of Surface Morphology and Defect Density for MBE GaAs Surfaces in the Production MBE Environment

Abstract

ABSTRACTIn the production MBE environment it is important to maintain low densities of oval defects and particle induced defects in epitaxial films that are used for the fabrication ofGaAs ICs. Most often, the grown layers are characterized on a sample basis by use of an optical microscope. The disadvantages of this technique are the time and labor involved.The data obtained is incomplete, dependent on training, and subjective. A preferred method would be to develop an inspection method that characterizes the surface morphology ofall MBE grown GaAs wafers and the resulting defect density. The use of a laser wafer surface scanning system has allowed us to reproducably inspect 100% of wafers. Rapid diagnosis of epitaxial problems has resulted in an improved understanding of how to routinely produce high quality epitaxial films for GaAs IC production. This work will highlight the production benefits derived from employing 100% inspection of MBE grown GaAs wafers and provide 2D maps. The relationship between gallium source operation and defect sizes will be discussed.