Optimization and characterization of III–V surface cleaning

Achieving clean surfaces is a major and challenging requirement for the study of surfaces and surface reactions. Nondestructive cleaning is a crucial step in semiconductor manufacturing, growth of materials, and processing. We use photoemission spectroscopy (PES) to systematically study the core and valence band electronic structure of various chemical treatments of InP(100), GaAs(100), and GaN(0001). These surfaces undergo wet chemical cleaning of H2SO2/H2O2/H2O followed by thermal heating. In order to achieve the necessary surface sensitivity and spectral resolution, synchrotron radiation in the energy range of 60-1000 eV is used for PES. In tuning the sulfuric acid based chemistry, we achieve oxygen free GaAs and InP surfaces, as shown in our valence band and core level PES analysis. Furthermore, core level PES shows oxygen coverage of the GaN surface is reduced to less than 0.1 monolayer (ML). The carbon coverage is also reduced dramatically for the III-V surfaces, <10% ML for InP and GaAs and approximately 1% ML for GaN. The chemical reactions and species at different cleaning stages are determined and cleaning mechanisms are proposed. Our study shows that material similarities do not imply exact correlation to the chemical cleaning properties among III-V materials. (C) 2003 American Vacuum Society.