Low-temperature Si in-situ cleaning and homoepitaxy by remote plasma-enhanced chemical vapor deposition

Abstract

The surface structure of the Si(100) substrate after an in situ remote hydrogen plasma clean, and the defect microstructure of epitaxial Si films grown by Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) in the temperature range of 15O°C-305°C are discussed. Auger Electron Spectroscopy (AES) analysis has been employed to examine the capability of this remote hydrogen plasma clean in terms of removing surface contaminants. Reflection High Energy Electron Diffraction (RHEED) and Transmission Electron Microscopy (TEM) have been utilized to investigate the surface structure in terms of crystallinity and defect generation. A remote hydrogen plasma clean which reduces carbon, oxygen and nitrogen contamination levels to below the detectability of AES analysis, while maintaining a defect-free surface, as indicated by TEM, has been developed. However, excessive plasma power causes defect generation on the Si surface, and the size of the defects is a function of substrate temperature during cleaning in the range of room temperature-305°C. Subsequently, epitaxial Si films grown by RPCVD at various temperatures (150°C-305°C) after optimal remote hydrogen plasma clean have been investigated in terms of defect microstructure and impurity content using RHEED, TEM and Secondary Ion Mass Spectroscopy (SIMS). Epitaxial Si films with very low defect density (4O6 cm2 or less) and low oxygen content (-3x1018 cm3) have been achieved by RPCVD.