Rheed Observations of Silicon (100) Surface Reconstruction after Remote Hydrogen Plasma Cleaning

Abstract

ABSTRACTLow temperature silicon epitaxy is critical to novel silicon-based devices requiring hyper-abrupt transitions in doping profiles or heterointerfaces. Epitaxy by Remote Plasma-Enhanced Chemical Vapor Deposition (RPCVD) consists of an in situ remote hydrogen plasma clean of the silicon surface followed by growth of silicon from silane at 220° - 400°C. Reconstruction of the silicon (100) surface from a (1×1) to a (2×1) structure after cleaning at 310°C is observed by RHEED, indicating an atomically clean surface. The removal of carbon and oxygen has been further substantiated by Auger Electron Spectroscopy (AES) and growth on these atomically clean substrates has produced good quality epitaxial films. Using remote hydrogen plasma cleans at lower temperature we report the first observation of third-order silicon surface reconstruction on a Si(100) surface, where two faint fractional order streaks between the sharp integral order streaks are observed. After a short (5 minute), low temperature (300-400 °C) anneal the third order pattern transforms rather quickly to a strong (2×1) reconstruction pattern. The third order pattern can then be restored by following the anneal with a repeat of the lower temperature hydrogen clean. Although the origin of the third order pattern is unclear at this time, we believe it is due to a Si-H complex formation at the silicon surface.