Instantaneous cleaning of silicon substrates by mesoplasma for high-rate and low-temperature epitaxy

Homoepitaxial films having properties identical to films deposited on the conventional wet-cleaned substrates have been achieved even in the absence of any substrate pre-treatment through the mesoplasma CVD. X-ray photoelectron spectroscopy reveals that the native oxide layer is effectively removed by exposure of the bare silicon substrates to the Ar–H2 plasma at exposure times as short as 2 s and temperatures less than 100 °C. Although an exposure to the Ar–H2 plasma is accompanied by an anisotropic island formation resulting in an increase in rms roughness (~ 5 nm) of the surface, addition of as little as 2 sccm SiH4 into the plasma reduces the roughness greatly. The absence of Si–Hx peaks in the FTIR spectrum and uniform concentration distribution of H and O atoms across the growth interface observed by SIMS analysis indicate that minimal damage was induced in the silicon film by the hydrogen while attaining high yield of surface cleaning. These suggest that surface interaction with Ar–H2 plasma at the mesoplasma condition supportively facilitate lateral growth at low temperature in the way of instantaneous surface cleaning and anisotropic Si etching structure favorable for incorporation of the atoms comprising the Si nanoclusters as growth precursors.