Can we control the thickness of ultrathin silica layers by hyperthermal silicon oxidation at room temperature?

Using reactive molecular dynamics simulations by means of the ReaxFF potential, we studied the growth mechanism of ultrathin silica (SiO ₂) layers during hyperthermal oxidation at room temperature. Oxidation of Si(100){2 × 1} surfaces by both atomic and molecular oxygen was investigated in the energy range 1-5 eV. The oxidation mechanism, which differs from thermal oxidation, is discussed. In the case of oxidation by molecular O ₂, silica is quickly formed and the thickness of the formed layers remains limited compared to oxidation by atomic oxygen. The Si/SiO ₂ interfaces are analyzed in terms of partial charges and angle distributions. The obtained structures of the ultrathin SiO ₂ films are amorphous, including some intrinsic defects. This study is important for the fabrication of silica-based devices in the micro- and nanoelectronics industry, and more specifically for the fabrication of metal oxide semiconductor devices.