A medium energy ion scattering analysis of the Si-SiO ₂ interface formed by ion beam oxidation of silicon

The Si-SiO ₂ interface formed by 3 keV O ⁺ ₂ ion bombardment on silicon at room temperature and 600°C was studied by in situ medium energy ion scattering spectroscopy (MEIS). The amorphization process at the initial stage of the oxygen ion bombardment and the subsequent formation of the suboxide layer and the disordered silicon layer at the Si-SiO ₂ interface were studied as a function of the ion dose from 2.5 × 10 ¹⁵ atoms/cm ² to 5 × 10 ¹⁷ atoms/cm ² at room temperature and 600°C. After reaching the steady state, below a ∼6 nm SiO ₂ layer, a ∼2 nm suboxide layer and a ∼3 nm disordered Si layer were observed at the Si-SiO ₂ interface. The annealing effect at 600°C decreased the number of disordered silicon atoms and the suboxide silicon atoms, which make the Si-SiO ₂ interface more abrupt, was more clearly observed at the initial stage of the bombardment.