A kinetic Monte Carlo study of the early stage of silicon oxidation is presented. The model assembles the most recently published dedicated surface mechanisms: oxygen incorporations, migrations, charge transfer effects. Simulations of the thermal oxidation at typical manufacturing temperature and pressure conditions are discussed. As revealed recently through Density Functional Theory investigations, we observe hexagonal patterns that can be here extended over the surface giving rise to a new model system of the Si/SiO2 interface as well as new associated specific defects. We show that our simulator is able to reproduce correctly the oxidation states of the silicon atoms which are specific of the Si/SiO2 interface.