Growth modes and characterization of thin RTP silicon oxides

For thin thermally grown oxides it is necessary to consider not only the transport of oxygen from the gas phase to the Si/SiO₂ interface but also the transport of silicon to the surface. The latter causes a SiO₂ growth at the SiO₂/gas interface and/or a desorption of the oxide as is known for instance from ultra high vacuum processing such as molecular beam epitaxy. Using well defined argon/oxygen mixtures in a RTP system the process can be switched between growth and cleaning (etching). Depending on process conditions the quality of thin oxides varies significantly with respect to interface quality and tunneling currents. The presented model explains this behaviour based on excess oxygen or silicon in the grown film. The optimum quality can be achieved if growth conditions near the equilibrium of the two processes are chosen.