Room temperature plasma oxidation (RTPO): a new approach to obtain ultrathin layers of SiO2 and high K dielectrics

This paper presents basic characteristics of the room temperature plasma oxidation (RTPO) process for preparation of less than 2 nn thick layers of SiO₂ and high k layers of TiO₂. The oxidation rate follows a power law with a proportionality constant depending on pressure, plasma power, temperature and reagent gas. The exponent depends only on the reactive gas. Surface roughness similar to thermal oxide films, surface state density below 3×10¹¹ cm^-2 and current density in the expected range for each corresponding thickness, were obtained by RTPO in a parallel plate reactor, at 180 mW/cm² and pressure range between 0.07 and 0.5 torn using O₂ as reactive gas. MOS capacitors with TiO₂ and stacked layers of TiO₂ over SiO₂ with equivalent thickness down to 2 nm were obtained and characterized.