KINETICS OF SILICON OXIDATION AND STRUCTURE OF OXIDE-FILMS OF THICKNESS LESS THAN 50-ANGSTROM

An investigation was made of the kinetics of low-temperature thermal oxidation of n- and p-type silicon with the (100) orientation. Oxide films of thickness d < 50 angstrom exhibited anomalous (with a negative growth rate) kinetics. Parallel measurements of the parameters of the oxide films by ellipsometric and Auger analysis methods showed that the process of thermal growth was accompanied by destruction of a natural oxide always present on the surface of silicon. The properties of the interface between the thermal oxide and the silicon substrate assumed, from a certain stage of the process, the properties of the Si-SiO2 interface. An investigation of the growth kinetics showed that "perfect" ultrathin oxide films were obtained provided the thermal oxidation was preceded by the removal of the natural oxide. The photoelectric and optical characteristics of structures consisting of polycrystalline p-type silicon, SiO2, and p-type Si carrying an oxide grown subject to this condition demonstrated that the conduction process in the oxide films of thickness d < 35 angstrom was of tunnel nature and the height of the potential barrier for holes at the Si-SiO2 interface was 2.2-3.0 eV.