MODELLIZATION OF THE SILICON RAPID THERMAL-OXIDATION IN THE INITIAL-STAGES ACCORDING TO THE SILICON FRAGMENTS MODEL

A recent study - using Rapid Thermal Processes (RTP) under a controlled atmosphere, isotopic tracing experiments and Nuclear Reaction Analysis (NRA) - has shown that the oxidation rate is initially controlled by the presence of silicon fragments in the volume of the silicon oxide freshly formed [1]. The existence of these inclusions of crystalline silicon leads to an increase of the reacting sites towards the oxidizing species (O2 or O) and then could be a reasonable explanation to the rapid initial growth regime not predicted by the Deal and Grove theory [2]. The modellization of the parallel oxidation at the interface Si/SiO2 and of the silicon fragments - approximated to be roughly spherical - shows that the incorporation of the oxygen in the film follows an order 3 polynomial time treatment dependence prior to the linear - parabolic regime of the Deal and Grove theory. With this modellization, we can estimate the maximum mean radius of the fragments and their number in a unit volume for a given temperature and gas pressure condition. From oxide growth kinetics measurements - obtained in the controlled atmosphere rapid thermal set-up of the GPS -, we found that the mean radius of the silicon fragments increases with the temperature and gas pressure whereas their concentration decreases.