Kinetics of Structural and Phase Transformations in Thin SiO[sub x] Films in the Course of a Rapid Thermal Annealing

Abstract

Infrared spectroscopy and analysis of photoluminescence spectra have been used to study variations in the composition of the oxide phase in a SiOx film and the precipitation of the Si phase in the course of a rapid thermal annealing for 1–40 s at temperatures of 500–1000°C. Kinetics of phase segregation has been observed for the first time at temperatures of 600–700°C: an increase in the amount of precipitated silicon as the annealing duration increases followed by an eventual leveling off. The phase separation is brought to completion in a time as short as 1 s at temperatures higher than 900°C. The diffusion coefficient is estimated in the context of a model of the diffusion-controlled formation of Si nanoparticles. The obtained values of the diffusion coefficient exceed, by five to ten orders of magnitude, those of the silicon diffusion coefficients in SiO2 and Si and are comparable to the diffusion coefficients of the oxygen contained in these structures. It is assumed that oxygen mobility forms the basis for the mechanism of structural and phase transformations in the SiOx layers and for the formation of Si nanoparticles in the course of annealing.