Influence of the annealing temperature on the IR properties of SiO 2 films grown from SiH 4 + O 2

Abstract

Dispersion analysis was performed on low pressure chemically vapor deposited (LPCVD) SiO 2 films grown from SiH 4 + O 2 at 425 °C. The transmission spectra were analyzed using four Lorentz oscillators within the range 900–1400 cm −1. It was found that the distribution of the Si O Si angles is a superposition of two Gaussians; one corresponding to bridges located in the bulk of the film and one corresponding to bridges located close to the boundaries of the film namely the interfaces of the films and the grain boundaries. The ratio between the bulk like Si O Si bridges over the boundary bridges was found equal to 0.61:1 indicating that films grown from SiH 4 + O 2 contain a higher number of boundary Si O Si bridges relative to those located in the bulk of the film. After annealing for 30 min at temperatures in the range from 550 to 950 °C, films were found to have a lower thickness. The calculated ratio of the two distributions after annealing have shown a clear reduction in the concentration of the boundary bridges as the temperature of annealing increases, in advance of the bridges located in the bulk of the film. For the film annealed at 950 °C for 30 min the ratio was found equal to 4.0:1 which is the same to that of thermally grown films at the same temperature.