Stress distribution in highly porous SiO2 films: results of the molecular dynamics simulation

Abstract

The stress distribution over the thickness of silicon dioxide thin films is studied using simulated thin film cluster. The atomistic cluster representing the film is deposited on a glassy substrate using the full-atomistic molecular dynamic simulation. The deposition angle is equal to 80°, which leads to the growth of a highly porous anisotropic film with low refractive index. The method for calculating the stress distribution is based on the integral relationship between the thickness-averaged stress and the stress distribution. In the present work, we focus on the application of this relationship to the atomistic modeling of stresses at the initial stage of thin film growth. It is found that in the transition layer between the substrate and the film the stress distribution function corresponds to the compressive stress. With the increase in film thickness, the stress distribution function changes sign and becomes tensile. It is shown that these results correspond to experimental data.