A study on the behavior of water absorption of SiOF thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition method

Fluorinated silicon oxide (SiOF) films were deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition (ECRPECVD). The behavior of residual stress was studied with water absorption. SiOF film showed compressive stress after deposition. The compressive stress increased after the exposure to room air. Fourier transformed infrared (FTIR) spectroscopy analysis was carried after the water absorption. However, tile change of chemical bonding structure was not observed during the water absorption in this study. After the exposure to room air, the films were kept in dry air. The residual stress returns to the initial value after I week. Considering the results of the residual stress and FTIR analysis, it is supposed that the water absorption in this study occurs entirely by physical adsorption of H2O molecules to Si-F bonds on the surface.