Room temperature deposition of silicon oxynitride films with low stress using sputtering-type electron cyclotron resonance plasmas

Silicon oxynitride (SiO_xN_y) films with low stress were deposited successfully at room temperature using sputtering-type electron cyclotron resonance (ECR) plasmas. Films were deposited for a wide range of flow rate ratio of O₂ to N₂ at a constant Ar flow rate. Film properties were verified by characterizations of refractive index (ellipsometry), structural properties (Fourier transform infrared and Auger electron spectroscopy), intrinsic stress, and barrier strength of water penetration (thermal desorption spectroscopy). A near-stoichiometric SiO_xN_y (x = 1.44 and y = 0.41) film with low stress could be formed at the optimum deposition condition, under which the SiO_xN_y film had a refractive index of 1.54. The results of thermal desorption spectroscopy measurements showed that the SiO_xN_y film had a higher barrier against moisture penetration relative to deposited SiO_x and SiN_y films. The SiO_xN_y film was directly deposited on the organic EL device and the applicability was shown clearly. These results indicate that this SiO_xN_y film deposited using a sputtering-type ECR plasma has the potential to be utilized as a passivation layer of organic EL devices, which are required to be formed at low temperature.