Preparation and characterization of SiN water-vapor permeation barrier coated by aerosol-type liquid precursor delivery system equipped on a cyclic chemical vapor deposition system

The preparation and characterization of SiN thin films using an aerosol-type liquid precursor delivery system (LDS) for application as a water-vapor permeation barrier layer in organic electronic devices is described. The proposed LDS consisted of three major parts: 1) an aerosol generator that transformed the liquid precursor to an aerosol molecule using a piezoelectric ultrasonic vibrator, 2) a vaporizer that transformed the injected aerosol molecules to a vapor state, and 3) a vapor storage canister. The instant evaporation fraction and maximum evaporation mass rate were measured to be 98.3% and 2.55 g/min, respectively. The temperature in the vaporizer was stable, showing a 1 °C variation from the set temperature. As the LDS temperature increased, the evaporation mass rate also increased from 0.035 to 2.55 g/min. A 30 nm thick SiN layer was prepared to evaluate the performance of the LDS, which was attached to a cyclic chemical vapor deposition system. The prepared SiN layer had a smooth surface with no defects or pinholes; the root mean square surface roughness of the prepared SiN film was measured to be 0.185 nm, which is adequate to be used as encapsulation layers in organic electronic devices. The water vapor transmission rate through the 30 nm thick SiN layer was calculated to be 1.31 × 10−6 g/m2/day by Ca-degradation test. The results indicated that the produced films meets the requirement for application as an encapsulation layer to protect the organic layer in organic electronic devices from water vapor penetration, especially in organic light-emitting diodes.