Permeation barrier properties of an Al2O3/ZrO2 multilayer deposited by remote plasma atomic layer deposition

We report the permeation barrier properties of Al2O3/ZrO2 multi-layers deposited by remote plasma atomic layer deposition. Electrical Ca degradation tests were performed to derive the water vapor transmission rate (WVTR) of Al2O3, ZrO2 and Al2O3/ZrO2 multi-layers at 50 °C and 50% relative humidity (RH). Al2O3/ZrO2 multi-layers exhibit better barrier properties than Al2O3 and ZrO2 layers, and when more individual layers were deposited in the same total thickness, the WVTR value was reduced further, indicating a better barrier property. The WVTR of the Al2O3 and ZrO2 layers were 9.5 × 10−3 and 1.6 × 10−2 g/m2 day, respectively, but when deposited alternatively with 1 cycle of each layer, the WVTR decreased to 9.9 × 10−4 g/m2 day. X-ray diffraction results indicated that ZrO2 has a monoclinic structure but Al2O3 and Al2O3/ZrO2 multi-layers show an amorphous structure. Cross sectional Al2O3/ZrO2 multi-layer structures and the formation of a ZrAlxOy phase are observed by transmission electron microscopy (TEM). X-ray photoelectron spectrometry (XPS) results indicate that Al2O3 and ZrO2 contain 33.7% and 37.8%, respectively, Al–OH and Zr–OH bonding. However, the ZrAlxOy phase contained 30.5% Al–OH and Zr–OH bonding. The results of transmittance measurement indicate that overall, Al2O3, ZrO2 and Al2O3/ZrO2 multi-layers show high transmittance greater than 80% in the visible region.