The protection of MgO film against hydration by using Al 2O 3 capping layer deposited by magnetron sputtering method

Abstract

Al 2O 3 capping layer was deposited by DC reactive sputtering method on MgO protective layer deposited by RF magnetron sputtering method. Thickness of capping layer, Al 2O 3, was varied from 1 to 15 nm. Deposited MgO thin films were hydrated in the ambience of 80% humidity and at room temperature. Surface morphology and rms roughness were observed by SEM and AMF, respectively. Chemical shift of electron binding energy was observed by XPS. And the composition and concentration of hydrogen were observed by RBS and ERD. From these analyses, it was found that Mg atoms diffused into Al 2O 3 layer and reacted with moisture at surface, forming Mg(OH) 2 phase during hydration reaction. At the thin capping layer region (1–5 nm thickness), as thickness of Al 2O 3 increased, total amount of hydration decreased. But, beyond 5 nm thickness, the tendency became reverse. Although Al 2O 3-capped MgO thin film was hydrated to some extent, total amount of hydration is much less than uncapped MgO single layer. Therefore, it can be concluded that Al 2O 3 might be suitable for protecting MgO layer against hydration.