Investigation of the defect density in ultra-thin Al 2O 3 films grown using atomic layer deposition

Abstract

The film perfection in terms of pinhole defect densities of ultra-thin Al 2O 3 grown by atomic layer deposition (ALD) has been quantitatively characterized. A significant defect density reduction from ~ 1.2 × 10 5/cm 2 to ~ 90/cm 2 was demonstrated for 2 nm-thick Al 2O 3 by using an ALD tungsten (W) buffer layer on the nickel (Ni) substrate. The reason for the defect reduction was attributed to efficient nucleation of ALD Al 2O 3 on ALD W. The effect of the buffer layer becomes less essential as the Al 2O 3 thickness increases, where the substrate surface physical conditions such as particle contamination become the main cause for defects.