Investigation of the initial stage of growth of Hf O2 films on Si(100) grown by atomic-layer deposition using in situ medium energy ion scattering

The initial stage of growth of Hf O2 films on p -type Si(100) grown by atomic-layer deposition (ALD) was investigated using in situ medium energy ion scattering (MEIS). The interaction between adsorbed Hf Cl4 molecules and the oxidized Si surface was examined as a function of growth cycles. The results clearly show that island-like growth occurs during the initial Hf O2 growth and the islands are then merged into a continuous atomic layer with an increase in ALD cycles. The morphology of thicker Hf O2 films remained essentially unchanged with growth cycles. Interfacial reactions between Hf and Si during the initial growth stage were minimal. As a result, the effect of insufficient nucleation density is a dominant factor in the initial stage of growth of hafnium oxide on the oxidized Si substrate, resulting in nonlinear growth behavior.