Effect of the chemical oxide layer thickness on the interfacial quality of ALD-grown HfO₂ on silicon

We report the effects of the thickness variation of the chemical oxide interfacial layer (IL) on the interfacial quality of the HfO₂/Si system in this paper. Metal-oxide-semiconductor capacitors using the HfO ₂/IL gate oxide stack were fabricated using the Ni/Ti metal gate. The capacitance-voltage (C-V) and ellipsometry measurements suggest that the chemical oxide interfacial layer of ∼0.45 nm is the minimum requirement for atomic layer deposition (ALD) growth of high quality HfO₂ on silicon and thicker chemical oxide interfacial layers (>0.45 nm) result in better interfaces for HfO₂ MOS structures with EOTs of < 1 nm.