Impact of ozone concentration on atomic layer deposited HfO 2 on GaAs

Abstract

Effect of ozone (O 3) concentration (90, 300 g/Nm 3) on atomic layer deposition of HfO 2 thin films on GaAs wafers using tetrakis (dimethylamino)hafnium (TDMAHf) as Hf precursor was systematically studied including MISCAP performance and related microstructure. High-resolution transmission electron microscopy analyses show that oxidation of the GaAs substrate enhances with O 3 concentration which leads to an increase in interfacial layer (IL) thickness between the high-k dielectric and the substrate. The thin IL was maintained after PDA, while the high-k (HfO 2) layer experienced shrinkage of ∼12% due to densification. However HfO 2 film deposited using O 3 concentration of 300 g/Nm 3 produced relatively thicker IL and thinner high-k layer which both did not show a noticeable change after PDA. This led to C max variations depending on the different O 3 concentration. In the case of O 3 concentration of 90 g/Nm 3, increase of leakage current density by an order was observed and corresponding micro-structural change is discussed.