Impact of ozone concentration on atomic layer deposited HfO2 on GaAs

Abstract

Effect of ozone (O-3) concentration (90, 300 g/Nm(3)) on atomic layer deposition of HfO2 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 (HfO2) layer experienced shrinkage of similar to 12% due to densification. However HfO2 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 microstructural change is discussed. (C) 2011 Elsevier B.V. All rights reserved.