Study of Oxides Formed in HfO2/Si Structure for High-k Dielectric Applications

Abstract

Transmission electron microscopy (TEM) techniques were used for characterization of annealing (400, 600 and 800 °C) influence on the structural properties of the HfO2 film (45 nm thick) deposited on Si substrate. Such structures are considered as high-k dielectric materials for application in novel semiconductor devices. The studies showed that independently of the annealing temperature a very thin and flat amorphous layer is formed between HfO2 layer and Si substrate. This result was also found in the non-annealed sample. EDXS examination confirmed that the stoichiometry for the hafnium oxide layer in each sample corresponds to 1:2 for Hf:O (i.e. to HfO2). TEM images revealed differences in the microstructure of HfO2 layers in annealed samples, however the layers have similar thickness and interface roughness in all studied samples.