Interfaces analysis of the HfO2/SiO2/Si structure

The physical and chemical properties of the HfO2/SiO2/Si stack have been analyzed using cross-section HR TEM, XPS, IR-spectroscopy and ellipsometry. HfO2 films were deposited by the MO CVD method using as precursors the tetrakis 2,2,6,6 tetramethyl-3,5 heptanedionate hafnium—Hf(dpm)4 and dicyclopentadienil-hafnium-bis-diethylamide—Сp2Hf(N(C2H5)2)2.The amorphous interface layer (IL) between HfO2 and silicon native oxide has been observed by the HRTEM method. The interface layer comprises hafnium silicate with a smooth varying of chemical composition through the IL thickness. The interface layer formation occurs both during HfO2 synthesis, and at the annealing of the HfO2/SiO2/Si stack. It was concluded from the XPS, and the IR-spectroscopy that the hafnium silicate formation occurs via a solid-state reaction at the HfO2/SiO2 interface, and its chemical structure depends on the thickness of the SiO2 underlayer.