Evaluation of tetrakis(diethylamino)hafnium Precursor in the Formation of Hafnium Oxide Films Using Atomic Layer Deposition

Abstract

Due to their compatibility with silicon interface and high dielectric constant, films containing hafnium oxide are becoming strong candidates in replacing silicon oxynitride as the gate dielectric layer in CMOS devices. To achieve ultimate conformality and thickness control, atomic layer deposition is receiving much more attention in recent years for nanometer size film applications. For hafnium oxide deposition by ALD, metal chlorides have traditionally been used as precursors with moisture being the co-reactant; however for gate oxide applications, metal chlorides are not considered suitable due to the corrosive nature of these compounds and the risks of film contamination. Hence, researchers are exploring alternate organometallic precursors in a CVD process with oxygen being the co-reactant. In this work, tetrakis (diethylamino) hafnium precursor is used in an ALD process with moisture co-reactant to deposit hafnium oxide films onto H-terminated Si substrate in a temperature regime of 200 to 350 C. Film composition is determined by x-ray analysis and is found to be stoichiometric without residue from ligand decomposition. Film thickness and uniformity is measured as a function of substrate temperature and reagent pulsing characteristics. These results will be presented and compared with that obtained with the more conventional hafnium chloride precursor.