Susceptibility of SiO₂, ZrO₂, and HfO₂ dielectrics to moisture contamination

Moisture contamination of HfO₂ and ZrO₂ ultrathin dielectric films, deposited by atomic layer chemical vapor deposition (ALCVD™), is investigated and compared to that of native SiO₂. Results show that HfO₂ and ZrO₂ surfaces adsorb higher amounts of moisture and bind moisture more strongly than SiO₂ surfaces. A multilayer model is developed to represent the dynamics of moisture interaction with these three oxides. Using this model, the fundamental kinetic parameters are determined. The adsorption rate constants are of the same order of magnitude for all three surfaces. However, the desorption rate constants for ZrO₂ and HfO₂ are almost three orders of magnitude lower than that for SiO₂. Activation energies for desorption of water molecules from the first two layers are 33, 27, and 19 kJ/mol, for ZrO ₂, HfO₂, and SiO₂, respectively. Results obtained in this study suggest that the HfO₂ and ZrO₂, as the new dielectric materials, are more prone to moisture contamination than SiO₂.