Thermodynamic analysis of moisture absorption phenomena in high-permittivity oxides as gate dielectrics of advanced complementary-metal-oxide-semiconductor devices

摘要

The moisture absorption phenomena in high-permittivity (k) oxides were analyzed from the view point of the thermodynamic process. The Gibbs free energy change (△G) in the moisture absorption reactions were calculated with the thermodynamic data of oxides, water (H_2O), and hydroxides. It was found from the calculation results that the moisture absorption is a common phenomenon in high-k oxides, especially in rare earth oxides. The results also show that lanthanum oxide (La_2O_3) has the largest moisture-absorption-reaction speed among main candidates for high-k gate oxides. Doping a second oxide could be a direct and effective method to enhance the moisture resistance of La_2O_3 films.