Growth of lanthanum oxide films for application as a gate dielectric in CMOS technology

Abstract

We have investigated properties of insulating lanthanum oxide (La 2O 3) films in connection with the replacement of silicon oxide (SiO 2) gate dielectrics in new generation of CMOS devices. The La 2O 3 layers were grown using metal organic chemical vapour deposition (MOCVD) at 500 °C. X-ray diffraction analysis revealed polycrystalline character of the films grown above 500 °C. The X-ray photoemission spectroscopy detected lanthanum carbonate as a principal impurity in the films and lanthanum silicate at the interface with silicon. Density of oxide charge, interface trap density, leakage currents and dielectric constant ( κ ) were extracted from the C - V and I - V measurements. Electrical properties, in particular dielectric constant of the MOCVD grown La 2O 3 are discussed with regard to the film preparation conditions. The as grown film had κ ∼ 11 . Electrical measurements indicate possible presence of oxygen vacancies in oxide layer. The O 2-annealed La 2O 3 film had κ ∼ 17 .