Tantalum oxide films on silicon grown by tantalum evaporation in atomic oxygen

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Tantalum pentoxide (Ta 20 5) thin layers were grown on Si(100) by evaporation of Ta in an atomic oxygen plasma. The physical and electrical properties of 1000 Å-thick as-deposited films were evaluated. Films grown at 650 °C without the presence of the plasma (molecular oxygen) were oxygen-deficient and poorly crystallized, whereas layers grown in the plasma (atomic oxygen) were stoichiometric (within 5%) and crystallized in the β-Ta 20 5 phase. A minimum flux of atomic oxygen during deposition, more than that required for growing films within 5% correct stoichiometry, was crucial for the suppression of the film leakage current. The electrical characterization of amorphous Ta 20 5 films grown at 400 °C resulted in I– V curves exhibiting an ohmic behaviour at low electric fields, <2 MV cm −1 (resistivity 10 14 Ωcm), and a leakage current density less than 10 −8 A cm −2 at 1 MV cm −1. The measured relative dielectric constant of amorphous Ta 2O 5 films was 26.