Physical and electrical degradation of ZrO₂ thin films with aluminum electrodes

Zirconium oxide thin films were deposited on p-type (100) silicon wafers by reactive d.c. magnetron sputtering. The as-deposited ZrO₂ films at the power of 300 W and at room temperature were amorphous and the ZrO ₂ films became polycrystalline with both the monoclinic and tetragonal phases after post-annealing at 450°C in N₂ ambient. The ZrO₂ films with Al electrode had the interfacial amorphous Al-O-containing layer, which was formed by their interaction, but the films with inactive electrodes such as Pt had no additional interfacial layer. The value of the capacitance equivalent thickness (CET) for ZrO₂ film with Al electrode was increased to about 12.4 Å compared with the film with Pt electrode due to the additional interfacial layer between Al and ZrO₂ film. The difference of flat band voltage (ΔV _FB) between the films with two different electrodes was about 1.2 V because of their work function difference.