Thin films of Al 2O 3, HfO 2, and an Al 2O 3/HfO 2 bilayer were investigated as potential replacements for the SiO 2 gate dielectric. The Al 2O 3 film showed an amorphous structure without an interfacial layer while the HfO 2 film showed a randomly oriented polycrystalline structure with a Hf-silicate interlayer, We noted that the two gate dielectrics Al 2O 3 and HfO 2 had characteristics complementary to each other and that it was possible to achieve a high-k gate oxide with a low leakage current and a large band gap by using an Al 2O 3/HfO 2 bilayer. The leakage currents of the Al 2O 3) HfO 2, and Al 2O 3/HfO 2 films were about 4.2 × 10 -8, 8.2 × 10 -4, and 2.4 × 10 -6 A/cm 2 at a gate bias voltage of |V G - V FB| = 2 V. The corresponding calculated equivalent oxide thicknesses (EOT) were about 2.3, 1.8, and 1.3 nm, respectively. The Al 2O 3/HfO 2 bilayer showed generally improved gate oxide characteristics compared to those of the individual Al 2O 3 and HfO 2 films.
|Number of pages||6|
|Journal||Journal of the Korean Physical Society|
|State||Published - 2005 Apr 1|
- Al O /HfO
- Gate oxide
- Leakage current