Thermal stability of Al- and Zr-doped HfO 2 thin films grown by direct current magnetron sputtering

Ultrathin HfO 2 dielectric films doped with Al and Zr were grown on p -type Si(100) substrates by dc magnetron sputtering, and their microstructural and electrical properties were examined. Compositions and chemical states of the dielectric films were analyzed by Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy. The HfO 2 films doped with Zr were crystallized even from the as-deposited state, however, the crystallization temperature of the HfO 2 film doped with 16% Al 2 O 3 was delayed up to 900 °C. As the annealing temperature increases, high-resolution transmission electron microscopy analyses of all doped HfO 2 films showed an increase of the interfacial layer thickness due to the diffusion of small partial pressure of oxygen in annealing ambient. Our results also showed that the addition of Al 2 O 3 to 14% is not useful for blocking the oxygen diffusion through the ( HfO 2 ) 0.86 ( Al 2 O 3 ) 0.14 film. From the capacitance-voltage measurements, the dielectric constants of the Al- and Zr-doped HfO 2 thin films were measured to be 18.7 and 7.6, respectively.