Microstructure and interfacial properties of HfO2–Al2O3 nanolaminate films

Abstract High- k HfO 2 –Al 2 O 3 composite gate dielectric thin films on Si(1 0 0) have been deposited by means of magnetron sputtering. The microstructure and interfacial characteristics of the HfO 2 –Al 2 O 3 films have been investigated by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and spectroscopic ellipsometry (SE). Analysis by XRD has confirmed that an amorphous structure of the HfO 2 –Al 2 O 3 composite films is maintained up to an annealing temperature of 800 °C, which is much higher than that of pure HfO 2 thin films. FTIR characterization indicates that the growth of the interfacial SiO 2 layer is effectively suppressed when the annealing temperature is as low as 800 °C, which is also confirmed by spectroscopy ellipsometry measurement. These results clearly show that the crystallization temperature of the nanolaminate HfO 2 –Al 2 O 3 composite films has been increased compared to pure HfO 2 films. Al 2 O 3 as a passivation barrier for HfO 2 high- k dielectrics prevents oxygen diffusion and the interfacial layer growth effectively.