Abstract
High κ HfO2 (κ =20) is currently employed as an alternative gate dielectric replacing SiO2 in CMOS scaling. There are three known crystal structures of HfO2, monoclinic, cubic, and tetragonal with varying dielectric constants [1]. Recently we showed HfO2 films epitaxially grown on GaAs(100) formed the stable monoclinic phase (α=γ = 90° and β∼ 99°) with the a and b axes aligned with the in-plane GaAs{\\\\\\\\\\\\\\\\{}100{\\\\\\\\\\\\\\\\}}axes resulting in four equivalent domains. This work demonstrates the successful alteration of the crystal structure of HfO2from the lower κ monoclinic phase to the higher κ (κ =30) cubic phase stabilized through epitaxy on GaAs(100) and Si(100) with the aid of Y2O3 doping (∼ 20{\\\\\\\\\\\\\\\\%} based on XPS). X-ray diffraction scans on these films clearly indicated the cubic symmetry. Doping Y2O3 is also to enhance the thermal stability of amorphous HfO2. Y2O3doping was shown to help raise the re-crystallization temperature of HfO2to becompatible with high temperature processing. [1] X. Zhao et al, PRB \\\\\\\\\\\\\\\\textbf{65}, 233106, (2002).