Comparison of Nanomechanical Behavior of the Amorphous and Crystalline Phases of ALD HfO2

Abstract

HfO2 films were deposited using atomic layer deposition (ALD) at temperatures ranging from 100oC to 250oC. We report detailed nanoindentation measurements on the pure amorphous, mixed-phase and polycrystalline phase of HfO2. We use nanoindentation techniques for determining the important mechanical properties such as hardness and effective modulus. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM) to determine the structural properties of the various phases of these ALD HfO2 films. We measured the effective modulus to be 370 GPa for amorphous low temperature ALD HfO2 and 240 GPa after crystallization with rapid thermal annealing (RTA). Similarly, the hardness measurements revealed a value of 18 GPa for amorphous HfO2 and a lower value of 15 GPa following the transition temperature from amorphous to polycrystalline HfO2.