Hardness, elastic modulus, and wear resistance of hafnium oxide-based films grown by atomic layer deposition

The investigation of mechanical properties of atomic layer deposition HfO₂ films is important for implementing these layers in microdevices. The mechanical properties of films change as a function of composition and structure, which accordingly vary with deposition temperature and post-annealing. This work describes elastic modulus, hardness, and wear resistance of as-grown and annealed HfO₂. From nanoindentation measurements, the elastic modulus and hardness remained relatively stable in the range of 163-165 GPa and 8.3-9.7 GPa as a function of deposition temperature. The annealing of HfO₂ caused significant increase in hardness up to 14.4 GPa due to film crystallization and densification. The structural change also caused increase in the elastic modulus up to 197 GPa. Wear resistance did not change as a function of deposition temperature, but improved upon annealing.