Effect of High-Temperature Annealing in Oxygen on the Properties of Hafnium Oxide Films Grown by Atomic Layer Deposition

We have studied the effect of pulse annealing on the crystallization of hafnium oxide films grown by atomic layer deposition and constructed a model for the crystallization process. Experimental data and simulation results suggest that the crystallization mechanism is rather complex and depends on temperature. At annealing temperatures in the range 600–700°C, the crystallization process follows a diffusion mechanism: oxygen diffuses into the film and interacts with oxygen vacancies and excess hafnium, resulting in nanocrystal growth. At higher temperatures, the activation energy for the crystallization process increases and exceeds the activation energy for oxygen diffusion. We assume that the crystallization process can involve double ionized oxygen vacancies.