Characterization of the annealing impact on La2O3/HfO2 and HfO2/La2O3 stacks for MOS applications

The impact of various rapid thermal annealing used during the integration on the La2O3/HfO2 and HfO2/La2O3 stacks deposited by Atomic Layer deposition was analyzed. The consequences of lanthanum localization in such stacks on the evolution of the films during the rapid thermal annealing are investigated in term of morphology, crystalline structure, silicate formation and film homogeneity as a function of the depth. It appeared that the La2O3 location has an impact on the temperature of the quadratic phase formation which could be linked to the formation of SiOHfLa silicate and the resistance of the films to dissolution in HF 0.05 wt%.