Optimization of annealing temperature for high-κ-based gate oxides using differential scanning calorimetry

This study investigates the crystallization process for thin high-kappa dielectric films and optimal annealing temperature range in the field of high-kappa dielectric-based metal-oxide-semiconductor (MOS) technology. A differential scanning calorimetry (DSC) technique is employed to understand the thermal behavior of thin high-kappa dielectric HfO2 films deposited on Si by radio frequency sputtering. The exothermic trends of the DSC signal and grazing incidence x-ray diffraction data indicate an amorphous-to-crystalline transition in the high-kappa films at higher temperatures. The enthalpy-temperature variation indicates a glass temperature (T-g) at similar to 590 degrees C, beyond which an amorphous to m-HfO2 crystalline transition takes place. Further, the Hf-silicate formation, observed in DSC measurements and corroborated by Fourier transformed infrared spectroscopy studies, indicates that the process of Hf-silicate formation begins at similar to 717 degrees C. High-frequency capacitance-voltage (C-V) and current density-voltage (J-V) characteristics establish that film crystallization is not the root cause of electrical degradation in the high-kappa-based MOS devices. Rather, the devices degrade due to formation of interfacial Hf-silicate. (C) 2015 American Vacuum Society.