Identification of annealing temperature for high--based gate oxides using differential scanning calorimetry
Abstract
This article identifies the process of crystallization of thin high- dielectric films and an optimal range of annealing temperature in the field of high- dielectric-based metal-oxide-semiconductor (MOS) technology for its improved electrical performances. Differential Scanning Calorimetry (DSC) technique is employed to understand the thermal behaviour of thin high- dielectric films of HfO2, deposited by rf sputtering, on Si. The exothermic trends of the DSC signal and Grazing Incidence X-ray diffraction (GIXRD) data indicate an amorphous to crystalline transition in the high- film at higher temperature. The enthalpy-temperature variation shows a glass temperature (Tg) at 590 oC beyond which an amorphous to m-HfO2 crystalline transition takes place. Further, the Hf-Silicate formation, observed in DSC measurement and corroborated by Fourier transformed Infrared Spectroscopy (FT-IR) studies, indicates that the process of formation of Hf-Silicate begins at 717 oC. High-frequency (HF) capacitance-voltage (C-V) and current density - voltage (J-V) characteristics establish that the crystallization of the film is not the root cause of degradation of the electrical properties of the high--based MOS devices, rather the device degrades due to formation of interfacial Hf-Silicate.