Abstract
Inelastic electron tunneling spectroscopy (IETS) has been extensively applied to characterize the microstructure, trap-related states, and interfacial properties in silicon MOS system due to its unique ability to detect the interaction of tunneling electrons with energy-loss modes in the tunnel barrier. In this work, we reported the study of IETS in silicon metal-oxide-semiconductor (MOS) device with HfO2, Y2O3, YDH (yttrium-doped HfO2), and stacked HfO2/Y2O3 as gate dielectric. A systematical comparison between high-κ dielectrics thin films deposited by MBE and ALD in terms of microstructure and interfacial properties was presented in this study. The trap-related state induced by electrical stress in high-κ dielectrics thin film was also investigated by IETS spectra. The vibrational modes of HfO2 and Y2O3 from IETS measurement were identified by referring to the results from Raman, Infrared spectroscopy, and IETS by other authors. IETS technique was also applied to study the structural phase transformation in yttrium-doped HfO2 thin film. In addition to vibrational modes and chemical bonding, the location and energy level of traps contained in stacked HfO2/Y2O3 structure can be estimated by analyzing the trap-related feature in IETS spectra through a simple modeling.