| The objectives of this dissertation research are to apply electron tunneling spectroscopy (ETS) to characterize MOS systems with various high-k gate dielectrics. The dielectrics studied include lanthanum aluminates (LaAlO3), lanthanum scandium oxide (LaScO3), silicon nitride (Si3N4), and hafnium oxide (HfO2).;ETS is capable of revealing the details of chemical bonding and composition information. Utilizing this non-invasive technique, we have identified the vibration modes of amorphous LaAlO3 and LaScO3. Detailed changes in the MOS system resulting from various processes, such as different oxygen pressures during film growth, are revealed by the variations of the tunneling spectra.;Aside from phonon study, ETS of trap-related defects in the gate dielectrics is also reported in the dissertation. The physical location and energy level of a particular trap could be obtained by the voltage polarity dependence of trap features in the spectrum. Using the trap features appearing in both voltage polarities, a method for estimating the density of traps is developed.;In addition to the usual ETS measurements at liquid helium temperature, room temperature measurements of trap-related features have been successfully demonstrated. The Si3N4 thin film investigated was intentionally made with high density of traps for SONOS memory application. We have been able to detect strong ETS signals at liquid nitrogen temperature (77K) and even at room temperature, in contrast to all the previous ETS measurements, which required liquid helium temperature (4.2K) to suppress the thermal broadening effects.;In addition to MOS capacitors made on degenerate Si substrates, ETS spectra on MOSFETs (specially designed for this purpose) with non-degenerate Si channels have been successfully demonstrated. |
