Abstract
Al/ZrO2/p-Si metal-insulator-silicon (MIS) capacitors fabricated to characterize the electrical properties of the ZrO2 dielectric. The leakage current density is -8.78×10-2 A/cm2 when the applied electric field is 1MV/cm and the ZrO2 thickness is 14.7 nm, and the dielectric constant measured from a separate metal-ZrO2-silicon capacitor is 14.4. The electrical conduction mechanisms of ZrO2 thin film as functions of temperature were studied. Both the intercept of the fitted Schottky emission line and the slope of the fitted Fowler-Nordheim tunneling line are functions of barrier height and electron effective mass in ZrO2. An analysis of self-consistent iteration method was used to show that the extracted Al/ZrO2 barrier-height and electron effective mass in the ZrO2 film (equivalent oxide thickness = 3.88 nm) are about 0.987 eV and 0.39 m0.N-channel metal-oxide-semiconductor field effect transistors (MOSFETs) using ZrO2 gate oxide were also fabricated successfully. The C-V, ID-VD and ID–VG characteristics are measured. The degradation mechanisms of effective electron channel mobility and the threshold voltage shift in ZrO2-gated n-MOSFETs have been studied by analyzing experimental data at various temperatures from 300 to 420K. The soft optical phonons are proposed to explain the extra source for severe phonon scattering in ZrO2-gated n-MOSFETs.The interface trapped charge density, the surface recombination velocity, and the minority carrier life time in the field-induced depletion region measured from gated diodes were 1.5x1012 cm-2-eV-1, 244 cm/s, and 2.55x10-6 sec, respectively.Secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD), and electron spectroscopy for chemical analysic (ESCA) were used to examine the material properties of ZrO2.A comparison with MOSFETs using SiO2 gate oxides was made. The ZrO2/Si interface is generally inferior compared with that of the SiO2/Si interface. But the ZrO2/Si interface is comparable to that of the Ta2O5/Si interface. The thermodynamic stability of ZrO2 gate oxide is much better than that of Ta2O5 gate oxide. In the future, MOSFETs with ZrO2 gate oxide will be a promising candidate for sub-0.1 □m MOSFETs.