Electrical characteristics and growth of ZrO2 as a gate dielectric

Abstract

We have studied ZrO2 thin film as an alternative gate dielectric. It was deposited on a Si substrate by RF reactive sputtering system which was optimized to achieve high quality thin film. O2 flow and power were modulated to control the interface quality and growth rate. This ZrO2 thin film was annealed from 600 oC to 900 oC for 30 sec with rapid thermal annealing (RTA) [1]. Pt was deposited as a top electrode for metal-oxide-semiconductor (MOS) capacitor by ultra high vacuum evaporation system and this capacitor was annealed at 450 oC for 30 sec with RTA in H2 + N2 ambient. Capacitance-voltage measurements showed an equivalent oxide thickness of less than 30 A with no significant dispersion of the capacitance for 1MHz frequency. Current-voltage measurements exhibited the low leakage current at -1.0V. Hysteresis shift in these films was measured to be less than 100mV. Interface state density and reliability were measured. We examined cross-sectional transmission electron microscopy and X-ray diffraction to observe reaction and crystallization of zirconium oxide [2]. We also examined the zirconium oxide formation depending on the annealing temperature by in-situ Auger electron spectroscopy system connected with ultrahigh vacuum furnace.