Dielectric properties of ultrathin hafnium oxide reoxidized with rapid thermal annealing (RTA) have been investigated. Capacitance equivalent oxide thickness (CET) of 45 Å hafnium oxide was scaled down to ∼10 Å with a leakage current less than 3×10−2 A/cm2 at −1.5 V (i.e., ∼2 V below VFB). Leakage current increase due to crystallization was not observed even after 900 °C rapid thermal annealing (RTA), but CET did increase after high temperature RTA due to the interfacial layer growth and possible silicate formation in the HfO2 film.

ZrO 2 thin film has been studied as an alternative gate dielectric. It was deposited directly on a Si substrate by reactive sputtering. An equivalent oxide thickness of less than 11 Å with a leakage current of 1.9×10−3 A/cm2 at −1.5 V relative to the flat band voltage has been obtained. Well-behaved capacitance–voltage characteristics with an interface state density of less than 1011 cm−2 eV−1 and no significant frequency dispersion have been achieved. Excellent reliability properties (e.g., low charge trapping rate, good time-dependent dielectric breakdown, low stress-induced leakage current, and high dielectric breakdown) have also been obtained.

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