Growth and characterization of Hf-aluminate high-k gate dielectric ultrathin films with equivalent oxide thickness less than 10 Å

Abstract

Ultrathin amorphous Hf-aluminate (Hf-Al-O) films have been deposited on p-type (100) Si substrates by pulsed-laser deposition using a composite target containing HfO₂ and Al₂O₃ plates. Transmission electron microscopy observation of Hf-Al-O films showed that the amorphous structure of Hf-Al-O films was stable under rapid thermal annealing at temperatures up to at least 1000 °C. Capacitance-voltage measurement of a 38 Å Hf-Al-O film revealed that the relative permittivity of the film was about 16. Such a film showed very low leakage current density of 4.6x10[sup -]³ A/cm² at 1 V gate bias. The Hf-Al-O film under optimized condition did not show any significant interfacial layer at the interface and an equivalent oxide thickness of less than 10 Å has been achieved. The formation of Hf-O and Al-O bonds in the film was revealed by x-ray photoelectron spectroscopy.