Hf–O–N and HfO2 barrier layers for Hf–Ti–O gate dielectric thin films

Hf–O–N and HfO2 thin films were evaluated as barrier layers for Hf–Ti–O metal oxide semiconductor capacitor structures. The films were processed by sequential pulsed laser deposition at 300 °C and ultra-violet ozone oxidation process at 500 °C. The as-deposited Hf–Ti–O films were polycrystalline in nature after oxidation at 500 °C and a fully crystallized (o)-HfTiO4 phase was formed upon high temperature annealing at 900 °C. The Hf–Ti–O films deposited on Hf–O–N barrier layer exhibited a higher dielectric constant than the films deposited on the HfO2 barrier layer. Leakage current densities lower than 5 × 10 A/cm2 were achieved with both barrier layers at a sub 20 Å equivalent oxide thickness.