FORMATION OF RELIABLE HfO2/HfSixOy GATE-DIELECTRIC FOR METAL-OXIDE-SEMICONDUCTOR DEVICES

The HfO2/HfSixOy thin film for gate oxides in the MOS device is obtained by a simple method which involves the oxidation of sputtered Hf metal films on Si followed by N2 annealing. Based on the TEM and XPS analyses, authors found that a high-quality HfO2 /HfSixOy stack layer is formed by the oxidation of the thin Hf film on Si. The hysteresis window of the Pd-HfO2/HfSixOy-Si MOS capacitors was negligible (i.e., < 10 mV). The equivalent oxide thickness (EOT) and leakage current density were 1.2 nm and 2x 10-3 A/cm2 at 1.5 V (after compensating the flatband voltage of 1.5 V), resp. Authors suggested that the low leakage current characteristics were obtained due to the presence of the amorphous HfSixOy buffer layer. The conduction mechanism of the Pd-HfO2 /HfSixOy-Si MOS capacitors is identified as Poole-Frenkel emission and as Fowler-Nordheim tunneling in low and high electric field regions, resp. 19 refs.