Charge Trapping Characteristics of W-La{sub}2O{sub}3-nSi MIS Capacitors After Post-Metallization Annealing in N{sub}2

摘要

In this paper, we report the effects of a N{sub}2-based Post-Metallization Annealing (PMA) thermal process on the reliability and charge trapping characteristics of tungsten-gated La{sub}2O{sub}3 thin films. The samples are stressed with a Constant Voltage Stress (CVS) under substrate injection so that electrons from the substrate are injected and trapped into localized states within the dielectric. Post-stress measurements of the flat band voltage Vfb of the samples have shown a positive shift indicating a net negative charge trapping effect within La{sub}2O{sub}3 and its interfaces. PMA samples have shown less Vfb shift after stress as compared to La{sub}2O{sub}3 films annealed before the gate metallization step. Moreover, relatively higher PMA temperatures will produce the higher endurance to Vfb shift while the Equivalent Oxide Thickness (EOT) of the MIS capacitors is compromised thus the necessity of a trade-off between less Vfb shift and low EOT is required.