Characteristics of Pr_2O_3 Gate Dielectric Thin-Film Transistors Fabricated on Fluorine-Ion-Implanted Polysilicon Films

摘要

A simple and effective scheme for fabricating high dielectric constant (high-kappa) praseodymium oxide (Pr_2O_3) gate dielectric thin-film transistors (Pr_2O_3 TFT) on fluorine-ion-implanted polysilicon films was proposed and demonstrated for the first time. Incorporating the fluorine-incorporation method with high-K Pr_2O_3 gate dielectric cannot only effectively passivate the trap states in the poly-Si film but also significantly increase the gate capacitance density. With the incorporation of fluorine ions, the electrical characteristics of Pr_2O_3 TFT can be remarkably improved, including smaller threshold voltage, steeper subthreshold swing, higher field-effect mobility, lower gate-induced drain leakage current, and better on/off current ratio. In addition, the incorporation of fluorine ions in the poly-Si film also improves the reliability of Pr_2O_3 TFT against hot-carrier stress, which is attributed to the formation of stronger Si-F bonds. Therefore, the proposed scheme is a promising technology for high-performance solid-phase crystallized poly-Si TFTs.