Effects of high-K dielectrics with metal gate for electrical characteristics of 18nm NMOS device

This paper presents a systematic study of various high-K materials on metal gate MOSFET for 18nm NMOS. From the study, we find a suitable combination materials between the high-K and metal gate, which has beneficial effects on the electrical characteristics of 18nm NMOS. The device shows a good improvement on its result of sub-threshold leakage current, I_OFF, and drive current, I_ON for different dielectric constants (k). The virtual design and fabrication of the device were performed by using Athena module. While electrical characteristic performance was simulated by using Atlas module of SILVACO software. Physical models of the 18nm NMOS were used for simulation from Al₂O₃, HfO₂, and TiO₂ as the material gate dielectric, with TiSi₂ as the metal gate, which provide higher physical thickness that able to reduce the sub-threshold leakage current I_OFF. Thus, excellent dielectric properties such as high-K constant, low I_OFF, higher I_ON, threshold voltage V_TH, and electrical characteristics were demonstrated. From the simulation results of I_ON and I_OFF, it was proven that HfO₂ is the best dielectric material with combination of metal gate, TiSi₂.