Threshold Voltage Sensitivity to Metal Gate Work-Function Based Performance Evaluation of Double-Gate n-FinFET Structures for LSTP Technology

This paper investigates the threshold voltage sensitivity to metal gate work-function for n-channel double gate fin field-effect transistor (FinFET) structures and evaluates the short channel performance of the device using threshold voltage dependence on metal gate work-function analysis. We carried out the study for a double gate n-channel fin field-effect transistor (n-FinFET) with parameters as per the projection report of International Technology Roadmap for Semiconductors, ITRS-2011 for low standby power (LSTP) 20 nm gate length technology node. In the present study device simulation have been carried out using PADRE simulator from MuGFET, which is based on the drift-diffusion theory. Our results show the accuracy and validity of classical drift-diffusion simulation results for transistor structures with lateral dimensions 10nm and above. The subthreshold behavior of device improves with increased metal gate work-function. The results also show that a higher gate work-function (≥5 eV) can fulfill the tolerable off-current as projected in ITRS 2011 report. The SCE in FinFET can reasonably be controlled and improved by proper adjustment of the metal gate work-function. DIBL is reduced with the increase in gate work function.