EFFECTS OF TEMPERATURE ON METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR CHARACTERISTICS

Abstract

The metal-oxide-semiconductor field-effect transistor (MOSFET) is a transistor used for amplifying and switching on circuits. In this study, the MOSFET parameters were computationally modeled, analysed and presented. The study focused on the temperature parameter. The microscopic variations in structure are due simply to the probabilistic nature of device geometry and atomic processes hence require statistical predictions. In this work, a 30nm process was modeled and I-V curves and thermal analysis were modeled mathematically. The junction temperature depends on the thermal resistance and the temperature coefficient of threshold voltage reduced with increasing gate length. Further still the threshold voltage increased with doping concentration. Carrier mobility exhibited a strong and a complex dependence on temperature; it reduces with increasing temperature. Scattering mechanisms are temperature dependent. The sheet resistance increases with increasing temperature. This had a significant impact on the carrier mobility. The carrier mobility is shown not to vary with thickness. The MOSFET frequency response was found to degrade with increasing temperature. At high temperature; the threshold voltage, charge mobility, source voltage degrade. This consequently reduces the efficiency of the MOSFET devices. The study therefore obtained a balance between scaling down devices and it efficiency consequences. The cost of silicon is high and therefore being able to fabricate many devices on tiny wafer without compromising the speed is important. The study shows that a compromise between size and heat generation has to be found.