A Thermal Circuit Representing Frequency Dependent Dynamic Heating Between Electron and Lattice in SOI-FinFET

Abstract

A thermal circuit model that represents dynamic heating between electron and lattice at different frequencies has been demonstrated here. The model is effective for circuit based predictive simulations of the phenomenon as found in scaled metal-oxide-semiconductor field effect transistor (MOSFET), where electron heating substantially impacts its electrical characteristics including hot carrier reliability. High field or frequencies of the input signal as in the case of radio frequency (rf) MOSFET restrict heat transfer from electron to the lattice due to weak energy relaxation via low energy acoustic phonons, as a result soon a thermal non-equilibrium is established whose thermal equivalent circuit representation is not known until now. T-CAD based hydrodynamic-thermodynamic (HD-TD) modeling though can extract electron and lattice temperatures employing their detail energy balance relations, yet its numerical solver is cumbersome. In this context, we found that numerical complexities can be reduced without compromising generality, if heating between electron and lattice would be represented by an equivalent thermal circuit model with physically justified circuit elements, which would be valid over a frequency band of the input signal till the isothermal frequency where self-heating is a concern. In this context, from detail thermodynamic principle we calculated electron thermal capacitance, resistance and thermal inductance those were incorporated to the existing standard thermal circuit model. The new model was furthermore validated employing a calibrated 14 nm SOI-FinFET.