Modeling the capacitance-voltage characteristics of the trench Insulated Gate Bipolar Transistor (TIGBT) by minimizing its Helmholtz Free Energy

High voltage (600 V and above) Insulated Gate Bipolar Transistors (IGBTs) are among the most commonly used power switching devices for a wide range of industrial applications. The recently developed Trench-Gated IGBT (TIGBT) is a three-terminal device of great complexity, consisting of a MOSFET and a BJT in tandem [1]. In this work, a terminal capacitance model of the TIGBT is constructed by combining the internal capacitances distributed throughout the structure, subject to the constraint of minimum Helmholtz Free Energy. The model is then compared with measured terminal capacitance-voltage characteristics of the device to identify contributions from individual internal capacitances. Because of being based on energy, our method directly produces all internal MOS as well as p-n junction capacitances.