Adopting the BSIM3 Model with Thermal Extension for a Si Vertical Power MOSFET

This work presents a modeling approach adopting the industry standard BSIM3 model with specific structural and thermal extensions for a Si vertical power MOSFET. The BSIM3 model, which is developed for CMOS logic devices, is adopted with its proven robustness and fidelity to describe the channel behavior of the power MOSFET. On the other hand, the extended components including the drift region, body-diode and drain-gate capacitance are defined according to the vertical MOSFET structure which is different from conventional CMOS devices. The temperature-dependent parameters in the original BSIM3 expression are used to contribute to an improved dynamic thermal model. The improved model can estimate the power loss-caused temperature increase and dynamically feed it back to the BSIM3 temperature-related parameters and instantaneously control the behavior of the electrical model. The parameters of the model are extracted based on the measurement of the static characteristics and the intrinsic capacitances of a Si vertical power MOSFET. The result shows that the proposed model is able to describe the device characteristics precisely.