MOSFETs typically employ a vertical conduction structure (such as VDMOSFETs and UMOSFETs), with the drain located at the bottom of the chip and the source at the top, allowing current to flow vertically through the chip. This design decouples the channel length from the voltage rating, enabling the device to withstand higher voltages while maintaining high switching speeds. Taking the most common N-channel enhancement-mode MOSFET as an example, its core principle is as follows: when a positive voltage is applied to the gate and exceeds the threshold voltage (VGS(th)), an N-type inversion layer—the conductive channel—is induced on the surface of the P-type semiconductor beneath the gate, allowing the source and drain to conduct; when the voltage is removed, the channel disappears, and the device turns off. The entire control process relies solely on the electric field effect and consumes virtually no current.