Floating Body Ring Termination for Trench Field Plate Power MOSFETs

The active regions of a trench field plate power MOSFET experience RESURF which is essentially 2-D in nature and can be easily optimized. However, for the same design parameters, the 3-D regions in the device termination can experience significantly weakened RESURF causing them to become the bottleneck for breakdown, thus undermining the 2-D optimization. To strengthen the RESURF in the termination, floating body rings between the active and the termination regions are introduced. Through the coupling of these floating rings, the body in the termination acquires a voltage bias which strengthens the RESURF and increases the breakdown voltage. The working principles of this design are discussed, and the concept is verified through 3-D TCAD simulations.