Trench MOSFET Source Contact Doping for Low On-Resistance

The patent applies local quality by creating different doping concentrations in specific regions: the drift zone maintains lower doping for voltage blocking, while the body zone receives higher doping concentration to reduce on-state resistance. This is achieved through selective doping processes that target different spatial locations within the semiconductor structure, allowing each region to optimize its electrical properties independently.

The patent segments the semiconductor structure into distinct functional zones with different doping characteristics. The drift zone and body zone are separated and independently doped, enabling the drift zone to maintain high voltage blocking capability while the body zone provides low resistance for current conduction. This segmentation resolves the contradiction by distributing different functional requirements to different spatial segments.

The patent converts the potentially harmful parasitic bipolar transistor effect into a beneficial low-impedance contact region. By intentionally creating a highly doped body zone that forms a pn junction with the drift zone, the structure utilizes the parasitic bipolar mechanism to provide a low-resistance path for current flow, thereby reducing on-state resistance while controlling the harmful effects through proper doping profiles.

The patent changes the doping concentration parameter in the body zone to a high level, creating a strongly doped region that forms a pn junction with the drift zone. This parameter change transforms the body zone into a low-impedance contact region that reduces on-state resistance while the junction structure controls the parasitic bipolar effect through proper electrical field management.