SUPERJUNCTION DEVICE AND FABRICATION METHOD THEREFOR

A super-junction device and a method of fabricating such a device are disclosed, in which a pillar of a second conductivity type situated at an interface between a transition region and a core region is narrowed in width across at least an upper thickness thereof, thereby reducing peak electric field strength in the transition region, increasing voltage endurance of the transition region and preventing the occurrence of avalanche breakdown first in the transition region. Additionally, a dopant ion concentration profile increasing in the direction from the transition region to the core region is created across upper portions of some pillars of the second conductivity type in the core region, which increases the presence of the dopant of the second conductivity type around the surface of the core region and thus stops a vertical electric field before it can reach wells of the second conductivity type. That is, an effective epitaxial thickness of the core region is reduced, which results in lower voltage endurance thereof. In this way, it is ensured that avalanche breakdown occurs first in the core region, resulting in improved EAS performance.