| abstract |
A trenched device, such as a DMOS transistor, provides for higher breakdown voltages than possible using trenched devices of the prior art. The trench extends only into the epitaxial layer, thereby minimizing breakdown problems associated with prior art trench devices in which the trench extends into the more highly doped substrate. However, in order to achieve higher breakdown voltages, the dopant concentration is increased in that portion of the epitaxial layer surrounding the bottom of the trench. Thus, a novel trenched device is taught which achieves higher breakdown voltages by causing the trench to be surrounded by relatively highly doped material, while not requiring the trench to extend into the more highly doped substrate itself. |