Patent ID: 7994017

Claim:
A method of manufacturing a MOSFET comprising: forming a trench in a first layer, the first layer having opposite first and second surfaces, the trench extending into the first layer from the first surface; epitaxially growing a second layer and then a third layer within the trench and over the first surface of the first layer; etching the second and third layers using a mask to expose the first surface, to remove the third layer and part of the second layer within a middle area of the trench, and to expose a surface of the second layer in a peripheral area of the trench, to provide a first structure; forming a gate oxide layer on the first structure; forming a gate electrode on the gate oxide layer over the surface of the second layer; etching the gate oxide layer within the middle area of the trench; forming a source electrode within the middle area of the trench in contact with the second and third layers; and forming a drain electrode over the second surface of the first layer, wherein the first and third layers have a conductivity type opposite a conductivity type of the second layer.