Trench transistor manufacturing method, by back-forming layer in upper trench region, and semiconductor material on side walls of trench before forming new semiconductor material on side walls

摘要

The method involves back-forming a first layer (DOX) in the upper trench region (30o), the filing (40) serving as a mask. The semiconductor material (20) on the side walls of the trench in the upper region of the trench are back-formed, with the first layer serving as a mask. A new semiconductor material (20n) of defined doping (p) is formed on the back-formed trench side walls near the upper trench region, forming a channel region of defined doping (p).