Top structure of super junction MOSFETs and methods of fabrication

A semiconductor power device formed on an upper epitaxial layer of a first conductivity type supported on a semiconductor substrate, comprising:

• a super junction structure with the epitaxial layer formed with a plurality of vertically extended doped columns of a second conductivity type wherein the doped columns of the second conductivity extend laterally along a first direction across the upper epitaxial layer;
• a plurality of transistor cells each includes a planar gate extending over a top surface along the first direction between two adjacent doped columns of the second conductivity type;
• and
• each of the planar gates further includes a middle trench gate extending downwardly into the epitaxial layer from a middle portion of the planar gate between two adjacent doped columns of the second conductivity type and wherein each of the middle trench gates is surrounded by a dopant region of the first conductivity type and wherein the middle trench gates and the dopant regions of the first conductivity type extending laterally along the first direction below the planar gates.