Trench-gate field effect transistor with channel enhancement region and methods of forming the same

A shielded gate field effect transistor comprising:

• body regions of a first conductivity type extending in a semiconductor region of a second conductivity type;
• gate trenches separated by the body regions;
• at least one conductive shield electrode disposed in each gate trench;
• a gate electrode disposed in each gate trench over but insulated from the at least one conductive shield electrode;
• a shield dielectric layer insulating the at least one conductive shield electrode from the semiconductor region;
• and
• a gate dielectric layer insulating each gate electrode from adjacent body regions;
• source regions of the second conductivity type extending in the body region adjacent the gate trenches, each source region and an interface between the corresponding body region and the semiconductor region defining a channel region therebetween, each channel region extending along sidewall of the corresponding gate trench;
• and
• a channel enhancement region of the second conductivity type adjacent each gate trench, the channel enhancement region partially extending into a lower portion of the corresponding channel region to thereby reduce a resistance of the channel region.