Shielded gate field effect transistors

An apparatus, comprising:

• a trench disposed in a semiconductor region of a first conductivity type;
• a shield electrode disposed in a lower portion of the trench, the shield electrode being insulated from the semiconductor region by a shield dielectric, the shield electrode having a curved top surface;
• a gate electrode disposed in the trench above the shield electrode, the gate electrode being insulated from the semiconductor region by a gate dielectric, the gate electrode having a bottom surface defining a plurality of protrusions including a first protrusion, a second protrusion, and a third protrusion, the second protrusion of the gate electrode being aligned along a centerline,
• the gate electrode having a bottom surface defining a first notch disposed on a first side of the centerline between the first protrusion and the second protrusion and a second notch disposed on a second side of the centerline between the second protrusion and the third protrusion;
• an inter-electrode dielectric disposed between the shield electrode and the gate electrode;
• a mesa adjacent the trench;
• and
• a region of a second conductivity disposed in the mesa and disposed above the semiconductor region of the first conductivity type.

An apparatus, comprising:

• a trench disposed in a semiconductor region, at least a portion of the trench has a tapered shape;
• a shield electrode disposed in a lower portion of the trench, the shield electrode being insulated from the semiconductor region by a shield dielectric;
• a gate electrode disposed in the trench above the shield electrode and aligned along a centerline, a portion of the trench disposed around the shield electrode having a width narrower than a width of a portion of the trench disposed around the gate electrode, the gate electrode having a bottom surface defining a plurality of notches and a plurality of protrusions, the plurality of notches including a first notch disposed between a first pair of protrusions from the plurality of protrusions, and including a second notch disposed between a second pair of protrusions from the plurality of protrusions, the first notch being disposed on a first side of the centerline and the second notch being disposed on a second side of the centerline;
• an inter-electrode dielectric disposed between the shield electrode and the gate electrode;
• a mesa disposed adjacent the trench and having a recessed portion;
• and
• a gate dielectric formed along a sidewall of an upper portion of the trench, the gate dielectric having a thickness less than a thickness of the inter-electrode dielectric.