A trench-gated MOSFET includes adjacent mesas formed on opposite sides of
a trench. A body region in the first mesa extends downward below the
level of the trenches and laterally across the bottom of the trenches.
The body region in the second mesa extends part of the way down the mesa,
leaving a portion of the drain abutting the trench. The body region in
the second mesa includes a channel region adjacent a wall of the trench.
The area where the drain abuts the trench is thus relatively restricted
and the drain-gate capacitance of the device is reduced. Moreover, the
drain-gate capacitance is made independent of the depth and width of the
trenches, allowing greater freedom in the design of the MOSFET.