LONG CHANNEL TRENCH-GATED POWER MOSFET HAVING FULLY DEPLETED BODY REGION

摘要

A trenched-gate power MOSFET includes a body region that is formed within a mesa between adjacent gate trenches. The doping concentration of the body region is established such that the body region does not fully deplete at normal drain voltages. The MOSFET also includes a gate which is doped with material of a conductivity type opposite to that of the body. The width of the mesa and the doping concentration of the body region and gate are established such that the body region is fully depleted by the combined effects of the source-body and drain body junctions and the gate. As a result, the conventional source-body short can be eliminated, providing a greater cell packing density and lower on- resistance while maintaining acceptable levels of leakage current when the MOSFET is in the off-state.