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

PROBLEM TO BE SOLVED: To provide a trench type MOSFET which provides a greater cell packing density and lower on-resistance while maintaining acceptable levels of leakage current when the MOSFET a is in an off-state. SOLUTION: In a trench-gated power MOSFET, a body region 107 is formed within a mesa between adjacent trenches, the body region 107 having doping concentration established such that the body region 107 is not fully depleted at drain voltage. The width of the mesa and the doping concentration of the body region 107 and a gate 103 doped with a material of the same conductivity type as that of the body region are established such that the body region is fully depleted by the combined effects of 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 the acceptable levels of leakage current when the MOSFET is in the off-state. COPYRIGHT: (C)2009,JPO&INPIT