Trench power MOSFET with reduced on-resistance

摘要

A semiconductor device includes a drift region, a well region extending above the drift region, an active trench including sidewalls and a bottom, the active trench extending through the well region and into the drift region and having at least portions of its sidewalls and bottom lined with dielectric material. The device further includes a shield disposed within the active trench and separated from the sidewalls of the active trench by the dielectric material, a gate disposed within the active trench above the first shield and separated therefrom by inter-electrode dielectric material, and source regions formed in the well region adjacent the active trench. The gate is separated from the sidewalls of the active trench by the dielectric material. The shield and the gate are made of materials having different work functions.