Three-dimensional (3D) trenched metal-oxide-semiconductor field-effect transistor (MOSFET) device including first doped wells and second doped wells and method for fabricating the same

A method for fabricating a three-dimensional (3D) trenched metal-oxide-semiconductor field-effect transistor (MOSFET) device comprising:

• forming an epitaxial layer with a first conductivity type on a semiconductor substrate;
• forming a doped area with a second conductivity type opposite to the first conductivity type in the epitaxial layer;
• forming a heavily-doped region with the first conductivity type in the doped area;
• forming first doped wells and second doped wells with the second conductivity type in the epitaxial layer, wherein the first doped wells and the second doped wells penetrate through the doped area and the heavily-doped region;
• forming a trenched gate in the epitaxial layer and the first doped wells, wherein the trenched gate penetrates through the doped area and the heavily-doped region and surrounds the second doped wells, thereby forming first heavily-doped areas with the first conductivity type in the doped area, the trenched gate has intersecting portions that are respectively formed in the first doped wells, bottoms of the first doped wells and the second doped wells are lower than a bottom of the trenched gate, the first heavily-doped areas respectively surround the second doped wells, and the trenched gate surrounds the first heavily-doped areas;
• forming a patterned insulation layer to cover the trenched gate, thereby exposing the first heavily-doped areas and the second doped wells;
• and
• forming a conduction layer on the patterned insulation layer, the first heavily-doped areas, and the second doped wells;
• wherein the doped area is directly connected with the first doped wells.