US Patent 9853125 Vertical tunneling field-effect transistor cell and fabricating the same

A tunneling field-effect transistor (TFET) device is disclosed. A frustoconical protrusion structure is disposed over the substrate and protrudes out of the plane of substrate. A drain region is disposed over the substrate adjacent to the frustoconical protrusion structure and extends to a bottom portion of the frustoconical protrusion structure as a raised drain region. A gate stack is disposed over the substrate. The gate stack has a planar portion, which is parallel to the surface of substrate and a gating surface, which wraps around a middle portion of the frustoconical protrusion structure, including overlapping with the raised drain region. An isolation dielectric layer is disposed between the planar portion of the gate stack and the drain region. A source region is disposed as a top portion of the frustoconical protrusion structure, including overlapping with a top portion of the gating surface of the gate stack.