The Vertical Replacement-Gate (VRG) MOSFET: A 50-nm Vertical MOSFET with Lithography-Independent Gate Length

We have fabricated and demonstrated a new device which we refer to as the Vertical Replacement-Gate (VRG) MOSFET. This is the first MOSFET ever built that combines (1) a physical gate length that is controlled precisely through a deposited film thickness independently of lithography and etch, and (2) a high-quality gate oxide that is grown on a single-crystal silicon channel. In addition to this unique combination, the VRG-MOSFET includes a self-aligned source and drain formed by solid source diffusion (SSD) and small parasitic overlap, junction, and source-drain capacitances. The drive current per coded micron of width is significantly higher than that of a planar MOSFET because each rectangular device pillar (with a thickness of minimum lithographic dimension) contains two MOSFETs driving in parallel. All of this is achieved using current manufacturing methods, materials, and tools, and competitive devices with 50-nm physical gate lengths (L sub G) have been demonstrated without advanced lithography.