The Vertical, Replacement-Gate MOSFET: A 50nm Vertical MOSFET with Lithography-Independent Critcal Dimensions
We have demonstrated a new device called the Vertical Replacement-Gate (VGR) MOSFET. This is the first MOSFET ever built in which: 1) all critical transistor dimensions are controlled precisely without lithography; 2) the gate length is defined by a deposited film thickness, independenty of lithography and etch; and 3) a high-quality gate oxide is grown on a single-crystal Si channel. In addition to this unique combination, the VRG-MOSFET includes a self-aligned S/D formed by solid source diffusion (SSD) and small parasitic overlay, junction, and S/D capacitances. The drive current per mu of coded width is larger than that of advanced planar MOSFETs because each 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 devices with 50-nm gate lengths (L sub G) have been demonstrated without advanced lithography.