A vacuum channel transistor having a vertical gate-all-around (GAA) architecture provides high performance for high-frequency applications, and features a small footprint compared with existing planar devices. The GAA vacuum channel transistor features stacked, tapered source and drain regions that are formed by notching a doped silicon pillar using a lateral oxidation process. A temporary support structure is provided for the pillar during formation of the vacuum channel. Performance of the GAA vacuum channel transistor can be tuned by replacing air in the channel with other gases such as helium, neon, or argon. A threshold voltage of the GAA vacuum channel transistor can be adjusted by altering dopant concentrations of the silicon pillar from which the source and drain regions are formed.

Vacuum transistors with carbon nanotube as the collector and/or emitter electrodes are provided. In one aspect, a method for forming a vacuum transistor includes the steps of: covering a substrate with an insulating layer; forming a back gate(s) in the insulating layer; depositing a gate dielectric over the back gate; forming a carbon nanotube layer on the gate dielectric; patterning the carbon nanotube layer to provide first/second portions thereof over first/second sides of the back gate, separated from one another by a gap G, which serve as emitter and collector electrodes; forming a vacuum channel in the gate dielectric; and forming metal contacts to the emitter and collector electrodes. Vacuum transistors are also provided.

An integrated vacuum microelectronic structure is described as having a highly doped semiconductor substrate, a first insulating layer placed above said doped semiconductor substrate, a first conductive layer placed above said first insulating layer, a second insulating layer placed above said first conductive layer, a vacuum trench formed within said first and second insulating layers and extending to the highly doped semiconductor substrate, a second conductive layer placed above said vacuum trench and acting as a cathode, a third metal layer placed under said highly doped semiconductor substrate and acting as an anode, said second conductive layer is placed adjacent to the upper edge of said vacuum trench, the first conductive layer is separated from said vacuum trench by portions of said second insulating layer and is in electrical contact with said second conductive layer.

The process is based upon the steps of: forming a trench in a body including a substrate and at least one insulating layer; and depositing a metal layer above the body for closing the open end or mouth of the trench. The trench is formed by selectively etching the body, wherein the reaction by-products deposit on the walls of the trench and form a passivation layer along the walls of the trench and a restriction element in proximity of the mouth of the trench.