Gate all around vacuum channel transistor
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.
1. A device, comprising:
a substrate;
a doped layer on the substrate, the doped layer having a pillar that includes:
a source in a first portion of the pillar, the source having a first tapered end; and
a drain in a second portion of the pillar, the drain having a second tapered end.
2. The device of claim 1 wherein the second tapered end is spaced apart from the first tapered end by a gap.
3. The device of claim 1 wherein the pillar extends away from the substrate.
4. The device of claim 3 wherein the first and second tapered ends face each other and are separated by a gap.
5. The device of claim 4 , further comprising a gate that is formed around the pillar.
6. The device of claim 1 , further comprising an oxide spacer around the pillar.
7. The device of claim 6 , further comprising a gas between the oxide spacer and the first and second tapered ends.
8. The device of claim 6 , further comprising a drain contact, the oxide spacer being separated from the second portion of the pillar by the drain contact.
9. A method, comprising:
forming a doped layer on a substrate;
forming a pillar in the doped layer, the forming of the pillar including:
forming a source in a first portion of the pillar, the source having a first tapered end; and
forming a drain in a second portion of the pillar, the drain having a second tapered end.
10. The method of claim 9 wherein forming the pillar includes forming a gap between the second tapered end and the first tapered end.
11. The method of claim 10 wherein forming the pillar includes forming the pillar extending away from the substrate.
12. The method of claim 11 wherein forming the pillar includes forming the first and second tapered ends facing each other and separated by the gap.
13. The method of claim 12 , further comprising forming a gate around the pillar.
14. A device, comprising:
a substrate;
a doped semiconductor layer on the substrate, the doped semiconductor layer including a pillar extending away from the substrate, the pillar including:
a source portion of the pillar having a first tapered end that faces away from the substrate; and
a drain portion of the pillar having a second tapered end that faces the first tapered end; and
an oxide spacer spaced apart from the drain portion of the pillar.
15. The device of claim 14 , wherein the first tapered end and the second tapered end are separated by a gap.
16. The device of claim 14 , further comprising a gas between the oxide spacer and the second tapered end.
17. The device of claim 14 , further comprising a gate around the pillar.
18. The device of claim 14 , wherein the drain portion of the pillar is spaced apart from the oxide spacer.
19. The device of claim 18 , further comprising a drain contact between the oxide spacer and the drain portion of the pillar.
20. The device of claim 14 , wherein sidewalls of the source portion abut the oxide spacer.