Diode structure

1. A structure comprising:

a substrate having a trench;

a first conductive region in the trench and separated from the substrate by a first distance shorter than 10 nm; and

a second conductive region in contact with the first conductive region the trench and extending deeper into the trench than the first conductive region.

2. The structure of claim 1 , wherein the second conductive region is separated from the substrate by a second distance greater than the first distance.

3. The structure of claim 1 , further comprising:

a first dielectric layer separating the first conductive region from the substrate; and

a second dielectric layer separating the second conductive region from the substrate.

4. The structure of claim 1 , wherein the substrate is semiconductor.

5. The structure of claim 4 , comprising a conductive layer covering the substrate and the trench, said conductive layer being electrically connected to the substrate and to the first and second conductive regions.

6. The structure of claim 5 , wherein said conductive layer is in contact with the substrate or separated from the substrate by less than 300 nm.

7. A diode comprising:

a substrate having a first trench that has a sidewall and a bottom surface;

a cathode and an anode coupled to the substrate;

a first conductive region in the trench and separated from the sidewall of the substrate by a first distance that is less than approximately 10 nm; and

a second conductive region in the trench in contact with the first conductive region and extending closer to the bottom surface than the first conductive region.

8. The diode of claim 7 , wherein the substrate includes a second trench, the diode further comprising:

at least one transistor having at least one channel region extending between the first and second trenches, the first conductive region defining a gate of the at least one transistor.

9. The diode of claim 8 , comprising:

a conductive layer covering the substrate and the first and second trenches; and

a contacting region in the substrate and electrically coupling the channel region to the conductive layer.

10. The diode of claim 8 , wherein the first and second conductive regions are semiconductor regions, the channel region and the first conductive regions being doped with opposite conductivity types.

11. The diode of claim 8 , comprising a drain region extending under the channel region and between the first and second trenches.

12. The diode of claim 11 , wherein the drain region is less heavily doped than the channel region.

13. The diode of claim 11 , wherein the drain region extends under the first and second trenches.

14. A method, comprising:

forming a trench in a substrate;

forming a conductive material in the trench including:

forming a first conductive region in the trench that is separated from the substrate by a first distance that is less than 10 nm; and

forming a second conductive region in the trench and extending farther into the trench than the first conductive region.

15. The method of claim 14 , comprising:

forming a first dielectric layer separating the first conductive region from the substrate; and

forming a second dielectric layer separating the second conductive region from the substrate, wherein forming the second dielectric layer includes forming the second dielectric layer on walls and a bottom of the trench and removing a portion of the second dielectric layer before forming the first conductive region at a location from which the portion of the second dielectric layer was removed.

16. The method of claim 15 , comprising thermally oxidizing walls of the trench delimiting the location from which the portion of the second dielectric layer was removed.

17. A diode comprising:

a semiconductor substrate having a first trench;

a cathode and an anode coupled to the substrate;

a first vertical transistor in the substrate, the first vertical transistor including a first source region electrically coupled to the anode, a first gate extending vertically into the substrate and electrically coupled to the anode, a first drain region electrically coupled to the cathode, a first channel region between the first source and drain regions, and a first gate dielectric extending in the substrate and between the first gate and the first channel region,

a first conductive region in the trench and separated from the substrate by a first distance shorter than 10 nm; and

a second conductive region in contact with the first conductive region in the trench and extending deeper into the trench than the first conductive region.

18. The diode of claim 17 , wherein the gate is the first conductive region that is separated from the first channel region by a first distance

and the second conductive region is separated from the drain region by a second distance that is greater than the first distance.

19. The diode of claim 17 , further comprising:

a second vertical transistor in the substrate, the second vertical transistor including a second source region electrically coupled to the anode, a second gate extending vertically into the substrate and electrically coupled to the anode, a second drain region electrically coupled to the cathode, a second channel region between the second source and drain regions, and a second gate dielectric extending in the substrate and between the second gate and the second channel region.

20. The diode of claim 19 , comprising:

a conductive layer covering the substrate and the first and second vertical transistors; and

a contacting region in the substrate and electrically coupling the first and second channel regions to the conductive layer.