Nanomechanical switches and circuits

• US 20020153584A1
• Filed: 06/07/2002
• Published: 10/24/2002
• Est. Priority Date: 11/09/2000
• Status: Active Grant

• Current Assignee: Alan C. Seabaugh, Gary A. Frazier
• Original Assignee: Alan C. Seabaugh, Gary A. Frazier
• Inventors: Seabaugh, Alan C., Frazier, Gary A.
• Granted Patent: US 6,495,905 B2
• Time in Patent Office: Days
• US Class Current: 257/448
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H01H 1/0094 Switches making use of nanoelectromechanical systems [NEMS]
• CPC Class Codes: Y10S 977/70 Nanostructure
• CPC Class Codes: Y10S 977/708 with distinct switching device
• CPC Class Codes: Y10S 977/709 including molecular switching device

Abstract

A highly miniaturized nanomechanical transistor switch is fabricated using a mechanical cantilever which creates a conductive path between two electrodes in its deflected state. In one embodiment, the cantilever is deflected by an electrostatic attraction arising from a voltage potential between the cantilever and a control electrode. In another embodiment, the cantilever is formed of a material with high magnetic permeability, and is deflected in response to complementary magnetic fields induced in the cantilever and in an adjacent electrode. The nanomechanical switch can be fabricated using well known semiconductor fabrication techniques, although semiconductor materials are not necessary for fabrication. The switch can rely upon physical contact between the cantilever and the adjacent electrode for current flow, or can rely upon sufficient proximity between the cantilever and the adjacent electrode to allow for tunneling current flow.

Claims

1. A nanomechanical switch comprising:

a substrate;

a first electrode formed on the substrate;

a second electrode formed on the substrate;

a third electrode having a cantilever member extending over the first and second electrodes;

a voltage source coupled between the first and third electrodes, wherein the cantilever member has an undeflected state when no bias is applied between the first and third electrodes, and a deflected state when a bias is applied between the first and third electrodes.

2. The nanomechanical switch of claim 1 wherein the cantilever member contacts the second electrode when in the deflected state.

3. The nanomechanical switch of claim 1 further comprising a lubricating layer formed atop of the second electrode.

4. The nanomechanical switch of claim 1 wherein the second electrode is between the first and third electrodes.

5. The nanomechanical switch of claim 1 wherein the cantilever is above spaced apart from the second electrode by between 10 and 40 angstroms in the undeflected state.

6. The nanomechanical switch of claim 1 wherein the cantilever member is formed of a refractory metal.

7. The nanomechanical switch of claim 1 further comprising an oxide feature formed on the substrate, on top of which is formed the third electrode.

8. The nanomechanical switch of claim 1 in which the cantilever element is 2000 angstroms in length.

9. The nanomechanical switch of claim 1 in which a vacuum is formed between the cantilever member and the second electrode.

10. The nanomechanical switch of claim 3 in which the lubricating layer is formed of an conductive material.

11. The nanomechanical switch of claim 3 in which the lubricating layer is formed of an insulative material.

13. The nanomechanical switch of claim 12 wherein current flowing in the base electrode induces complementary magnetic fields within the cantilever and the collector electrode.

14. The nanomechanical switch of claim 12 wherein the cantilever is spaced apart from the base electrode by less than 40 angstroms when in an undeflected state.

15. The nanomechanical switch of claim 12 wherein the collector electrode is higher, relative the plane of the substrate, than the base electrode.

16. The nanomechanical switch of claim 12 further comprising a lubricating layer formed atop the collector electrode.

17. The nanomechanical switch of claim 12 further comprising interconnection conductors connecting the switch with other circuit elements.

18. The nanomechanical switch of claim 12 wherein a vacuum gap is formed between the cantilever and the collector electrode.

19. The nanomechanical switch of claim 12 wherein a noble gas is placed between the cantilever and the collector electrode.

20. The nanomechanical switch of claim 12 wherein the spacing between the base and collector electrodes is less than 0.07 micrometers.

21. The nanomechanical switch of claim 12 wherein the base collector is formed of a superconducting material.

12. A nanomechanical switch comprising:

a substrate;

formed on the substrate, an emitter electrode including a cantilever element extending from the emitter electrode, the emitter being formed of a material having a magnetic permeability greater than one;

a base electrode formed on the substrate, at least a portion of the base electrode being beneath the cantilever element;

a collector electrode formed on the substrate adjacent the base electrode, at least a portion of the collector electrode being beneath the cantilever element and being formed of a material having a magnetic permeability greater than one; and

a current source coupled to the base electrode.

22. A logic circuit comprising:

an insulating material;

a first pad formed on the insulating material;

a first cantilever element having a first end connected to the first pad and a free end extending substantially horizontally over and spaced apart from the insulating material;

a second pad formed on the insulating material and lying at least in part beneath the first cantilever element;

a third pad formed on the insulating material and lying at least in part beneath the first cantilever element; and

a voltage source connected to the second pad, wherein the free end of the cantilever element deflects toward the third pad in response to a voltage being applied to the second pad, thus allowing current flow between the first and second pads.

23. The logic circuit of claim 22 further comprising:

a fourth pad connected to the third pad,

a second cantilever element having a first end connected to the fourth pad and a free end extending substantially horizontally over and spaced apart from the insulating material;

a fifth pad formed on the insulating material and lying at least in part beneath the second cantilever element;

a sixth pad formed on the insulating material and lying at least in part beneath the cantilever element; and

a second voltage source connected to the fifth pad, wherein the free end of the second cantilever element deflects toward the sixth pad in response to a voltage being applied to the fifth pad, thus allowing current flow between the fourth and sixth pads.

24. The logic circuit of claim 22 wherein the first pad forms a first source electrode, the second pad forms a first gate electrode, and the third pad forms a drain electrode, and further comprising:

a second source electrode formed on the insulating material;

a second cantilever element having a first end connected to the second source electrode and a free end extending substantially horizontally over and spaced apart from the insulating material;

a second gate electrode formed on the insulating material and lying at least in part beneath the second cantilever element; and

wherein the drain electrode lies at least in part beneath the first cantilever element and the second cantilever element.

25. The logic circuit of claim 22 wherein the insulating material is quartz.

26. The logic circuit of claim 22 wherein the insulating material is silicon dioxide formed on a bulk semiconductor substrate.

27. The logic circuit of claim 22 wherein the insulating material is sapphire.

30. The complementary pair nanomechanical circuit of claim 29 wherein the axis of motion is substantially parallel to a substrate upon which the electrodes are formed.

31. The complementary pair nanomechanical circuit of claim 29 wherein the free end of the cantilever member deflects in the first direction in response to a control voltage being applied to the first control electrode and moves in the second direction in response to a control voltage being applied to the second control electrode.

32. The complementary pair nanomechanical circuit of claim 29 wherein the first and second control electrodes are spaced apart from the cantilever member by a distance that is greater than the distance between the cantilever member and the source and drain electrodes.

28. A complementary pair nanomechanical circuit comprising:

a gate electrode formed on a substrate;

an output electrode formed on the substrate and having a cantilever member integral therewith, the cantilever member being spaced apart from the plane of the substrate and overlying a portion of the gate electrode, the cantilever member having a free end that is deflected from its normal position to a deflected position in response to an electrostatic attraction between the cantilever member and the gate electrode;

a source electrode lying at least in part beneath the free end of the cantilever member, and positioned such that the free end of the cantilever member contacts the source electrode when in deflected from its normal position; and

a drain electrode lying at least in part above the free end of the cantilever member, and positioned such that the free end of the cantilever member contacts the drain electrode when in its normal position.

29. A complementary pair nanomechanical circuit comprising:

a first electrode having formed therewith a laterally extending cantilever member, the cantilever member having a free end having a normal position and a first deflected position in a first direction of an axis of motion, and a second deflected position in a second direction of the axis of motion;

a first control electrode positioned adjacent but spaced apart from the cantilever member in the first direction;

a drain electrode positioned adjacent but spaced apart from the free end of the cantilever member in the first direction;

a second control electrode positioned adjacent but spaced apart from the cantilever member in the second direction; and

a source electrode positioned adjacent but spaced apart from the free end of the cantilever member in the second direction.

33. An integrated circuit comprising:

a substrate;

a power conductor;

a ground conductor;

an input terminal;

a logic circuit comprising a plurality of nanomechanical switches, at least one nanomechanical switch being coupled to said power conductor, and at least one nanomechanical switch being coupled to said ground conductor, each nanomechanical switch comprising;

a first electrode;

a second electrode

a third electrode having a cantilever member extending substantially parallel to the substrate and extending over the first and second electrodes; and

a voltage source coupled between the first and second electrodes, wherein the cantilever member has an undeflected state when no bias is applied between the first and third electrodes, and a deflected state when a bias is applied between the first and second electrodes.

34. The integrated circuit of claim 33 wherein said logic circuit comprises an arithmetic logic unit.

35. The integrated circuit of claim 33 wherein said integrated circuit further comprises a memory array.

36. The integrated circuit of claim 33 wherein the memory array is comprised of nanomechanical switching elements.

37. The integrated circuit of claim 33 further including a second logic circuit fabricated from MOS transistors.