Nano-vacuum-tubes and their application in storage devices
View Patent ↗The scale of the devices in a diode array storage device, and their cost, are reduced by changing the semiconductor based diodes in the storage array to cold cathode, field emitter based devices. The field emitters and a field emitter array may be fabricated utilizing a topography-based lithographic technique.
1. A structure comprising:
a first plurality of conductors;
a second plurality of conductors overlapping the first plurality of conductors, wherein each point of intersection between the first and second pluralities of conductors defines a memory bit; and
a plurality of non-linear electron-emitting devices, wherein (i) each device is disposed at a point of intersection between the first and second pluralities of conductors, and (ii) the first and second pluralities of conductors are disposed on a single substrate.
2. The structure of claim 1 , wherein each of the non-linear electron-emitting devices is a field emission device.
3. The structure of claim 2 , wherein each of the non-linear electron-emitting devices is a cold emission device.
4. The structure of claim 1 , wherein each of the non-linear electron-emitting devices comprises a sealed cavity.
5. The structure of claim 4 , wherein the cavity comprises a vacuum.
6. The structure of claim 4 , wherein the cavity contains one or more gases, each gas consisting essentially of a noble gas.
7. The structure of claim 4 , wherein the cavity comprises at least one phosphorescent material.
8. The structure of claim 1 , further comprising address circuitry connected to at least one of the first and second plurality of conductors, the address circuitry selecting one of the first and second pluralities of conductors.
9. The structure of claim 8 , wherein the address circuitry comprises a first array of non-linear electron-emitting devices.
10. The structure of claim 8 , further comprising output detection circuitry connected to at least one of the first and second plurality of conductors, the output detection circuitry detecting a low impedance current path or a high impedance current path at the memory bit selected by the address circuitry.
11. The structure of claim 10 , wherein the output detection circuitry comprises a second array of non-linear electron-emitting devices.
12. The structure of claim 10 , wherein (i) the low impedance current path results from the presence of a non-linear electron-emitting device at the memory bit selected by the address circuitry, and (ii) the high impedance current path results from the absence of a non-linear electron emitting device at the memory bit selected by the address circuitry.
13. The structure of claim 1 , wherein the first and second pluralities of conductors are disposed within a discrete package.
14. The structure of claim 13 , wherein the package has a removable form factor.
15. The structure of claim 13 , wherein the package comprises at least one logic device.
16. The structure of claim 15 , wherein the at least one logic device comprises a controller.
17. The structure of claim 13 , further comprising:
disposed on the substrate over the first and second pluralities of conductors, a third plurality of conductors; and
disposed on the substrate over the first and second pluralities of conductors, a fourth plurality of conductors overlapping the third plurality of conductors,
wherein each point of intersection between the third and fourth pluralities of conductors defines a memory bit.
18. The structure of claim 1 , wherein the first and second pluralities of conductors are disposed within a display device.
19. The structure of claim 1 , wherein the first and second pluralities of conductors are disposed within a programmable logic array.
20. The structure of claim 1 , wherein the plurality of non-linear electron-emitting devices emit electrons in a direction toward the substrate.
21. The structure of claim 1 , wherein each of the non-linear electron-emitting devices comprises an emitter tip.
22. The structure of claim 21 , further comprising, disposed between the emitter tip and one of the second plurality of conductors overlying the emitter tip, a layer of material capable of exhibiting at least two discrete impedance levels at each memory bit.
23. The structure of claim 22 , wherein the material comprises at least one fuseable or antifuseable material.
24. The structure of claim 22 , wherein the material comprises at least one phase-change material or magnetic material.
25. The structure of claim 24 , wherein the material comprises a chalcogenide.
26. The structure of claim 21 , wherein the emitter tip of at least one of the plurality of non-linear electron-emitting devices is melted, rendering the non-linear electron-emitting device non-functional.
27. The structure of claim 21 , wherein the emitter tip of each of the non-linear electron-emitting devices is disposed within a recessed cup and spaced apart from an opposing surface of the recessed cup.
28. The structure of claim 27 , wherein the opposing surface of the recessed cup comprises the bottom surface of the recessed cup.
29. The structure of claim 27 , wherein each recessed cup is disposed within the substrate.
30. A method comprising:
forming a structure comprising:
a first plurality of conductors;
a second plurality of conductors overlapping the first plurality of conductors, wherein each point of intersection between the first and second pluralities of conductors defines a memory bit; and
a plurality of non-linear electron-emitting devices, wherein (i) each device is disposed at a point of intersection between the first and second pluralities of conductors, and (ii) the first and second pluralities of conductors are disposed on a single substrate,
wherein the plurality of non-linear electron-emitting devices is formed on the substrate by the steps of:
forming a first plurality of recesses in a top surface of the substrate;
forming a layer of emitter tip material over the substrate, wherein a first portion of the layer is disposed above the first plurality of recesses and a second portion of the layer is disposed within the first plurality of recesses; and
removing the first portion of the layer of emitter tip material.
31. The method of claim 30 , wherein removing the first portion of the layer of emitter tip material comprises planarization.
32. The method of claim 30 , wherein forming the first plurality of recesses comprises the steps of:
forming a masking layer over the substrate;
removing portions of the masking layer in a first plurality of regions; and
etching the substrate in the first plurality of regions.
33. The method of claim 30 , wherein forming the first plurality of recesses comprises imprinting the top surface of the substrate.
34. The method of claim 30 , wherein forming the first plurality of recesses comprises embossing the top surface of the substrate.
35. The method of claim 30 , wherein forming the first plurality of recesses comprises injection molding the top surface of the substrate.
36. The method of claim 30 , further comprising forming a second plurality of recesses in the top surface of the substrate, wherein after removing the first portion of the layer of emitter tip material, each of the second plurality of recesses is substantially free of emitter tip material.
37. The method of claim 36 , wherein a depth of the second plurality of recesses is less than a depth of the first plurality of recesses.