Unified switch array for memory devices
View Patent ↗An array of vertically constructed, electronic switches is disclosed having three, four or more contacts and having a common bottom contact and a plurality of common middle contacts. This switch array will find use in memory devices or display devices.
1. A two dimensional array of switches comprising three or more layers of alternating polarity doped semiconductor material whereby the bottom layer is continuous among switches in two dimensions, the top layer is isolated across switches in two dimensions, and at least one intervening layer is continuous among switches in one dimension and isolated in the other dimension.
2. The array of switches of claim 1 whereby the bottom common contact has low resistance.
3. The array of switches of claim 1 whereby the layers within a given switch cooperate to form a vertical transistor.
4. The array of switches of claim 3 whereby the transistors are the bipolar type.
5. The transistors of claim 4 whereby said transistors have sufficient gain to allow operation when the center common contact has moderate or high resistance.
6. The array of switches of claim 1 whereby the layers within a given switch cooperate to form four-layer diodes or SCR's.
7. The switches of claim 6 whereby the four-layer diodes or SCR's have sufficient gain to allow operation when the center common contact(s) has moderate or high resistance.
8. The switches of claim 1 whereby a reference voltage is applied a middle layer of some of the switches in the array.
9. The array of switches of claim 1 whereby the switches are operated to select a memory cell in a memory device.
10. The array of switches of claim 1 whereby the switches are operated to select a pixel cell in a display device.
11. The array of switches of claim 1 whereby the switches are operated to select a sensing cell in a sensor device.
12. A semiconductor memory device comprising a two dimensional array of switches fabricated out of three or more layers of alternating polarity doped semiconductor material whereby the bottom layer is continuous among switches in two dimensions, the top layer is isolated across switches in two dimensions, and at least one intervening layer is continuous among switches in one dimension and isolated in the other dimension.
13. The memory device of claim 12 wherein at least one storage location is programmed with data comprising at least one of music, video, computer software, a computer application, reference data, text, or a diagram.
14. The memory device of claim 12 wherein the device is disposed within a package that is removable and interchangeable among a plurality of host devices.
15. The memory device of claim 12 wherein bit information is retained at a given memory cell by a phase-change material.
16. The memory device of claim 15 wherein the phase-change material is a Chalcogenide alloy.
17. The memory device of claim 12 wherein bit information is retained at a given memory cell by a magnetic or magnetoresistive material.
18. The memory device of claim 12 wherein bit information is retained at a given memory cell by utilizing a magnetic tunnel junction or spin-transfer torque element.
19. The memory device of claim 12 wherein bit information is retained at a given memory cell by utilizing a fuse or antifuse material.
20. A method for forming a two dimensional array of switches comprising the steps of (i) creating three or more layers of alternating polarity doped semiconductor material by deposition, epitaxial growth and/or implantation, (ii) performing a first etch to form a first plurality of spaces between rows of switches such that the etch stops upon or within a low level layer, (iii) performing a second etch to individually define the tops of each switch such that the bottom of said second etch stops upon or within a layer that is below a high level layer and above said low level layer, such that said low level layer is continuous among switches in two dimensions, the high level layer is isolated across switches in two dimensions, and at least one intervening layer is continuous among switches in one dimension and isolated in the other dimension.