Cross point memory cell with distributed diodes and method of making same

• US 7,733,685 B2
• Filed: 07/09/2008
• Issued: 06/08/2010
• Est. Priority Date: 07/09/2008
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk 3D LLC (Western Digital Corporation)
• Inventors: Scheuerlein, Roy E., Fasoli, Luca
• Primary Examiner(s): NGUYEN, TAN
• Application Number:
  US12/216,678
• Publication Number:
  US 20100008124A1
• Time in Patent Office: 699 Days
• Field of Search: 365/69
• US Class Current: 365/148
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/0007 comprising metal oxide memory material, e.g. perovskites
• CPC Class Codes: G11C 13/0011 comprising conductive bridging RAM [CBRAM] or programming metallization cells [PMCs]
• CPC Class Codes: G11C 13/0014 comprising cells based on organic memory material
• CPC Class Codes: G11C 13/0016 comprising polymers
• CPC Class Codes: G11C 13/003 Cell access
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 17/16 using electrically-fusible links
• CPC Class Codes: G11C 2213/16 Memory cell being a nanotube, e.g. suspended nanotube
• CPC Class Codes: G11C 2213/19 Memory cell comprising at least a nanowire and only two terminals
• CPC Class Codes: G11C 2213/32 Material having simple binary metal oxide structure
• CPC Class Codes: G11C 2213/33 Material including silicon
• CPC Class Codes: G11C 2213/35 Material including carbon, e.g. graphite, grapheme
• CPC Class Codes: G11C 2213/72 Array wherein the access device being a diode
• CPC Class Codes: G11C 2213/74 Array wherein each memory cell has more than one access device
• CPC Class Codes: G11C 2213/78 Array wherein the memory cells of a group share an access device, all the memory cells of the group having a common electrode and the access device being not part of a word line or a bit line driver
• CPC Class Codes: G11C 2213/81 Array wherein the array conductors, e.g. word lines, bit lines, are made of nanowires
• CPC Class Codes: H10B 63/20 comprising selection components having two electrodes, e.g. diodes
• CPC Class Codes: H10B 63/22 of the metal-insulator-metal type
• CPC Class Codes: H10B 63/80 : Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
• CPC Class Codes: H10B 63/82 : the switching components having a common active material layer
• CPC Class Codes: H10N 70/021 : Formation of the switching material, e.g. layer deposition
• CPC Class Codes: H10N 70/023 : by chemical vapor deposition, e.g. MOCVD, ALD
• CPC Class Codes: H10N 70/026 : by physical vapor deposition, e.g. sputtering
• CPC Class Codes: H10N 70/20 : Multistable switching devices, e.g. memristors
• CPC Class Codes: H10N 70/231 : based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/245 : the species being metal cations, e.g. programmable metallization cells
• CPC Class Codes: H10N 70/883 : Oxides or nitrides
• CPC Class Codes: H10N 70/8845 : Carbon or carbides

Abstract

A cross point memory cell includes a portion of a first distributed diode, a portion of a second distributed diode, a memory layer located between the portion of the first distributed diode and the portion of a second distributed diode, a bit line electrically connected to the first distributed diode, and a word line electrically connected to the second distributed diode.

Claims

1. A cross point memory cell, comprising:

a portion of a first distributed diode;

a portion of a second distributed diode;

a memory layer located directly between the portion of the first distributed diode and the portion of a second distributed diode;

a bit line electrically connected to the first distributed diode; and

a word line electrically connected to the second distributed diode.

2. The cross point memory cell of claim 1, wherein the memory layer comprises a discontinuous layer whose portions are located only in locations between the first distributed diode and the second distributed diode where the first distributed diode crosses the second distributed diode.

3. The cross point memory cell of claim 1, wherein the memory layer comprises a continuous layer which extends beyond the first and the second distributed diodes.

4. The cross point memory cell of claim 1, wherein:

the first distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode;

the second distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode; and

the memory layer comprises a resistivity switching material selected from an antifuse dielectric, fuse, diode and antifuse dielectric arranged in a series, a polysilicon memory effect material, a metal oxide or switchable complex metal oxide material, a carbon nanotube material, a graphene switchable resistance material, a phase change material, a conductive bridge element, an electrolyte switching material, a switchable polymer material, or a carbon resistivity switching material.

5. A memory device comprising a plurality of cross point memory cells, wherein:

each memory cell of the plurality of memory cells comprises a resistivity switching material located directly between two distributed diodes; and

each one of said two distributed diodes of each memory cell is shared with different memory cells of the plurality of memory cells.

6. The device of claim 5, further comprising a plurality of bit lines and a plurality of word lines, such that a unique current path exists through each memory cell between each bit line and each word line.

7. The device of claim 6, wherein:

the plurality of memory cells comprise a first memory cell, a second memory cell, a third memory cell and a fourth memory cell;

the first memory cell comprises a first distributed diode which is shared with the second memory cell, a first resistivity switching material region, and a second distributed diode which is shared with the third memory cell;

the second memory cell comprises the first distributed diode, a second resistivity switching material region, and a third distributed diode which is shared with the fourth memory cell;

a first unique current path between a first bit line of the plurality of bit lines and a first word line of the plurality of word lines passes through the first distributed diode, the first resistivity switching material region and the second distributed diode; and

a second unique current path between the first bit line of the plurality of bit lines and a second word line of the plurality of word lines passes through the first distributed diode, the second resistivity switching material region and the third distributed diode.

8. The device of claim 7, wherein:

each of the first, second, and third distributed diodes comprise rail shaped diodes;

the first resistivity switching material region is located between the first and the second distributed diodes;

the second resistivity switching material region is located between the first and the third distributed diodes;

the plurality of bit lines are located above the first, second, and third distributed diodes, such that the first bit line electrically contacts the first distributed diode; and

the plurality of word lines are located below the first, second, and third distributed diodes, such that the first word line electrically contacts the second distributed diode and second word line electrically contacts the third distributed diode.

9. The device of claim 5, wherein:

each memory cell comprises a one time programmable or a rewritable nonvolatile memory;

each distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode; and

each resistivity switching material comprises an antifuse dielectric, fuse, diode and antifuse dielectric arranged in a series, polysilicon memory effect material, metal oxide or switchable complex metal oxide material, carbon nanotube material, graphene switchable resistance material, phase change material, conductive bridge element, electrolyte switching material, switchable polymer material, or a carbon resistivity switching material.

10. A semiconductor device comprising a plurality of cross point memory cells, wherein each memory cell of the plurality of memory cells comprises:

a first rail structure, wherein the first rail structure comprises a first distributed diode;

a second rail structure, wherein the second rail structure comprises a second distributed diode; and

a memory layer located directly between the first and the second rail structures.

11. The device of claim 10, wherein:

the first rail structures further comprises a bit line;

the second rail structure further comprises a word line; and

a current path between the bit line and the word line passes through the memory layer at a junction where the first rail structure and the second rail structure cross.

12. The device of claim 11, wherein the first rail structure is segmented into first rail structure segments comprising one bit line and two or more first distributed diodes and the second rail structure is segmented into second rail structure segments comprising one word line and two or more distributed second diodes.

13. The device of claim 11, further comprising:

a plurality of first rail structures;

a plurality of second rail structures crossing over the plurality of first rail structures;

a plurality of bit lines electrically connected to respective ones of the plurality of first rail structures; and

a plurality of word lines electrically connected to respective ones of the plurality of second rail structures.

14. The device of claim 13, wherein the plurality of first rail structures cross the plurality of second rail structures at a 90 degree angle.

15. The device of claim 10, wherein:

the first distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode;

the second rail distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode; and

the memory layer comprises an antifuse dielectric, fuse, diode and antifuse dielectric arranged in a series, polysilicon memory effect material, metal oxide or switchable complex metal oxide material, carbon nanotube material, graphene switchable resistance material, phase change material, conductive bridge element, electrolyte switching material, switchable polymer material, or a carbon resistivity switching material.

16. The device of claim 10, wherein the first and the second distributed diodes comprise nanowires.

17. The device of claim 10, wherein the memory layer is selected from:

(a) a discontinuous memory layer whose portions are located only in locations between the first and the second rail structures where the first rail structures cross the second rail structures;

(b) a continuous memory layer;

or

(c) a rail shaped memory layer which is located in the first rail structure or in the second rail structure.

18. The device of claim 10, further comprising a monolithic three dimensional array of repeating first and second rail structures.

19. The device of claim 10, wherein:

the device comprises a plurality of memory cells;

a first memory cell of the plurality of memory cells comprises the memory layer, the first and the second distributed diodes; and

each one of said first and second distributed diodes of the first memory cell is shared with different memory cells of the plurality of memory cells.

20. A method of manufacturing a semiconductor device, comprising:

forming a first rail structure, wherein the first rail structure comprises a first distributed diode;

forming a memory layer directly over the first rail structure; and

forming a second rail structure directly over the first layer of memory material, wherein the second rail structure comprises a second distributed diode.

21. The method of claim 20, further comprising forming a plurality of bit lines and a plurality of word lines, such that a unique current path exists through the first layer of memory material between each bit line and each word line.

22. The method of claim 20, further comprising:

forming a first conductive layer over a substrate;

forming a first diode material on the first conductive layer;

etching the first diode material and first conductive layer to form a plurality of first rail structures each comprising a first distributed diode and a word line;

forming the memory layer on the first rail structures;

forming a second diode material on the memory layer;

forming a second conductive layer on the second diode material; and

etching the second diode material and second conductive layer to form a plurality of second rail structures each comprising a second distributed diode and a bit line.

23. The method of claim 20, further comprising:

forming a first conductive layer over a substrate;

forming a first diode material on the first conductive layer;

forming the memory layer on the first diode material;

etching the memory layer, the first diode material, first conductive layer to form a plurality of first rail structures each comprising a portion of the memory layer, a first distributed diode and a word line;

forming a second diode material on the memory layer;

forming a second conductive layer on the second diode material; and

etching the second diode material and second conductive layer to form a plurality of second rail structures each comprising a second distributed diode and a bit line.

24. The method of claim 20, further comprising:

forming a first conductive layer over a substrate;

forming a first diode material on the first conductive layer;

etching the first diode material and first conductive layer to form a plurality of first rail structures each comprising a first distributed diode and a word line;

forming the memory layer on the first rail structures;

forming a second diode material on the memory layer;

forming a second conductive layer on the second diode material; and

etching the memory layer, the second diode material and second conductive layer to form a plurality of second rail structures each comprising the memory layer, a second distributed diode and a bit line.

25. The method of claim 20, further comprising:

forming a first conductive layer over a substrate;

forming a first diode material on the first conductive layer;

forming the memory layer on the first diode material;

etching the memory layer, the first diode material, first conductive layer to form a plurality of first rail structures each comprising a portion of the memory layer, a first distributed diode and a word line;

forming a second diode material on the memory layer;

forming a second conductive layer on the second diode material; and

etching the memory layer, the second diode material and second conductive layer to form a plurality of second rail structures each comprising a second distributed diode and a bit line, such that the memory layer portions are located only at an intersection of the first and the second rail structures.

26. The method of claim 20, wherein:

the first distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode;

the second distributed diode comprises a p-n semiconductor diode, a p-i-n semiconductor diode, a metal insulator metal (MIM) diode, or a metal insulator-insulator metal (MIIM) diode; and

the memory layer comprises an antifuse dielectric, fuse, diode and antifuse dielectric arranged in a series, polysilicon memory effect material, metal oxide or switchable complex metal oxide material, carbon nanotube material, graphene switchable resistance material, phase change material, conductive bridge element, electrolyte switching material, switchable polymer material, or a carbon resistivity switching material.

27. A memory array, comprising:

a plurality of bit lines;

a plurality of word lines;

a plurality of first distributed diodes;

a plurality of second distributed diodes; and

a plurality of memory cells;

wherein;

each memory cell of the plurality of the memory cells comprises a memory layer located between a portion of one of the plurality of the first distributed diodes and a portion of one of the plurality of the second distributed diodes;

at least two of the plurality of the first distributed diodes are connected to each one of the plurality of bit lines;

at least two of plurality of the second distributed diodes are connected to each one of the plurality of word lines;

each of the plurality of the first distributed diodes is connected to the memory layer of at least two of the plurality of the memory cells; and

each of the plurality of the second distributed diodes is connected to the memory layer of at least two of the plurality of the memory cells.

28. The array of claim 27, wherein:

each of the plurality of the first distributed diodes is connected to the memory layer of four to sixteen memory cells; and

each of the plurality of the second distributed diodes is connected to the memory layer of four to sixteen memory cells.

29. The array of claim 27, wherein the first distributed diode and the second distributed diode of each of the plurality of the memory cells is shared with different memory cells of the plurality of the memory cells.