Memory elements and cross point switches and arrays of same using nonvolatile nanotube blocks

• US 7,835,170 B2
• Filed: 08/08/2007
• Issued: 11/16/2010
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: Nantero Incorporated
• Original Assignee: Nantero Incorporated
• Inventors: Bertin, Claude L., Sivarajan, Ramesh, Rueckes, Thomas, Huang, X. M. Henry
• Primary Examiner(s): Nguyen; Dang T
• Assistant Examiner(s): Sofocleous; Alexander
• Application Number:
  US11/835,613
• Publication Number:
  US 20080142850A1
• Time in Patent Office: 1,196 Days
• Field of Search: 365/148, 365/151, 977/943
• 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 13/0002 using resistive RAM [RRAM] elements
• CPC Class Codes: G11C 13/0021 Auxiliary circuits
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• 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 17/165 Memory cells which are electrically programmed to cause a change in resistance, e.g. to permit multiple resistance steps to be programmed rather than conduct to or from non-conduct change of fuses and antifuses digital stores using resistance random access memory elements G11C13/0002
• 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 2213/35 Material including carbon, e.g. graphite, grapheme
• CPC Class Codes: G11C 2213/77 Array wherein the memory element being directly connected to the bit lines and word lines without any access device being used
• CPC Class Codes: G11C 2213/79 Array wherein the access device being a transistor
• CPC Class Codes: G11C 2213/82 Array having, for accessing a cell, a word line, a bit line and a plate or source line receiving different potentials
• CPC Class Codes: G11C 5/063 Voltage and signal distribution in integrated semi-conductor memory access lines, e.g. word-line, bit-line, cross-over resistance, propagation delay
• CPC Class Codes: H01L 27/10 including a plurality of individual components in a repetitive configuration
• CPC Class Codes: H01L 27/105 including field-effect components
• CPC Class Codes: H01L 29/0665 the shape of the body defining a nanostructure nanotechnology per se B82B
• CPC Class Codes: H01L 29/0669 Nanowires or nanotubes carbon nanotubes as material of solid-state device active part H10K85/211
• CPC Class Codes: H01L 29/0673 oriented parallel to a substrate
• CPC Class Codes: H10B 20/00 : Read-only memory [ROM] devices
• CPC Class Codes: H10B 99/00 : Subject matter not provided for in other groups of this subclass
• CPC Class Codes: H10K 10/50 : Bistable switching devices
• CPC Class Codes: H10K 85/221 : Carbon nanotubes
• CPC Class Codes: Y10S 977/943 : Information storage or retrieval using nanostructure

Abstract

Under one aspect, a covered nanotube switch includes: (a) a nanotube element including an unaligned plurality of nanotubes, the nanotube element having a top surface, a bottom surface, and side surfaces; (b) first and second terminals in contact with the nanotube element, wherein the first terminal is disposed on and substantially covers the entire top surface of the nanotube element, and wherein the second terminal contacts at least a portion of the bottom surface of the nanotube element; and (c) control circuitry capable of applying electrical stimulus to the first and second terminals. The nanotube element can switch between a plurality of electronic states in response to a corresponding plurality of electrical stimuli applied by the control circuitry to the first and second terminals. For each different electronic state, the nanotube element provides an electrical pathway of different resistance between the first and second terminals.

Claims

1. A covered nanotube switch, comprising:

(a) a nanotube element comprising a nanotube fabric, the nanotube element having a top surface, a bottom surface, and a plurality of side surfaces;

(b) first and second conductive terminals in contact with the nanotube element, wherein the first conductive terminal is disposed on and substantially covering the entire top surface of the nanotube element, and wherein the second conductive terminal contacts at least a portion of the bottom surface of the nanotube element; and

(c) control circuitry in electrical communication with and capable of applying electrical stimulus to the first and second conductive terminals,

wherein the nanotube element is capable of switching between a plurality of electronic states in response to a corresponding plurality of electrical stimuli applied by the control circuitry to the first and second conductive terminals, and

wherein, for each different electronic state of the plurality of electronic states, the nanotube element provides an electrical pathway of corresponding different resistance between the first and second conductive terminals.

2. The covered nanotube switch of claim 1, wherein the first conductive terminal is also disposed on and substantially covers at least one side surface of the plurality of side surfaces.

3. The covered nanotube switch of claim 1, wherein the first conductive terminal is also disposed on and substantially covers the plurality of side surfaces.

4. The covered nanotube switch of claim 3, further comprising an insulator layer in contact with the bottom surface of the nanotube element, the insulator layer and the second conductive terminal together substantially covering the entire bottom surface of the nanotube element.

5. The covered nanotube switch of claim 1, further comprising an insulator layer in contact with at least one of the bottom surface of the nanotube element and one of the side surfaces of the nanotube element.

6. The covered nanotube switch of claim 5, wherein the insulator layer comprises one of SiO₂, SiN, and Al₂O₃.

7. The covered nanotube switch of claim 1, further comprising a passivation layer overlying at least the first conductive terminal, the passivation layer substantially sealing the first and second conductive terminals and the nanotube element to the environment.

8. The covered nanotube switch of claim 7, wherein the passivation layer comprises one of SiO₂, SiN, Al₂O₃, polyimide, phosphosilicate glass oxide, polyvinylidine fluoride, polypropylene carbonate, and polyethylene carbonate.

9. The covered nanotube switch of claim 1, wherein the second conductive terminal contacts substantially the entire bottom surface of the nanotube element.

10. The covered nanotube switch of claim 1, wherein the first and second conductive terminals each comprise a conductive material independently selected from the group consisting of Ru, Ti, Cr, Al, Al(Cu), Au, Pd, Pt, Ni, Ta, W, Cu, Mo, Ag, In, Ir, Pb, Sn, TiAu, TiCu, TiPd, PbIn, TiW, RuN, RuO, TiN, TaN, CoSi_x, and TiSi_x.

11. A covered nanotube switch, comprising:

(a) a nanotube element comprising a nanotube fabric, the nanotube element having top and bottom surfaces;

(b) first and second conductive terminals in contact with the nanotube element and in spaced relation to each other;

(c) a first insulator layer in contact with the top surface of the nanotube element;

(d) a second insulator layer in contact with the bottom surface of the nanotube element,

wherein the first and second conductive terminals and the first and second insulator layers together substantially surround the nanotube element; and

(e) control circuitry in electrical communication with and capable of applying electrical stimulus to the first and second conductive terminals,

wherein the nanotube element is capable of switching between a plurality of electronic states in response to a corresponding plurality of electrical stimuli applied by the control circuitry to the first and second conductive terminals, and

wherein, for each different electronic state of the plurality of electronic states, the nanotube element provides an electrical pathway of corresponding different resistance between the first and second conductive terminals.

12. The covered nanotube switch of claim 11, wherein at least a portion of the first insulator layer is separated from the top surface of the nanotube element by a gap.

13. The covered nanotube switch of claim 12, further wherein at least a portion of the second insulator layer is separated from the bottom surface of the nanotube element by a gap.

14. The covered nanotube switch of claim 11, wherein the first and second conductive terminals contact the bottom surface of the nanotube element and wherein the first insulator layer contacts the entire top surface of the nanotube element.

15. The covered nanotube switch of claim 11, wherein the first and second conductive terminals contact the top surface of the nanotube element.

16. The covered nanotube switch of claim 11, wherein the first conductive terminal contacts the bottom surface of the nanotube element and the second conductive terminal contacts the top surface of the nanotube element.

17. The covered nanotube switch of claim 11, wherein the first and second insulator layers each comprise an insulative material independently selected from the group consisting of SiO₂, SiN, and Al₂O₃.

18. The covered nanotube switch of claim 11, wherein the first and second conductive terminals each comprise a conductive material independently selected from the group consisting of Ru, Ti, Cr, Al, Al(Cu), Au, Pd, Pt, Ni, Ta, W, Cu, Mo, Ag, In, Ir, Pb, Sn, TiAu, TiCu, TiPd, PbIn, TiW, RuN, RuO, TiN, TaN, CoSi_x, and TiSi_x.

19. A covered nanotube switch, comprising:

(a) a nanotube element comprising a nanotube fabric, the nanotube element having top and bottom surfaces;

(b) first and second conductive terminals in contact with the nanotube element and in spaced relation to each other;

(c) a first insulator layer arranged over and in spaced relation to the top surface of the nanotube element;

(d) a second insulator layer arranged under and in spaced relation to the bottom surface of the nanotube element,

wherein the first and second conductive terminals and the first and second insulator layers together substantially surround the nanotube element; and

(e) control circuitry in electrical communication with and capable of applying electrical stimulus to the first and second conductive terminals,

wherein the nanotube element is capable of switching between a plurality of electronic states in response to a corresponding plurality of electrical stimuli applied by the control circuitry to the first and second conductive terminals, and

wherein, for each different electronic state of the plurality of electronic states, the nanotube element provides an electrical pathway of corresponding different resistance between the first and second conductive terminals.

20. The covered nanotube switch of claim 19, wherein the first and second insulator layers each comprise an insulative material independently selected from the group consisting of SiO₂, SiN, and Al₂O₃.

21. The covered nanotube switch of claim 19, wherein the first and second conductive terminals each comprise a conductive material independently selected from the group consisting of Ru, Ti, Cr, Al, Al(Cu), Au, Pd, Pt, Ni, Ta, W, Cu, Mo, Ag, In, Ir, Pb, Sn, TiAu, TiCu, TiPd, PbIn, TiW, RuN, RuO, TiN, TaN, CoSi_x, and TiSi_x.