Magnetic random access memory (MRAM) array with magnetic tunnel junction (MTJ) cells and remote diodes

{
  "publication_number": "US6097625A",
  "country": "US",
  "kind": "A",
  "title": "Magnetic random access memory (MRAM) array with magnetic tunnel junction (MTJ) cells and remote diodes",
  "abstract": "A nonvolatile memory cell includes a substrate, a diode, a first conductive line, a magnetic tunnel junction device, a by-pass conductor and a second conductive line. The diode is formed in the substrate and includes an n-type region and a p-type region. The first conductive line is formed on the substrate and is electrically connected to the n-type region of the diode. The magnetic tunnel junction device is formed on the first conductive line. The by-pass conductor electrically connects the p-type region of the diode to the magnetic tunnel junction device. The second conductive line is formed on and is electrically connected to the magnetic tunnel junction device.",
  "claims": [
    "1. A nonvolatile memory cell, comprising: a substrate; an isolation device formed in the substrate, the isolation device including at least a first region and a second region in the substrate; a first conductive line formed on the substrate; a magnetic tunnel junction device formed over the first conductive line; a by-pass conductor electrically connecting the first region of the isolation device to the magnetic tunnel junction device; and a second conductive line formed on and being electrically connected to the magnetic tunnel junction device.",
    "2. The nonvolatile memory cell according to claim 1, wherein the isolation device is a diode, and wherein the second region is electrically connected to the first conductive line.",
    "3. The nonvolatile memory cell according to claim 2, wherein the first region is a p-type region and the second region is an n-type region.",
    "4. The nonvolatile memory cell according to claim 2, wherein the first region is an n-type region and the second region is a p-type region.",
    "5. The nonvolatile memory cell according to claim 2, further comprising a region of polysilicon gate material formed on the diode below the first conductive line.",
    "6. The nonvolatile memory cell according to claim 2, wherein the by-pass conductor is connected to the first region of the diode below the first conductive line.",
    "7. The nonvolatile memory cell according to claim 2, wherein the by-pass conductor is formed using a lithographic technique.",
    "8. The nonvolatile memory cell according to claim 2, wherein the by-pass conductor is formed using a sidewall deposition technique.",
    "9. The nonvolatile memory cell according to claim 2, wherein the nonvolatile memory cell is about 1.6 μm or less by about 1.92 μm or less in size.",
    "10. The nonvolatile memory cell according to claim 1, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a drain region, the second region is a source region that is electrically connected to the first conductive line, and the metal-oxide semiconductor transistor includes a gate region that is electrically connected to the by-pass conductor.",
    "11. The nonvolatile memory cell according to claim 1, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a source region, the second region is a drain region that is electrically connected to the first conductive, line, and the metal-oxide semiconductor transistor includes a gate region that is electrically connected to the first conductive line.",
    "12. The nonvolatile memory cell according to claim 1, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a drain region and the second region is a source region that is electrically connected to a ground potential, the metal-oxide semiconductor transistor further including a gate region that is electrically connected to a control line.",
    "13. The nonvolatile memory cell according to claim 12, further comprising: a reference resistor corresponding to the nonvolatile memory cell; and an amplifier having a first input and a second input, the first input being electrically connected to the second conductive line, the second input being electrically connected to the reference resistor, the amplifier outputting a signal related to a sensed resistance of the magnetic tunnel junction device with respect to a sensed resistance of the reference resistor.",
    "14. A nonvolatile memory cell array, comprising: a substrate; a plurality of first conductive lines, each first conductive line being formed on the substrate; a plurality of second conductive lines overlapping the first conductive lines at a plurality of intersection regions; and a plurality of nonvolatile memory cells, a nonvolatile memory cell being formed at an intersection region, each nonvolatile memory cell including, an isolation device formed in the substrate, the isolation device including a first region and a second region in the substrate; a magnetic tunnel junction device formed over the first conductive line; a by-pass conductor electrically connecting the first region of the isolation device to the magnetic tunnel junction device; and a second conductive line of the plurality of second conductive lines being formed on and being electrically connected to the magnetic tunnel junction device.",
    "15. The nonvolatile memory cell array according to claim 14, wherein the isolation device is a diode, and the second region is electrically connected to a first conductive line of the plurality of first conductive lines.",
    "16. The nonvolatile memory cell array according to claim 15, wherein the first region is a p-type region and the second region is an n-type region.",
    "17. The nonvolatile memory cell array according to claim 15, wherein the first region is an n-type region and the second region is a p-type region.",
    "18. The nonvolatile memory cell array according to claim 15, wherein the nonvolatile memory cell includes a region of polysilicon gate material formed on the diode below the first conductive line.",
    "19. The nonvolatile memory cell array according to claim 15, wherein the by-pass conductor is connected to the first region of the diode below the first conductive line.",
    "20. The nonvolatile memory cell array according to claim 15, wherein the by-pass conductor is formed using a lithographic technique.",
    "21. The nonvolatile memory cell array according to calling 15, wherein the by-pass conductor is formed using a sidewall deposition technique.",
    "22. The nonvolatile memory cell array according to claim 15, wherein the nonvolatile memory cell is about 1.6 μm or less by about 1.92 μm or less in size.",
    "23. The nonvolatile memory cell array according to claim 14, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a drain region, the second region is a source region that is electrically connected to a first conductive line of the plurality of first conductive lines, and the metal-oxide semiconductor transistor includes a gate region that is electrically connected to the by-pass conductor.",
    "24. The nonvolatile memory cell array according to claim 14, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a source region, the second region is a drain region that is electrically connected to a first conductive line of the plurality of first conductive lines, and the metal-oxide semiconductor transistor includes a gate region that is electrically connected to the first conductive line.",
    "25. The nonvolatile memory cell array according to claim 14, wherein the isolation device is a metal-oxide semiconductor transistor, the first region is a drain region and the second region is a source region that is electrically connected to a ground potential, the metal-oxide semiconductor transistor further including a gate region that is electrically connected to a control line.",
    "26. The nonvolatile memory cell array according to claim 25, further comprising: a reference resistor corresponding to the nonvolatile memory cell; and an amplifier having a first input and a second input, the first input being electrically connected to the second conductive line, the second input being electrically connected to the reference resistor, the amplifier outputting a signal related to a sensed resistance of the magnetic tunnel junction device with respect to a sensed resistance of the reference resistor."
  ],
  "description_excerpt": "The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms provided for by the terms of contract No. MDS 972-96-C0014 awarded by the Advanced Research Projects Agency.\n\n1. Field of the Invention\n\nThe present invention relates to the field of data storage. More particularly, the present invention relates to a physical configuration of a magnetic tunnel junction (MTJ) device memory cell.\n\n2. Description of the Related Art\n\nU.S. Pat. No. 5,640,343 to Gallagher et al. discloses two configurations of a magnetic tunnel junction (MTJ) device memory cell. The first configuration, shown in FIGS. 1B and 1C of U.S. Pat. No. 5,640,343, represents an ideal cross point array structure that uses a thin film diode. The second configuration, shown in FIGS. 10A-10C, includes a buried row line that uses a single crystal silicon diode, but requires an additional global row line to be formed on top of the memory cell.\n\nThe quality of thin film diodes limits the first configuration to low sense currents and, consequently, a slower operational performance. The second configuration has a large spacing between the global row line and the magnetic element that requires a larger current through the row line when writing the cell than that through the row line of the first configuration.",
  "cpc": [
    "G11C 11/15",
    "H10B 69/00"
  ],
  "ipc": [
    "G11C 11/15",
    "H10B 69/00"
  ],
  "assignees": [
    "International Business Machines Corp"
  ],
  "inventors": [
    "Roy Edwin Scheuerlein"
  ],
  "filing_date": "1998-07-16",
  "publication_date": "2000-08-01",
  "grant_date": "2000-08-01",
  "priority_date": "1998-07-16",
  "application_number": "US-11626198-A",
  "family_id": "22366141",
  "cited_by_count": 157,
  "citations": [
    "US5361226A",
    "US5347485A",
    "US5448515A",
    "US5640343A",
    "US5793697A",
    "US5768181A"
  ]
}