Patents Assigned to Sandisk 3D LLC
  • Patent number: 7283414
    Abstract: The preferred embodiments described below provide a method and memory device for improving the precision of a temperature-sensor circuit. In one preferred embodiment, first and second temperature-dependent reference voltages are generated and compared, and an operating condition of the memory array is controlled based on the result of the comparison. Instead of using a temperature-dependent reference voltage, a temperature-dependent reference current can be used. Other embodiments are disclosed, and each of the embodiments can be used alone or together in combination.
    Type: Grant
    Filed: May 24, 2006
    Date of Patent: October 16, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Kenneth So, Ali Al-Shamma
  • Publication number: 20070236981
    Abstract: A nonvolatile memory cell includes a layer of a resistivity-switching metal oxide or nitride compound, the metal oxide or nitride compound including one metal, and a dielectric rupture antifuse formed in series. The dielectric rupture antifuse may be either in its initial, non-conductive state or a ruptured, conductive state. The resistivity-switching metal oxide or nitride layer can be in a higher- or lower-resistivity state. By using both the state of the resistivity-switching layer and the antifuse to store data, more than two bits can be stored per memory cell.
    Type: Application
    Filed: March 31, 2006
    Publication date: October 11, 2007
    Applicant: SanDisk 3D, LLC
    Inventor: S. Herner
  • Patent number: 7280397
    Abstract: A shadow RAM or “non-volatile SRAM” memory cell is implemented in a much smaller area by building the cell upward rather than outward. By stacking non-volatile storage devices above or below an SRAM cell, a smaller cell can be provided and result in a lower cost memory device. In certain embodiments, such a memory cell includes a pair of cross-coupled devices disposed on a first device layer and defining a pair of internal cross-coupled nodes, and a pair of non-volatile storage devices disposed on a second device layer above or below the pair of cross-coupled devices and coupled to the cross-coupled nodes.
    Type: Grant
    Filed: July 11, 2005
    Date of Patent: October 9, 2007
    Assignee: SanDisk 3D LLC
    Inventor: Roy E. Scheuerlein
  • Publication number: 20070228354
    Abstract: A memory cell is described, the memory cell comprising a dielectric rupture antifuse and a layer of a resistivity-switching material arranged electrically in series, wherein the resistivity-switching material is a metal oxide or nitride compound, the compound including exactly one metal. The dielectric rupture antifuse is ruptured in a preconditioning step, forming a rupture region through the antifuse. The rupture region provides a narrow conductive path, serving to limit current to the resistivity-switching material, and improving control when the resistivity-switching layer is switched between higher-and lower-resistivity states.
    Type: Application
    Filed: March 31, 2006
    Publication date: October 4, 2007
    Applicant: SanDisk 3D, LLC
    Inventor: Roy Scheuerlein
  • Publication number: 20070228414
    Abstract: In the present invention a metal oxide or nitride compound which is a wide-band-gap semiconductor abuts a silicon, germanium, or alloy of silicon and/or germanium of the opposite conductivity type to form a p-n heterojunction. This p-n heterojunction can be used to advantage in various devices. In preferred embodiments, one terminal of a vertically oriented p-i-n heterojunction diode is a metal oxide or nitride layer, while the rest of the diode is formed of a silicon or silicon-germanium resistor; for example a diode may include a heavily doped n-type silicon region, an intrinsic silicon region, and a nickel oxide layer serving as the p-type terminal. Many of these metal oxides and nitrides exhibit resistivity-switching behavior, and such a heterojunction diode can be used in a nonvolatile memory cell, for example in a monolithic three dimensional memory array.
    Type: Application
    Filed: March 31, 2006
    Publication date: October 4, 2007
    Applicant: SanDisk 3D, LLC
    Inventors: Tanmay Kumar, S. Herner
  • Patent number: 7277336
    Abstract: A method is provided comprising reading a set of memory cells indicating whether stored redundancy information is reliable and, if the set of memory cells indicates that the stored redundancy information is reliable, determining whether to read primary memory or redundant memory based on the stored redundancy information. Another method is provided comprising reading a set of memory cells associated with a group of memory cells in a primary memory, the set of memory cells indicating whether data can be reliably stored in the group of memory cells; if the set of memory cells indicates that data can be reliably stored in the group of memory cells, storing data in the group of memory cells; and if the set of memory cells does not indicate that data can be reliably stored in the group of memory cells, storing data in a group of memory cells in a redundant memory. In another preferred embodiment, a method for providing memory redundancy is provided.
    Type: Grant
    Filed: December 28, 2004
    Date of Patent: October 2, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Alper Ilkbahar, Derek J. Bosch
  • Patent number: 7277343
    Abstract: The preferred embodiments described below provide a method and memory device for improving the precision of a temperature-sensor circuit. In one preferred embodiment, first and second temperature-dependent reference voltages are generated and compared, and an operating condition of the memory array is controlled based on the result of the comparison. Instead of using a temperature-dependent reference voltage, a temperature-dependent reference current can be used. Other embodiments are disclosed, and each of the embodiments can be used alone or together in combination.
    Type: Grant
    Filed: January 4, 2007
    Date of Patent: October 2, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Kenneth So, Ali Al-Shamma
  • Patent number: 7276403
    Abstract: The present invention relates to use of selective oxidation to oxidize silicon in the presence of tungsten and/or tungsten nitride in memory cells and memory arrays. This technique is especially useful in monolithic three dimensional memory arrays. In one aspect of the invention, the silicon of a diode-antifuse memory cell is selectively oxidized to repair etch damage and reduce leakage, while exposed tungsten of adjacent conductors and tungsten nitride of a barrier layer are not oxidized. In some embodiments, selective oxidation may be useful for gap fill. In another aspect of the invention, TFT arrays made up of charge storage memory cells comprising a polysilicon/tungsten nitride/tungsten gate can be subjected to selective oxidation to passivate the gate polysilicon and reduce leakage.
    Type: Grant
    Filed: September 28, 2005
    Date of Patent: October 2, 2007
    Assignee: Sandisk 3D LLC
    Inventor: S. Brad Herner
  • Patent number: 7272052
    Abstract: A decoding circuit for non-binary groups of memory line drivers is disclosed. In one embodiment, an integrated circuit is disclosed comprising a binary decoder and circuitry operative to perform a non-binary arithmetic operation, wherein a result of the non-binary arithmetic operation is provided as input to the binary decoder. In another embodiment, an integrated circuit is disclosed comprising a memory array comprising a plurality of array lines, a non-integral-power-of-two number of array line driver circuits, and control circuitry configured to select one of the array line driver circuits. The control circuitry can comprise a binary decoder and a pre-decoder portion that performs a non-binary arithmetic operation. The concepts described herein may be used alone or in combination.
    Type: Grant
    Filed: June 7, 2005
    Date of Patent: September 18, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Roy E. Scheuerlein, Christopher J. Petti, Luca G. Fasoli
  • Patent number: 7265049
    Abstract: The invention is a chemically grown oxide layer which prevents dopant diffusion between semiconductor layers. The chemically grown oxide layer may be so thin that it does not form a barrier to electrical conduction, and thus may be formed within active devices such as diodes or bipolar transistors. Such a chemically grown oxide film is advantageously used to prevent dopant diffusion in a vertically oriented polysilicon diode formed in a monolithic three dimensional memory array.
    Type: Grant
    Filed: August 31, 2005
    Date of Patent: September 4, 2007
    Assignee: SanDisk 3D LLC
    Inventors: S. Brad Herner, Victoria L. Eckert
  • Patent number: 7265000
    Abstract: A very high density field programmable memory is disclosed. An array is formed vertically above a substrate using several layers, each layer of which includes vertically fabricated memory cells. The cell in an N level array may be formed with N+1 masking steps plus masking steps needed for contacts. Maximum use of self alignment techniques minimizes photolithographic limitations. In one embodiment the peripheral circuits are formed in a silicon substrate and an N level array is fabricated above the substrate.
    Type: Grant
    Filed: February 14, 2006
    Date of Patent: September 4, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Vivek Subramanian, James M. Cleeves
  • Patent number: 7250646
    Abstract: There is provided a monolithic three dimensional TFT mask ROM array. The array includes a plurality of device levels. Each of the plurality of device levels contains a first set of enabled TFTs and a second set of partially or totally disabled TFTs.
    Type: Grant
    Filed: October 18, 2004
    Date of Patent: July 31, 2007
    Assignee: Sandisk 3D, LLC.
    Inventors: Andrew J. Walker, Christopher Petti
  • Patent number: 7243203
    Abstract: The embodiments herein describe a memory device and method for reading and writing data. In one embodiment, a memory device is provided comprising a memory array and first and second data buffers in communication with the memory array. The second data buffer comprises a larger storage capacity than the first data buffer. During a write operation, data is stored in the second data buffer and then stored in the memory array. During a read operation, data is read from the memory array and then stored in the first data buffer but not in the second data buffer. Because the smaller-storage-capacity buffer takes less time to fill than the larger-storage-capacity buffer, there is less of a delay in outputting data from the memory device as compared to memory devices that use a larger-storage-capacity buffer for both read and write operations. Other embodiments are provided, and each of the embodiments can be used alone or in combination with one another.
    Type: Grant
    Filed: June 13, 2003
    Date of Patent: July 10, 2007
    Assignee: SanDisk 3D LLC
    Inventor: Roy E. Scheuerlein
  • Patent number: 7238607
    Abstract: When chemical mechanical planarization (CMP) is used to planarize a surface coexposing patterned features and dielectric fill, where patterned features and the fill are formed of materials having very different CMP removal rates or characteristics, the planarized surface may have excessively rough, dishing or recessing may take place, or one or more or the materials may be damaged. In structures in which planarity is important, these problems can be prevented by forming a capping layer on the patterned features, wherein the CMP removal rate of the material forming the capping layer is similar to the CMP removal rate of the dielectric fill.
    Type: Grant
    Filed: September 28, 2005
    Date of Patent: July 3, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Samuel V. Dunton, S. Brad Herner
  • Patent number: 7236023
    Abstract: Apparatus and methods are described for providing an adaptive trip point detector circuit that receives an input signal at an input signal node and generates an output signal at an output signal node, the output signal changing from a first value to a second value when the input signal exceeds a trip point reference value. In particular, the trip point reference value is adjusted to compensate for variations in process or temperature, without requiring an externally-supplied reference signal.
    Type: Grant
    Filed: April 14, 2005
    Date of Patent: June 26, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Tyler J. Thorp, Mark G. Johnson, Brent Haukness
  • Patent number: 7233024
    Abstract: A three-dimensional (3D) high density memory array includes multiple layers of segmented bit lines (i.e., sense lines) with segment switch devices within the memory array that connect the segments to global bit lines. The segment switch devices reside on one or more layers of the integrated circuit, preferably residing on each bit line layer. The global bit lines reside preferably on one layer below the memory array, but may reside on more than one layer. The bit line segments preferably share vertical connections to an associated global bit line. In certain EEPROM embodiments, the array includes multiple layers of segmented bit lines with segment connection switches on multiple layers and shared vertical connections to a global bit line layer. Such memory arrays may be realized with much less write-disturb effects for half selected memory cells, and may be realized with a much smaller block of cells to be erased.
    Type: Grant
    Filed: March 31, 2003
    Date of Patent: June 19, 2007
    Assignee: SanDisk 3D LLC
    Inventors: Roy E. Scheuerlein, Alper Ilkbahar, Luca Fasoli
  • Patent number: 7233522
    Abstract: An exemplary NAND string memory array provides for capacitive boosting of a half-selected memory cell channel to reduce program disturb effects of the half selected cell. To reduce the effect of leakage current degradation of the boosted level, multiple programming pulses of a shorter duration are employed to limit the time period during which such leakage currents may degrade the voltage within the unselected NAND strings. In addition, multiple series select devices at one or both ends of each NAND string further ensure reduced leakage through such select devices, for both unselected and selected NAND strings. In certain exemplary embodiments, a memory array includes series-connected NAND strings of memory cell transistors having a charge storage dielectric, and includes more than one plane of memory cells formed above a substrate.
    Type: Grant
    Filed: December 5, 2003
    Date of Patent: June 19, 2007
    Assignee: SanDisk 3D LLC
    Inventors: En-Hsing Chen, Andrew J. Walker, Roy E. Scheuerlein, Sucheta Nallamothu, Alper Ilkbahar, Luca G. Fasoli
  • Patent number: 7227188
    Abstract: A method to enhance grain size in polysilicon films while avoiding formation of hemispherical grains (HSG) is disclosed. The method begins by depositing a first amorphous silicon film, then depositing silicon nuclei, which will act as nucleation sites, on the amorphous film. After deposition of silicon nuclei, crystallization, and specifically HSG, is prevented by lowering temperature and/or raising pressure. Next a second amorphous silicon layer is deposited over the first layer and the nuclei. Finally an anneal is performed to induce crystallization from the embedded nuclei. Thus grains are formed from the silicon bulk, rather than from the surface, HSG is avoided, and a smooth polysilicon film with enhanced grain size is produced.
    Type: Grant
    Filed: January 29, 2004
    Date of Patent: June 5, 2007
    Assignee: Sandisk 3D LLC
    Inventor: Shuo Gu
  • Patent number: 7224013
    Abstract: The invention provides for a junction diode including a heavily doped first region having a first conductivity type, a second lightly doped or intrinsic region having a second conductivity type, and a third heavily doped region having a second conductivity type. The junction diode comprises more than one semiconductor or semiconductor alloy. In preferred embodiments, the lightly doped or intrinsic region has a higher proportion of germanium than on or the other or both of the heavily doped regions. In preferred embodiments, the junction diode is vertically oriented, and the top region has a higher proportion of silicon than the other regions.
    Type: Grant
    Filed: September 29, 2004
    Date of Patent: May 29, 2007
    Assignee: Sandisk 3D LLC
    Inventors: S. Brad Herner, Andrew J. Walker
  • Publication number: 20070114509
    Abstract: Oxides of both nickel and cobalt have lower resistivity than either nickel oxide or cobalt oxide. Nickel oxide and cobalt oxide can be reversibly switched between two or more stable resistivity states by application of suitable electrical pulses. It is expected that oxides including both nickel and cobalt, or (NixCoy)O, will switch between resistivity states at lower voltage and/or current than will nickel oxide or cobalt oxide. A layer of (NixCoy)O can be paired with a diode or transistor to form a nonvolatile memory cell.
    Type: Application
    Filed: May 24, 2006
    Publication date: May 24, 2007
    Applicant: SanDisk 3D LLC
    Inventor: S. Herner