Patents by Inventor Jeffrey W. Lutze

Jeffrey W. Lutze has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7161836
    Abstract: The maximum allowable number of voltage programming pulses to program memory elements of a non-volatile memory device is adjusted to account for changes in the memory elements which occur over time. Programming pulses are applied until the threshold voltage of one or more memory elements reaches a certain verify level, after which a defined maximum number of additional pulses may be applied to other memory elements to allow them to also reach associated target threshold voltage levels. The technique enforces a maximum allowable number of programming pulses that can change over time as the memory is cycled.
    Type: Grant
    Filed: August 1, 2005
    Date of Patent: January 9, 2007
    Assignee: Sandisk Corporation
    Inventors: Jun Wan, Jeffrey W. Lutze
  • Patent number: 7154779
    Abstract: A non-volatile memory device has a channel region between source/drain regions, a floating gate, a control gate, a first dielectric region between the channel region and the floating gate, and a second dielectric region between the floating gate and the control gate. The first dielectric region includes a high-K material. The non-volatile memory device is programmed and/or erased by transferring charge between the floating gate and the control gate via the second dielectric region.
    Type: Grant
    Filed: January 21, 2004
    Date of Patent: December 26, 2006
    Assignee: Sandisk Corporation
    Inventors: Nima Mokhlesi, Jeffrey W. Lutze
  • Patent number: 7057931
    Abstract: A method for programming a storage element and a storage element programmed using gate induced junction leakage current are provided. The element may include at least a floating gate on a substrate, an active region in the substrate, and a second gate adjacent to the floating gate. The method may include the steps of: creating an inversion region in the substrate below the floating gate by biasing the first gate; and creating a critical electric field adjacent to the second gate. Creating a critical electric field may comprise applying a first positive bias to the active region; and applying a bias less than the first positive bias to the second gate. The element further includes a first bias greater than zero volts applied to the active region and a second bias greater than the first bias applied to the floating gate and a third bias less than or equal to zero applied to the second gate.
    Type: Grant
    Filed: November 7, 2003
    Date of Patent: June 6, 2006
    Assignee: Sandisk Corporation
    Inventors: Jeffrey W. Lutze, Chan-Sui Pang
  • Patent number: 7049652
    Abstract: An array of a pillar-type nonvolatile memory cells (803) has each memory cell isolated from adjacent memory cells by a trench (810). Each memory cell is formed by a stacking process layers on a substrate: tunnel oxide layer (815), polysilicon floating gate layer (819), ONO or oxide layer (822), polysilicon control gate layer (825). Many aspects of the process are self-aligned. An array of these memory cells will require less segmentation. Furthermore, the memory cell has enhanced programming characteristics because electrons are directed at a normal or nearly normal angle (843) to the floating gate (819).
    Type: Grant
    Filed: December 10, 2003
    Date of Patent: May 23, 2006
    Assignee: SanDisk Corporation
    Inventors: Nima Mokhlesi, Jeffrey W. Lutze
  • Patent number: 7046555
    Abstract: A number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.
    Type: Grant
    Filed: September 17, 2003
    Date of Patent: May 16, 2006
    Assignees: SanDisk Corporation, Kabushiki Kaisha Toshiba
    Inventors: Jeffrey W. Lutze, Jian Chen, Yan Li, Kazunori Kanebako, Tomoharu Tanaka
  • Patent number: 7023737
    Abstract: The maximum allowable number of voltage programming pulses to program memory elements of a non-volatile memory device is adjusted to account for changes in the memory elements which occur over time. Programming pulses are applied until the threshold voltage of one or more memory elements reaches a certain verify level, after which a defined maximum number of additional pulses may be applied to other memory elements to allow them to also reach associated target threshold voltage levels. The technique enforces a maximum allowable number of programming pulses that can change over time as the memory is cycled.
    Type: Grant
    Filed: August 1, 2005
    Date of Patent: April 4, 2006
    Assignee: Sandisk Corporation
    Inventors: Jun Wan, Jeffrey W. Lutze
  • Patent number: 7009889
    Abstract: Systems and methods in accordance with various embodiments can provide for comprehensive erase verification and defect detection in non-volatile semiconductor memory. In one embodiment, the results of erasing a group of storage elements is verified using a plurality of test conditions to better detect defective and/or insufficiently erased storage elements of the group. For example, the results of erasing a NAND string can be verified by testing charging of the string in a plurality of directions with the storage elements biased to turn on if in an erased state. If a string of storage elements passes a first test process or operation but fails a second test process or operation, the string can be determined to have failed the erase process and possibly be defective. By testing charging or conduction of the string in a plurality of directions, defects in any transistors of the string that are masked under one set of conditions may be exposed under a second set of bias conditions.
    Type: Grant
    Filed: May 28, 2004
    Date of Patent: March 7, 2006
    Assignee: Sandisk Corporation
    Inventors: Dat Tran, Kiran Ponnuru, Jian Chen, Jeffrey W. Lutze, Jun Wan
  • Patent number: 6975537
    Abstract: A non-volatile semiconductor memory system (or other type of memory system) is programmed in a manner that avoids program disturb. In one embodiment that includes a flash memory system using a NAND architecture, program disturb is avoided by increasing the channel potential of the source side of the NAND string during the programming process. One exemplar implementation includes applying a voltage (e.g. Vdd) to the source contact and turning on the source side select transistor for the NAND sting corresponding to the cell being inhibited. Another implementation includes applying a pre-charging voltage to the unselected word lines of the NAND string corresponding to the cell being inhibited prior to applying the program voltage.
    Type: Grant
    Filed: February 3, 2005
    Date of Patent: December 13, 2005
    Assignee: Sandisk Corporation
    Inventors: Jeffrey W. Lutze, Jian Chen, Yan Li, Masaaki Higashitani
  • Patent number: 6917542
    Abstract: In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
    Type: Grant
    Filed: July 29, 2003
    Date of Patent: July 12, 2005
    Assignee: Sandisk Corporation
    Inventors: Jian Chen, Yan Li, Jeffrey W. Lutze
  • Patent number: 6914823
    Abstract: In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
    Type: Grant
    Filed: July 29, 2003
    Date of Patent: July 5, 2005
    Assignee: Sandisk Corporation
    Inventors: Jian Chen, Yan Li, Jeffrey W. Lutze
  • Patent number: 6859397
    Abstract: A non-volatile semiconductor memory system (or other type of memory system) is programmed in a manner that avoids program disturb. In one embodiment that includes a flash memory system using a NAND architecture, program disturb is avoided by increasing the channel potential of the source side of the NAND string during the programming process. One exemplar implementation includes applying a voltage (e.g. Vdd) to the source contact and turning on the source side select transistor for the NAND sting corresponding to the cell being inhibited. Another implementation includes applying a pre-charging voltage to the unselected word lines of the NAND string corresponding to the cell being inhibited prior to applying the program voltage.
    Type: Grant
    Filed: March 5, 2003
    Date of Patent: February 22, 2005
    Assignee: SanDisk Corporation
    Inventors: Jeffrey W. Lutze, Jian Chen, Yan Li, Masaaki Higashitani
  • Publication number: 20040174748
    Abstract: A non-volatile semiconductor memory system (or other type of memory system) is programmed in a manner that avoids program disturb. In one embodiment that includes a flash memory system using a NAND architecture, program disturb is avoided by increasing the channel potential of the source side of the NAND string during the programming process. One exemplar implementation includes applying a voltage (e.g. Vdd) to the source contact and turning on the source side select transistor for the NAND sting corresponding to the cell being inhibited. Another implementation includes applying a pre-charging voltage to the unselected word lines of the NAND string corresponding to the cell being inhibited prior to applying the program voltage.
    Type: Application
    Filed: March 5, 2003
    Publication date: September 9, 2004
    Inventors: Jeffrey W. Lutze, Jian Chen, Yan Li, Masaaki Higashitani