Patents by Inventor Guirong Liang

Guirong Liang 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: 8526233
    Abstract: In a non-volatile storage system, one or more substrate channel regions for an unselected NAND string are boosted during programming to inhibit program disturb. A voltage applied to one or more unselected word lines associated with at least a first channel region is increased during a program pulse time period in which a program pulse is applied to a selected word line. The increase can be gradual, in the form of a ramp, or step-wise. The boosting level of the first channel region can be maintained. The increase in the voltage applied to the one or more unselected word lines can vary with temperature as well. Before the program pulse time period, the voltage applied to the one or more unselected word lines can be ramped up at a faster rate for a second, adjacent channel region than for the first channel region, to help isolate the channel regions.
    Type: Grant
    Filed: May 23, 2011
    Date of Patent: September 3, 2013
    Assignee: SanDisk Technologies Inc.
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee, Anubhav Khandelwal, Henry Chin, Guirong Liang, Dana Lee
  • Patent number: 8416624
    Abstract: Techniques are presented for use in memory devices to improve reliability and endurance by reducing the widening in state distributions, that occurs after multiple write/erase cycles. One set of techniques uses a pre-conditioning operation where a pulse series, which may include program and gentle erase, are applied to one or more wordlines while a voltage differential is applied in the wordline direction, bitline direction, or both. Another set of techniques uses a dual or multi-pulse program process, where an increased wordline-to-wordline differential used in the first pulse of a pair.
    Type: Grant
    Filed: March 25, 2011
    Date of Patent: April 9, 2013
    Assignee: SanDisk Technologies, Inc.
    Inventors: Bo Lei, Guirong Liang, Anubhav Khandelwal, Jun Wan
  • Publication number: 20130070531
    Abstract: A programming technique which reduces program disturb in a non-volatile storage system is disclosed. A positive voltage may be applied to a substrate (e.g., p-well) during programming. Biasing the substrate may improve boosting of channels of unselected NAND strings, which may reduce program disturb. The substrate may be charged up during the programming operation, and discharged after programming. Therefore, for operations such as verify and read, the substrate may be grounded. In one embodiment, the substrate is charged just prior to applying a program pulse, then discharged prior to a program verify operation. In one embodiment, the substrate is charged while unselected word lines are ramped up to a pass voltage. The substrate bias may depend on program voltage, temperature, and/or hot count.
    Type: Application
    Filed: September 16, 2011
    Publication date: March 21, 2013
    Inventors: Dengtao Zhao, Guirong Liang, Deepanshu Dutta
  • Patent number: 8395936
    Abstract: In a non-volatile storage system, during a verify operation, a verify voltage of a currently-sensed target data state is applied to a selected word line. A higher, nominal bit line voltage is used for the storage elements which have the currently-sensed target data state and a verify status of pass or no pass, a target data state lower than the currently-sensed target data state and a verify status of pass or no pass, or a target data state higher than the currently-sensed target data state and a verify status of pass. A lower bit line voltage is used for the storage elements which have the target data state higher than the currently-sensed target data state and a verify status of no pass, to enhance channel-to-channel coupling, as an offset to floating gate-to-floating gate coupling which is later caused by these storage elements.
    Type: Grant
    Filed: May 9, 2011
    Date of Patent: March 12, 2013
    Assignee: SanDisk Technologies Inc.
    Inventors: Haibo Li, Guirong Liang
  • Publication number: 20120300550
    Abstract: In a non-volatile storage system, one or more substrate channel regions for an unselected NAND string are boosted during programming to inhibit program disturb. A voltage applied to one or more unselected word lines associated with at least a first channel region is increased during a program pulse time period in which a program pulse is applied to a selected word line. The increase can be gradual, in the form of a ramp, or step-wise. The boosting level of the first channel region can be maintained. The increase in the voltage applied to the one or more unselected word lines can vary with temperature as well. Before the program pulse time period, the voltage applied to the one or more unselected word lines can be ramped up at a faster rate for a second, adjacent channel region than for the first channel region, to help isolate the channel regions.
    Type: Application
    Filed: May 23, 2011
    Publication date: November 29, 2012
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee, Anubhav Khandelwal, Henry Chin, Guirong Liang, Dana Lee
  • Publication number: 20120287716
    Abstract: In a non-volatile storage system, during a verify operation, a verify voltage of a currently-sensed target data state is applied to a selected word line. A higher, nominal bit line voltage is used for the storage elements which have the currently-sensed target data state and a verify status of pass or no pass, a target data state lower than the currently-sensed target data state and a verify status of pass or no pass, or a target data state higher than the currently-sensed target data state and a verify status of pass. A lower bit line voltage is used for the storage elements which have the target data state higher than the currently-sensed target data state and a verify status of no pass, to enhance channel-to-channel coupling, as an offset to floating gate-to-floating gate coupling which is later caused by these storage elements.
    Type: Application
    Filed: May 9, 2011
    Publication date: November 15, 2012
    Inventors: Haibo Li, Guirong Liang
  • Publication number: 20110286279
    Abstract: Techniques are presented for use in memory devices to improve reliability and endurance by reducing the widening in state distributions, that occurs after multiple write/erase cycles. One set of techniques uses a pre-conditioning operation where a pulse series, which may include program and gentle erase, are applied to one or more wordlines while a voltage differential is applied in the wordline direction, bitline direction, or both. Another set of techniques uses a dual or multi-pulse program process, where an increased wordline-to-wordline differential used in the first pulse of a pair.
    Type: Application
    Filed: March 25, 2011
    Publication date: November 24, 2011
    Inventors: Bo Lei, Guirong Liang, Anubhav Khandelwal, Jun Wan
  • Publication number: 20050281082
    Abstract: The present invention provides an organic bistable device for use in non-volatile memories. The organic bistable device comprises a first and a second metal electrode sandwiching a first and a second organic layer with a metal-nanocluster layer positioned between the first and second organic layers. The device further comprises a first electron blocking layer positioned between the metal-nanocluster layer and one of the metal electrodes. This structure provides an organic bistable device with improved charge retention characteristics.
    Type: Application
    Filed: June 17, 2004
    Publication date: December 22, 2005
    Inventors: Mamoru Miyawaki, Guirong Liang