Patents by Inventor Shih-Chung Lee

Shih-Chung Lee 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: 7599224
    Abstract: Coarse/fine programming of non-volatile memory is provided in which memory cells are programmed at a first rate of programming prior to reaching a coarse verify level for their intended state and a second rate of programming after reaching the coarse verify level but before reaching the final verify level for their intended state. Large sub-threshold swing factors associated with smaller memory cells can affect the accuracy of sense operations, particularly when sensing at a fine verify level after sensing at a coarse verify level without pre-charging the bit line between the different sensings. Different reference potentials are utilized when sensing at a coarse verify level and a final verify level. The different between the reference potentials can compensate for any discharge of the bit line during the coarse level sensing.
    Type: Grant
    Filed: July 3, 2007
    Date of Patent: October 6, 2009
    Assignee: SanDisk Corporation
    Inventor: Shih-Chung Lee
  • Patent number: 7596031
    Abstract: A coarse/fine programming technique is used for programming to lower states while using a standard technique (not coarse/fine programming) for programming to the highest state(s). However, when the programming of the lower states is finished, a number of programming pulses are still needed to program the highest state. To improve the programming speed, a bigger step size and longer programming pulse can be used from the moment that the lowest states have been programmed. At the same time, the programming technique for the highest state can be changed to a coarse/fine programming technique.
    Type: Grant
    Filed: October 30, 2006
    Date of Patent: September 29, 2009
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee
  • Patent number: 7508715
    Abstract: Coarse/fine programming of non-volatile memory is provided in which memory cells are programmed at a first rate of programming prior to reaching a coarse verify level for their intended state and a second rate of programming after reaching the coarse verify level but before reaching the final verify level for their intended state. Large sub-threshold swing factors associated with smaller memory cells can affect the accuracy of sense operations, particularly when sensing at a fine verify level after sensing at a coarse verify level without pre-charging the bit line between the different sensings. Different reference potentials are utilized when sensing at a coarse verify level and a final verify level. The different between the reference potentials can compensate for any discharge of the bit line during the coarse level sensing.
    Type: Grant
    Filed: July 3, 2007
    Date of Patent: March 24, 2009
    Assignee: SanDisk Corporation
    Inventor: Shih-Chung Lee
  • Publication number: 20090010067
    Abstract: Coarse/fine programming of non-volatile memory is provided in which memory cells are programmed at a first rate of programming prior to reaching a coarse verify level for their intended state and a second rate of programming after reaching the coarse verify level but before reaching the final verify level for their intended state. Large sub-threshold swing factors associated with smaller memory cells can affect the accuracy of sense operations, particularly when sensing at a fine verify level after sensing at a coarse verify level without pre-charging the bit line between the different sensings. Different reference potentials are utilized when sensing at a coarse verify level and a final verify level. The different between the reference potentials can compensate for any discharge of the bit line during the coarse level sensing.
    Type: Application
    Filed: July 3, 2007
    Publication date: January 8, 2009
    Inventor: Shih-Chung Lee
  • Publication number: 20090010068
    Abstract: Coarse/fine programming of non-volatile memory is provided in which memory cells are programmed at a first rate of programming prior to reaching a coarse verify level for their intended state and a second rate of programming after reaching the coarse verify level but before reaching the final verify level for their intended state. Large sub-threshold swing factors associated with smaller memory cells can affect the accuracy of sense operations, particularly when sensing at a fine verify level after sensing at a coarse verify level without pre-charging the bit line between the different sensings. Different reference potentials are utilized when sensing at a coarse verify level and a final verify level. The different between the reference potentials can compensate for any discharge of the bit line during the coarse level sensing.
    Type: Application
    Filed: July 3, 2007
    Publication date: January 8, 2009
    Inventor: Shih-Chung Lee
  • Patent number: 7466590
    Abstract: A low voltage (e.g. of the order of or one to three volts) instead of an intermediate VPASS voltage (e.g. of the order of five to ten volts) is applied to word line zero immediately adjacent to the source or drain side select gate of a flash device such as a NAND flash device and one or more additional word lines next to such word line to reduce or prevent the shifting of threshold voltage of the memory cells coupled to word line zero during the programming cycles of the different cells of the NAND strings. This may be implemented in any one of a variety of different self boosting schemes including erased areas self boosting and local self boosting schemes. In a modified erased area self boosting scheme, low voltages are applied to two or more word lines on the source side of the selected word line to reduce band-to-band tunneling and to improve the isolation between two boosted channel regions.
    Type: Grant
    Filed: December 28, 2005
    Date of Patent: December 16, 2008
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Hironobu Nakao, Shih-Chung Lee
  • Patent number: 7463522
    Abstract: Non-volatile storage in which program disturb is reduced by preventing source side boosting in selected NAND strings. A self-boosting mode which includes an isolation word line is used. A channel area of an inhibited NAND string is boosted on a source side of the isolation word line before the channel is boosted on a drain side of the isolation word line. Further, storage elements near the isolation word line are kept in a conducting state during the source side boosting so that the source side channel is connected to the drain side channel. In this way, in selected NAND strings, source side boosting can not occur and thus program disturb due to source side boosting can be prevented. After the source side boosting, the source side channel is isolated from the drain side channel, and drain side boosting is performed.
    Type: Grant
    Filed: May 7, 2007
    Date of Patent: December 9, 2008
    Assignee: SanDisk Corporation
    Inventors: Yingda Dong, Jeffrey W. Lutze, Shih-Chung Lee, Gerrit Jan Hemink, Ken Oowada
  • Patent number: 7460404
    Abstract: Program disturb is reduced in non-volatile storage by preventing source side boosting in selected NAND strings. A self-boosting mode which includes an isolation word line is used. A channel area of an inhibited NAND string is boosted on a source side of the isolation word line before the channel is boosted on a drain side of the isolation word line. Further, storage elements near the isolation word line are kept in a conducting state during the source side boosting so that the source side channel is connected to the drain side channel. In this way, in selected NAND strings, source side boosting can not occur and thus program disturb due to source side boosting can be prevented. After the source side boosting, the source side channel is isolated from the drain side channel, and drain side boosting is performed.
    Type: Grant
    Filed: May 7, 2007
    Date of Patent: December 2, 2008
    Assignee: SanDisk Corporation
    Inventors: Yingda Dong, Jeffrey W. Lutze, Shih-Chung Lee, Gerrit Jan Hemink, Ken Oowada
  • Publication number: 20080279007
    Abstract: Program disturb is reduced in non-volatile storage by preventing source side boosting in selected NAND strings. A self-boosting mode which includes an isolation word line is used. A channel area of an inhibited NAND string is boosted on a source side of the isolation word line before the channel is boosted on a drain side of the isolation word line. Further, storage elements near the isolation word line are kept in a conducting state during the source side boosting so that the source side channel is connected to the drain side channel. In this way, in selected NAND strings, source side boosting can not occur and thus program disturb due to source side boosting can be prevented. After the source side boosting, the source side channel is isolated from the drain side channel, and drain side boosting is performed.
    Type: Application
    Filed: May 7, 2007
    Publication date: November 13, 2008
    Inventors: Yingda Dong, Jeffrey W. Lutze, Shih-Chung Lee, Gerrit Jan Hemink, Ken Oowada
  • Publication number: 20080279008
    Abstract: Non-volatile storage in which program disturb is reduced by preventing source side boosting in selected NAND strings. A self-boosting mode which includes an isolation word line is used. A channel area of an inhibited NAND string is boosted on a source side of the isolation word line before the channel is boosted on a drain side of the isolation word line. Further, storage elements near the isolation word line are kept in a conducting state during the source side boosting so that the source side channel is connected to the drain side channel. In this way, in selected NAND strings, source side boosting can not occur and thus program disturb due to source side boosting can be prevented. After the source side boosting, the source side channel is isolated from the drain side channel, and drain side boosting is performed.
    Type: Application
    Filed: May 7, 2007
    Publication date: November 13, 2008
    Inventors: Yingda Dong, Jeffrey W. Lutze, Shih-Chung Lee, Gerrit Jan Hemink, Ken Oowada
  • Publication number: 20080137432
    Abstract: In a non-volatile memory system, the programming time period allocated for the program pulse is adjusted as a function of the voltage level of the pump pulse required so that the total number of pump pulses required to program the charge storage element to the required threshold voltage is reduced. For example, programming time period may be increased with an increase in the voltage level of the pump pulse required. This allows the programming time period of the program pulse to be increased to a value that compensates for the increased charge-up time that is required for the higher amplitude program pulses to reach the desired programming voltage.
    Type: Application
    Filed: January 24, 2008
    Publication date: June 12, 2008
    Inventors: Shih-Chung Lee, Toru Miwa
  • Publication number: 20080101126
    Abstract: A coarse/fine programming technique is used for programming to lower states while using a standard technique (not coarse/fine programming) for programming to the highest state(s). However, when the programming of the lower states is finished, a number of programming pulses are still needed to program the highest state. To improve the programming speed, a bigger step size and longer programming pulse can be used from the moment that the lowest states have been programmed. At the same time, the programming technique for the highest state can be changed to a coarse/fine programming technique.
    Type: Application
    Filed: October 30, 2006
    Publication date: May 1, 2008
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee
  • Publication number: 20080084747
    Abstract: A non-volatile semiconductor storage system is programmed in a manner that reduces program disturb by applying a higher boosting voltage on one or more word lines that are connected non-volatile storage elements that may be partially programmed.
    Type: Application
    Filed: September 27, 2006
    Publication date: April 10, 2008
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee
  • Publication number: 20080084748
    Abstract: A non-volatile semiconductor storage system is programmed in a manner that reduces program disturb by applying a higher boosting voltage on one or more word lines that are connected non-volatile storage elements that may be partially programmed.
    Type: Application
    Filed: September 27, 2006
    Publication date: April 10, 2008
    Inventors: Gerrit Jan Hemink, Shih-Chung Lee
  • Patent number: 7330373
    Abstract: In a non-volatile memory system, the programming time period allocated for the program pulse is adjusted as a function of the voltage level of the pump pulse required so that the total number of pump pulses required to program the charge storage element to the required threshold voltage is reduced. For example, programming time period may be increased with an increase in the voltage level of the pump pulse required. This allows the programming time period of the program pulse to be increased to a value that compensates for the increased charge-up time that is required for the higher amplitude program pulses to reach the desired programming voltage.
    Type: Grant
    Filed: March 28, 2006
    Date of Patent: February 12, 2008
    Assignee: SanDisk Corporation
    Inventors: Shih-Chung Lee, Toru Miwa
  • Patent number: 7327608
    Abstract: In a non-volatile memory system, the programming time period allocated for the program pulse is adjusted as a function of the voltage level of the pump pulse required so that the total number of pump pulses required to program the charge storage element to the required threshold voltage is reduced. For example, programming time period may be increased with an increase in the voltage level of the pump pulse required. This allows the programming time period of the program pulse to be increased to a value that compensates for the increased charge-up time that is required for the higher amplitude program pulses to reach the desired programming voltage.
    Type: Grant
    Filed: March 28, 2006
    Date of Patent: February 5, 2008
    Assignee: SanDisk Corporation
    Inventors: Shih-Chung Lee, Toru Miwa
  • Publication number: 20070237008
    Abstract: In a non-volatile memory system, the programming time period allocated for the program pulse is adjusted as a function of the voltage level of the pump pulse required so that the total number of pump pulses required to program the charge storage element to the required threshold voltage is reduced. For example, programming time period may be increased with an increase in the voltage level of the pump pulse required. This allows the programming time period of the program pulse to be increased to a value that compensates for the increased charge-up time that is required for the higher amplitude program pulses to reach the desired programming voltage.
    Type: Application
    Filed: March 28, 2006
    Publication date: October 11, 2007
    Inventors: Shih-Chung Lee, Toru Miwa
  • Publication number: 20070236991
    Abstract: In a non-volatile memory system, the programming time period allocated for the program pulse is adjusted as a function of the voltage level of the pump pulse required so that the total number of pump pulses required to program the charge storage element to the required threshold voltage is reduced. For example, programming time period may be increased with an increase in the voltage level of the pump pulse required. This allows the programming time period of the program pulse to be increased to a value that compensates for the increased charge-up time that is required for the higher amplitude program pulses to reach the desired programming voltage.
    Type: Application
    Filed: March 28, 2006
    Publication date: October 11, 2007
    Inventors: Shih-Chung Lee, Toru Miwa
  • Publication number: 20060198195
    Abstract: A low voltage (e.g. of the order of or one to three volts) instead of an intermediate VPASS voltage (e.g. of the order of five to ten volts) is applied to word line zero immediately adjacent to the source or drain side select gate of a flash device such as a NAND flash device and one or more additional word lines next to such word line to reduce or prevent the shifting of threshold voltage of the memory cells coupled to word line zero during the programming cycles of the different cells of the NAND strings. This may be implemented in any one of a variety of different self boosting schemes including erased areas self boosting and local self boosting schemes. In a modified erased area self boosting scheme, low voltages are applied to two or more word lines on the source side of the selected word line to reduce band-to-band tunneling and to improve the isolation between two boosted channel regions.
    Type: Application
    Filed: December 28, 2005
    Publication date: September 7, 2006
    Inventors: Gerrit Hemink, Hironobu Nakao, Shih-Chung Lee