Patents by Inventor Teruhiko Kamei

Teruhiko Kamei 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: 7733701
    Abstract: A process for reading data (including verifying during programming) from a selected non-volatile storage elements of a group (e.g., NAND string) of non-volatile storage elements includes maintaining an intermediate voltage as a control gate voltage for an unselected non-volatile storage element and subsequently changing the control gate voltage for the unselected non-volatile storage element from the intermediate voltage to a read enable voltage. The control gate voltage for the selected non-volatile storage element is raised from a standby voltage (which is different than the intermediate voltage) to a read compare voltage. While the control gate for the selected non-volatile storage element is at the read compare voltage and the control gate for the unselected non-volatile storage element is at the read enable voltage, the state of the selected non-volatile storage element is sensed to determine information about the data stored in the selected non-volatile storage element.
    Type: Grant
    Filed: May 4, 2009
    Date of Patent: June 8, 2010
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7724580
    Abstract: A set non-volatile storage elements are subjected to a programming process in order to store a set of data. During the programming process, one or more verification operations are performed to determine whether the non-volatile storage elements have reached their target condition to store the appropriate data. Decisions about whether to continue programming or whether the programming is successful are made based on whether overlapping groups of the non-volatile storage elements have less than a threshold number of non-volatile storage elements that are not properly programmed.
    Type: Grant
    Filed: April 28, 2009
    Date of Patent: May 25, 2010
    Assignee: SanDisk Corporation
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze
  • Patent number: 7606084
    Abstract: Non-volatile memory read operations compensate for floating gate coupling when the apparent threshold voltage of a memory cell may have shifted. A memory cell of interest can be read using a reference value based on a level of charge read from a neighboring memory cell. Misreading the neighboring cell may have greater effects in particular programming methodologies, and more specifically, when reading the neighboring cell for particular states or charge levels in those methodologies. In one embodiment, memory cells are programmed to create a wider margin between particular states where misreading a neighboring cell is more detrimental. Further, memory cells are read in one embodiment by compensating for floating gate coupling based on the state of a neighboring cell when reading at certain reference levels but not when reading at other reference levels, such as those where a wider margin has been created.
    Type: Grant
    Filed: June 19, 2006
    Date of Patent: October 20, 2009
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7606100
    Abstract: A set of non-volatile storage elements is divided into subsets for erasing in order to avoid over-erasing faster erasing storage elements. The entire set of elements is erased until a first subset of the set of elements is verified as erased. The first subset can include the faster erasing cells. Verifying the first subset includes excluding a second subset from verification. After the first subset is verified as erased, they are inhibited from erasing while the second subset is further erased. The set of elements is verified as erased when the second subset is verified as erased. Verifying that the set of elements is erased can include excluding the first subset from verification or verifying both the first and second subsets together. Different step sizes are used, depending on which subset is being erased and verified in order to more efficiently and accurately erase the set of elements.
    Type: Grant
    Filed: February 29, 2008
    Date of Patent: October 20, 2009
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Publication number: 20090257282
    Abstract: A trial programming process is performed for a first set of one or more non-volatile storage elements to test usage of the non-volatile storage system. Based on this trial programming, a programming signal is calibrated by adjusting its initial magnitude. The calibrated programming signal is then used to program a second set of non-volatile storage elements (which may or may not include the first set).
    Type: Application
    Filed: June 26, 2009
    Publication date: October 15, 2009
    Inventors: Teruhiko Kamei, Yan Li
  • Patent number: 7602652
    Abstract: Non-volatile memory read operations compensate for floating gate coupling when the apparent threshold voltage of a memory cell may have shifted. A memory cell of interest can be read using a reference value based on a level of charge read from a neighboring memory cell. Misreading the neighboring cell may have greater effects in particular programming methodologies, and more specifically, when reading the neighboring cell for particular states or charge levels in those methodologies. In one embodiment, memory cells are programmed to create a wider margin between particular states where misreading a neighboring cell is more detrimental. Further, memory cells are read in one embodiment by compensating for floating gate coupling based on the state of a neighboring cell when reading at certain reference levels but not when reading at other reference levels, such as those where a wider margin has been created.
    Type: Grant
    Filed: February 27, 2008
    Date of Patent: October 13, 2009
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Publication number: 20090213658
    Abstract: A process for reading data (including verifying during programming) from a selected non-volatile storage elements of a group (e.g., NAND string) of non-volatile storage elements includes maintaining an intermediate voltage as a control gate voltage for an unselected non-volatile storage element and subsequently changing the control gate voltage for the unselected non-volatile storage element from the intermediate voltage to a read enable voltage. The control gate voltage for the selected non-volatile storage element is raised from a standby voltage (which is different than the intermediate voltage) to a read compare voltage. While the control gate for the selected non-volatile storage element is at the read compare voltage and the control gate for the unselected non-volatile storage element is at the read enable voltage, the state of the selected non-volatile storage element is sensed to determine information about the data stored in the selected non-volatile storage element.
    Type: Application
    Filed: May 4, 2009
    Publication date: August 27, 2009
    Inventor: Teruhiko Kamei
  • Publication number: 20090207661
    Abstract: A set non-volatile storage elements are subjected to a programming process in order to store a set of data. During the programming process, one or more verification operations are performed to determine whether the non-volatile storage elements have reached their target condition to store the appropriate data. Decisions about whether to continue programming or whether the programming is successful are made based on whether overlapping groups of the non-volatile storage elements have less than a threshold number of non-volatile storage elements that are not properly programmed.
    Type: Application
    Filed: April 28, 2009
    Publication date: August 20, 2009
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze
  • Patent number: 7570520
    Abstract: A trial programming process is performed for a first set of one or more non-volatile storage elements to test usage of the non-volatile storage system. Based on this trial programming, a programming signal is calibrated by adjusting its initial magnitude. The calibrated programming signal is then used to program a second set of non-volatile storage elements (which may or may not include the first set).
    Type: Grant
    Filed: December 27, 2006
    Date of Patent: August 4, 2009
    Assignee: SanDisk Corporation
    Inventors: Teruhiko Kamei, Yan Li
  • Patent number: 7551482
    Abstract: A trial programming process is performed for a first set of one or more non-volatile storage elements to test usage of the non-volatile storage system. Based on this trial programming, a programming signal is calibrated by adjusting its initial magnitude. The calibrated programming signal is then used to program a second set of non-volatile storage elements (which may or may not include the first set).
    Type: Grant
    Filed: December 27, 2006
    Date of Patent: June 23, 2009
    Assignee: SanDisk Corporation
    Inventors: Teruhiko Kamei, Yan Li
  • Patent number: 7545681
    Abstract: A set non-volatile storage elements are subjected to a programming process in order to store a set of data. During the programming process, one or more verification operations are performed to determine whether the non-volatile storage elements have reached their target condition to store the appropriate data. Decisions about whether to continue programming or whether the programming is successful are made based on whether overlapping groups of the non-volatile storage elements have less than a threshold number of non-volatile storage elements that are not properly programmed.
    Type: Grant
    Filed: November 27, 2006
    Date of Patent: June 9, 2009
    Assignee: SanDisk Corporation
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze
  • Patent number: 7545675
    Abstract: A process for reading data (including verifying during programming) from a selected non-volatile storage elements of a group (e.g., NAND string) of non-volatile storage elements includes maintaining an intermediate voltage as a control gate voltage for an unselected non-volatile storage element and subsequently changing the control gate voltage for the unselected non-volatile storage element from the intermediate voltage to a read enable voltage. The control gate voltage for the selected non-volatile storage element is raised from a standby voltage (which is different than the intermediate voltage) to a read compare voltage. While the control gate for the selected non-volatile storage element is at the read compare voltage and the control gate for the unselected non-volatile storage element is at the read enable voltage, the state of the selected non-volatile storage element is sensed to determine information about the data stored in the selected non-volatile storage element.
    Type: Grant
    Filed: December 16, 2005
    Date of Patent: June 9, 2009
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7522457
    Abstract: The erase voltage applied to a set of non-volatile storage elements being erased is structured to provide controlled shifts in the threshold voltage of the storage elements. The erase voltage is applied as a series of voltage pulses, when necessary, to shift the threshold voltage of to-be-erased memory cells below a verify level indicative of an erased condition. To avoid over-erasing the memory cells, the second erase voltage pulse is decreased, or not increased, in magnitude when compared to the previously applied voltage pulse. By decreasing or not increasing the size of the erase voltage, the amount of charge transferred from the cells by the second pulse is controlled to more accurately position an erased threshold voltage distribution for the cells near the verify level. Subsequent erase voltage pulses are increased in magnitude to provide further erasing when needed.
    Type: Grant
    Filed: July 5, 2007
    Date of Patent: April 21, 2009
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Patent number: 7518911
    Abstract: A method for programming a non-volatile memory system. The method includes programming a first non-volatile storage element on a first word line and a first NAND string to store ā€œnā€ bits of data. A second non-volatile storage element on the first word line and a second NAND string is programmed to store n+1 bits of data. The second non-volatile storage element is a neighbor to the first non-volatile storage element. A third non-volatile storage element on a second word line and the second NAND string is programmed to store n bits of data. The third non-volatile storage element is a neighbor to the second non-volatile storage element. A fourth non-volatile storage element on the second word line and the first NAND string is programmed to store n+1 bits of data.
    Type: Grant
    Filed: May 25, 2006
    Date of Patent: April 14, 2009
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7489547
    Abstract: A NAND type flash memory is organized into NAND strings with each being a chain of memory cells in series and connected via select transistors on both ends of the string to either a bit line or a source line. The memory cells adjacent both ends of a NAND string are particularly susceptible to errors due to program disturb. An adaptive memory-state partitioning scheme is employed to overcome the errors, in which each memory cells are generally partitioned to store multiple bits of data, except for the ones adjacent both ends where relatively less bits are stored. In this way, the storage of relatively less bits in the memory cells adjacent both ends of a NAND string affords sufficient margin to overcome the errors. For example, in a memory designed to store 2-bit data, the cells adjacent both ends of a NAND string would each be configured to store one bit of the 2-bit data.
    Type: Grant
    Filed: December 29, 2006
    Date of Patent: February 10, 2009
    Assignee: Sandisk Corporation
    Inventors: Farookh Moogat, Teruhiko Kamei
  • Patent number: 7489548
    Abstract: A NAND type flash memory is organized into NAND strings with each being a chain of memory cells in series and connected via select transistors on both ends of the string to either a bit line or a source line. The memory cells adjacent both ends of a NAND string are particularly susceptible to errors due to program disturb. An adaptive memory-state partitioning scheme is employed to overcome the errors, in which each memory cells are generally partitioned to store multiple bits of data, except for the ones adjacent both ends where relatively less bits are stored. In this way, the storage of relatively less bits in the memory cells adjacent both ends of a NAND string affords sufficient margin to overcome the errors. For example, in a memory designed to store 2-bit data, the cells adjacent both ends of a NAND string would each be configured to store one bit of the 2-bit data.
    Type: Grant
    Filed: December 29, 2006
    Date of Patent: February 10, 2009
    Assignee: SanDisk Corporation
    Inventors: Farookh Moogat, Teruhiko Kamei
  • Patent number: 7486564
    Abstract: A set of non-volatile storage elements is divided into subsets for soft programming in order to more fully soft-program slower soft programming elements. The entire set of elements is soft-programmed until verified as soft programmed (or until a first subset of elements is verified as soft programmed while excluding a second subset from verification). After the set is verified as soft programmed, a first subset of elements is inhibited from further soft programming while additional soft programming is carried out on a second subset of elements. The second subset can include slower soft programming elements. The second subset can then undergo soft programming verification while excluding the first subset from verification. Soft programming and verifying for the second subset can continue until it is verified as soft programmed. Different step sizes can be used for increasing the size of the soft programming signal, depending on which subset is being soft programmed and verified.
    Type: Grant
    Filed: December 6, 2005
    Date of Patent: February 3, 2009
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Patent number: 7480176
    Abstract: Non-volatile memory read operations compensate for floating gate coupling when the apparent threshold voltage of a memory cell may have shifted. A memory cell of interest can be read using a reference value based on a level of charge read from a neighboring memory cell. Misreading the neighboring cell may have greater effects in particular programming methodologies, and more specifically, when reading the neighboring cell for particular states or charge levels in those methodologies. In one embodiment, memory cells are programmed to create a wider margin between particular states where misreading a neighboring cell is more detrimental. Further, memory cells are read in one embodiment by compensating for floating gate coupling based on the state of a neighboring cell when reading at certain reference levels but not when reading at other reference levels, such as those where a wider margin has been created.
    Type: Grant
    Filed: February 27, 2008
    Date of Patent: January 20, 2009
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7457166
    Abstract: The erase voltage applied to a set of non-volatile storage elements being erased is structured to provide controlled shifts in the threshold voltage of the storage elements. The erase voltage is applied as a series of voltage pulses, when necessary, to shift the threshold voltage of to-be-erased memory cells below a verify level indicative of an erased condition. To avoid over-erasing the memory cells, the second erase voltage pulse is decreased, or not increased, in magnitude when compared to the previously applied voltage pulse. By decreasing or not increasing the size of the erase voltage, the amount of charge transferred from the cells by the second pulse is controlled to more accurately position an erased threshold voltage distribution for the cells near the verify level. Subsequent erase voltage pulses are increased in magnitude to provide further erasing when needed.
    Type: Grant
    Filed: July 5, 2007
    Date of Patent: November 25, 2008
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Patent number: 7440319
    Abstract: A set non-volatile storage elements are subjected to a programming process in order to store a set of data. During the programming process, one or more verification operations are performed to determine whether the non-volatile storage elements have reached their target condition to store the appropriate data. Decisions about whether to continue programming or whether the programming is successful are made based on whether overlapping groups of the non-volatile storage elements have less than a threshold number of non-volatile storage elements that are not properly programmed.
    Type: Grant
    Filed: November 27, 2006
    Date of Patent: October 21, 2008
    Assignee: SanDisk Corporation
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze