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: 7440322
    Abstract: Method and system for memory devices is provided. The system includes a plurality of non-volatile storage elements connected in a string between a source side element and a drain side element; a plurality of bit lines, wherein each bit line is connected to a plurality of non-volatile storage elements; and a plurality of word lines, the plurality of word lines include a dummy word line between a source side select element and a first word line that is connected to a first non-volatile storage element to be programmed, wherein a program voltage is applied to the first non-volatile storage element connected to the first word line and an intermediate voltage is applied to a second non-volatile storage element connected to the dummy word line.
    Type: Grant
    Filed: April 20, 2006
    Date of Patent: October 21, 2008
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7408804
    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: August 5, 2008
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Patent number: 7403424
    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: December 6, 2005
    Date of Patent: July 22, 2008
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Patent number: 7400537
    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: December 6, 2005
    Date of Patent: July 15, 2008
    Assignee: SanDisk Corporation
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Publication number: 20080158969
    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: Application
    Filed: December 29, 2006
    Publication date: July 3, 2008
    Inventors: Farookh Moogat, Teruhiko Kamei
  • Publication number: 20080158997
    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: Application
    Filed: February 29, 2008
    Publication date: July 3, 2008
    Inventors: Gerrit Jan Hemink, Teruhiko Kamei
  • Publication number: 20080158979
    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: December 27, 2006
    Publication date: July 3, 2008
    Inventors: Teruhiko Kamei, Yan Li
  • Publication number: 20080158996
    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: Application
    Filed: February 27, 2008
    Publication date: July 3, 2008
    Inventor: Teruhiko Kamei
  • Publication number: 20080158968
    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: Application
    Filed: December 29, 2006
    Publication date: July 3, 2008
    Inventors: Farookh Moogat, Teruhiko Kamei
  • Publication number: 20080158980
    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: December 27, 2006
    Publication date: July 3, 2008
    Inventors: Teruhiko Kamei, Yan Li
  • Publication number: 20080144368
    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: Application
    Filed: February 27, 2008
    Publication date: June 19, 2008
    Inventor: Teruhiko Kamei
  • Publication number: 20080126676
    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: November 27, 2006
    Publication date: May 29, 2008
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze
  • Publication number: 20080127104
    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: November 27, 2006
    Publication date: May 29, 2008
    Inventors: Yan Li, Teruhiko Kamei, Jeffrey W. Lutze
  • Patent number: 7369437
    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: May 6, 2008
    Assignee: Sandisk Corporation
    Inventor: Teruhiko Kamei
  • Patent number: 7352628
    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: April 1, 2008
    Assignee: SanDisk Corporation
    Inventor: Teruhiko Kamei
  • Publication number: 20080019164
    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: Application
    Filed: July 5, 2007
    Publication date: January 24, 2008
    Inventors: Gerrit Hemink, Teruhiko Kamei
  • Publication number: 20080013360
    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: Application
    Filed: July 5, 2007
    Publication date: January 17, 2008
    Inventors: Gerrit Hemink, Teruhiko Kamei
  • Publication number: 20070291546
    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: Application
    Filed: June 19, 2006
    Publication date: December 20, 2007
    Inventor: Teruhiko Kamei
  • Publication number: 20070291556
    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: Application
    Filed: June 19, 2006
    Publication date: December 20, 2007
    Inventor: Teruhiko Kamei
  • Publication number: 20070274128
    Abstract: A non-volatile memory system and a method for programming is provided. The memory system includes a first set of memory cells that can operate in multiple states X; and a second set of memory cells that can operate in multiple states Y; wherein the multiple state X and multiple state Y are selected so that memory cells can effectively store data in 0.5 bit increments. The method includes programming an even memory cell of the first set and a first word line and an odd memory cell in the first word line and of the second set is programmed next.
    Type: Application
    Filed: May 25, 2006
    Publication date: November 29, 2007
    Inventor: Teruhiko Kamei