Patents by Inventor Shigekazu Yamada

Shigekazu Yamada 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: 8760933
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Grant
    Filed: September 11, 2012
    Date of Patent: June 24, 2014
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20140160851
    Abstract: Some embodiments include apparatuses and methods having a memory cell string including memory cells located in different levels of the apparatus and a data line coupled to the memory cell string. The memory cell string includes a pillar body associated with the memory cells. At least one of such apparatus can include a module configured to store information in a memory cell among memory cells and/or to determine a value of information stored in a memory cell among memory cells. The module can also be configured to apply a voltage having a positive value to the data line and/or a source to control a potential of the body. Other embodiments are described.
    Type: Application
    Filed: December 6, 2012
    Publication date: June 12, 2014
    Applicant: Micron Technology, Inc.
    Inventors: Han Zhao, Akira Goda, Krishna K. Parat, Aurelio Giancarlo Mauri, Haitao Liu, Toru Tanzawa, Shigekazu Yamada, Koji Sakui
  • Publication number: 20140133249
    Abstract: Methods, apparatuses, and integrated circuits for measuring leakage current are disclosed. In one such example method, a word line is charged to a first voltage, and a measurement node is charged to a second voltage, the second voltage being less than the first voltage. The measurement node is proportionally coupled to the word line. A voltage on the measurement node is compared with a reference voltage. A signal is generated, the signal being indicative of the comparison. Whether a leakage current of the word line is acceptable or not can be determined based on the signal.
    Type: Application
    Filed: January 21, 2014
    Publication date: May 15, 2014
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20140071772
    Abstract: Described examples include leakage measurement systems and methods for measuring leakage current between a word line at a boosted voltage and a word line at a supply voltage. The boosted voltage may be generated by charge pump circuitry. Examples of leakage measurement systems described herein may be included in memory devices.
    Type: Application
    Filed: November 19, 2013
    Publication date: March 13, 2014
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8634264
    Abstract: Methods, apparatuses, and integrated circuits for measuring leakage current are disclosed. In one such example method, a word line is charged to a first voltage, and a measurement node is charged to a second voltage, the second voltage being less than the first voltage. The measurement node is proportionally coupled to the word line. A voltage on the measurement node is compared with a reference voltage. A signal is generated, the signal being indicative of the comparison. Whether a leakage current of the word line is acceptable or not can be determined based on the signal.
    Type: Grant
    Filed: October 26, 2011
    Date of Patent: January 21, 2014
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20140003151
    Abstract: Methods for programming select gates, memory devices, and memory systems are disclosed. In one such method for programming, a program inhibit voltage is transferred from a source to unselected bit lines. Bit line-to-bit line capacitance, between the unselected bit lines and selected bit lines to be program inhibited, boosts the bit line voltage of the selected, inhibited bit lines to a target inhibit voltage. In one embodiment, the voltage on the selected, inhibited bit line can be increased in a plurality of inhibit steps whereby either one, two, or all of the steps can be used during the programming of unprogrammed select gates.
    Type: Application
    Filed: September 5, 2013
    Publication date: January 2, 2014
    Applicant: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Aaron Yip
  • Publication number: 20130315001
    Abstract: Semiconductor memory devices and methods include a flash memory cell array fabricated in a well, with memory cells in the same column connected to each other in series and connected to a respective bit line. The memory devices also include a column decoder, a data register buffer unit, a row decoder, an erase control unit, and an input/output buffer unit. In one or more embodiments, the erase control unit applies voltages to the well to erase the memory cells in a manner that avoids breaking down p-n junctions formed by transistors fabricated in the well. In another embodiment, high voltage transistors are used to selectively isolate the bit lines from and couple the bit lines to a peripheral circuit in pairs so that each high voltage transistor is shared by two bit lines.
    Type: Application
    Filed: August 1, 2013
    Publication date: November 28, 2013
    Applicant: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Patent number: 8588007
    Abstract: Described examples include leakage measurement systems and methods for measuring leakage current between a word line at a boosted voltage and a word line at a supply voltage. The boosted voltage may be generated by charge pump circuitry. Examples of leakage measurement systems described herein may be included in memory devices.
    Type: Grant
    Filed: February 28, 2011
    Date of Patent: November 19, 2013
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8542534
    Abstract: Methods for programming select gates, memory devices, and memory systems are disclosed. In one such method for programming, a program inhibit voltage is transferred from a source line to unselected bit lines. Bit line-to-bit line capacitance, between the unselected bit lines and selected bit lines to be program inhibited, boosts the bit line voltage of the selected, inhibited bit lines to a target inhibit voltage. In one embodiment, the voltage on the selected, inhibited bit line can be increased in a plurality of inhibit steps whereby either one, two, or all of the steps can be used during the programming of unprogrammed select gates.
    Type: Grant
    Filed: April 8, 2010
    Date of Patent: September 24, 2013
    Assignee: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Aaron Yip
  • Patent number: 8503249
    Abstract: Semiconductor memory devices and methods include a flash memory cell array fabricated in a well, with memory cells in the same column connected to each other in series and connected to a respective bit line. The memory devices also include a column decoder, a data register buffer unit, a row decoder, an erase control unit, and an input/output buffer unit. In one or more embodiments, the erase control unit applies voltages to the well to erase the memory cells in a manner that avoids breaking down p-n junctions formed by transistors fabricated in the well. In another embodiment, high voltage transistors are used to selectively isolate the bit lines from and couple the bit lines to a peripheral circuit in pairs so that each high voltage transistor is shared by two bit lines.
    Type: Grant
    Filed: July 29, 2011
    Date of Patent: August 6, 2013
    Assignee: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Patent number: 8482986
    Abstract: A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.
    Type: Grant
    Filed: July 16, 2012
    Date of Patent: July 9, 2013
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8462559
    Abstract: Memory devices and erase methods for memories are disclosed, such as those adapted to discharge an erase voltage from a memory block while protecting low voltage string select gate transistors by maintaining the string select gate transistors in a turned on state during discharge.
    Type: Grant
    Filed: December 20, 2011
    Date of Patent: June 11, 2013
    Assignee: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Publication number: 20130107640
    Abstract: Methods, apparatuses, and integrated circuits for measuring leakage current are disclosed. In one such example method, a word line is charged to a first voltage, and a measurement node is charged to a second voltage, the second voltage being less than the first voltage. The measurement node is proportionally coupled to the word line. A voltage on the measurement node is compared with a reference voltage. A signal is generated, the signal being indicative of the comparison. Whether a leakage current of the word line is acceptable or not can be determined based on the signal.
    Type: Application
    Filed: October 26, 2011
    Publication date: May 2, 2013
    Applicant: Micron Technology, Inc.
    Inventor: SHIGEKAZU YAMADA
  • Patent number: 8363490
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Grant
    Filed: September 22, 2011
    Date of Patent: January 29, 2013
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20130003464
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Application
    Filed: September 11, 2012
    Publication date: January 3, 2013
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20120281482
    Abstract: A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.
    Type: Application
    Filed: July 16, 2012
    Publication date: November 8, 2012
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8284613
    Abstract: A semiconductor memory device is described that can, in certain embodiments, reduce a delay in access time and/or an area of a memory cell array. In one or more embodiments, a flash memory device that includes a memory cell array, a data register, a state machine, input/output pads, a row decoder, and a column decoder. The memory cell array includes a pre-charge unit that is placed between a plurality of memory cell arrays. The pre-charge unit pre-charges a bit line in a read operation. A data register is separated from the pre-charge unit and is located away from the arrays. Write data are coupled from a data register to the arrays, and read data are coupled from the arrays to the data register.
    Type: Grant
    Filed: June 16, 2010
    Date of Patent: October 9, 2012
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20120218833
    Abstract: Described examples include leakage measurement systems and methods for measuring leakage current between a word line at a boosted voltage and a word line at a supply voltage. The boosted voltage may be generated by charge pump circuitry. Examples of leakage measurement systems described herein may be included in memory devices.
    Type: Application
    Filed: February 28, 2011
    Publication date: August 30, 2012
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8238165
    Abstract: A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.
    Type: Grant
    Filed: January 14, 2011
    Date of Patent: August 7, 2012
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8194446
    Abstract: Methods for programming a memory array and memory devices are disclosed. In one such method, inhibited bit lines are charged to an inhibit voltage that is less than a supply voltage. The word lines of memory cells to be programmed are biased at a programming preparation voltage that is less than a nominal programming preparation voltage as used in the conventional art. Programming pulses can be applied to selected word lines of the memory cells to be programmed when the uninhibited bit lines are at 0V.
    Type: Grant
    Filed: March 18, 2011
    Date of Patent: June 5, 2012
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada