Patents by Inventor Tetsuya Ishimaru

Tetsuya Ishimaru 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: 7667259
    Abstract: A method of manufacturing a non-volatile semiconductor memory device is provided which overcomes a problem of penetration of implanted ions due to the difference of an optimal gate height in simultaneous formation of a self-align split gate type memory cell utilizing a side wall structure and a scaled MOS transistor. A select gate electrode to form a side wall in a memory area is formed to be higher than that of the gate electrode in a logic area so that the height of the side wall gate electrode of the self-align split gate memory cell is greater than that of the gate electrode in the logic area. Height reduction for the gate electrode is performed in the logic area before gate electrode formation.
    Type: Grant
    Filed: June 14, 2006
    Date of Patent: February 23, 2010
    Assignee: Renesas Technology Corp.
    Inventors: Kan Yasui, Digh Hisamoto, Tetsuya Ishimaru, Shin-Ichiro Kimura
  • Publication number: 20090152619
    Abstract: Provided is a nonvolatile semiconductor memory device having a split gate structure, wherein a memory gate is formed over a convex shaped substrate and side surfaces of it is used as a channel. The nonvolatile semiconductor memory device according to the present invention is excellent in read current driving power even if a memory cell is scaled down.
    Type: Application
    Filed: February 10, 2009
    Publication date: June 18, 2009
    Inventors: DIGH HISAMOTO, Kan Yasui, Shinichiro Kimura, Tetsuya Ishimaru
  • Patent number: 7529126
    Abstract: Disclosed here is a method for speeding up data writing and reducing power consumption by reducing the variation of the threshold voltage of each of non-volatile memory cells at data writing. When writing data in a memory cell, a voltage of about 8V is applied to the memory gate line, a voltage of about 5V is applied to the source line, a voltage of about 1.5V is applied to the selected gate line respectively. At that time, in the writing circuit, the writing pulse is 0, the writing latch output a High signal, and a NAND-circuit outputs a Low signal. And, a constant current of about 1iA flows in a constant current source transistor and the bit line is discharged by a constant current of about 1iA to flow a current in the memory cell.
    Type: Grant
    Filed: June 23, 2006
    Date of Patent: May 5, 2009
    Assignee: Renesas Technology Corp.
    Inventors: Toshihiro Tanaka, Takashi Yamaki, Yutaka Shinagawa, Daisuke Okada, Digh Hisamoto, Kan Yasui, Tetsuya Ishimaru
  • Patent number: 7504689
    Abstract: Provided is a nonvolatile semiconductor memory device having a split gate structure, wherein a memory gate is formed over a convex shaped substrate and side surfaces of it is used as a channel. The nonvolatile semiconductor memory device according to the present invention is excellent in read current driving power even if a memory cell is scaled down.
    Type: Grant
    Filed: July 15, 2005
    Date of Patent: March 17, 2009
    Assignee: Renesas Technology Corp.
    Inventors: Digh Hisamoto, Kan Yasui, Shinichiro Kimura, Tetsuya Ishimaru
  • Publication number: 20090050956
    Abstract: In a memory cell including an nMIS for memory formed on the sides of an nMIS for select and an nMIS for select via dielectric films and a charge storage layer, the thickness of a gate dielectric under the gate longitudinal direction end of a select gate electrode is formed thicker than that of the gate dielectric under the gate longitudinal direction center and the thickness of the lower layer dielectric film that is positioned between the select gate electrode and the charge storage layer and is nearest to a semiconductor substrate is formed 1.5 times or below of the thickness of the lower layer dielectric film positioned between the semiconductor substrate and the charge storage layer.
    Type: Application
    Filed: August 14, 2008
    Publication date: February 26, 2009
    Inventors: TETSUYA ISHIMARU, YOSHIYUKI KAWASHIMA, YASUHIRO SHIMAMOTO, KAN YASUI, TSUYOSHI ARIGANE, TOSHIYUKI MINE
  • Publication number: 20090050955
    Abstract: A charge storage layer interposed between a memory gate electrode and a semiconductor substrate is formed shorter than a gate length of the memory gate electrode or a length of insulating films so as to make the overlapping amount of the charge storage layer and a source region to be less than 40 nm. Therefore, in the write state, since the movement in the transverse direction of the electrons and the holes locally existing in the charge storage layer decreases, the variation of the threshold voltage when holding a high temperature can be reduced. In addition, the effective channel length is made to be 30 nm or less so as to reduce an apparent amount of holes so that coupling of the electrons with the holes in the charge storage layer decreases; therefore, the variation of the threshold voltage when holding at room temperature can be reduced.
    Type: Application
    Filed: August 8, 2008
    Publication date: February 26, 2009
    Inventors: Kenichi AKITA, Daisuke OKADA, Keisuke KUWAHARA, Yasufumi MORIMOTO, Yasuhiro SHIMAMOTO, Kan YASUI, Tsuyoshi ARIGANE, Tetsuya ISHIMARU
  • Publication number: 20090014775
    Abstract: An operation scheme for operating stably a semiconductor nonvolatile memory device is provided. When hot-hole injection is conducted in the semiconductor nonvolatile memory device of a split gate structure, the hot-hole injection is verified using a crossing point that does not change with time. Thus, an erased state can be verified without being aware of any time-varying changes. Also, programming or programming/erasure is conducted by repeating pulse voltage or multi-step voltage application to a gate section multiple times.
    Type: Application
    Filed: September 19, 2008
    Publication date: January 15, 2009
    Inventors: Digh Hisamoto, Kan Yasui, Tetsuya Ishimaru, Shinichiro Kimura, Daisuke Okada
  • Publication number: 20080290401
    Abstract: An erase method where a corner portion on which an electric field concentrates locally is provided on the memory gate electrode, and charges in the memory gate electrode are injected into a charge trap film in a gate dielectric with Fowler-Nordheim tunneling operation is used. Since current consumption at the time of erase can be reduced by the Fowler-Nordheim tunneling, a power supply circuit area of a memory module can be reduced. Since write disturb resistance can be improved, a memory array area can be reduced by adopting a simpler memory array configuration. Owing to both the effects, an area of the memory module can be largely reduced, so that manufacturing cost can be reduced. Further, since charge injection centers of write and erase coincide with each other, so that (program and erase) endurance is improved.
    Type: Application
    Filed: May 20, 2008
    Publication date: November 27, 2008
    Inventors: Kan YASUI, Tetsuya Ishimaru, Digh Hisamoto, Yasuhiro Shimamoto
  • Publication number: 20080265286
    Abstract: A memory cell includes an ONO film composed of a stacked film of a silicon nitride film SIN which is a charge trapping portion and oxide films BOTOX and TOPOX positioned under and over the silicon nitride film, a memory gate electrode MG over the ONO film, a source region MS, and a drain region MD, and program or erase is performed by hot carrier injection in the memory cell. In the memory cell, a total concentration of N—H bonds and Si—H bonds contained in the silicon nitride film SIN is made to be 5×1020 cm?3 or less.
    Type: Application
    Filed: April 24, 2008
    Publication date: October 30, 2008
    Inventors: Tetsuya ISHIMARU, Yasuhiro Shimamoto, Toshiyuki Mine, Yasunobu Aoki, Koichi Toba, Kan Yasui
  • Patent number: 7443731
    Abstract: An operation scheme for operating stably a semiconductor nonvolatile memory device is provided. When hot-hole injection is conducted in the semiconductor nonvolatile memory device of a split gate structure, the hot-hole injection is verified using a crossing point that does not change with time. Thus, an erased state can be verified without being aware of any time-varying changes. Also, programming or programming/erasure is conducted by repeating pulse voltage or multi-step voltage application to a gate section multiple times.
    Type: Grant
    Filed: March 27, 2007
    Date of Patent: October 28, 2008
    Assignee: Renesas Technology Corp.
    Inventors: Digh Hisamoto, Kan Yasui, Tetsuya Ishimaru, Shinichiro Kimura, Daisuke Okada
  • Publication number: 20080258205
    Abstract: An erase current of a non-volatile semiconductor memory device is decreased. A memory cell of the non-volatile semiconductor memory device comprises a source region and a drain region formed in a semiconductor substrate. Over a portion of the semiconductor substrate between the source region and the drain region, a select gate electrode is formed via a gate dielectric film. On a side wall of the select gate electrode, a memory gate electrode is formed via a bottom silicon oxide film and a charge-trapping silicon oxynitride film. In the memory cell configured as above, erase operation is performed as follows. By applying a positive voltage to the memory gate electrode, holes are injected from the memory gate electrode into the silicon oxynitride film to decrease a threshold voltage in a program state to a certain level. Thereafter, hot holes generated by a band-to-band tunneling phenomenon are injected into the silicon oxynitride film and the erase operation is completed.
    Type: Application
    Filed: April 15, 2008
    Publication date: October 23, 2008
    Inventors: Tetsuya ISHIMARU, Yasuhiro SHIMAMOTO, Kan YASUI
  • Publication number: 20080048249
    Abstract: An interface between a bottom oxide film and a silicon nitride film in a neighborhood of a bottom part of a select gate is located at a position as high as or higher than that of an interface between a silicon substrate (p-type well) and a gate insulating film (d?0) Further, the gate insulating film and the bottom oxide film are successively and smoothly jointed in the neighborhood of the bottom part of the select gate. By this configuration, localization in a distribution of electrons injected into the silicon nitride film in the writing is mitigated and electrons to be left unerased by hot-hole erasing are reduced. Therefore, not only the increase ratio of the electrons left unerased in the writing can be reduced, but also the problem in which the threshold voltage does not decrease to the predetermined voltage in the deletion can be suppressed.
    Type: Application
    Filed: July 5, 2007
    Publication date: February 28, 2008
    Inventors: NAOKI TEGA, Hiroshi Miki, Yasuhiro Shimamoto, Digh Hisamoto, Tetsuya Ishimaru
  • Publication number: 20080029805
    Abstract: Performance and reliability of a semiconductor device including a non-volatile memory are improved. A memory cell of the non-volatile memory includes, over an upper portion of a semiconductor substrate, a select gate electrode formed via a first dielectric film and a memory gate electrode formed via a second dielectric film formed of an ONO multilayered film having a charge storing function. The first dielectric film functions as a gate dielectric film, and includes a third dielectric film made of silicon oxide or silicon oxynitride and a metal-element-containing layer made of a metal oxide or a metal silicate formed between the select gate electrode and the third dielectric film. A semiconductor region positioned under the memory gate electrode and the second dielectric film has a charge density of impurities lower than that of a semiconductor region positioned under the select gate electrode and the first dielectric film.
    Type: Application
    Filed: July 13, 2007
    Publication date: February 7, 2008
    Inventors: Yasuhiro SHIMAMOTO, Digh Hisamoto, Tetsuya Ishimaru, Shinichiro Kimura
  • Patent number: 7286401
    Abstract: Disclosed here is a nonvolatile semiconductor memory device used to prevent data loss that might occur in unselected memory cells due to a disturbance that might occur during programming/erasing in/from those memory cells. In the nonvolatile semiconductor memory device, the number of programming/erasing operations performed in a data storage block over a programming/erasing unit of the subject nonvolatile memory is recorded in an erasing/programming counter EW CT provided in each data storage block. When the value of the erasing/programming counter reaches a predetermined value, the data storage block corresponding to the erasing/programming counter is refreshed. In the refreshing operation, the data in the data storage block is stored in a temporary storing region provided in the data storage block, then the data in a temporary storing region of the data storage area is erased and the data stored temporarily is programmed in the data storage block again.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: October 23, 2007
    Assignee: Renesas Technology Corp.
    Inventors: Tetsuya Ishimaru, Takanori Yamazoe
  • Publication number: 20070183206
    Abstract: An operation scheme for operating stably a semiconductor nonvolatile memory device is provided. When hot-hole injection is conducted in the semiconductor nonvolatile memory device of a split gate structure, the hot-hole injection is verified using a crossing point that does not change with time. Thus, an erased state can be verified without being aware of any time-varying changes. Also, programming or programming/erasure is conducted by repeating pulse voltage or multi-step voltage application to a gate section multiple times.
    Type: Application
    Filed: March 27, 2007
    Publication date: August 9, 2007
    Inventors: Digh Hisamoto, Kan Yasui, Tetsuya Ishimaru, Shinichiro Kimura, Daisuke Okada
  • Publication number: 20070170495
    Abstract: Performance of a non-volatile semiconductor storage device which performs electron writing by hot electrons and hole erasure by hot holes is improved. A non-volatile memory cell which performs a writing operation by electrons and an erasure operation by holes has a p-type well region, isolation regions, a source region, and a drain region provided on an Si substrate. A control gate electrode is formed via a gate insulating film between the source region and the drain region. In a left-side side wall of the control gate electrode, a bottom Si oxide film, an electric charge holding film, a top Si oxide film, and a memory gate electrode are formed. The electric charge holding film is formed from an Si nitride film stoichiometrically excessively containing silicon.
    Type: Application
    Filed: December 15, 2006
    Publication date: July 26, 2007
    Inventors: Toshiyuki Mine, Kan Yasui, Tetsuya Ishimaru, Yasuhiro Shimamoto
  • Publication number: 20070145455
    Abstract: A method of manufacturing a non-volatile semiconductor memory device is provided which overcomes a problem of penetration of implanted ions due to the difference of an optimal gate height in simultaneous formation of a self-align split gate type memory cell utilizing a side wall structure and a scaled MOS transistor. A select gate electrode to form a side wall in a memory area is formed to be higher than that of the gate electrode in a logic area so that the height of the side wall gate electrode of the self-align split gate memory cell is greater than that of the gate electrode in the logic area. Height reduction for the gate electrode is performed in the logic area before gate electrode formation.
    Type: Application
    Filed: June 14, 2006
    Publication date: June 28, 2007
    Inventors: Kan Yasui, Digh Hisamoto, Tetsuya Ishimaru, Shin-ichiro Kimura
  • Patent number: 7212444
    Abstract: An operation scheme for operating stably a semiconductor nonvolatile memory device is provided. When hot-hole injection is conducted in the semiconductor nonvolatile memory device of a split gate structure, the hot-hole injection is verified using a crossing point that does not change with time. Thus, an erased state can be verified without being aware of any time-varying changes. Also, programming or programming/erasure is conducted by repeating pulse voltage or multi-step voltage application to a gate section multiple times.
    Type: Grant
    Filed: May 26, 2005
    Date of Patent: May 1, 2007
    Assignee: Renesas Technology Corp.
    Inventors: Digh Hisamoto, Kan Yasui, Tetsuya Ishimaru, Shinichiro Kimura, Daisuke Okada
  • Publication number: 20070035155
    Abstract: An opening and closing device for opening and closing a bonnet provided in the rear part of the machine body is arranged in such a manner as to ensure as large an opening portion to be formed when the bonnet is opened as possible.
    Type: Application
    Filed: March 2, 2005
    Publication date: February 15, 2007
    Applicant: SHIN CATERPILLAR MITSUBISHI LTD.
    Inventors: Tetsuya Ishimaru, Ryu Kudo, Makoto Fujiwara
  • Patent number: 7130223
    Abstract: Characteristics of a nonvolatile semiconductor memory device are improved. The memory cell comprises: an ONO film constituted by a silicon nitride film SIN for accumulating charge and by oxide films BOTOX and TOPOX disposed thereon and thereunder; a memory gate electrode MG disposed at an upper portion thereof; a select gate electrode SG disposed at a side portion thereof through the ONO film; a gate oxide film SGOX disposed thereunder.
    Type: Grant
    Filed: October 18, 2005
    Date of Patent: October 31, 2006
    Assignee: Renesas Technology Corp.
    Inventors: Tetsuya Ishimaru, Nozomu Matsuzaki, Hitoshi Kume