Patents by Inventor Ichiro Fujiwara

Ichiro Fujiwara 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: 6870765
    Abstract: A method of erasing a non-volatile semiconductor memory device comprising, to raise the convergence of the erasure voltage, performing a write-erase operation, at least one write-erase operation after erasure, or a plurality of write-erase operations as an operation when erasing a memory transistor including dispersed charge storing means in a gate insulating film interposed between a channel-forming region of the semiconductor and a gate electrode and, to increase the erasure speed, optimizing an erasure voltage and/or an erasure time in accordance with the phenomenon of the absolute value of a voltage of an inflection point taking an extremum at the erasing side in a hysteresis curve shown the change of threshold voltage with respect to an applied voltage of the memory transistor becoming larger along with a shortening of a voltage application time.
    Type: Grant
    Filed: February 5, 2004
    Date of Patent: March 22, 2005
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Publication number: 20040251488
    Abstract: A nonvolatile semiconductor memory device enabling a high sensitivity read operation by a low voltage, provided with a gate insulating film comprised of a bottom insulating film, a charge storing film, and a top insulating film successively stacked from the bottom, the bottom insulating film including a silicon oxynitride film directly under the charge storing film, and reading a bit of data stored at a local portion of a sub-source line side of a memory transistor and a bit of data stored at a local portion of a sub-bit line side independently by the reverse read method, whereby the incubation time is suppressed by the presence of silicon oxynitride, the controllability of the thickness of the charge storing film is improved, and the threshold voltage in an erase state is decreased, and a method of high sensitivity reading whereby a lower voltage and improved operational reliability are achieved.
    Type: Application
    Filed: June 7, 2004
    Publication date: December 16, 2004
    Inventors: Ichiro Fujiwara, Akira Nakagawara
  • Patent number: 6794712
    Abstract: A nonvolatile semiconductor memory device featuring a reducing operating voltage while maintaining a good disturbance characteristic and high speed in a write operation, including a gate insulating film and gate electrode stacked on a channel forming region of a semiconductor provided on the surface of a substrate and planarly dispersed charge storing means such as carrier traps in a nitride film or near the interface with the top insulating film, provided in the gate insulating film, the gate insulating film including an FN tunnel film having a dielectric constant larger than that of a silicon oxide film and exhibiting an FN electroconductivity, whereby the thickness of the gate insulating film, converted to that of a silicon oxide film, can be reduced and the voltage can be reduced.
    Type: Grant
    Filed: November 1, 1999
    Date of Patent: September 21, 2004
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Publication number: 20040156240
    Abstract: A method of erasing a non-volatile semiconductor memory device comprising, to raise the convergence of the erasure voltage, performing a write-erase operation, at least one write-erase operation after erasure, or a plurality of write-erase operations as an operation when erasing a memory transistor including dispersed charge storing means in a gate insulating film interposed between a channel-forming region of the semiconductor and a gate electrode and, to increase the erasure speed, optimizing an erasure voltage and/or an erasure time in accordance with the phenomenon of the absolute value of a voltage of an inflection point taking an extremum at the erasing side in a hysteresis curve shown the change of threshold voltage with respect to an applied voltage of the memory transistor becoming larger along with a shortening of a voltage application time.
    Type: Application
    Filed: February 5, 2004
    Publication date: August 12, 2004
    Inventor: Ichiro Fujiwara
  • Publication number: 20040070020
    Abstract: A nonvolatile semiconductor memory device having MONOS type memory cells of increased efficiency by hot electron injection and improved scaling characteristics includes a channel forming region in the vicinity of a surface of a substrate, first and second impurity regions, acting as a source and a drain in operation, formed in the vicinity of the surface of the substrate sandwiching the channel forming region between them, a gate insulating film stacked on the channel forming region and having a plurality of films, and a charge storing means that is formed in the gate insulating film dispersed in the plane facing the channel forming region. A bottom insulating film includes a dielectric film that exhibits a FN type electroconductivity and makes the energy barrier between the bottom insulating film and the substrate lower than that between silicon dioxide and silicon.
    Type: Application
    Filed: December 14, 2000
    Publication date: April 15, 2004
    Inventors: Ichiro Fujiwara, Toshio Kobayashi
  • Patent number: 6721205
    Abstract: A nonvolatile semiconductor memory device with high reliability (free from troubles in storing data), a high charge injection efficiency, and enabling parallel operation in a VG cell array, includes channel forming regions, a charge storing film which consists of stacked dielectric films and is capable of storing a charge, two storage portions forming parts of the charge storing film and overlapping the channel forming regions, a single layer dielectric film between the storage portions and in contact with the channel forming region, a control gate electrode on the single layer dielectric film, and a memory gate electrode on the storage portions.
    Type: Grant
    Filed: December 14, 2000
    Date of Patent: April 13, 2004
    Assignee: Sony Corporation
    Inventors: Toshio Kobayashi, Hiroyuki Moriya, Ichiro Fujiwara
  • Patent number: 6717860
    Abstract: A method of erasing a non-volatile semiconductor memory device comprising, to raise the convergence of the erasure voltage, performing a write-erase operation, at least one write-erase operation after erasure, or a plurality of write-erase operations as an operation when erasing a memory transistor including dispersed charge storing means in a gate insulating film interposed between a channel-forming region of the semiconductor and a gate electrode and, to increase the erasure speed, optimizing an erasure voltage and/or an erasure time in accordance with the phenomenon of the absolute value of a voltage of an inflection point taking an extremum at the erasing side in a hysteresis curve shown the change of threshold voltage with respect to an applied voltage of the memory transistor becoming larger along with a shortening of a voltage application time.
    Type: Grant
    Filed: September 18, 2000
    Date of Patent: April 6, 2004
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Publication number: 20040042295
    Abstract: A nonvolatile semiconductor memory apparatus suitable to logic incorporation, by which a charge injection efficiency is high and hot electrons (HE) can be effectively injected at a low voltage is provided. A memory transistor (M) comprises first and second source/drain regions (S, SSL, D, SBL) formed on a semiconductor substrate (SUB, W), a charge storage film (GD) having a charge storage faculty and a gate electrode (WL). Memory peripheral circuits (2a to 9) generate a first voltage (Vd) and a second voltage (Vg−Vwell), apply the first voltage (Vd) to the second source/drain region (D, SBL) by using potential (0V) of the first source/drain region (S, SSL) as reference, apply the second voltage (Vg−Vwell) to the gate electrode (WL), generate hot electrons (HE) by ionization collision on the second source/drain region (D, SBL) side, and inject the hot electrons (HE) to the charge storage film (GD) from the second source/drain region (D, SBL) side at the time of writing data.
    Type: Application
    Filed: September 17, 2003
    Publication date: March 4, 2004
    Inventors: Ichiro Fujiwara, Hiromi Nobukata
  • Patent number: 6674120
    Abstract: A MONOS memory transistor capable of high speed write with a small current and superior in scaling, comprised of substrate (well W), a channel forming region, a first and a second impurity regions SBLi, SBLi+1 comprised of an opposite conductivity type semiconductor and sandwiching the channel forming region between them and acting as a source and a drain in operation, gate insulating films 10a, 10b, 14 and gate electrode WL on the channel forming region, and a charge storing means (carrier trap) which is formed in the gate insulating films 10a and 10b and dispersed in the plane facing the channel forming region and in the direction of thickness and is injected with hot holes caused by a band-to-band tunnel current from the impurity regions SLi or SLi+1 in operation.
    Type: Grant
    Filed: April 27, 2001
    Date of Patent: January 6, 2004
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Publication number: 20030183873
    Abstract: A nonvolatile semiconductor memory device featuring a reducing operating voltage while maintaining a good disturbance characteristic and high speed in a write operation, including a gate insulating film and gate electrode stacked on a channel forming region of a semiconductor provided on the surface of a substrate and planarly dispersed charge storing means such as carrier traps in a nitride film or near the interface with the top insulating film, provided in the gate insulating film, the gate insulating film including an FN tunnel film having a dielectric constant larger than that of a silicon oxide film and exhibiting an FN electroconductivity, whereby the thickness of the gate insulating film, converted to that of a silicon oxide film, can be reduced and the voltage can be reduced.
    Type: Application
    Filed: March 31, 2003
    Publication date: October 2, 2003
    Inventor: Ichiro Fujiwara
  • Publication number: 20030161192
    Abstract: A nonvolatile semiconductor memory device with high reliability (free from troubles in storing data), a high charge injection efficiency, and enabling parallel operation in a VG cell array, includes channel forming regions, a charge storing film which consists of stacked dielectric films and is capable of storing a charge, two storage portions forming parts of the charge storing film and overlapping the channel forming regions, a single layer dielectric film between the storage portions and in contact with the channel forming region, a control gate electrode on the single layer dielectric film, and a memory gate electrode on the storage portions.
    Type: Application
    Filed: December 14, 2000
    Publication date: August 28, 2003
    Inventors: Toshio Kobayashi, Hiroyuki Moriya, Ichiro Fujiwara
  • Publication number: 20030127680
    Abstract: Provided are a memory device capable of accurately reading out data, a method of manufacturing the same, and an integrated circuit. A first control electrode substantially faces a second control electrode with a conduction region and a storage region in between. At the time of “the reading of data”, an electric potential is applied to the first control electrode. During “the reading of data”, a change in an electric potential between the conduction region and the storage region is prevented, and therefore, unintentional writing or erasing of information is prevented, so that written information can be accurately read out.
    Type: Application
    Filed: December 20, 2002
    Publication date: July 10, 2003
    Inventors: Kazumasa Nomoto, Noriyuki Kawashima, Ichiro Fujiwara, Kenichi Taira
  • Publication number: 20030122204
    Abstract: The memory device has a plurality of dielectric films including charge storage layers CS having a charge holding capability therein and stacked on an active region of a semiconductor SUB and electrodes G on the plurality of dielectric films. Each charge storage layer CS includes a first nitride film CS1 made of silicon nitride or silicon oxynitride and a second nitride film CS2 made of silicon nitride or silicon oxynitride and having a higher charge trap density than the first nitride film CS1. The first nitride film CS1 is formed by chemical vapor deposition using a first gas which contains a first silicon-containing gas containing chlorine with a predetermined percent composition and a nitrogen-containing gas as starting materials. The second nitride film CS2 is formed by chemical vapor deposition using a second gas which contains a second silicon-containing gas having a lower chlorine percent composition than the above predetermined percent composition and a nitrogen-containing gas as starting materials.
    Type: Application
    Filed: November 12, 2002
    Publication date: July 3, 2003
    Inventors: Kazumasa Nomoto, Hiroshi Aozasa, Ichiro Fujiwara, Shinji Tanaka
  • Patent number: 6541326
    Abstract: A nonvolatile semiconductor memory device featuring a reducing operating voltage while maintaining a good disturbance characteristic and high speed in a write operation, including a gate insulating film and gate electrode stacked on a channel forming region of a semiconductor provided on the surface of a substrate and planarly dispersed charge storing means such as carrier traps in a nitride film or near the interface with the top insulating film, provided in the gate insulating film, the gate insulating film including an FN tunnel film having a dielectric constant larger than that of a silicon oxide film and exhibiting an FN electroconductivity, whereby the thickness of the gate insulating film, converted to that of a silicon oxide film, can be reduced and the voltage can be reduced.
    Type: Grant
    Filed: April 6, 2001
    Date of Patent: April 1, 2003
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Patent number: 6525379
    Abstract: Provided are a memory device capable of accurately reading out data, a method of manufacturing the same, and an integrated circuit. A first control electrode substantially faces a second control electrode with a conduction region and a storage region in between. At the time of “the reading of data”, an electric potential is applied to the first control electrode. During “the reading of data”, a change in an electric potential between the conduction region and the storage region is prevented, and therefore, unintentional writing or erasing of information is prevented, so that written information can be accurately read out.
    Type: Grant
    Filed: July 31, 2001
    Date of Patent: February 25, 2003
    Assignee: Sony Corporation
    Inventors: Kazumasa Nomoto, Noriyuki Kawashima, Ichiro Fujiwara, Kenichi Taira
  • Publication number: 20030025147
    Abstract: A semiconductor device enabling word lines to be arranged at close intervals, comprising a plurality of memory transistors arranged in an array and a plurality of word lines serving also as gate electrodes of memory transistors in a same row, extending in a row direction, and repeating in a column direction, where insulating films are formed between the plurality of word lines to insulate and isolate the word lines from each other and where a dimension of separation of word lines is defined by the thickness of the insulating films.
    Type: Application
    Filed: July 17, 2002
    Publication date: February 6, 2003
    Inventors: Kazumasa Nomoto, Toshio Kobayashi, Akihiro Nakamura, Ichiro Fujiwara, Toshio Terano
  • Patent number: 6483118
    Abstract: The present invention provides a positron source essentially consisting of a carbon member having 18F bound onto the surface thereof, a method of a preparing the same, and an automated system for supplying the same. In the present invention, the positron source is prepared by irradiating a solution 35 containing both H218O and a small amount of natural fluorine ions with a beam of charged particles to generate 18F, and then passing an electric current through the solution 35 using a carbon member 40 as an anode to cause to bind the generated 18F onto the surface of the carbon member 40.
    Type: Grant
    Filed: July 19, 2001
    Date of Patent: November 19, 2002
    Assignee: Riken
    Inventors: Ichiro Fujiwara, Yoshiko Ito, Ren Iwata, Toshio Hyodo, Yasushige Yano, Akira Goto, Yuji Ikegami, Yoshio Nomiya
  • Patent number: 6434053
    Abstract: A MONOS type memory transistor increased in injection efficiency or storing a plurality of bits of data by local injection of a charge into part of a plane area of distribution of a charge storing means, comprised of a channel forming region of a first conductivity type, source and drain regions of a second conductivity type, gate insulating films formed on the channel forming region, gate electrodes, and a charge storing means (charge traps) formed in the gate insulating film and dispersed in a plane facing the channel forming region and the thickness direction and in which hot electrons caused by a band-to-band tunneling current are injected from the source and drain regions, where in the gate insulating film, between a first storage region and a second storage region into which electrons are locally injected, there is a third region into which hot electrons are not injected.
    Type: Grant
    Filed: December 5, 2000
    Date of Patent: August 13, 2002
    Assignee: Sony Corporation
    Inventor: Ichiro Fujiwara
  • Publication number: 20020097621
    Abstract: A MONOS type memory transistor increased in injection efficiency or storing a plurality of bits of data by local injection or a charge into part of a plane area of distribution of a charge storing means, comprised of a channel forming region of a first conductivity type, source and drain regions of a second conductivity type, gate insulating films formed on the channel forming region, gate electrodes, and a charge storing means (charge traps) formed in the gate insulating film and dispersed in a plane facing the channel forming region and the thickness direction and in which hot electrons caused by a band-to-band tunneling current are injected from the source and drain regions, where in the gate insulating film, between a first storage region and a second storage region into which electrons are locally injected, there is a third region into which hot electrons are not injected.
    Type: Application
    Filed: December 5, 2000
    Publication date: July 25, 2002
    Inventor: Ichiro Fujiwara
  • Publication number: 20020089012
    Abstract: Provided are a memory device capable of accurately reading out data, a method of manufacturing the same, and an integrated circuit. A first control electrode substantially faces a second control electrode with a conduction region and a storage region in between. At the time of “the reading of data”, an electric potential is applied to the first control electrode. During “the reading of data”, a change in an electric potential between the conduction region and the storage region is prevented, and therefore, unintentional writing or erasing of information is prevented, so that written information can be accurately read out.
    Type: Application
    Filed: July 31, 2001
    Publication date: July 11, 2002
    Inventors: Kazumasa Nomoto, Noriyuki Kawashima, Ichiro Fujiwara, Kenichi Taira