Patents by Inventor Hiroshi Kujirai

Hiroshi Kujirai 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: 8455944
    Abstract: A semiconductor device includes, on a semiconductor substrate, an active region surrounded by an STI region, a gate trench formed in one direction transverse to the active region, a gate insulating film formed on a side surface of the gate trench, an insulating film formed on a bottom of the gate trench and thicker than the gate insulating film, and a gate electrode having at least a part of the gate electrode formed in the gate trench. Portions of the semiconductor substrate present in the active region and located on both sides of the gate trench in an extension direction of the gate trench function as a source region and a drain region, respectively. A portion of the semiconductor substrate located between the side surface of the active region (the side of the STI region) and the side surface of the gate trench functions as a channel region.
    Type: Grant
    Filed: July 19, 2011
    Date of Patent: June 4, 2013
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 8431986
    Abstract: A semiconductor device includes a silicon pillar formed substantially perpendicular to a principal surface of a silicon substrate, a first impurity diffusion layer and a second impurity diffusion layer arranged below and above the silicon pillar, respectively, a gate electrode arranged to penetrate through the silicon pillar in a horizontal direction, a gate dielectric film arranged between the gate electrode and the silicon pillar, a back-gate electrode arranged adjacent to the silicon pillar, and a back-gate dielectric film arranged between the back-gate electrode and the silicon pillar.
    Type: Grant
    Filed: February 8, 2011
    Date of Patent: April 30, 2013
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 8426903
    Abstract: There are provided: a silicon pillar that is formed almost perpendicularly to a main surface of a substrate; first and second impurity diffused layers that are arranged in a lower part and an upper part of the silicon pillar, respectively; a gate electrode that is arranged horizontally through the silicon pillar; and a gate insulating film that is arranged between the gate electrode and the silicon pillar. The silicon pillar consequently has a small volume, which makes it possible to reduce the leak current of the transistor or thyristor formed in the silicon pillar.
    Type: Grant
    Filed: December 27, 2010
    Date of Patent: April 23, 2013
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 8173515
    Abstract: An oxide film and a liner film are formed on an inner wall of a trench in a semiconductor substrate. After filling an SOD film in the trench, a heat treatment is carried out. Part of the liner film in contact with the SOD film is removed to expose part of the SOD film. A heat treatment is carried out on the SOD film. An isolating region is formed by filling an insulating film in the trench.
    Type: Grant
    Filed: July 2, 2009
    Date of Patent: May 8, 2012
    Assignee: Elpida Memory, Inc.
    Inventors: Toshiya Nakamori, Hiroshi Kujirai
  • Publication number: 20110272760
    Abstract: A semiconductor device includes, on a semiconductor substrate, an active region surrounded by an STI region, a gate trench formed in one direction transverse to the active region, a gate insulating film formed on a side surface of the gate trench, an insulating film formed on a bottom of the gate trench and thicker than the gate insulating film, and a gate electrode having at least a part of the gate electrode formed in the gate trench. Portions of the semiconductor substrate present in the active region and located on both sides of the gate trench in an extension direction of the gate trench function as a source region and a drain region, respectively. A portion of the semiconductor substrate located between the side surface of the active region (the side of the STI region) and the side surface of the gate trench functions as a channel region.
    Type: Application
    Filed: July 19, 2011
    Publication date: November 10, 2011
    Applicant: ELPIDA MEMORY, INC.
    Inventor: Hiroshi KUJIRAI
  • Patent number: 8013386
    Abstract: A semiconductor device includes, on a semiconductor substrate, an active region surrounded by an STI region, a gate trench formed in one direction transverse to the active region, a gate insulating film formed on a side surface of the gate trench, an insulating film formed on a bottom of the gate trench and thicker than the gate insulating film, and a gate electrode having at least a part of the gate electrode formed in the gate trench. Portions of the semiconductor substrate present in the active region and located on both sides of the gate trench in an extension direction of the gate trench function as a source region and a drain region, respectively. A portion of the semiconductor substrate located between the side surface of the active region (the side of the STI region) and the side surface of the gate trench functions as a channel region.
    Type: Grant
    Filed: November 28, 2006
    Date of Patent: September 6, 2011
    Assignee: Elpida Memory, Inc
    Inventor: Hiroshi Kujirai
  • Publication number: 20110193159
    Abstract: A semiconductor device includes a silicon pillar formed substantially perpendicular to a principal surface of a silicon substrate, a first impurity diffusion layer and a second impurity diffusion layer arranged below and above the silicon pillar, respectively, a gate electrode arranged to penetrate through the silicon pillar in a horizontal direction, a gate dielectric film arranged between the gate electrode and the silicon pillar, a back-gate electrode arranged adjacent to the silicon pillar, and a back-gate dielectric film arranged between the back-gate electrode and the silicon pillar.
    Type: Application
    Filed: February 8, 2011
    Publication date: August 11, 2011
    Applicant: ELPIDA MEMORY, INC.
    Inventor: Hiroshi KUJIRAI
  • Publication number: 20110156120
    Abstract: There are provided: a silicon pillar that is formed almost perpendicularly to a main surface of a substrate; first and second impurity diffused layers that are arranged in a lower part and an upper part of the silicon pillar, respectively; a gate electrode that is arranged horizontally through the silicon pillar; and a gate insulating film that is arranged between the gate electrode and the silicon pillar. The silicon pillar consequently has a small volume, which makes it possible to reduce the leak current of the transistor or thyristor formed in the silicon pillar.
    Type: Application
    Filed: December 27, 2010
    Publication date: June 30, 2011
    Applicant: ELPIDA MEMORY, INC.
    Inventor: Hiroshi KUJIRAI
  • Patent number: 7923773
    Abstract: A bottom of a gate trench has a first bottom relatively far from an STI and a second bottom relatively near from the STI. A portion, in an active region, configuring the second bottom of the gate trench configures a side-wall channel region, and has a thin-film SOI structure sandwiched between the gate electrode and the STI. On the other hand, a portion configuring the first bottom of the gate trench functions as a sub-channel region. A curvature radius of the second bottom is larger than a curvature radius of the first bottom. In an approximate center in a length direction of the gate trench, a bottom of a trench is approximately flat, and on the other hand, in ends of the length direction, a nearly whole bottom of the trench is curved.
    Type: Grant
    Filed: October 22, 2008
    Date of Patent: April 12, 2011
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 7892925
    Abstract: A method of forming a semiconductor device is provided. A hollowed portion is formed over an active region of a semiconductor substrate. The bottom of the hollowed portion is lowered in level than the surface of an isolation region of the substrate. A first mask is formed in the hollowed portion, except on a side region that is adjacent to the boundary between the active region and the isolation region. A trench is formed in the side region of the active region by using the first mask and the isolation region as a mask.
    Type: Grant
    Filed: September 16, 2008
    Date of Patent: February 22, 2011
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 7867856
    Abstract: A semiconductor device includes an element isolation region formed in a semiconductor substrate, an active region surrounded by the element isolation region, and a gate electrode formed in one direction to cross the active region. The semiconductor substrate includes two gate trenches formed in parallel to a major axis direction of the active region in the active region, and a fin-shaped part which is located between the two gate trenches. The gate electrode is buried in the two gate trenches and formed on the fin-shaped part. The fin-shaped part serves as a channel region. A fin field effect transistor in which a width of the channel region is smaller than a gate length is thereby obtained.
    Type: Grant
    Filed: June 24, 2010
    Date of Patent: January 11, 2011
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Patent number: 7816208
    Abstract: A method of manufacturing a semiconductor device includes: a first step of forming an STI region and an active region surrounded by the STI region on a semiconductor substrate; a second step of forming a protection film protecting a shoulder part of the STI region in a boundary between the active region and the STI region; a third step of forming a gate trench in the active region so as to leave a part of the semiconductor substrate located between a side surface of the STI region and a side surface of the gate trench; a fourth step of forming a gate insulating film on the side surface of the gate trench; a fifth step of forming a gate electrode, at least a part of the gate electrode being buried in the gate trench; and a sixth step of forming a source region and a drain region in regions located on both sides of the gate trench in an extension direction of the gate trench, respectively, so that the part of the semiconductor substrate functions as a channel region.
    Type: Grant
    Filed: July 6, 2007
    Date of Patent: October 19, 2010
    Assignee: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Publication number: 20100261328
    Abstract: A semiconductor device includes an element isolation region formed in a semiconductor substrate, an active region surrounded by the element isolation region, and a gate electrode formed in one direction to cross the active region. The semiconductor substrate includes two gate trenches formed in parallel to a major axis direction of the active region in the active region, and a fin-shaped part which is located between the two gate trenches. The gate electrode is buried in the two gate trenches and formed on the fin-shaped part. The fin-shaped part serves as a channel region. A fin field effect transistor in which a width of the channel region is smaller than a gate length is thereby obtained.
    Type: Application
    Filed: June 24, 2010
    Publication date: October 14, 2010
    Inventor: Hiroshi KUJIRAI
  • Patent number: 7687849
    Abstract: Disclosed is a technique for reducing the leak current by reducing contamination of metal composing a polymetal gate of a MISFET. Of a polycrystalline silicon film, a WN film, a W film, and a cap insulating film formed on a gate insulating film on a p-type well (semiconductor substrate), the cap insulating film, the W film, and the WN film are etched and the over-etching of the polycrystalline silicon film below them is performed. Then, a sidewall film is formed on sidewalls of these films. Thereafter, after etching the polycrystalline silicon film with using the sidewall film as a mask, a thermal treatment is performed in an oxidation atmosphere, by which a light oxide film is formed on the sidewall of the polycrystalline silicon film. As a result, the contamination on the gate insulating film due to the W and the W oxide can be reduced, and also, the diffusion of these materials into the semiconductor substrate (p-type well) and the resultant increase of the leak current can be prevented.
    Type: Grant
    Filed: May 29, 2008
    Date of Patent: March 30, 2010
    Assignee: Elpida Memory, Inc.
    Inventors: Hiroshi Kujirai, Kousuke Okuyama, Kazuhiro Hata, Kiyonori Oyu, Ryo Nagai, Hiroyuki Uchiyama, Takahiro Kumauchi, Teruhisa Ichise
  • Publication number: 20100022069
    Abstract: An oxide film and a liner film are formed on an inner wall of a trench in a semiconductor substrate. After filling an SOD film in the trench, a heat treatment is carried out. Part of the liner film in contact with the SOD film is removed to expose part of the SOD film. A heat treatment is carried out on the SOD film. An isolating region is formed by filling an insulating film in the trench.
    Type: Application
    Filed: July 2, 2009
    Publication date: January 28, 2010
    Applicant: Elpida Memory, Inc.
    Inventors: Toshiya NAKAMORI, Hiroshi Kujirai
  • Patent number: 7649256
    Abstract: A semiconductor chip having a thickness of 130 micrometers or less includes a mechanically ground bottom surface corresponding to a central circuit area, and a polished bottom surface corresponding to a peripheral scribe area. The mechanically ground bottom surface prevents heavy metals attached onto the bottom surface of the wafer from diffusing toward the source/drain regions of the semiconductor substrate and thereby from degrading the transistor characteristics.
    Type: Grant
    Filed: July 8, 2005
    Date of Patent: January 19, 2010
    Assignee: Elpida Memory, Inc.
    Inventors: Hiroshi Kujirai, Kiyonori Oyu
  • Publication number: 20090101971
    Abstract: A bottom of a gate trench has a first bottom relatively far from an STI and a second bottom relatively near from the STI A portion, in an active region, configuring the second bottom of the gate trench configures a side-wall channel region, and has a thin-film SOI structure sandwiched between the gate electrode and the STI. On the other hand, a portion configuring the first bottom of the gate trench functions as a sub-channel region. A curvature radius of the second bottom is larger than a curvature radius of the first bottom. In an approximate center in a width direction of the gate trench, a bottom of a trench is approximately flat, and on the other hand, in ends of the width direction, a nearly whole bottom of the trench is curved.
    Type: Application
    Filed: October 22, 2008
    Publication date: April 23, 2009
    Applicant: ELPIDA MEMORY, INC.
    Inventor: Hiroshi KUJIRAI
  • Publication number: 20090075444
    Abstract: A method of forming a semiconductor device is provided. A hollowed portion is formed over an active region of a semiconductor substrate. The bottom of the hollowed portion is lowered in level than the surface of an isolation region of the substrate. A first mask is formed in the hollowed portion, except on a side region that is adjacent to the boundary between the active region and the isolation region. A trench is formed in the side region of the active region by using the first mask and the isolation region as a mask.
    Type: Application
    Filed: September 16, 2008
    Publication date: March 19, 2009
    Applicant: Elpida Memory, Inc.
    Inventor: Hiroshi Kujirai
  • Publication number: 20080237752
    Abstract: Disclosed is a technique for reducing the leak current by reducing contamination of metal composing a polymetal gate of a MISFET. Of a polycrystalline silicon film, a WN film, a W film, and a cap insulating film formed on a gate insulating film on a p-type well (semiconductor substrate), the cap insulating film, the W film, and the WN film are etched and the over-etching of the polycrystalline silicon film below them is performed. Then, a sidewall film is formed on sidewalls of these films. Thereafter, after etching the polycrystalline silicon film with using the sidewall film as a mask, a thermal treatment is performed in an oxidation atmosphere, by which a light oxide film is formed on the sidewall of the polycrystalline silicon film. As a result, the contamination on the gate insulating film due to the W and the W oxide can be reduced, and also, the diffusion of these materials into the semiconductor substrate (p-type well) and the resultant increase of the leak current can be prevented.
    Type: Application
    Filed: May 29, 2008
    Publication date: October 2, 2008
    Inventors: Hiroshi Kujirai, Kousuke Okuyama, Kazuhiro Hata, Kiyonori Oyu, Ryo Nagai, Hiroyuki Uchiyama, Takahiro Kumauchi, Teruhisa Ichise
  • Patent number: 7417291
    Abstract: Disclosed is a technique for reducing the leak current by reducing contamination of metal composing a polymetal gate of a MISFET. Of a polycrystalline silicon film, a WN film, a W film, and a cap insulating film formed on a gate insulating film on a p-type well (semiconductor substrate), the cap insulating film, the W film, and the WN film are etched and the over-etching of the polycrystalline silicon film below them is performed. Then, a sidewall film is formed on sidewalls of these films. Thereafter, after etching the polycrystalline silicon film with using the sidewall film as a mask, a thermal treatment is performed in an oxidation atmosphere, by which a light oxide film is formed on the sidewall of the polycrystalline silicon film. As a result, the contamination on the gate insulating film due to the W and the W oxide can be reduced, and also, the diffusion of these materials into the semiconductor substrate (p-type well) and the resultant increase of the leak current can be prevented.
    Type: Grant
    Filed: April 18, 2007
    Date of Patent: August 26, 2008
    Assignee: Elpida Memory, Inc.
    Inventors: Hiroshi Kujirai, Kousuke Okuyama, Kazuhiro Hata, Kiyonori Oyu, Ryo Nagai, Hiroyuki Uchiyama, Takahiro Kumauchi, Teruhisa Ichise