Patents by Inventor Masafumi Ishiyama

Masafumi Ishiyama 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: 9946153
    Abstract: Provided is a mask blank in which a thin film for transfer pattern formation is provided on a main surface of a transparent substrate. The thin film is made of a material containing a transition metal and silicon and further containing at least one of oxygen and nitrogen. The thin film has as its surface layer an oxide layer with an oxygen content higher than that of the thin film of a region other than the surface layer. The thin film is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side. The oxide layer is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side.
    Type: Grant
    Filed: September 19, 2016
    Date of Patent: April 17, 2018
    Assignee: HOYA CORPORATION
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama
  • Publication number: 20170003583
    Abstract: Provided is a mask blank in which a thin film for transfer pattern formation is provided on a main surface of a transparent substrate. The thin film is made of a material containing a transition metal and silicon and further containing at least one of oxygen and nitrogen. The thin film has as its surface layer an oxide layer with an oxygen content higher than that of the thin film of a region other than the surface layer. The thin film is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side. The oxide layer is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side.
    Type: Application
    Filed: September 19, 2016
    Publication date: January 5, 2017
    Applicant: HOYA CORPORATION
    Inventors: Teiichiro UMEZAWA, Masafumi Ishiyama
  • Patent number: 9470971
    Abstract: Provided is a mask blank in which a thin film for transfer pattern formation is provided on a main surface of a transparent substrate. The thin film is made of a material containing a transition metal and silicon and further containing at least one of oxygen and nitrogen. The thin film has as its surface layer an oxide layer with an oxygen content higher than that of the thin film of a region other than the surface layer. The thin film is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side. The oxide layer is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side.
    Type: Grant
    Filed: May 9, 2013
    Date of Patent: October 18, 2016
    Assignee: HOYA CORPORATION
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama
  • Patent number: 9159351
    Abstract: A perpendicular magnetic recording medium includes a substrate, a soft magnetic layer, a pre-underlayer, an underlayer, and a main recording layer serving as a magnetic recording layer. The pre-underlayer contains seed crystal grains that serve as a base for crystal grains of the underlayer, and an addition substance that is added between the seed crystal grains and composed of an element having an atomic radius smaller than that of an element forming the seed crystal grains.
    Type: Grant
    Filed: October 14, 2008
    Date of Patent: October 13, 2015
    Assignee: WD Media (Singapore) PTE. LTD
    Inventors: Kazuaki Sakamoto, Kong Kim, Takahiro Onoue, Masafumi Ishiyama, Teiichiro Umezawa, Kenji Ayama
  • Publication number: 20150104735
    Abstract: Provided is a mask blank in which a thin film for transfer pattern formation is provided on a main surface of a transparent substrate. The thin film is made of a material containing a transition metal and silicon and further containing at least one of oxygen and nitrogen. The thin film has as its surface layer an oxide layer with an oxygen content higher than that of the thin film of a region other than the surface layer. The thin film is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side. The oxide layer is formed so that the thickness of its outer peripheral portion is greater than that of its central portion on the main surface side.
    Type: Application
    Filed: May 9, 2013
    Publication date: April 16, 2015
    Applicant: HOYA CORPORATION
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama
  • Patent number: 8871368
    Abstract: A perpendicular magnetic recording medium with SNR improved by reducing noise due to an auxiliary recording layer so that a higher recording density can be achieved. The perpendicular magnetic recording medium 100 includes a base, at least a magnetic recording layer 122 having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a non-magnetic split layer 124 disposed on the magnetic recording layer 122 and containing Ru and oxygen; and an auxiliary recording layer 126 that is disposed on the split layer 124 and that is magnetically approximately continuous in an in-plane direction of a main surface of the base 110.
    Type: Grant
    Filed: September 16, 2009
    Date of Patent: October 28, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Takahiro Onoue, Teiichiro Umezawa, Toshiaki Tachibana, Masafumi Ishiyama
  • Patent number: 8795857
    Abstract: A perpendicular magnetic recording medium of the invention is characterized by having, on a disk substrate 110, a soft magnetic layer 14, a magnetic recording layer 22, a continuous layer 24 magnetically continuous in the in-plane direction of the substrate, a blocking layer 25 for blocking shock imposed on the continuous layer, and a medium protective layer 28 containing carbon formed on the blocking layer.
    Type: Grant
    Filed: September 24, 2008
    Date of Patent: August 5, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Kenji Ayama, Tokichiro Sato, Teiichiro Umezawa, Masafumi Ishiyama
  • Patent number: 8709532
    Abstract: In a magnetic disk having a magnetic layer, a protection layer, and a lubrication layer formed on a substrate in this order, a surface free energy ?S of a surface of the magnetic disk derived by an extended Fowkes equation is greater than 0 and no greater than 24 mN/m. ?Sd (dispersion force component of surface free energy) forming the surface free energy ?S is greater than 0 and no greater than 17 mN/m, ?Sp (dipole component of surface free energy) forming the surface free energy ?S is greater than 0 and no greater than 1 mN/m, and ?Sh (hydrogen bonding force component of surface free energy) forming the surface free energy ?S is greater than 0 and no greater than 6 mN/m.
    Type: Grant
    Filed: April 12, 2010
    Date of Patent: April 29, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventor: Masafumi Ishiyama
  • Patent number: 8623528
    Abstract: An object of the present invention is to provide a method of manufacturing a perpendicular magnetic recording medium (100) in which both of a coercive force Hc and reliability can be achieved at a higher level even with heating at the time of forming a medium protective layer (126) and to provide the perpendicular magnetic recording medium (100).
    Type: Grant
    Filed: March 25, 2009
    Date of Patent: January 7, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama, Tokichiro Sato, Kenji Ayama, Takahiro Onoue, Junichi Horikawa
  • Patent number: 8425975
    Abstract: Provided is a magnetic disk (10) for a magnetic recording, which comprises a magnetic layer (4) for a magnetic recording, a protecting layer (5) formed over the magnetic layer (4) for protecting the magnetic layer (4), and a lubricating layer (6) formed over the protecting layer (5). The protecting layer (5) is a layer composed substantially of carbon, hydrogen and nitrogen. The atomic ratio (N/C) of nitrogen and carbon, which was calculated from the spectral intensities of N1s and C1s detected for a detection angle of 7 degrees of photoelectrons by an angularly resolved X-ray photoelectron spectroscopy, is 0.15 to 0.25. This constitution of the protecting layer (5) is excellent in wear resistance and sliding characteristics even for a film thickness of 3 nm or less and provides a magnetic disk which can avoid a high fly write trouble or the like.
    Type: Grant
    Filed: September 19, 2008
    Date of Patent: April 23, 2013
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventor: Masafumi Ishiyama
  • Patent number: 8309239
    Abstract: A vertical magnetic recording disc (100) includes a base (10), a magnetic recording layer (22), and a medium protection layer (26). The magnetic recording layer (22) is a ferromagnetic layer having a granular structure where a granular portion is formed. The medium protection layer (26) contains nitrogen (N) atoms and carbon (C) atoms with a number ratio (N/C) in a range from 0.050 to 0.150. In a Raman spectrum obtained by exciting the medium protection layer (26) by argon ion laser light of wavelength 514.5 nm, from which a fluorescence is removed, the peak ratio Dh/Gh is in a range from 0.70 to 0.95, when a D peak Dh appearing in the vicinity of 1350 cm?1 is separated from G peak Gh appearing in the vicinity of 1520 cm?1 by the Gauss function.
    Type: Grant
    Filed: March 28, 2008
    Date of Patent: November 13, 2012
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama, Kenji Ayama, Tokichiro Sato
  • Patent number: 8142916
    Abstract: Provided is a magnetic recording medium which maintains high S/N ratio and coercive force (Hc) and has high recording density, even with fine magnetic particles, by further improving crystal orientation of a magnetic recording layer. The magnetic recording medium is provided with an orientation control layer (16), a nonmagnetic under layer (18), and a magnetic recording layer (22) on a substrate. The orientation control layer (16) has an fcc structure and a (111) plane parallel to the substrate. The under layer (18) has an hcp structure and a (0001) plane parallel to the substrate. An atomic distance of the (111) plane of the orientation control layer (16) is ?0.2 ? to +0.15 ? to a lattice spacing of the under layer (18).
    Type: Grant
    Filed: March 28, 2008
    Date of Patent: March 27, 2012
    Assignee: WD Media (Singapore) Pte, Ltd
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama, Kenji Ayama, Tokichiro Sato
  • Patent number: 8092931
    Abstract: A protection layer containing carbon as a major component is deposited by plasma CVD. The protection layer has film quality such that, when a spectrum is obtained by excluding photoluminescence from a Raman spectrum in a wavenumber band from 900 cm?1 to 1800 cm?1 obtained by exciting the protection layer with an argon ion laser beam having a wavelength of 514.5 nm and the spectrum is subjected to waveform separation by the Gaussian function to split a D peak appearing around 1350 cm?1 and a G peak appearing around 1520 cm?1, the ratio Dw/Gw between a half width Dw of the D peak and a half width Gw of the G peak exceeds 0 and is not greater than 2.7.
    Type: Grant
    Filed: June 18, 2008
    Date of Patent: January 10, 2012
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Masafumi Ishiyama, Kenji Ayama
  • Patent number: 8057926
    Abstract: The present invention provides a perpendicular magnetic recording medium that can reduce noise by further size reduction and isolation of magnetic grains in a magnetic recording layer and can increase the recording density by improvement of the SNR. A typical configuration of a perpendicular magnetic recording medium according to the present invention is a perpendicular magnetic recording medium having a magnetic recording layer with a granular structure in which non-magnetic grain boundary portions are formed between magnetic grains that have grown continuously in a columnar shape, wherein the grain boundary portions contain a plurality of kinds of oxides.
    Type: Grant
    Filed: September 26, 2008
    Date of Patent: November 15, 2011
    Assignee: WD Media(Singapore) Pte. Ltd.
    Inventors: Kenji Ayama, Tokichiro Sato, Teiichiro Umezawa, Masafumi Ishiyama, Junichi Horikawa
  • Publication number: 20110244119
    Abstract: A vertical magnetic recording disc (100) includes a base (10), a magnetic recording layer (22), and a medium protection layer (26). The magnetic recording layer (22) is a ferromagnetic layer having a granular structure where a granular portion is formed. The medium protection layer (26) contains nitrogen (N) atoms and carbon (C) atoms with a number ratio (N/C) in a range from 0.050 to 0.150. In a Raman spectrum obtained by exciting the medium protection layer (26) by argon ion laser light of wavelength 514.5 nm, from which a fluorescence is removed, the peak ratio Dh/Gh is in a range from 0.70 to 0.95, when a D peak Dh appearing in the vicinity of 1350 cm?1 is separated from G peak Gh appearing in the vicinity of 1520 cm?1 by the Gauss function.
    Type: Application
    Filed: June 20, 2011
    Publication date: October 6, 2011
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: TEIICHIRO UMEZAWA, MASAFUMI ISHIYAMA, KENJI AYAMA, TOKICHIRO SATO
  • Publication number: 20110212346
    Abstract: An object of the present invention is to provide a perpendicular magnetic recording medium the SNR of which is improved by reducing noise thought to be due to an auxiliary recording layer so that a higher recording density can be achieved, and a method of manufacturing the same. In order to achieve the above object, a representative configuration of a perpendicular magnetic recording medium 100 according to the present invention includes, on a base, at least a magnetic recording layer 122 having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a non-magnetic split layer 124 disposed on the magnetic recording layer 122 and containing Ru and oxygen; and an auxiliary recording layer 126 that is disposed on the split layer 124 and that is magnetically approximately continuous in an in-plane direction of a main surface of the base 110.
    Type: Application
    Filed: September 16, 2009
    Publication date: September 1, 2011
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: Takahiro Onoue, Teiichiro Umezawa, Toshiaki Tachibana, Masafumi Ishiyama
  • Publication number: 20110111262
    Abstract: An object of the present invention is to provide a method of manufacturing a perpendicular magnetic recording medium (100) in which both of a coercive force Hc and reliability can be achieved at a higher level even with heating at the time of forming a medium protective layer (126) and to provide the perpendicular magnetic recording medium (100).
    Type: Application
    Filed: March 25, 2009
    Publication date: May 12, 2011
    Applicant: WD Media (Singapore) Pte. Ltd.
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama, Tokichiro Sato, Kenji Ayama, Takahiro Onoue, Junichi Horikawa
  • Publication number: 20100323221
    Abstract: Provided is a magnetic disk (10) for a magnetic recording, which comprises a magnetic layer (4) for a magnetic recording, a protecting layer (5) formed over the magnetic layer (4) for protecting the magnetic layer (4), and a lubricating layer (6) formed over the protecting layer (5). The protecting layer (5) is a layer composed substantially of carbon, hydrogen and nitrogen. The atomic ratio (N/C) of nitrogen and carbon, which was calculated from the spectral intensities of N1s and C1s detected for a detection angle of 7 degrees of photoelectrons by an angularly resolved X-ray photoelectron spectroscopy, is 0.15 to 0.25. This constitution of the protecting layer (5) is excellent in wear resistance and sliding characteristics even for a film thickness of 3 nm or less and provides a magnetic disk which can avoid a high fly write trouble or the like.
    Type: Application
    Filed: September 19, 2008
    Publication date: December 23, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventor: Masafumi Ishiyama
  • Publication number: 20100279151
    Abstract: A perpendicular magnetic recording medium includes a substrate, a soft magnetic layer, a pre-underlayer, an underlayer, and a main recording layer serving as a magnetic recording layer. The pre-underlayer contains seed crystal grains that serve as a base for crystal grains of the underlayer, and an addition substance that is added between the seed crystal grains and composed of an element having an atomic radius smaller than that of an element forming the seed crystal grains.
    Type: Application
    Filed: October 14, 2008
    Publication date: November 4, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Kazuaki Sakamoto, Kong Kim, Takahiro Onoue, Masafumi Ishiyama, Teiichiro Umezawa, Kenji Ayama
  • Publication number: 20100215992
    Abstract: A magnetic recording medium used for perpendicular magnetic recording, the magnetic recording medium comprising: a substrate having a first surface and a second surface opposite to the first surface; a magnetic recording medium constituent layer formed on the first surface of the substrate, the magnetic recording medium constituent layer including at least a magnetic recording layer; a non-magnetic metal film formed on the second surface of the substrate; and a carbon-based protective film formed on the non-magnetic metal film.
    Type: Application
    Filed: February 22, 2010
    Publication date: August 26, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Junichi HORIKAWA, Kenji AYAMA, Masafumi ISHIYAMA, Toshikatsu YAMAGUCHI, Yusuke SETO