Patents by Inventor Osamu Nagarekawa

Osamu Nagarekawa 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).

  • Method of manufacturing a mask blank including a modified chromium compound
    Patent number: 4657648
    Abstract: In a photo-mask blank, a transparent substrate is covered with a shading layer including chromium and chromium carbide. Covered on the shading layer, is an antireflection layer which includes chromium and chromium nitride. The shading and the antireflection layers are deposited in the same hollow space by sputtering. An etch rate of the shading layer is adjustable to that of the antireflection layer to make both etch rates equal and, thereby, to reduce undercuts appearing at the shading layer.
    Type: Grant
    Filed: October 1, 1984
    Date of Patent: April 14, 1987
    Inventors: Osamu Nagarekawa, Shigekazu Matsui
  • Photo-mask blank for use in lithography including a modified chromium compound
    Patent number: 4530891
    Abstract: In a photo-mask blank, a transparent substrate is covered with a shading layer including chromium and chromium carbide. On the shading layer is an antireflection layer which includes chromium and chromium nitride. The shading and the antireflection layers are deposited in the same hollow space by sputtering. The etch rate of the shading layer is adjustable to that of the antireflection layer to make both etch rates equal and, thereby, to reduce undercuts appearing at the shading layer.
    Type: Grant
    Filed: December 29, 1983
    Date of Patent: July 23, 1985
    Assignee: Hoya Electronics Co., Ltd.
    Inventors: Osamu Nagarekawa, Shigekazu Matsui
  • Photomask blank
    Patent number: D543160
    Type: Grant
    Filed: September 23, 2004
    Date of Patent: May 22, 2007
    Assignee: Hoya Corporation
    Inventors: Masaru Mitsui, Shigekazu Matsui, Masao Ushida, Osamu Nagarekawa
  • Photomask blank
    Patent number: D568839
    Type: Grant
    Filed: January 23, 2007
    Date of Patent: May 13, 2008
    Assignee: Hoya Corporation
    Inventors: Masaru Mitsui, Shigekazu Matsui, Masao Ushida, Osamu Nagarekawa