Patents by Inventor Atsushi YOKOHATA

Atsushi YOKOHATA 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: 10295477
    Abstract: A photomask blank having a thin film on a transparent substrate is inspected for defects by irradiating inspection light to a surface region of the blank, collecting the reflected light from the irradiated region via an inspection optical system to form a magnified image of the region, extracting a feature parameter of light intensity distribution from the magnified image, and identifying the bump/pit shape of the defect based on the feature parameter combined with the structure of the thin film. The defect inspection method is effective for discriminating defects of bump or pit shape in a highly reliable manner. On application of the defect inspection method, photomask blanks having no pinhole defects are available at lower costs and higher yields.
    Type: Grant
    Filed: January 25, 2018
    Date of Patent: May 21, 2019
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo Terasawa, Hiroshi Fukuda, Atsushi Yokohata, Takahiro Kishita, Daisuke Iwai
  • Publication number: 20180209916
    Abstract: A photomask blank having a thin film on a transparent substrate is inspected for defects by irradiating inspection light to a surface region of the blank, collecting the reflected light from the irradiated region via an inspection optical system to form a magnified image of the region, extracting a feature parameter of light intensity distribution from the magnified image, and identifying the bump/pit shape of the defect based on the feature parameter combined with the structure of the thin film. The defect inspection method is effective for discriminating defects of bump or pit shape in a highly reliable manner. On application of the defect inspection method, photomask blanks having no pinhole defects are available at lower costs and higher yields.
    Type: Application
    Filed: January 25, 2018
    Publication date: July 26, 2018
    Applicant: Shin-Etsu Chemical Co., Ltd.
    Inventors: Tsuneo TERASAWA, Hiroshi FUKUDA, Atsushi YOKOHATA, Takahiro KISHITA, Daisuke IWAI
  • Patent number: 9829787
    Abstract: A method of inspecting a defect present at a surface portion of a photomask blank having at least one thin film formed on a substrate by use of the inspecting optical system. The method includes setting the distance between the defect and an objective lens of an inspecting optical system to a defocus distance, applying inspection light to the defect through the objective lens, collecting reflected light from the region irradiated with the inspection light, through the objective lens, as a magnified image, identifying a light intensity variation portion of the magnified image, and determining the rugged shape of the defect on the basis of a variation in light intensity of the light intensity variation portion of the magnified image.
    Type: Grant
    Filed: June 14, 2016
    Date of Patent: November 28, 2017
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo Terasawa, Hiroshi Fukuda, Takahiro Kishita, Daisuke Iwai, Atsushi Yokohata
  • Patent number: 9829442
    Abstract: Disclosed is a method of inspecting a defect present at a surface portion of a photomask blank which includes an optical film, and a thin film. The method includes: selecting and designating an inspection treatment procedure and a criterion for determination of rugged shape of the defect which correspond to modes of the optical film and the thin film of the photomask blank; applying inspection light to a region including the defect while maintaining a distance between the defect and an objective lens of an inspecting optical system, based on the designated inspection treatment procedure, and collecting reflected light from the region irradiated with the inspection light, as a magnified image of the region, through the inspecting optical system; and determining the rugged shape of the defect, from light intensity distribution of the magnified image, based on the designated criterion for determination.
    Type: Grant
    Filed: September 2, 2016
    Date of Patent: November 28, 2017
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo Terasawa, Atsushi Yokohata, Daisuke Iwai, Takahiro Kishita, Hiroshi Fukuda
  • Patent number: 9772551
    Abstract: The defect size of a photomask blank is evaluated. An inspection-target photomask blank is irradiated with inspection light and reflected light of the region of the inspection-target photomask blank irradiated with the inspection light is collected through an objective lens of an inspection optical system as a magnified image of the region. Then, an intensity change part in the light intensity distribution profile of the magnified image is identified. Next, a difference in the light intensity of the intensity change part is obtained and the width of the intensity change part is obtained as the apparent width of the defect. Then, the width of the defect is calculated on the basis of a predetermined conversion expression showing the relationship among the difference in the light intensity, the apparent width of the defect, and the actual width of the defect, and the width of the defect is estimated.
    Type: Grant
    Filed: October 23, 2015
    Date of Patent: September 26, 2017
    Assignee: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo Terasawa, Takahiro Kishita, Daisuke Iwai, Hiroshi Fukuda, Atsushi Yokohata
  • Publication number: 20170068158
    Abstract: Disclosed is a method of inspecting a defect present at a surface portion of a photomask blank which includes an optical film, and a thin film. The method includes: selecting and designating an inspection treatment procedure and a criterion for determination of rugged shape of the defect which correspond to modes of the optical film and the thin film of the photomask blank; applying inspection light to a region including the defect while maintaining a distance between the defect and an objective lens of an inspecting optical system, based on the designated inspection treatment procedure, and collecting reflected light from the region irradiated with the inspection light, as a magnified image of the region, through the inspecting optical system; and determining the rugged shape of the defect, from light intensity distribution of the magnified image, based on the designated criterion for determination.
    Type: Application
    Filed: September 2, 2016
    Publication date: March 9, 2017
    Applicant: Shin-Etsu Chemical Co., Ltd.
    Inventors: Tsuneo TERASAWA, Atsushi YOKOHATA, Daisuke IWAI, Takahiro KISHITA, Hiroshi FUKUDA
  • Publication number: 20160377553
    Abstract: A method of inspecting a defect present at a surface portion of a photomask blank having at least one thin film formed on a substrate by use of the inspecting optical system. The method includes setting the distance between the defect and an objective lens of an inspecting optical system to a defocus distance, applying inspection light to the defect through the objective lens, collecting reflected light from the region irradiated with the inspection light, through the objective lens, as a magnified image, identifying a light intensity variation portion of the magnified image, and determining the rugged shape of the defect on the basis of a variation in light intensity of the light intensity variation portion of the magnified image.
    Type: Application
    Filed: June 14, 2016
    Publication date: December 29, 2016
    Applicant: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo TERASAWA, Hiroshi FUKUDA, Takahiro KISHITA, Daisuke IWAI, Atsushi YOKOHATA
  • Publication number: 20160116837
    Abstract: The defect size of a photomask blank is evaluated. An inspection-target photomask blank is irradiated with inspection light and reflected light of the region of the inspection-target photomask blank irradiated with the inspection light is collected through an objective lens of an inspection optical system as a magnified image of the region. Then, an intensity change part in the light intensity distribution profile of the magnified image is identified. Next, a difference in the light intensity of the intensity change part is obtained and the width of the intensity change part is obtained as the apparent width of the defect. Then, the width of the defect is calculated on the basis of a predetermined conversion expression showing the relationship among the difference in the light intensity, the apparent width of the defect, and the actual width of the defect, and the width of the defect is estimated.
    Type: Application
    Filed: October 23, 2015
    Publication date: April 28, 2016
    Applicant: SHIN-ETSU CHEMICAL CO., LTD.
    Inventors: Tsuneo TERASAWA, Takahiro KISHITA, Daisuke IWAI, Hiroshi FUKUDA, Atsushi YOKOHATA