Patents by Inventor Kunihiko Kasama

Kunihiko Kasama 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).

  • Patterning method of chemical amplification type resist film for far ultraviolet radiation
    Patent number: 6242160
    Abstract: KrF excimer laser beam is selectively irradiated to a resist film. At this time, an incident light (KrF excimer laser beam) is reflected at the surface of an antireflection film to be a first reflected light, and is reflected at the surface of a film to be patterned to be a second reflected light. A standing wave is obtained by interference between the incident light and the first and the second reflected light. A light intensity of this standing wave has extreme maximum and extreme minimum appearing alternately, and a pair of extreme minimum and extreme maximum is across the first interface. A reflection index of the first reflected light is a range of 10 to 20%. Also, the thickness of the antireflection film is adjusted so that the extreme maximum of the pair is located in the resist film and the extreme minimum of the pair is located in the antireflection film.
    Type: Grant
    Filed: June 27, 1997
    Date of Patent: June 5, 2001
    Assignee: NEC Corporation
    Inventors: Shinichi Fukuzawa, Kunihiko Kasama
  • Pattern forming method
    Patent number: 5792596
    Abstract: In a method of forming a pattern, a photo-mask including a desired pattern is provided. A photo-sensitive resin film is spin-coated on a semiconductor substrate. Subsequently, the surface of the photo-sensitive resin film is changed to have a resistivity against a development solution. Next, light is illuminated to transmit the photo-mask. As a result, the resistivity of only the surface portion of the photo-sensitive resin film corresponding to the desired pattern is decreased based on the property of photo-sensitive resin film by the light having transmitted the photo-mask. Last, the photo-sensitive layer is developed with the development solution.
    Type: Grant
    Filed: February 6, 1996
    Date of Patent: August 11, 1998
    Assignee: NEC Corporation
    Inventors: Tadao Yasuzato, Shinji Ishida, Kunihiko Kasama, Yoko Iwabuchi
  • Photo-mask used in aligner for exactly transferring main pattern assisted by semi-transparent auxiliary pattern and process of fabrication thereof
    Patent number: 5786113
    Abstract: A photo-mask has a main pattern implemented by a photo-shield strip and an auxiliary pattern implemented by semi-transparent strips, and the photo-shield strip is equal in width to the semi-transparent strips so as to allow the photo-shield strip to be close to the resolution limit without destroy of the effects of the auxiliary pattern.
    Type: Grant
    Filed: June 24, 1996
    Date of Patent: July 28, 1998
    Assignee: NEC Corporation
    Inventors: Shuichi Hashimoto, Kunihiko Kasama
  • Resist material
    Patent number: 5665519
    Abstract: A vertically orienting compound is added to a chemical amplification type resist to progress acid catalysis during baking after exposure and penetration of a developer in a developing step in the direction of depth of the resist. This improves the resist shape, the dimensional uniformity, and the resolving power in a lithography step.
    Type: Grant
    Filed: January 30, 1996
    Date of Patent: September 9, 1997
    Assignee: NEC Corporation
    Inventor: Kunihiko Kasama