Patents by Inventor Akihiko Igawa

Akihiko Igawa 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).

  • Publication number: 20060057468
    Abstract: In the process wherein a high heat resistance is required for a photoresist pattern such as a manufacture of a TFT active matrix substrate, a super high heat resistant positive pattern is formed using a positive-working photosensitive composition. The pattern forming method of the present invention comprising steps of: applying a photosensitive composition onto a substrate comprising (a) an alkali-soluble resin, (b) a photosensitizer having a quinone diazide group, (c) a photo acid generator, (d) a crosslinking agent and (e) a solvent; then exposing the substrate to light through a mask; forming a positive image by developing and removing the exposed area to light; exposing a whole area of the positive image to light; and post-baking, if necessary. In the case of using 1,2-naphthoquinone-4-sulfonyl compound as the photosensitizer having a quinone diazide group, the above component (c) can be omitted since this compound also functions as a photo acid generator of the component (c).
    Type: Application
    Filed: November 14, 2003
    Publication date: March 16, 2006
    Inventors: Akihiko Igawa, Atsuko Yamamoto
  • Patent number: 6933100
    Abstract: A method of forming a minute resist pattern wherein a positive-working photoresist composition containing 3 to 15 parts by weight of a quinone diazide group-containing photosensitizer relative to 100 parts by weight of alkali-soluble novolak resin is developed by an aqueous organic or inorganic alkali solution having a lower alkali concentration than that of the conventional one as the developer. The preferable example of the organic alkali materials in the developer is quaternary ammonium hydroxide, and the preferable example of the inorganic alkali materials in the developer is alkali metal hydroxide. The concentrations of the quaternary ammonium hydroxide and the alkali metal hydroxide in the developing solution are 2.2% by weight or less and 0.4% by weight or less respectively. Using such developing solution, high sensitivity, a high film retention rate, high resolution, low process dependency of dimension accuracy, and a formation of excellent pattern profile can be achieved.
    Type: Grant
    Filed: December 18, 2002
    Date of Patent: August 23, 2005
    Assignee: Clariant Finance (BVI) Limited
    Inventors: Akihiko Igawa, Jun Ikemoto
  • Publication number: 20030108822
    Abstract: A method of forming a minute resist pattern wherein a positive-working photoresist composition containing 3 to 15 parts by weight of a quinone diazide group-containing photosensitizer relative to 100 parts by weight of alkali-soluble novolak resin is developed by an aqueous organic or inorganic alkali solution having a lower alkali concentration than that of the conventional one as the developer. The preferable example of the organic alkali materials in the developer is quaternary ammonium hydroxide, and the preferable example of the inorganic alkali materials in the developer is alkali metal hydroxide. The concentrations of the quaternary ammonium hydroxide and the alkali metal hydroxide in the developing solution are 2.2% by weight or less and 0.4% by weight or less respectively. Using such developing solution, high sensitivity, a high film retention rate, high resolution, low process dependency of dimension accuracy, and a formation of excellent pattern profile can be achieved.
    Type: Application
    Filed: December 18, 2002
    Publication date: June 12, 2003
    Applicant: Clariant Finance (BVI) Limited
    Inventors: Akihiko Igawa, Jun Ikemoto
  • Patent number: 6514676
    Abstract: A method of forming a minute resist pattern wherein a positive-working photoresist composition containing 3 to 15 parts by weight of a quinone diazide group-containing photosensitizer relative to 100 parts by weight of alkali-soluble novolak resin is developed by an aqueous organic or inorganic alkali solution having a lower alkali concentration than that of the conventional one as the developer. The preferable example of the organic alkali materials in the developer is quaternary ammonium hydroxide, and the preferable example of the inorganic alkali materials in the developer is alkali metal hydroxide. The concentrations of the quaternary ammonium hydroxide and the alkali metal hydroxide in the developing solution are 2.2% by weight or less and 0.4% by weight or less respectively. Using such developing solution, high sensitivity, a high film retention rate, high resolution, low process dependency of dimension accuracy, and a formation of excellent pattern profile can be achieved.
    Type: Grant
    Filed: August 1, 2000
    Date of Patent: February 4, 2003
    Assignee: Clariant Finance (BVI) Limited
    Inventors: Akihiko Igawa, Jun Ikemoto
  • Patent number: 5964951
    Abstract: A rinsing solution for lithography which comprises a homogeneous solution of a water-soluble organic solvent and water. The water-soluble organic solvent may be any water-miscible organic solvent that have been used as solvents or rinsing solutions for resists or anti-reflective coatings. Preferred examples of the water-soluble organic solvent are a mixture of propylene glycol monoethyl ether and propylene glycol monometyl ether acetate, a mixture of propylene glycol monomethyl ether and propylene glycol monometyl ether acetate, and ethyl lactate. This rinsing solution is useful for dissolving away or stripping away cured or non-cured unnecessary resists, anti-reflective coatings, etc. from substrates such as in integrated circuit elements, color filters, liquid crystal display elements, etc. or from a resist-applying apparatus.
    Type: Grant
    Filed: December 23, 1997
    Date of Patent: October 12, 1999
    Assignee: Clariant International Ltd.
    Inventors: Kenji Yamamoto, Akihiko Igawa
  • Patent number: 5541036
    Abstract: A negative photoresist composition comprising:(A) a compound represented by the following formula (I): ##STR1## wherein R.sup.1 and R.sup.2 which are different from each other represent a hydrogen atom or a group represented by the following formula (II): ##STR2## (B) an alkoxymethylated melamine, and (C) a novolak resin.The photoresist composition has resolution below submicron, and can form resist patterns with an ideal rectangular profile.
    Type: Grant
    Filed: April 16, 1993
    Date of Patent: July 30, 1996
    Assignee: Hoechst Japan Limited
    Inventors: Akihiko Igawa, Masato Nishikawa, Georg Pawlowski, Ralph Dammel
  • Patent number: 4956320
    Abstract: A positive temperature coefficient semiconductor ceramic is prepared by adding from 0.2 to 12 mole % of silicon monoxide to a barium titanate family semiconductor ceramic which has been made into a semiconductor by the addition of a trace amount of a semiconductor agent.
    Type: Grant
    Filed: February 13, 1989
    Date of Patent: September 11, 1990
    Assignee: Kurabe Industrial Co., Ltd.
    Inventors: Masahiro Asakura, Akihiko Igawa