Patents by Inventor Hatsuyuki Tanka

Hatsuyuki Tanka 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).

  • Developer solution for positive-working photoresist compositions comprising a base and a non-ionic surfactant
    Patent number: 4820621
    Abstract: The aqueous developer solution for a positive-working photoresist composition comprises, as dissolved in an aqueous solvent, a water-soluble organic basic compound and a specific non-ionic surface active agent which may be an alkyl-substituted phenyl or naphthyl ether of polyoxyethyleneglycol in a specified concentration. The developer solution is advantageous in respect of the completeness of removal of film residua and scums from the substrate surface after development so that the patterned photoresist layer is imparted with greatly increased accuracy and fidelity of the pattern reproduction.
    Type: Grant
    Filed: June 26, 1987
    Date of Patent: April 11, 1989
    Assignee: Tokyo Ohka Kogyo Co., Ltd.
    Inventors: Hatsuyuki Tanka, Yoshiyuki Sato, Hidekatsu Kohara, Toshimasa Nakayama