Patents by Inventor Tatsuro Ohkawa

Tatsuro Ohkawa 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: 6414325
    Abstract: A charged particle beam exposure apparatus capable of detecting a partial unevenness and adjusting the height of the surface of a specimen to be exposed is disclosed. This charged particle beam exposure apparatus comprises a charged particle beam source, a charged particle beam shaper, a deflector for changing the position where the charged particle beam is radiated on the specimen, a projector for projecting the charged particle beam on the specimen, and a control unit for controlling the deflector and the projector at the time of exposure. A pattern is plotted on the specimen by the charged particle beam being converged and deflected appropriately. The apparatus further comprises a stage for moving the specimen within the apparatus, and a height measuring unit for measuring the height distribution in a predetermined range of the specimen with at least a predetermined density while the specimen is loaded in the apparatus.
    Type: Grant
    Filed: July 13, 1999
    Date of Patent: July 2, 2002
    Assignee: Advantest Corporation
    Inventors: Akio Yamada, Tatsuro Ohkawa
  • Patent number: 6407398
    Abstract: An electron beam exposure apparatus, enabling detection of the height of a sample simply and with a high accuracy, including an electron gun, a converging unit able to converge an electron beam on a sample and make the focus position dynamically move, a deflecting unit for deflecting the electron beam, a movement mechanism for carrying and moving the sample, a deflection data and incident angle relationship storing circuit for storing the incident angle of the electron beam on the sample when the electron beam is deflected by the deflecting unit, a mark position detecting unit for detecting changes in reflected electrons at a mark provided on the sample when scanning the mark by the electron beam and thereby detecting the position of the mark, a mark position difference calculating unit for using the mark position detecting unit to scan a first mark provided on the sample by an electron beam of a first incident angle and a second mark in a predetermined positional relationship with the first mark by an electr
    Type: Grant
    Filed: November 17, 1999
    Date of Patent: June 18, 2002
    Assignee: Advantest Corporation
    Inventors: Masaki Kurokawa, Tatsuro Ohkawa, Yoshihisa Ooae
  • Publication number: 20010013581
    Abstract: A method of exposing a wafer to a charged-particle beam by directing to the wafer the charged-particle beam deflected by a deflector includes the steps of arranging a plurality of first marks at different heights, focusing the charged-particle beam on each of the first marks by using a focus coil provided above the deflector, obtaining a focus distance for each of the first marks, obtaining deflection-efficiency-correction coefficients for each of the first marks, and using linear functions of the focus distance for approximating the deflection-efficiency-correction coefficients to obtain the deflection-efficiency-correction coefficients for an arbitrary value of the focus distance. A device for carrying out the method is also set forth.
    Type: Application
    Filed: April 6, 2001
    Publication date: August 16, 2001
    Inventors: Akio Takemoto, Yoshihisa Ooaeh, Tomohiko Abe, Hiroshi Yasuda, Takamasa Satoh, Hideki Nasuno, Hidefumi Yabara, Kenichi Kawakami, Kiichi Sakamoto, Tomohiro Sakazaki, Isamu Seto, Masami Takigawa, Tatsuro Ohkawa
  • Patent number: 6242751
    Abstract: A method of exposing a wafer to a charged-particle beam by directing to the wafer the charged-particle beam deflected by a deflector includes the steps of arranging a plurality of first marks at different heights, focusing the charged-particle beam on each of the first marks by using a focus coil provided above the deflector, obtaining a focus distance for each of the first marks, obtaining deflection-efficiency-correction coefficients for each of the first marks, and using linear functions of the focus distance for approximating the deflection-efficiency-correction coefficients to obtain the deflection-efficiency-correction coefficients for an arbitrary value of the focus distance. A device for carrying out the method is also set forth.
    Type: Grant
    Filed: July 15, 1999
    Date of Patent: June 5, 2001
    Assignee: Fujitsu Limited
    Inventors: Akio Takemoto, Yoshihisa Ooaeh, Tomohiko Abe, Hiroshi Yasuda, Takamasa Satoh, Hideki Nasuno, Hidefumi Yabara, Kenichi Kawakami, Kiichi Sakamoto, Tomohiro Sakazaki, Isamu Seto, Masami Takigawa, Tatsuro Ohkawa
  • Patent number: 5969365
    Abstract: A method of exposing a wafer to a charged-particle beam by directing to the wafer the charged-particle beam deflected by a deflector includes the steps of arranging a plurality of first marks at different heights, focusing the charged-particle beam on each of the first marks by using a focus coil provided above the deflector, obtaining a focus distance for each of the first marks, obtaining deflection-efficiency-correction coefficients for each of the first marks, and using linear functions of the focus distance for approximating the deflection-efficiency-correction coefficients to obtain the deflection-efficiency-correction coefficients for an arbitrary value of the focus distance. A device for carrying out the method is also set forth.
    Type: Grant
    Filed: August 26, 1997
    Date of Patent: October 19, 1999
    Assignee: Fujitsu Limited
    Inventors: Akio Takemoto, Yoshihisa Ooaeh, Tomohiko Abe, Hiroshi Yasuda, Takamasa Satoh, Hideki Nasuno, Hidefumi Yabara, Kenichi Kawakami, Kiichi Sakamoto, Tomohiro Sakazaki, Isamu Seto, Masami Takigawa, Tatsuro Ohkawa
  • Patent number: 5966200
    Abstract: The present invention is a charged particle beam exposure apparatus comprising: a column portion in which an optical system for a charged particle beam is disposed; a chamber to be coupled with the column portion; a movable sample stage located in the chamber for mounting a sample thereon; and a stage position measurement device, having an optical path for measurement, along which a laser beam having a predetermined frequency is projected and is reflected by reflection means provided on the sample stage, and an optical path for reference, which in length almost equals a distance between a starting point of the optical path for measurement and the origin of the optical system in the column portion and for which the length is increased at a rate substantially consistent with a thermal expansion coefficient as material of the chamber is expanded, for measuring a change in position of the sample stage by employing a laser optical signal for measurement, which passes along the optical path for measurement, and a r
    Type: Grant
    Filed: October 10, 1997
    Date of Patent: October 12, 1999
    Assignees: Fujuitsu Limited, Advantest Corporation
    Inventors: Kenichi Kawakami, Tatsuro Ohkawa, Kazushi Ishida, Akiyoshi Tsuda
  • Patent number: 5945683
    Abstract: An electron beam exposure device includes an alignment optical system; an electromagnetic lens system; a stage on which the sample is provided; and an electron gun. The electron gun is comprised of an electron generating source; an electron generating source heating element which generates heat for increasing the temperature of the electron generating source; a supporting member which supports the electron generating source and the electron generating source heating element; and a Wehnelt. The electron beam exposure device is provided with at least one auxiliary heating element located at respective portion thermally connected to the electron generating source heating element.
    Type: Grant
    Filed: August 5, 1997
    Date of Patent: August 31, 1999
    Assignees: Fujitsu Limited, Advantest Corporation
    Inventors: Tatsuro Ohkawa, Yoshihisa Ooae, Hitoshi Tanaka, Hiroshi Yasuda
  • Patent number: 5892237
    Abstract: In a charged particle beam exposure method and an apparatus therefor, wherein the intensity of the charged particle beam used for irradiation is increased to a maximum to improve a throughput for an exposure procedure, accordingly, the temperature of a sample, such as a wafer, is elevated and thermal expansion occurs. The thermal expansion that occurs has reproducibility based on the intensity of the projected charged particle beam. Therefore, a coefficient of thermal expansion is detected by monitoring the intensity of the projected charged particle beam. A shifting distance for each irradiation position which is acquired from the thermal expansion is added as a compensation value for deflection of the charged particle beam, to provide an accurate exposure procedure.
    Type: Grant
    Filed: March 11, 1997
    Date of Patent: April 6, 1999
    Assignee: Fujitsu Limited
    Inventors: Kenichi Kawakami, Hiroshi Yasuda, Akio Yamada, Tatsuro Ohkawa, Mitsuhiro Nakano, Atsushi Saito, Yoshihisa Ooae
  • Patent number: 5757015
    Abstract: A method of exposing a wafer to a charged-particle beam by directing to the wafer the charged-particle beam deflected by a deflector includes the steps of arranging a plurality of first marks at different heights, focusing the charged-particle beam on each of the first marks by using a focus coil provided above the deflector, obtaining a focus distance for each of the first marks, obtaining deflection-efficiency-correction coefficients for each of the first marks, and using linear functions of the focus distance for approximating the deflection-efficiency-correction coefficients to obtain the deflection-efficiency-correction coefficients for an arbitrary value of the focus distance. A device for carrying out the method is also set forth.
    Type: Grant
    Filed: April 18, 1996
    Date of Patent: May 26, 1998
    Assignee: Fujitsu Limited
    Inventors: Akio Takemoto, Yoshihisa Ooaeh, Tomohiko Abe, Hiroshi Yasuda, Takamasa Satoh, Hideki Nasuno, Hidefumi Yabara, Kenichi Kawakami, Kiichi Sakamoto, Tomohiro Sakazaki, Isamu Seto, Masami Takigawa, Tatsuro Ohkawa
  • Patent number: 5708276
    Abstract: An electron-beam exposure device having at least one deflector for deflecting an electron beam and detecting a position of a position-detection mark with the electron beam includes a plurality of detectors detecting electrons scattered from the position-detection mark, a plurality of amplifiers, each of the amplifiers amplifying an output of a corresponding one of the detectors, and a setting unit for setting amplification factors of the amplifiers such that a magnitude of an output from each of the amplifiers is constant irrespective of a deflected position of the electron beam at a time of detection of the position of the position-detection mark.
    Type: Grant
    Filed: February 13, 1996
    Date of Patent: January 13, 1998
    Assignee: Fujitsu Limited
    Inventors: Tatsuro Ohkawa, Kawakami Kenichi, Yoshihisa Ooae, Tohru Ikeda, Kazushi Ishida