Patents by Inventor Mitsufumi Koyama

Mitsufumi Koyama 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).

  • Method of cutting a workpiece with a wire saw
    Patent number: 5931147
    Abstract: There is disclosed a method of slicing a semiconductor ingot in which the ingot is pressed against a moving wire. A thinner portion of the wire is used at the beginning of slicing to cut a portion of the ingot where the cutting length is shorter than a predetermined length, and a thicker portion of the wire is used when the cutting length becomes longer than the predetermined length. Subsequently, a thinner portion of the wire is used when the slicing approaches to the end and the cutting length becomes shorter than a predetermined length. A portion of the wire used in previous slicing is used as the thinner portion. Alternatively, the thinner portion is formed through use of a die. The slicing method makes it possible to cut the ingot into a plurality of wafers having a uniform thickness.
    Type: Grant
    Filed: March 20, 1997
    Date of Patent: August 3, 1999
    Assignee: Shin-Etsu Handotai Co., Ltd.
    Inventors: Yasuaki Nakazato, Noriaki Kubota, Hisakazu Takano, Mitsufumi Koyama