Patents by Inventor Masashi Sonokawa

Masashi Sonokawa 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 and apparatus for production of single crystal
    Patent number: 5851283
    Abstract: A single crystal production apparatus based on an HMCZ method for production a large-diametered single crystal having a uniform microscopic oxygen concentration distribution in its crystal growth direction to thereby provide a wafer having a high in-plane uniformity of oxygen concentration distribution. In the single crystal production apparatus based on the HMCZ method, when B denotes a vertical position of the bottom surface of a melt within a crucible and L denotes the depth of the melt at the time of starting crystal pulling operation, a vertical position of the coil central axis Cc of superconducting electromagnets 12 and 15 is controlled to be a proper value included in a range from a position below the position B by {(1/3).times.L} to a position above the position B by {(1/3).times.L} to pull the single crystal.
    Type: Grant
    Filed: December 20, 1996
    Date of Patent: December 22, 1998
    Assignee: Shin-Etsu Handotai Co. Ltd.
    Inventors: Ryouji Hoshi, Masashi Sonokawa, Izumi Fusegawa, Tomohiko Ohta