Patents by Inventor George Stephanopoulos

George Stephanopoulos 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).

  • Control system for the czochralski process
    Patent number: 4857278
    Abstract: The control system includes a master loop for controlling crystal interface diameter and slave control loops for controlling the melt and the crystal thermal environment. Diameter and meniscus angle signals are partitioned into both a low frequency and a high frequency signal. The low frequency signal is used to adjust the set point of the melt. The higher frequency signal is used to control the crystal pull rate. The crystal control slave loop regulates crystal heat flux which may include following a heat flux trajectory. The heat flux trajectory may also be used to adjust the melt temperature set point.
    Type: Grant
    Filed: July 13, 1987
    Date of Patent: August 15, 1989
    Assignee: Massachusetts Institute Of Technology
    Inventors: Michael A. Gevelber, George Stephanopoulos