Patents by Inventor Andrew J. Graven

Andrew J. Graven 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 clamping a substrate
    Patent number: 5894400
    Abstract: A method and apparatus for securely clamping a substrate to an electrostatic chuck during processing of a substrate. The method generally includes the steps of forming an initial electrostatic clamping force between the electrostatic chuck and the substrate, modifying the initial electrostatic clamping force when an rf voltage is applied to the electrostatic chuck during processing, and restoring the initial electrostatic clamping force with an offset voltage applied to the electrostatic chuck. The present invention also includes an electrostatic chuck having at least one electrode and a dielectric on the surface of the electrode for supporting a substrate. A voltage source is coupled to the electrode for electrostatically clamping the substrate to the surface of the electrostatic chuck with an initial electrostatic force. An rf source is coupled to the electrode for applying rf voltage to the electrostatic chuck and causing a change in the initial electrostatic force.
    Type: Grant
    Filed: May 29, 1997
    Date of Patent: April 13, 1999
    Assignee: WJ Semiconductor Equipment Group, Inc.
    Inventors: Andrew J. Graven, Melvin Schmidt, Kenneth A. McCuen, Yunju Ra