Patents by Inventor Fred W. Freerks

Fred W. Freerks 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).

  • Flow verification for process gas in a wafer processing system apparatus and method
    Patent number: 5220515
    Abstract: The flow of process gas used in a semiconductor wafer fabrication system is verified against the known flow of a verification gas using a derivative of the ideal gas law:n'.sub.pro =(P'.sub.pro /P'.sub.ver) n'.sub.verwheren'.sub.pro is the flow rate of the process gas,n'.sub.ver is the flow rate of the verification gas,P'.sub.pro is the rate of change with respect to time of the process gas pressure entering the chamber, andP'.sub.ver is the rate of change with respect to time of the verification gas pressure entering the chamber.The volume and temperature are maintained constant during the verification procedure.
    Type: Grant
    Filed: April 22, 1991
    Date of Patent: June 15, 1993
    Assignee: Applied Materials, Inc.
    Inventors: Fred W. Freerks, Richard C. Muh