Patents by Inventor Sairam Sankaranarayanan

Sairam Sankaranarayanan 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).

  • Patent number: 7710565
    Abstract: A method for correcting systematic errors in an optical measurement tool in which a first diffraction spectrum is measured from a standard substrate including a layer having a known refractive index and a known extinction coefficient by exposing the standard substrate to a spectrum of electromagnetic energy. A tool-perfect diffraction spectrum is calculated for the standard substrate. A hardware systematic error is calculated by comparing the measured diffraction spectrum to the calculated tool-perfect diffraction spectrum. A second diffraction spectrum from a workpiece is measured by exposing the workpiece to the spectrum of electromagnetic energy, and the measured second diffraction spectrum is corrected based on the calculated hardware systematic error to obtain a corrected diffraction spectrum.
    Type: Grant
    Filed: December 14, 2007
    Date of Patent: May 4, 2010
    Assignee: Tokyo Electron Limited
    Inventors: Sanjeev Kaushal, Sairam Sankaranarayanan, Kenji Sugishima
  • Patent number: 7561269
    Abstract: An optical measurement system and wafer processing tool for correcting systematic errors in which a first diffraction spectrum is measured from a standard substrate including a layer having a known refractive index and a known extinction coefficient by exposing the standard substrate to a spectrum of electromagnetic energy. A tool-perfect diffraction spectrum is calculated for the standard substrate. A hardware systematic error is calculated by comparing the measured diffraction spectrum to the calculated tool-perfect diffraction spectrum. A second diffraction spectrum from a workpiece is measured by exposing the workpiece to the spectrum of electromagnetic energy, and the measured second diffraction spectrum is corrected based on the calculated hardware systematic error to obtain a corrected diffraction spectrum.
    Type: Grant
    Filed: December 14, 2007
    Date of Patent: July 14, 2009
    Assignee: Tokyo Electron Limited
    Inventors: Sanjeev Kaushal, Sairam Sankaranarayanan, Kenji Sugishima
  • Publication number: 20090153842
    Abstract: An optical measurement system and wafer processing tool for correcting systematic errors in which a first diffraction spectrum is measured from a standard substrate including a layer having a known refractive index and a known extinction coefficient by exposing the standard substrate to a spectrum of electromagnetic energy. A tool-perfect diffraction spectrum is calculated for the standard substrate. A hardware systematic error is calculated by comparing the measured diffraction spectrum to the calculated tool-perfect diffraction spectrum. A second diffraction spectrum from a workpiece is measured by exposing the workpiece to the spectrum of electromagnetic energy, and the measured second diffraction spectrum is corrected based on the calculated hardware systematic error to obtain a corrected diffraction spectrum.
    Type: Application
    Filed: December 14, 2007
    Publication date: June 18, 2009
    Applicant: TOKYO ELECTRON LIMITED
    Inventors: Sanjeev Kaushal, Sairam Sankaranarayanan, Kenji Sugishima
  • Publication number: 20090157343
    Abstract: A method for correcting systematic errors in an optical measurement tool in which a first diffraction spectrum is measured from a standard substrate including a layer having a known refractive index and a known extinction coefficient by exposing the standard substrate to a spectrum of electromagnetic energy. A tool-perfect diffraction spectrum is calculated for the standard substrate. A hardware systematic error is calculated by comparing the measured diffraction spectrum to the calculated tool-perfect diffraction spectrum. A second diffraction spectrum from a workpiece is measured by exposing the workpiece to the spectrum of electromagnetic energy, and the measured second diffraction spectrum is corrected based on the calculated hardware systematic error to obtain a corrected diffraction spectrum.
    Type: Application
    Filed: December 14, 2007
    Publication date: June 18, 2009
    Applicant: TOKYO ELECTRON LIMITED
    Inventors: Sanjeev Kaushal, Sairam Sankaranarayanan, Kenji Sugishima