Patents by Inventor Thiloma I. Perera

Thiloma I. Perera 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).

  • Characterization of semiconductor resist material during processing
    Patent number: 4874240
    Abstract: Several methods for evaluating certain changes induced in a film of semiconductor resist material after the coat process and before or at completion of the softbake process, by monitoring thickness of and absorption by a film of resist material.
    Type: Grant
    Filed: March 1, 1988
    Date of Patent: October 17, 1989
    Assignee: Hoechst Celanese
    Inventors: Michael P. C. Watts, Thiloma I. Perera, David W. Myers, Robert G. Ozarski, John F. Schipper, Raul V. Tan
  • Absorption measurements of materials
    Patent number: 4857738
    Abstract: Two methods of determination of the chemical changes induced in a film of material such as photoresist that has been exposed to electromagnetic radiation. Two methods use measurement of polarized light reflected by the film mounted on a substrate to determine a real refractive index or a complex refractive index of the film. Two other methods use measurement of polarized light by the film mounted on a (partly) transparent substrate to determine a real refractive index or a complex refractive index of the film.
    Type: Grant
    Filed: December 18, 1987
    Date of Patent: August 15, 1989
    Assignee: General Signal Corporation
    Inventors: David W. Myers, Robert G. Ozarski, Thiloma I. Perera, John F. Schipper, Raul V. Tan, Michael P. C. Watts