Patents by Inventor Wildey E. Johnson

Wildey E. Johnson 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 measuring thickness of epitaxial layer by infrared reflectance
    Patent number: 4555767
    Abstract: Method and apparatus measure the thickness of an epi layer grown on a substrate. IR energy 12 is directed onto the epi layer 13 and a portion 14 of the energy is reflected from the surface of the epi layer and from the interface of the epi layer and substrate. The spectral reflectance of the reflected energy is measured by means of a Fourier transform IR spectrometer 10. The measured values of spectral reflectance are correlated with a series of theoretical reflectance values determined for different thicknesses of an epi layer in a range including the nominal thickness. The measured or actual epi thickness is determined from the correlation analysis.
    Type: Grant
    Filed: October 28, 1982
    Date of Patent: November 26, 1985
    Assignee: International Business Machines Corporation
    Inventors: William R. Case, Wildey E. Johnson