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Apparatus for measuring thickness profile and refractive index distribution of multiple layers of thin films by means of two-dimensional refrectometry and method of measuring the same

  • US 20040246493A1
  • Filed: 03/10/2004
  • Published: 12/09/2004
  • Est. Priority Date: 09/21/2001
  • Status: Active Grant
First Claim
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1. An apparatus for measuring thickness and refractive index of a single or multiple layers of thin films, said apparatus comprising;

  • a substrate carrier for supporting a substrate;

    an optical unit for providing a light source and a reflected light from said substrate for said measurements;

    an optical filter set for filtering said reflected light by different wavelength;

    a two-dimensional array type of CCD sensors;

    an image grabber for capturing images generated by said CCD sensors;

    a data processing unit for computing and generating one or more measurement data of thickness, thickness profile or refractive index of thin films using said image data captured by said image grabber in groups of pixels of at least (3×

    3) pixels, and by means of repeated and iterative use of a nonlinear error minimization method;

    means for computing theoretical values of reflectivity or refractive index;

    means for finding a minimum error between a computed and a measured reflectivity or refractive index values by iterative and repeated use of a nonlinear error minimization method;

    a system controller unit containing image processing, information processing and system control functions for processing said image data.

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