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Particle detecting apparatus using two light beams

  • US 6,266,137 B1
  • Filed: 03/30/1999
  • Issued: 07/24/2001
  • Est. Priority Date: 04/10/1998
  • Status: Expired due to Fees
First Claim
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1. A particle detecting apparatus for testing a substrate and a film provided on a top surface of said substrate, comprising:

  • a light source section for emitting first and second light beams respectively having first and second wavelengths which are different from each other, wherein said first and second light beams are directed to said substrate at a same time and orthogonal to said top surface;

    an optical system for directing said first and second light beams to an incident point on said substrate, wherein said first and second light beams are scattered by said top surface of said substrate to produce first and second scattered light beams;

    a light quantity measuring section for measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam, wherein said light quantity measuring section comprises;

    a beam collecting section for collecting said first scattered light beam and said second scattered light beam, comprising a set of optical fibers, wherein a first end of each of said optical fibers is arranged on a semi-spherical surface having the incident point as a center and a second end is connected to a light wave guide for guiding said first scattered light beam and said second scattered light beam;

    a spectroscope for separating said first scattered light beam and said second scattered light beam guided by said light wave guide;

    a first measuring section for measuring said quantity of said first scattered light beam separated by said spectroscope; and

    a second measuring section for measuring said quantity of said second scattered light beam separated by said spectroscope; and

    an operation section for detecting a foreign particle located on said film and in said film, and determining a diameter of said foreign particle and a depth of said foreign particle, based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second light beams.

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