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Heterodyne reflectometer for film thickness monitoring and method for implementing

  • US 7,339,682 B2
  • Filed: 02/25/2005
  • Issued: 03/04/2008
  • Est. Priority Date: 02/25/2005
  • Status: Active Grant
First Claim
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1. A heterodyne reflectometer for measuring thickness of a target layer deposed on a substrate comprising:

  • an optical light source for producing a split frequency, dual polarized beam;

    a beam path diverting optical component for propagating the split frequency, dual polarized beam toward an exposed target layer deposed on a substrate at a predetermined angle of incidence;

    a first heterodyne detector for receiving the split frequency, dual polarized beam and generating a reference electrical heterodyne beat signal;

    a second heterodyne detector for receiving a reflected split frequency, dual polarized beam from the target layer and generating a measurement electrical heterodyne beat signal;

    a phase detector for receiving reference electrical heterodyne beat signal and the measurement electrical heterodyne beat signal, and detecting a phase shift between said reference and measurement electrical heterodyne beat signals; and

    a data processor for calculating a thickness relating to the target layer from the phase shift.

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