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POLARIZED IMAGE ACQUISITION APPARATUS, PATTERN INSPECTION APPARATUS, POLARIZED IMAGE ACQUISITION METHOD, AND PATTERN INSPECTION METHOD

  • US 20180364472A1
  • Filed: 06/01/2018
  • Published: 12/20/2018
  • Est. Priority Date: 06/19/2017
  • Status: Active Grant
First Claim
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1. A polarized image acquisition apparatus comprising:

  • a stage configured to be movable and to mount thereon a mask substrate for exposure on which a pattern is formed;

    an objective lens configured to receive a transmitted light having passed through the mask substrate;

    a diaphragm configured to be rotatable, to restrict a passage region of a light having passed through the objective lens to two regions opposite to each other with respect to a central axis in 4n equal regions divided rotationally symmetrically in a plane orthogonal to a traveling direction of the light having passed through the objective lens, and to change an angle of the passage region so that each the two regions of the 4n equal regions become passage regions in order;

    a rotating half-wave plate configured to convert, for each of the angle of the passage region, a P-polarized component having passed through the diaphragm and being in same direction as the angle of the passage region and an S-polarized component having passed through the diaphragm and being in a direction orthogonal to the angle of the passage region into a polarized wave in a first direction and a polarized wave in a second direction, where the first and second directions have been set previously and are orthogonal to each other;

    a Rochon prism configured to separate a trajectory of the polarized wave in the first direction from a trajectory of the polarized wave in the second direction;

    an image forming lens configured to focus and form an image of the polarized wave in the first direction having passed through the Rochon prism, at an image formation position, and an image of the polarized wave in the second direction having passed through the Rochon prism, at an other image formation position;

    a mirror configured to reflect the polarized wave in the second direction, at the other image formation position of the polarized wave in the second direction which is different from the image formation position of the polarized wave in the first direction;

    a first image sensor configured to capture an optical image of a polarized wave of the P-polarized component and an optical image of a polarized wave of the S-polarized component, as an optical image of the polarized wave in the first direction, while replacing the optical image of the polarized wave of the P-polarized component and the optical image of the polarized wave of the S-polarized component with each other depending on the angle of the passage region of the diaphragm; and

    a second image sensor configured to capture an optical image of a polarized wave of the S-polarized component and an optical image of a polarized wave of the P-polarized component, as an optical image of the polarized wave in the second direction, while replacing the optical image of the polarized wave of the S-polarized component and the optical image of the polarized wave of the P-polarized component with each other depending on the angle of the passage region of the diaphragm.

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