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Optical position assessment apparatus and method

  • US 7,477,403 B2
  • Filed: 05/27/2004
  • Issued: 01/13/2009
  • Est. Priority Date: 05/27/2004
  • Status: Active Grant
First Claim
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1. An optical position measurement apparatus, comprising:

  • an illumination system that supplies a beam of radiation;

    a substrate table that supports a substrate;

    a projection system that projects the beam of radiation onto a target portion of the substrate;

    a positioning system that causes relative movement between the substrate and the projection system; and

    a measurement system that determines a position of at least a component of the projection system relative to the substrate, the measurement system comprising,an array of lenses arranged such that each lens in the array focuses a respective portion of the beam onto a respective part of the target portion,an array of detectors arranged such that each corresponding detector in the array detects light reflected from a previously formed portion of a feature on the substrate through a corresponding lens in the array and provides an output representative of an intensity of light reflected from the portion of the feature on the substrate to the detector through the corresponding lens, anda processor connected to the outputs of the detectors that derives data representing the position of the lens array relative to the substrate from the outputs of the detectors, which processor sends a signal to the positioning system to relatively align the substrate during exposure of a subsequently formed portion of the feature on the substrate.

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