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Apparatus for SLM-based optical lithography with gray level capability

  • US 7,639,416 B2
  • Filed: 10/24/2007
  • Issued: 12/29/2009
  • Est. Priority Date: 08/24/2002
  • Status: Active Grant
First Claim
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1. A lithographic tool, comprising:

  • a spatial light modulator, said spatial light modulator comprising an area array of individually switchable elements, said elements of said spatial light modulator being arranged in rows and columns on a rectangular grid;

    a light source configured to continuously illuminate said spatial light modulator;

    imaging optics configured to continuously project an image of said spatial light modulator on a photosensitive material, said photosensitive material comprising an area array of pixels, the size and configuration of said pixels corresponding to the projected spacing and configuration of individually switchable elements in said spatial light modulator, wherein said photosensitive material coats the surface of a substrate;

    a control system configured to control switching of said individually switchable elements of said spatial light modulator for defining features in said photosensitive material, said switching being between at least two states, wherein a first state allows light to reach said photosensitive material and a second state stops light from reaching said photosensitive material; and

    a stage configured to move said substrate relative to said projected image, whereby a pixel in said photosensitive material receives, in serial, doses of energy from multiple elements of said spatial light modulator;

    wherein the direction of movement of said substrate is neither parallel nor orthogonal to said columns of said elements of said spatial light modulator and wherein said control system is further configured to control switching of said elements of said spatial light modulator to vary the number of elements of said spatial light modulator that serially contribute to a total dose of energy received by any pixel in said photosensitive material, whereby some pixels in said photosensitive material receive different, non-zero, total doses of energy.

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