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Apparatus and method for aligning integrated circuit layers using multiple grating materials

  • US 10,635,007 B1
  • Filed: 11/13/2018
  • Issued: 04/28/2020
  • Est. Priority Date: 11/13/2018
  • Status: Active Grant
First Claim
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1. An apparatus for aligning layers of an integrated circuit (IC), the apparatus comprising:

  • an insulator layer positioned above a semiconductor substrate;

    a first diffraction grating within a first region of the insulator layer, the first diffraction grating including a first grating material within the first region of the insulator layer; and

    a second diffraction grating within a second region of the insulator layer, the second diffraction grating including a second grating material within the second region of the insulator layer, wherein the second grating material is different from the first grating material, and wherein an optical contrast between the first and second grating materials is greater than an optical contrast between the second grating material and the insulator layer,wherein the first diffraction grating includes a unitary layer of the first grating material, and wherein the second diffraction grating includes a semiconductor layer over the substrate, and the second grating material over the semiconductor layer.

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