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Wafer alignment mark scheme

  • US 9,640,487 B2
  • Filed: 04/16/2015
  • Issued: 05/02/2017
  • Est. Priority Date: 03/28/2012
  • Status: Active Grant
First Claim
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1. A wafer alignment apparatus, comprising:

  • a light source;

    a light detection device; and

    a rotation device configured to rotate a first wafer and a second wafer,wherein the light source is disposed between the first wafer and the second wafer and configured to provide a first light directed to the first wafer and a second light directed to the second wafer, wherein the first light is directed in a different direction than the second light, wherein the light detection device is configured to detect a first reflected light intensity from the first wafer to find a position of at least one first wafer alignment mark of a plurality of first wafer alignment marks in a backside surface of the first wafer and to detect a second reflected light intensity from the second wafer to find a position of at least one second wafer alignment mark of a plurality of second wafer alignment marks in a frontside surface of the second wafer, wherein the first reflected light intensity from each first wafer alignment mark of the plurality of first wafer alignment marks is identifiably different, wherein the second reflected light intensity from each second wafer alignment mark of the plurality of second wafer alignment marks is identifiably different, the backside surface of the first wafer facing the frontside surface of the second wafer, the frontside surface of second wafer being configured for integrated circuit structures.

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