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Integrated circuit structure analysis

  • US 5,191,213 A
  • Filed: 07/05/1991
  • Issued: 03/02/1993
  • Est. Priority Date: 07/05/1990
  • Status: Expired due to Term
First Claim
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1. Apparatus for determining the structure of an integrated circuit of the type comprising different layers, including metallic and non-metallic features, and a body including at least one region with a higher type-p or type-n dopant concentration with respect to adjacent regions, said apparatus comprising:

  • an electron beam source;

    means for focussing an electron beam from said source and for controllably scanning said electron beam over a surface of said integrated circuit;

    a first detector responsive to backscattered electrons from the surface of said integrated circuit to represent said metallic features;

    a second detector responsive to secondary electrons emitted by said surface to represent said non-metallic features; and

    processing means coupled to each of said first and second detectors and operable to derive a representation of said metallic and non-metallic features of said layers from signals from said first and second detectors;

    the improvement comprising means for representing said one region with the higher type-p or type-n dopant concentration as induced at a Schottky barrier junction in said one region, said means comprising;

    a third detector connected with a metallisation layer of one of a first type of metal or a second type of metal to define the Schottky barrier junction with said region with respecitve ones of the higher type-p dopant concentration or type-n dopant concentration, andcurrent sensing means connected with said third detector for sensing a current arising from said Schottky barrier junction as said electron beam scans said metallisation layer; and

    wherein said processing means are also coupled to said third detector and are operable to derive a representation of said at least one region with the higher type-p doped or type-n doped concentration from signals from said third detector.

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