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Locating a field of view in which selected IC conductors are unobscured

  • US 5,392,222 A
  • Filed: 12/30/1991
  • Issued: 02/21/1995
  • Est. Priority Date: 12/30/1991
  • Status: Expired due to Term
First Claim
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1. In a system comprising means for supporting an IC device having multiple physical layers and multiple internal nets, and controllable positioning means for positioning a field of view relative to the device, a method of positioning the field of view relative to the device such that multiple, selected nets of the device are-within the field of view, comprising the steps of:

  • a. preparing a processed data set which (1) describes each physical layer of the device as a plurality of reduced polygons, each reduced polygon having dimensions at least as great as a predetermined minimum feature dimension, and (2) associates each of the reduced polygons with a physical layer of the device and with at least one net of the device;

    b. for each selected net, preparing a transformed data set which describes a plurality of dilated polygons associated with the selected net, each dilated polygon defining the periphery of a region encompassed by the field of view when a point within the field of view is traced around the periphery of a reduced polygon;

    c. mapping a bit plane for each selected net, each mapped bit plane defining the two-dimensional extent of dilated polygons associated with the selected net;

    d. identifying any two-dimensional overlap regions over which a plurality of the dilated polygons defined by the bit planes overlap one another; and

    e. if at least one said overlap region is identified, controlling said controllable positioning means to position the field of view relative to said device at a location which corresponds to at least one said overlap region.

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