Browse Prior Art Database

Three-Dimensional Defect Measurement Tool

IP.com Disclosure Number: IPCOM000122176D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Vadehra, SK: AUTHOR

Abstract

All dimensions of a defect - a void or an elevation can be measured and categorized by this system. The system provides solution for contrast variation among parts, "soft" boundary detection of gentle defect slopes, and low contrast generated by shallow defects.

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Three-Dimensional Defect Measurement Tool

      All dimensions of a defect - a void or an elevation can
be measured and categorized by this system.  The system provides
solution for contrast variation among parts, "soft" boundary
detection of gentle defect slopes, and low contrast generated by
shallow defects.

      A digital image analyzer is used for the X, Y dimension
determination.  An intensity feedback control system eliminates the
effects of contrast variation in parts.  A defect contour
linearization algorithm "sharpens" the boundaries of a defect.  An
"absolute threshold" detection algorithm automatically adjusted grey
levels to detect the shallow defects.

      An auto laser focusing system is used for the Z measurement.  A
micrometer scale is attached to the stage of this microscope.  The
focused laser beam on the surface provides the reference point for
the scale.  The beam then is moved to the highest/lowest point of the
defects.  The difference in the elevation of the beam focusing
position provides the Z dimension.

      The figure below shows the integrated system.  The light
intensity, threshold, and focus offsets for all objectives are
automated.