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Proceedings Paper

Optical Measurement Of Contacts
Author(s): Peter Waksman
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Paper Abstract

Optical measurement of contacts and vias is possible because when a microscope is focused at a plane near to the bottom of a contact, light is reflected from the bottom and forms a characteristic image: a dark ring surrounding a brighter center. The dark ring image is common to a variety of substrates, including resist on poly, etched metal, nitride, resist on doped glass on grainy metal, etc.. Using image processing and dedicated measurement algorithms, it is possible to separate the dark ring from the brighter center by a "contour" or edge, and to measure the diameters (in x or y) and the area inside the contour. Also, by comparing these measurements against reference measurements it is possible to determine if the contact is open or closed. These measurements can be repeated with precision between .01 and .02 microns (depending on materials) and can be calibrated to a standard such as a SEM or an electrical test.

Paper Details

Date Published: 19 July 1989
PDF: 6 pages
Proc. SPIE 1087, Integrated Circuit Metrology, Inspection, and Process Control III, (19 July 1989); doi: 10.1117/12.953116
Show Author Affiliations
Peter Waksman, Interactive Video Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 1087:
Integrated Circuit Metrology, Inspection, and Process Control III
Kevin M. Monahan, Editor(s)

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