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Proceedings Paper

Phase Gratings As Waferstepper Alignment Marks For All Process Layers
Author(s): S. Wittekoek; J. van der Werf; R. A. George
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Paper Abstract

The performance of a wafer stepper alignment system based upon phase gratings etched in the silicon has been investigated both experimentally and theoretically. Measurements of the alignment accuracy as a function of the light intensity reflected from the wafer show that the accuracy is better than 0.1 micron down to reflectivities as low as 0.15%. The various factors influencing the alignment signal by processing layers have been analyzed. A standard marker geometry is given, which produces a 0.1 micron alignment accuracy for the vast majority of processing conditions. For some special cases such as planarizing resist layers a different marker geometry is preferrable.

Paper Details

Date Published: 23 July 1985
PDF: 8 pages
Proc. SPIE 0538, Optical Microlithography IV, (23 July 1985); doi: 10.1117/12.947743
Show Author Affiliations
S. Wittekoek, Philips Research Laboratory (Netherlands)
J. van der Werf, Philips Research Laboratory (Netherlands)
R. A. George, ASM Lithography (Netherlands)

Published in SPIE Proceedings Vol. 0538:
Optical Microlithography IV
Harry L. Stover, Editor(s)

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