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Proceedings Paper

Parameters Affecting Alignment Dispersion On An Optical Wafer Stepper
Author(s): Alain Charles
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Paper Abstract

Alignment dispersion can only consume a small part of the overlay budget. Thus, it is important to study the causes of alignment dispersion. Two parameters which damage alignment dispersion have been studied. The first stems from the centrifugal forces acting on the photoresist in the vicinity of the alignment mark which produce an asymmetrical modulation leading to a misalignment component. The effect of the grid layout, alignment mark design, are studied. Rather than on modify the spin resist process, or remove the resist on the alignment target, a new kind of alignment mark, which is much less sensitive to this effect, is proposed. The second is the roughness of the Aluminium substrate. In order to measure the effect of the surface roughness on alignment performance, different aluminium grain sizes have been prepared and tested. The study has been performed for two alignment marks and two resist systems.

Paper Details

Date Published: 11 October 1989
PDF: 8 pages
Proc. SPIE 1138, Optical Microlithography and Metrology for Microcircuit Fabrication, (11 October 1989); doi: 10.1117/12.961745
Show Author Affiliations
Alain Charles, C.N.E.T. (France)

Published in SPIE Proceedings Vol. 1138:
Optical Microlithography and Metrology for Microcircuit Fabrication
Michel J. Lacombat; Stefan Wittekoek, Editor(s)

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