Photocopying – Projection printing and copying cameras – Distortion introducing or rectifying
Reexamination Certificate
2007-07-03
2007-07-03
Fuller, Rodney (Department: 2851)
Photocopying
Projection printing and copying cameras
Distortion introducing or rectifying
C355S077000
Reexamination Certificate
active
10998179
ABSTRACT:
A lithographic system includes an illumination system for providing a projection beam of radiation, a mask table for supporting a mask, the mask serving to impart the projection beam with a pattern in its cross-section, a substrate table for holding a substrate, and a projection system for projecting the patterned beam onto a target portion of the substrate. The system also comprises a processor arranged to calculate overlay corrections using a reference height map representing a surface of the substrate table or the mask table. Feed forward correction of non-flatness induced wafer grid distortion is allowed during alignment and during exposure, thereby reducing overlay errors caused by differences in flatness characteristics. It provides an indirect qualification method for overlay accuracy related to exposure chuck flatness based on height map information.
REFERENCES:
patent: 5191200 (1993-03-01), van der Werf et al.
patent: 6597434 (2003-07-01), Van Dijsseldonk
patent: 6924884 (2005-08-01), Boonman et al.
patent: 6950176 (2005-09-01), LaFontaine et al.
Brinkhof Ralph
Levasier Leon Martin
Maria Zaal Koen Jacobus Johannes
Oesterholt Rene
Ottens Joost Jeroen
ASML Netherlands B.V.
Fuller Rodney
Pillsbury Winthrop Shaw & Pittman LLP
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