Appeal No. 1996-2284
Application No. 08/228,889
March 6, 1995, Figure 1 was amended to add two members 575
connecting metrology plate 49 to lens 3. The detectors thus
supported are located in the image plane of the lens as
reflected by the folding mirrors so as to receive images of
the alignment marks. The servo system shown in Figure 3
corrects any detected positional errors by actuating linear
motors 19 to shift the position of the reticle chuck 15 and
thereby reticle 13 relative to the metrology plate, folding
mirrors, and detectors.
The claims
Claims 1 and 5, the only independent claims, read as
follows:
1. A lithographic alignment system to correct
misalignments resulting from environmental effects on the
lens, said alignment system including,
a lens for projecting images from an object plane to an
image plane,
a reticle, a reticle chuck to hold said reticle in said
object plane, alignment means to align said reticle and
thereby align said reticle, said reticle bearing a working
pattern and a first pair of fiducial marks positioned on
opposite sides of said working pattern, illumination means for
5Paper No. 8, entered pursuant to the advisory action
mailed March 15, 1995 (paper No. 9).
4
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