Photocopying – Projection printing and copying cameras – Illumination systems or details
Reexamination Certificate
2005-12-06
2005-12-06
Mathews, Alan (Department: 2851)
Photocopying
Projection printing and copying cameras
Illumination systems or details
C053S077000, C359S730000
Reexamination Certificate
active
06972830
ABSTRACT:
The present invention is a catadioptric system having a reticle optical group, a beam splitter, an aspheric mirror, a baffle plate, a folding mirror and a semiconductor wafer optical group. The reticle optical group, the beam splitter and the semiconductor wafer optical group are placed on the same beam axis, different from aspheric mirror and folding mirror axis. The light passes through an image pattern on the reticle and is reflected by the beam splitter onto the aspheric mirror. The aspheric mirror reflects the light back through the beam splitter onto the folding mirror. The folding mirror reflects the light back to the beam splitter. The beam splitter reflects the light onto the semiconductor wafer optical group. A plurality of quarter wave plates can be placed in optical paths between optical elements of the present invention to change polarization of an incoming light. Before light passes through the semiconductor wafer optical group, it passes through the baffle plate, which prevents any background scattered light caused by internal reflections within the beam splitter from entering the semiconductor wafer optical group. In another embodiment, a spacer plate is inserted into the beam splitter. The spacer plate creates an offset between reticle optical group beam axis and semiconductor wafer optical group beam axis. This reduces direct passage of light from reticle optical group to semiconductor wafer optical group.
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Written Opinion for Singapore Patent Appl. No. 200306876-4, 10 pages, dated Apr. 8, 2005.
Copy of Danish Search Report for Singapore Appln. 200306876-4 mailed Jul. 23, 2004.
ASML Holding N.V.
Mathews Alan
Sterne Kessler Goldstein & Fox P.L.L.C.
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