Photocopying – Projection printing and copying cameras – Illumination systems or details
Reexamination Certificate
2006-06-06
2006-06-06
Perkey, W. B. (Department: 2851)
Photocopying
Projection printing and copying cameras
Illumination systems or details
C355S077000
Reexamination Certificate
active
07057709
ABSTRACT:
A lithographic mask is illuminated with light from different directions such that intensities of a plurality of incident beams of light provide a largest possible integrated process window defined in terms of an allowed range for defining shapes. Constrained sets of intensity parameters are imposed. A first set of intensity parameters represents maximum possible intensities that can be permitted for overexposed tolerance positions. A second set of intensity parameters represents minimum possible intensities that can be permitted for underexposed tolerance positions. Optimum source intensities of incident beams are defined using a linear program and constraints. The optimum source intensities maximize an integrated range of dose and focal variations without causing printed shapes to depart from the allowed range. Apparatus are detailed and variations are described.
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Gutierrez Kevin
Harrington & Smith ,LLP
Morris Daniel P.
Perkey W. B.
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