Illumination optical system for EUV projection lithography
AssigneeCarl Zeiss SMT GmbH
InventorsJoachim Kalden, Stig Bieling
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Abstract
An illumination optical unit for EUV projection lithography includes a field facet mirror with a plurality of field facets for guiding illumination light into an object field where a lithography mask is arrangeable. At least one spectral output coupling mirror section is arranged on the field facet mirror. The mirror section serves to output couple the spectral analysis partial beam from a beam path of the illumination light. A detector serves for the spectral analysis of the spectral analysis partial beam. This can yield an illumination optical unit in which process monitoring during the projection exposure is improved.
Claims24
An illumination optical unit, comprising:
- a field facet mirror comprising a plurality of field facets configured to guide illumination light into an object field, the field fact mirror comprising a mirror section configured to output couple a spectral analysis partial beam from a beam path of the illumination light to the object field;
- and
- a detector configured to monitor an intensity of light at multiple different wavelengths within the spectral analysis partial beam,
- wherein the illumination optical unit is an EUV projection lithography illumination optical unit, and a path of the spectral analysis partial beam is different from the beam path of the illumination light.
Dependencies are inferred from the claim text.