Illumination system for EUV projection lithography
AssigneeCarl Zeiss SMT GmbH
InventorsMichael Patra, Ralf Mueller
Life of this patent
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Abstract
An illumination system for EUV projection lithography has a beam shaping optical unit for generating an EUV collective output beam from an EUV raw beam of a synchrotron-radiation-based light source. An output coupling optical unit serves for generating a plurality of EUV individual output beams from the EUV collective output beam. In each case a beam guiding optical unit serves for guiding the respective EUV individual output beam toward an object field in which a lithography mask is arrangable. The result is an illumination system with which EUV light of a synchrotron-radiation-based light source is guided to the greatest possible extent without losses and at the same time flexibly.
Claims22
A beam guiding optical unit, comprising:
- a focusing assembly configured to transfer an EUV individual output beam into an intermediate focus of the beam guiding optical unit,
- wherein:
- the focusing assembly comprises:
- an ellipsoidal mirror with a major semiaxis a of the ellipsoidal mirror;
- and
- a paraboloidal mirror with a focal length f of the paraboloidal mirror,
- a ratio a to f is greater than 50;
- and
- the beam guiding unit is an EUV lithography beam guiding unit.
A beam guiding optical unit, comprising:
- a focusing assembly configured to transfer an EUV individual output beam into an intermediate focus of the beam guiding optical unit,
- wherein:
- the focusing assembly has an effective deflection angle for a central chief ray of the EUV output beam;
- the effective deflection angle is less than double an angle between a central chief ray and a marginal ray at the intermediate focus of the beam guiding optical unit;
- and
- the beam guiding unit is an EUV lithography beam guiding unit.
A system comprising:
- a beam guiding unit;
- and
- a beam shaping optical unit-which comprises at least two groups of mirrors on which EUV radiation impinges with grazing incidence during use of the beam shaping optical unit,
- wherein each mirror group has a common group incidence plane, the group incidence planes of the mirror groups differ from one another, and the beam shaping unit is an EUV lithography beam shaping unit, and
- wherein the beam guiding unit comprises a focusing assembly configured to transfer an EUV individual output beam into an intermediate focus of the beam guiding optical unit, and the focusing assembly comprises a Wolter mirror group of type III, and the beam guiding unit is an EUV lithography beam guiding unit.
Dependencies are inferred from the claim text.