Patent ID: 11906904
Assignee: CARL ZEISS SMT GMBH
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 26:
27. An apparatus, comprising:
an illumination system configured to illuminate an object surface with a working wavelength of electromagnetic radiation;
a projection lens comprising a plurality of optical elements in a beam path of the operating wavelength of the electromagnetic radiation to image a pattern arranged in the object surface into an image surface of the projection lens via the operating wavelength of the electromagnetic radiation, the plurality of optical elements comprising a replaceable optical element;
a correction optical element; and
an interchange device configured to replace the replaceable optical element with the correction optical element,
wherein:
the correction optical element comprises a body comprising a surface which comprises regions consisting of diffraction structures configured to diffract an operating wavelength of electromagnetic radiation;
the regions of the surface of the correction element consist of diffraction structures comprise a first region of the surface of the correction element and a second region of the surface of the correction element;
the first region of the surface of the correction element consists of first diffraction structures having a first density of diffraction structures;
the second region of the surface of the correction element consists of second diffraction structures having a second density of diffraction structures;
the second density of diffraction structures is different from the first density of diffraction structures; and
the operating wavelength of the electromagnetic radiation is in the DUV range.