An optical element for an optical system, in particular an optical system of a microlithographic projection exposure apparatus or mask inspection apparatus, and a method for correcting the wavefront effect of an optical element. The optical element has at least one correction layer (12, 22) and a manipulator that manipulates the layer stress in this correction layer such that a wavefront aberration present in the optical system is at least partially corrected by this manipulation. The manipulator has a radiation source for spatially resolved irradiation of the correction layer with electromagnetic radiation (5). This spatially resolved irradiation enables a plurality of spaced apart regions (12a, 12b, 12c, . . . ; 22a, 22b, 22c, . . . ) to be generated, equally modified in terms of their respective structures, in the correction layer.

A diffractive optical element may include sub-wavelength period stack-and-gap structured layers providing transmissive phase delay at a wavelength. The sub-wavelength period stack-and-gap structured layers may include a set of thin anti-reflection layers that are index matched to an environment or a substrate over a range of fill factors of the sub-wavelength period.

An optical manipulator (MAN) includes an optical element (OE), in particular composed of fused silica, and an actuating device (DR) that reversibly changes the surface form (SF) of the optical element (OE). The actuating device (DR) has a plurality of actuators (AK) that mechanically act on the optical element (OE) at a plurality of contact areas. The optical element (OE) at least at action regions in vicinities of the contact areas of the actuators (AK) is prestressed to an compressive stress of more than 1 MPa, preferably of more than 100 MPa, particularly preferably of more than 500 MPa. Also disclosed are a projection lens provided with at least one such optical manipulator (MAN), a projection exposure apparatus having such a projection lens, and a method for producing such an optical manipulator (MAN).

An apparatus and a method for detecting an optimal focal plane of a lithographic projection objective lens, the apparatus including: an illumination device, a beam splitting device, a lens array, a mask plate, a reflecting device, a photoelectric detector and a controller. The illumination device generates a collimated beam, which is transmitted through the beam splitting device, focused by the lens array to the mask plate for spatial-filtering, and delivered to the lithographic projection objective lens. The reflecting device reflects a focused beam passing through the lithographic projection objective lens to generate a reflected beam. The photoelectric detector detects an intensity of the reflected beam from the reflecting device after being spatial-filtered via the mask plate and generates a beam intensity signal. The controller controls a movement of a workpiece table and/or collects the beam intensity signal generated by the photoelectric detector.

An overlay metrology tool and diffraction-based overlay measurements are described herein. The tool includes a light source for generating an incident light that illuminates stacked overlay targets formed within material layers of a wafer and a light sensing system for measuring characteristics of a diffracted light beam reflected from the surface of the wafer. During a single illumination of the wafer and without rotating a polarization of the incident light beam, the light sensing system generates three components of the diffracted light beam having one or more polarizations and intensities, according to an overlay recipe associated with the stacked overlay targets.

An EUV lithography apparatus may include a light source, an EUV mask and a carbon-based optical filter. The light source may generate an EUV light. The EUV mask may be configured to apply the EUV light to a photoresist film on a substrate. The carbon-based optical filter may filter a light having an OoB wavelength in the EUV light. Thus, the EUV light may not include the light having the OoB wavelength to decrease an error of a photoresist pattern formed using the EUV light.

An overlay metrology tool and diffraction-based overlay measurements are described herein. The tool includes a light source for generating an incident light that illuminates stacked overlay targets formed within material layers of a wafer and a light sensing system for measuring characteristics of a diffracted light beam reflected from the surface of the wafer. During a single illumination of the wafer and without rotating a polarization of the incident light beam, the light sensing system generates three components of the diffracted light beam having one or more polarizations and intensities, according to an overlay recipe associated with the stacked overlay targets.

The invention relates to a sensor (SE) comprising: a radiation source (LS) to emit radiation (LI) having a coherence length towards a sensor target (GR); and a polarizing beam splitter (PBS) to split radiation diffracted by the sensor target into radiation with a first polarization state and radiation with a second polarization state, wherein the first polarization state is orthogonal to the second polarization state, and wherein the sensor is configured such that after passing the polarizing beam splitter radiation with the first polarization state has an optical path difference relative to radiation with the second polarization state that is larger than the coherence length.

A wafer holding device (200, 415) is configured to hold a wafer (205, 416) during operation of a microlithographic projection exposure apparatus and includes at least one sensor that is positionable in different rotational positions.

The invention relates to an inspection device for masks for semiconductor lithography, comprising an imaging device for imaging a mask, and an image recording device, wherein one or more correction bodies which exhibit a dispersive behavior for at least one subrange of the illumination radiation used for the imaging are arranged in the light path between the mask and the image recording device. The invention furthermore relates to a method for taking account of longitudinal chromatic aberrations in inspection devices for masks, comprising the following steps: recording a specific number of images having differently defocused positions, and selecting a subset of the images and simulating a longitudinal chromatic aberration of a projection exposure apparatus.