DE102021201816A1 - OPTICAL SYSTEM, MOUNTING DEVICE AND METHOD FOR POSITION MEASUREMENT OF A MEASUREMENT OBJECT - Google Patents

Abstract

An optical system (208) for a mounting device (200) for a lithography system (100A, 100B), having a camera (210) for recording an image (218) of at least part of a measurement object (202) and a measurement mark (216), a Background body (224) with a fluorescent coating (226), which is set up to be arranged behind the measurement object (202) as seen from the camera (210), and an illumination device (212) for illuminating and exciting a fluorescence of the fluorescent coating (226), wherein the camera (210) has a filter (240) for transmitting a fluorescent light (234) emitted by the fluorescent coating (226).

Description

The present invention relates to an optical system, a mounting device and a method for measuring the position of a measurement object.

Microlithography is used to produce microstructured components such as integrated circuits. The microlithography process is carried out using a lithography system which has an illumination system and a projection system. The image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, for example a silicon wafer, in order to place the mask structure on the light-sensitive coating of the substrate transferred to.

In the lithography system, optical elements such as mirrors must be positioned very precisely. For example, facets of a facet mirror of the lithography system have to be positioned very precisely. When manufacturing the lithography system, it is therefore necessary to precisely determine and, if necessary, to correct the current position of an optical element, for example a facet of a facet mirror, before the final assembly of the optical element. A position is measured, for example, by recording a contour of the optical element, for example a contour of the facet of the facet mirror, relative to a measurement marking arranged next to it using a camera system. The contour of the optical element is recorded against a light image background and thus made visible. In addition, the measurement mark is illuminated from the front so that it can be seen. The disadvantage here is that two lighting devices are required, one for generating the bright image background (backlighting) and one for illuminating the measuring mark (reflected light illumination). In addition, unwanted stray light from the edges of the optical element can make position measurement in the captured image difficult.

Against this background, an object of the present invention is to provide an improved optical system, a mounting device with this optical system and an improved method for measuring the position of a measurement object.

Accordingly, an optical system for a mounting device for a lithography system is proposed, which has a camera for recording an image of at least part of a measurement object and a measurement marking. The optical system also has a background body with a fluorescent coating, which is set up to be arranged behind the measurement object as seen from the camera. Furthermore, the optical system has an illumination device for illuminating and for exciting a fluorescence of the fluorescent coating. In addition, the camera has a filter for letting through a fluorescent light emitted by the fluorescent coating.

Because the background body has the fluorescent coating, a background light against which the measurement object can be recorded can be easily provided. In particular, it is not necessary for the background body to be self-luminous. Consequently, no lighting device and/or connections for a lighting device, such as an electrical connection, are required on the background body itself. This is particularly advantageous when the optical system is to be mobile with the background body and is to be moved within a production plant. By providing sufficiently bright background lighting, the measurement object can be clearly displayed as a dark contour against the light background.

Because the camera has the filter for letting through a fluorescent light emitted by the fluorescent coating, it can be reduced or avoided that stray light scattered by the measurement object enters the camera. In particular, an excitation light scattered by the measurement object is partially or completely filtered out by the filter. The measurement object can thus be recognized and measured better in the recorded image.

In particular, the illumination device emits an excitation light with a first wavelength range. The excitation light is UV light, for example. The excitation light has, for example, an intensity maximum at a wavelength of less than 400 nm, for example at 365 nm. The excitation light impinging on the fluorescent coating of the background body stimulates the fluorescent coating to emit fluorescent light in a second wavelength range. In particular, the first wavelength range of the excitation light is different from the second wavelength range of the fluorescent light. The second wavelength range is, for example, shifted to longer wavelengths relative to the first wavelength range. The second wavelength range may partially overlap the first wavelength range, or the first and second wavelength ranges may be disjoint be to each other. In the example in which the excitation light has an intensity maximum at a wavelength of less than 400 nm, e.g. 365 nm, the fluorescent light has an intensity maximum at a wavelength of greater than 400 nm, e.g. 435 nm.

In particular, the camera is set up to record the image of the at least one part of the measurement object against the fluorescent light emitted by the fluorescent coating of the background body. In particular, the measurement object appears dark against the bright background of the fluorescent light in the image recorded by the camera. The measurement object itself is in particular non-fluorescent.

For example, the measurement mark itself also appears dark against the bright background of the fluorescent light in the image captured by the camera. In this case, the measurement marking itself is in particular non-fluorescent. In another embodiment, the measurement marking can also be fluorescent and stand out against a dark background of the measurement marking.

The image recorded with the camera can be used, for example, to measure the position of the measurement object with respect to the two spatial directions (X direction, Y direction) perpendicular to the direction of an optical axis of the camera (Z direction). The measurement mark is arranged, for example, in a plane (XY plane) perpendicular to the camera optical axis direction (Z direction).

The fluorescent coating is applied in particular to a surface of the background body that faces the camera. In particular, said surface and the fluorescent coating are arranged in a plane (XY plane) perpendicular to the direction of the optical axis of the camera (Z direction).

The filter is in particular a bandpass filter, a narrowband filter, a shortpass filter and/or a longpass filter.

In the example in which the excitation light has an intensity maximum at a wavelength of less than 400 nm (e.g. 365 nm) and the fluorescent light has an intensity maximum at a wavelength of more than 400 nm (e.g. 435 nm), the filter is set up, for example, to only transmit light with wavelengths of 400 nm or greater.

The optical system is set up in particular to be used in an assembly device of a lithography system. The optical system is used in particular to position the measurement object precisely before final mounting on a carrier and/or frame.

The lithography system is, for example, a DUV or an EUV lithography system. EUV stands for "extreme ultraviolet" and refers to a working light wavelength between 0.1 nm and 30 nm. DUV also stands for "deep ultraviolet" and denotes a working light wavelength between 30 nm and 250 nm.

The DUV or EUV lithography system includes a beam shaping and illumination system and a projection system. In particular, with the DUV or EUV lithography system, the image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, for example a silicon wafer to transfer the mask pattern to the photosensitive coating of the substrate.

According to one embodiment, the filter of the camera is set up to filter out light with wavelengths outside the wavelengths of the fluorescent light.

According to a further embodiment, the optical system also has the measurement object, the measurement object being an optical element, a mirror, a facet mirror and/or a facet of a facet mirror for a lithography system.

A faceted mirror has multiple facets supported by a faceted mirror frame. Each facet has a reflective layer.

According to a further embodiment, the camera is set up to record at least one contour of the measurement object.

The contour of the measurement object is in particular a border and/or an edge of the measurement object. The contrast between the contour of the measurement object and the background is particularly high due to the advantageous backlighting by means of the fluorescent light and the filter of the camera, which only lets the fluorescent light through.

According to a further embodiment, the camera has a telecentric lens.

Thanks to the telecentric lens, the measurement object can be captured without perspective distortion will. In particular, the camera has a lens that is telecentric on the object side, in which the entrance pupil is at infinity, so that the principal rays in the object space all run parallel to the optical axis.

According to a further embodiment, the optical system further comprises the measurement object and the measurement mark, wherein at least a part of a surface of the measurement object facing the camera and the measurement mark are arranged at the same height relative to the camera.

As a result, a sharp image can be recorded by the camera of at least part of the measurement object and the measurement marking, even if the depth of field of the camera is limited.

According to a further embodiment, the optical system also has the measurement marking, the measurement marking having measurement points.

According to a further embodiment, the optical system also comprises a measuring marking device which has the measuring marking and a further fluorescent coating. In addition, the illumination device is set up to illuminate and excite fluorescence of the further fluorescent coating, and the filter of the camera is set up to let through a fluorescent light emitted by the further fluorescent coating.

In particular, as seen from the camera, the measurement marking is arranged in front of the further fluorescent coating.

The additional fluorescent coating is applied in particular to a surface of the measurement marking device that faces the camera. Said surface and the further fluorescent coating are arranged, for example, in a plane (XY plane) perpendicular to the direction of the optical axis of the camera (Z direction). The additional fluorescent coating of the measurement marking device and the fluorescent coating of the background body are, for example, parallel to one another.

In particular, the fluorescent coating of the background body and the further fluorescent coating of the measurement marking device have the same fluorescent material. In particular, the fluorescent light emitted by the additional fluorescent coating of the measurement marking device has the same wavelength range as the fluorescent light emitted by the fluorescent coating of the background body.

According to a further aspect, an assembly device for a lithography system is proposed which has the optical system described above.

The mounting device can in particular have a holding device for holding the measurement object. The holding device can, for example, have actuators for moving the measurement object. The holding device is, for example, a gripping arm. The holding device serves in particular to arrange the measurement object on a carrier and/or frame on which the measurement object is to be mounted.

The mounting device also has, for example, the carrier and/or the frame on which the measurement object is to be mounted. The measurement object is, for example, welded to/on the carrier/frame (e.g. by means of laser welding) as soon as it has been positioned precisely in a predetermined position by means of the mounting device which has the optical system.

The mounting device can in particular have a computing device connected to the camera of the optical system. The computing device is set up, for example, to use image processing to measure a current position of the measurement object relative to the measurement marking in the image recorded by the camera, to determine a deviation in the current position of the measurement object from a predetermined position, and to determine an actuator of a holding device that holds the measurement object , in order to move the measurement object according to the determined deviation.

1. a) Ausstrahlen eines Fluoreszenzlichts als ein Hintergrundlicht, und
2. b) Aufnehmen eines Bildes von zumindest einem Teil des Messobjekts und einer Messmarkierung gegen den fluoreszierenden Hintergrund, wobei Licht mit Wellenlängen außerhalb der Wellenlängen des Fluoreszenzlichts herausgefiltert wird.

According to a further aspect, a method for measuring the position of a measurement object is proposed. The procedure has the steps:

1. a) emitting a fluorescent light as a background light, and
2. b) taking an image of at least a part of the measurement object and a measurement marking against the fluorescent background, whereby light with wavelengths outside the wavelengths of the fluorescent light is filtered out.

According to an embodiment, the method comprises the step of: illuminating a fluorescent coating of a background body with an excitation light and exciting a fluorescence of the fluorescent coating so that the background body emits the fluorescent light as the background light.

"A" is not necessarily to be understood as being limited to exactly one element. Rather, a plurality of elements, such as two, three or more, can also be provided. Any other count word used here should also not be understood to mean that there is a restriction to precisely the stated number of elements. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

The embodiments and features described for the optical system apply correspondingly to the proposed assembly device and the proposed method and vice versa.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with regard to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

• 1A zeigt eine schematische Ansicht einer Ausführungsform einer EUV-Lithographieanlage;
• 1B zeigt eine schematische Ansicht einer Ausführungsform einer DUV-Lithographieanlage;
• 2 zeigt eine schematische Ansicht einer Montagevorrichtung für die Lithographieanlage aus 1A oder 1B;
• 3 zeigt eine schematische Ansicht eines optischen Systems der Montagevorrichtung aus 2;
• 4 zeigt ein mit einer Kamera des optischen Systems aus 3 aufgenommenes Bild; und
• 5 zeigt ein Flussablaufdiagramm zur Veranschaulichung eines Verfahrens zur Positionsmessung eines Messobjekts mit dem optischen System aus 3.

Further advantageous refinements and aspects of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the enclosed figures.

• 1A shows a schematic view of an embodiment of an EUV lithography system;
• 1B shows a schematic view of an embodiment of a DUV lithography system;
• 2 FIG. 12 shows a schematic view of an assembly device for the lithography system 1A or 1B ;
• 3 FIG. 12 shows a schematic view of an optical system of the assembly device 2 ;
• 4 shows a with a camera of the optical system 3 captured image; and
• 5 FIG. 12 shows a flow chart to illustrate a method for measuring the position of a measurement object using the optical system 3 .

Elements that are the same or have the same function have been provided with the same reference symbols in the figures, unless otherwise stated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

1A shows a schematic view of an EUV lithography system 100A, which includes a beam shaping and illumination system 102 and a projection system 104 . EUV stands for "extreme ultraviolet" (English: extreme ultraviolet, EUV) and designates a wavelength of the working light between 0.1 nm and 30 nm. The beam shaping and illumination system 102 and the projection system 104 are each in a vacuum chamber, not shown Housing provided, each vacuum housing is evacuated by means of an evacuation device, not shown. The vacuum housings are surrounded by a machine room, not shown, in which drive devices are provided for mechanically moving or adjusting optical elements. Furthermore, electrical controls and the like can also be provided in this machine room.

The EUV lithography system 100A has an EUV light source 106A. A plasma source (or a synchrotron), for example, can be provided as the EUV light source 106A, which emits radiation 108A in the EUV range (extreme ultraviolet range), ie for example in the wavelength range from 5 nm to 20 nm. The EUV radiation 108A is bundled in the beam shaping and illumination system 102 and the desired operating wavelength is filtered out of the EUV radiation 108A. The EUV radiation 108A generated by the EUV light source 106A has a relatively low transmissivity through air, which is why the beam guidance spaces in the beam shaping and illumination system 102 and in the projection system 104 are evacuated.

This in 1A The beam shaping and illumination system 102 shown has five mirrors 110, 112, 114, 116, 118. After passing through the beam shaping and illumination system 102 , the EUV radiation 108A is directed onto a photomask (reticle) 120 . The photomask 120 is also designed as a reflective optical element and can be arranged outside of the systems 102, 104. Furthermore, the EUV radiation 108A can be directed onto the photomask 120 by means of a mirror 122 . The photomask 120 has a structure which is imaged on a wafer 124 or the like in reduced form by means of the projection system 104 .

The projection system 104 (also referred to as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 onto the wafer 124 . In this case, individual mirrors M1 to M6 of the projection system 104 can be symmetrical to an optical axis 126 of the projection system 104 can be arranged. It should be noted that the number of mirrors M1 to M6 of the EUV lithography tool 100A is not limited to the illustrated number. More or fewer mirrors M1 to M6 can also be provided. Furthermore, the mirrors M1 to M6 are usually curved on their front side for beam shaping.

1B FIG. 12 shows a schematic view of a DUV lithography system 100B, which comprises a beam shaping and illumination system 102 and a projection system 104. FIG. DUV stands for "deep ultraviolet" (Engl .: deep ultraviolet, DUV) and denotes a wavelength of the working light between 30 nm and 250 nm 1A described - be arranged in a vacuum housing and/or surrounded by a machine room with corresponding drive devices.

The DUV lithography system 100B has a DUV light source 106B. An ArF excimer laser, for example, can be provided as the DUV light source 106B, which emits radiation 108B in the DUV range at, for example, 193 nm.

This in 1B The beam shaping and illumination system 102 shown directs the DUV radiation 108B onto a photomask 120. The photomask 120 is designed as a transmissive optical element and can be arranged outside of the systems 102, 104. The photomask 120 has a structure which is imaged on a wafer 124 or the like in reduced form by means of the projection system 104 .

The projection system 104 has a plurality of lenses 128 and/or mirrors 130 for imaging the photomask 120 onto the wafer 124 . In this case, individual lenses 128 and/or mirrors 130 of the projection system 104 can be arranged symmetrically to an optical axis 126 of the projection system 104 . It should be noted that the number of lenses 128 and mirrors 130 of the DUV lithography tool 100B is not limited to the number illustrated. More or fewer lenses 128 and/or mirrors 130 can also be provided. Furthermore, the mirrors 130 are typically curved on their front side for beam shaping.

An air gap between the last lens 128 and the wafer 124 can be replaced by a liquid medium 132 having a refractive index>1. The liquid medium 132 can be, for example, ultrapure water. Such a structure is also referred to as immersion lithography and has an increased photolithographic resolution. The medium 132 can also be referred to as an immersion liquid.

2 shows a schematic view of an assembly device 200 for the lithography system 100A, 100B. The mounting device 200 serves to mount a measurement object 202 on a carrier 204 . The measurement object 202 is, for example, an optical element, a mirror, a facet mirror and/or a facet of a facet mirror for the lithography system 100A, 100B. The measurement object 202 can be, for example, any of the mirrors 110 to 118, 122, 130, M1 to M6 of the lithography system 100A, 100B. The measurement object 202 can also be another component of the lithography system 100A, 100B.

In the in the 2 until 4 In the example shown, the measurement object 202 is a facet of a facet mirror for the lithography system 100A, 100B. The facet mirror is, for example, a field facet mirror or a pupil facet mirror. The facet mirror is, for example, the mirror 112 or the mirror 114 of the radiation and illumination system 102 of the EUV lithography system 100A 1A . However, the facet mirror can also be another mirror of the EUV or DUV lithography system 100A, 100B.

In the in the 2 until 4 In the example shown, the mounting device 200 serves to mount the facet as the measurement object 202 on a joint (flexure) as the carrier 204 . The hinge (support 204) is attached to a faceted mirror frame (not shown) in a later assembly step. During operation of the lithography system 100A, 100B, the joint 204 is used to suitably align a mirror surface 206 of the facet 202 .

Before the facet (measurement object 202) is finally mounted on the joint (carrier 204), a very precise positioning of the facet 202 on the joint 204 is required. For this purpose, the instantaneous position of the facet (object to be measured 202 ) is determined by means of an optical system 208 which includes a camera 210 and an illumination device 212 . The optical system 208 also includes a measurement marker 214 having a measurement marker 216 ( 4 ). In this example, the measurement marking 216 comprises a plurality of evenly arranged points 216, only a few of which are in 4 are provided with a reference number. By means of the camera 210 ( 2 ) becomes an image 218 ( 4 ) recorded by at least a part of the measurement object 202 (facet) and at least a part of the measurement marking 216. The position of the measurement object 202 (facet) relative to the measurement marking 216 is determined from the recorded image 218 by means of image processing. For image processing For processing and position measurement, the assembly device 200 has a computing device (not shown) connected to the camera 210 .

In order to be able to clearly recognize the measurement object 202 in the recorded image 218, the measurement object 202 is placed against a light background 220 ( 4 ) recorded. In particular, a part of the measurement object 202 that has a contour 222 of the measurement object 202 is captured by the camera 210 . To create the light background 220 ( 4 ) has the optical system 208 ( 2 ) a background body 224 with a fluorescent coating 226 on. The background body 224 with the fluorescent coating 226 is arranged behind the measurement object 202, in particular as seen from the camera 210, so that it illuminates the measurement object 202 from behind.

In the example shown, the measurement marking device 214 also has a further fluorescent layer 228 which provides a background light 230 ( 4 ) for the measurement mark 216 can generate.

3 shows how the optical system 208 works. The illumination device 212 emits an excitation light 232, e.g. a UV light, towards the background body 224 and the measurement marker 214 . The excitation light 232 impinges on the fluorescent coating 226 of the background body 224 and on the additional fluorescent coating 228 of the measurement marking device 214. The excitation light 232 excites the fluorescent coating 226 and the additional fluorescent coating 228 to fluoresce. As a result, the fluorescent coating 226 and the further fluorescent coating 228 emit a fluorescent light 234 and 236, respectively. The wavelength range of the fluorescent light 234, 236 is shifted compared to the wavelength range of the excitation light 232. For example, when fluorescence occurs, the wavelength range of the fluorescent light 234, 236 is shifted towards longer wavelengths compared to the wavelength range of the excitation light 232 due to the Stokes shift, since only part of the absorbed energy of the excitation light 232 is emitted in the form of the fluorescent light 234, 236.

The excitation light 232 of the illumination device 212, which strikes the measurement object 202 at least partially from the front as seen from the camera 210, can be scattered on the measurement object 202. Stray light 238 from the measurement object 202 (e.g. the edges of the measurement object 202) makes it difficult to see the measurement object 202, in particular contours 222 ( 4 ) of the measurement object 202 in the image 218 recorded by the camera 210.

In order to avoid scattered light 238, which can be caused by excitation light 232 scattered on the measurement object 202, reaching the camera 210, the camera 210 has a narrow-band filter 240. The narrow band filter 240 filters out light having wavelengths outside of the fluorescent light 234,236 wavelengths. Only the fluorescent light 234, 236 emitted by the fluorescent coating 226 and the further fluorescent coating 228 is allowed to pass through, while an excitation light 232 (scattered light 238) scattered by the measurement object 202 is partially or completely filtered out by the narrow band filter 42. The contours 222 ( 4 ) of the measurement object 202 better in the image 218 ( 4 ) can be detected and measured.

The camera 210 has, for example, a telecentric lens 242 ( 2 ) so that the measurement object 202 and the measurement mark 216 can be captured without perspective distortion.

At least part of the surface 206 of the measurement object 202 facing the camera 210 and the measurement marking 216 ( 4 ) are at the same height H1 ( 2 ) relative to the height H2 of the camera 210. As a result, both the measurement object 202 and the measurement marking 216 can be recorded sharply, in particular even with a restricted depth of field.

The position of the measurement object 202 with respect to the two spatial directions X and Y perpendicular to the direction Z of an optical axis 244 of the camera 210 can be measured using the image 218 recorded with the camera 210 ( 2 ). The measurement marking device 214 and the measurement marking 216 are arranged in particular in an XY plane which runs perpendicularly to the Z direction of the optical axis 244 of the camera 210 .

The fluorescent coating 226 is applied in particular to a surface 246 of the background body 224 facing the camera 210 ( 2 ). In particular, the surface 246 and the fluorescent coating 226 are arranged in an XY plane perpendicular to the Z direction of the optical axis 244 of the camera 210 .

The following is related to 5 a method for measuring the position of a measurement object is described.

In a first step S1 of the method, the measurement object 202 is held by a gripper arm (not shown) on carrier 204 ( 2 ) arranged.

In a second step S2 of the method, the fluorescent coating 226 of the background body 224 and the further fluorescent coating 228 of the measurement marking device 214 are irradiated with the excitation light 232, so that the fluorescent coatings 226 and 228 are excited to fluoresce.

In a third step S3 of the method, the fluorescent coatings 226, 228 of the background body 224 and of the measurement marking device 214 emit the fluorescent light 234 and 236, respectively.

In a fourth step S4 of the method, an image 218 ( 4 ) of at least part of the measurement object 202 and the measurement marking 216 against a light background 220 and 230, respectively. In this case, light with wavelengths outside the wavelengths of the fluorescent light 234 or 236 is filtered out by means of the narrow-band filter 240 . As a result, an image 218 can be obtained in which the contours 222 of the measurement object 202 can be clearly seen against the light background 220 produced by the fluorescent coating 226 . In addition, the measurement marking 216 can be seen clearly in the image 218 in front of the light background 230 produced by the further fluorescent coating 228 .

In a fifth step S5 of the method, the position of the object 202 relative to the measurement marking 216 in the image 218 is determined using image processing.

If the position of the object 202 determined in step S5 deviates from a predetermined position of the object 202, then in step S6 the object 202 is moved towards the predetermined position, for example by means of a gripping arm (not shown).

Steps S2 to S5 are repeated until the position of the object 202 determined in step S5 matches the predetermined position.

The measurement object 202 is attached to the carrier 204 in step S6. In the example shown, the measurement object 202 is a facet of a facet mirror and the carrier 204 is a joint. In this case, in step S6, the facet 202 is attached to the carrier 204, for example by means of laser welding.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

Reference List

100A

EUV lithography system

100B

DUV lithography system

102

Beam shaping and lighting system

104

projection system

106A

EUV light source

106B

DUV light source

108A

EUV radiation

108B

DUV radiation

110

mirror

112

mirror

114

mirror

116

mirror

118

mirror

120

photomask

122

mirror

124

wafers

126

optical axis

128

lens

130

mirror

132

medium

200

assembly device

202

measurement object

204

carrier

206

surface

208

optical system

210

camera

212

lighting device

214

measurement marking device

216

measurement mark

218

picture

220

background

222

contour

224

background body

226

fluorescent coating

228

fluorescent coating

230

background

232

excitation light

234

fluorescent light

236

fluorescent light

240

filter

242

lens

244

optical axis

246

surface

H1

Height

H2

Height

M1

mirror

M2

mirror

M3

mirror

M4

mirror

M5

mirror

M6

mirror

S1

process step

S2

process step

S3

process step

S4

process step

S5

process step

S6

process step

Claims (11)

Optical system (208) for a mounting device (200) for a lithography system (100A, 100B), having a camera (210) for recording an image (218) of at least part of a measurement object (202) and a measurement marking (216), a background body (224) with a fluorescent coating (226), which is set up to be arranged behind the measurement object (202) as seen from the camera (210), and an illumination device (212) for illuminating and exciting a fluorescence of the fluorescent coating (226), wherein the camera (210) includes a filter (240) for transmitting fluorescent light (234) emitted by the fluorescent coating (226). Optical system after claim 1 , wherein the filter (240) of the camera (210) is adapted to filter out light with wavelengths outside the wavelengths of the fluorescent light (234). Optical system after claim 1 or 2 , further comprising the measurement object (202), wherein the measurement object is an optical element, a mirror, a facet mirror and / or a facet of a facet mirror for the lithography system (100A, 100B). Optical system according to one of Claims 1 - 3 , wherein the camera (210) is set up to record at least one contour (222) of the measurement object (202). Optical system according to one of Claims 1 - 4 , wherein the camera (210) has a telecentric lens (242). Optical system according to one of Claims 1 - 5 , further comprising the measurement object (202) and the measurement mark (216), wherein at least a part of a camera (210) facing surface (206) of the measurement object (202) and the measurement mark (216) at the same height (H1) relative to the camera (210) are arranged. Optical system according to one of Claims 1 - 6 , further comprising the measurement mark (216), wherein the measurement mark (216) has measurement points. Optical system according to one of Claims 1 - 7 , further comprising a measurement marking device (214), which has the measurement marking (216) and a further fluorescent coating (228), wherein the illumination device (212) is set up to illuminate and to excite fluorescence of the further fluorescent coating (228), and wherein the filter (240) of the camera (210) is set up to let through a fluorescent light (236) emitted by the further fluorescent coating (228). Mounting device (200) for a lithography system (100A, 100B), which has an optical system (208) according to one of Claims 1 - 8th having. Method for measuring the position of a measurement object (202), with the steps: a) emitting (S3) a fluorescent light (234) as a backlight (220), and b) Recording (S4) an image (218) of at least part of the measurement object (202) and a measurement marking (216) against the fluorescent background (220), wherein light with wavelengths outside the wavelengths of the fluorescent light (234) is filtered out. procedure after claim 10 , wherein it comprises the step of: illuminating (S2) a fluorescent coating (226) of a background body (224) with an excitation light (232) and exciting a fluorescence of the fluorescent coating (226) so that the background body (224) emits the fluorescent light (234) as the background light (220).

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