Method for adusting a first element of a lithography apparatus towards a second element of a lithography apparatus by a tunable spacer

Abstract

A method adjusts a first element of a lithography apparatus toward a second element of the lithography apparatus via a tunable spacer which is arranged between the first element and the second element. The method includes: determining an actual location of the first element; determining a nominal location of the first element; unloading the tunable spacer; adjusting a height of the tunable spacer to bring the first element from the actual location to the nominal location; and loading the tunable spacer.

Claims

1. A method of adjusting a first element of a lithography apparatus relative to a second element of the lithography apparatus via a tunable spacer arranged between the first and second elements, the method comprising: a) removing at least a portion of a weight of the first element from the tunable spacer; b) while the weight of the first element is at least partially removed from the tunable spacer, adjusting a height of the tunable spacer so that the tunable spacer has an adjusted height; and c) while the tunable spacer has the adjusted height, putting the weight of the first element on the tunable spacer to adjust the first element relative to the second element, wherein: before a) while the weight of the first element is on the tunable spacer, the first element has a first location; after c) while the weight of the first element is on the tunable spacer, the first element has a second location; and the second location of the first element is different from the first location of the first element.

2. The method of claim 1, further comprising, before a): determining the first location of the first element; and determining the second location of the first element.

3. The method of claim 2, wherein determining the first location of the first element comprises measuring the first location of the first element or calculating the first location of the first element.

4. The method of claim 2, wherein determining the second location of the first element comprises calculating the second location of the first element.

5. The method of claim 2, wherein determining the first location of the first element comprises determining the first location of the first element relative to the second element.

6. The method of claim 1, wherein b) comprises steplessly adjusting the height of the tunable spacer.

7. The method of claim 1, wherein a) comprises lifting the first element from the tunable spacer to at least partially remove the weight of the first element from the tunable spacer.

8. The method of claim 1, wherein c) comprises settling the first element on the tunable spacer to put the weight of the first element on the tunable spacer.

9. The method of claim 1, wherein b) comprises using a gear mechanism to adjust the height of the tunable spacer, wherein the gear mechanism comprises a part of the tunable spacer.

10. The method of claim 9, wherein b) comprises adjusting the height of the tunable spacer via a linear movement of a displacement element of the tunable spacer relatively toward a housing element of the tunable spacer along a first spatial direction.

11. The method of claim 10, wherein, during b), the gear mechanism transfers the linear movement of the displacement element along the first spatial direction into a linear movement of the displacement element along a second spatial direction different from the first spatial direction.

12. The method of claim 10, further comprising, during the linear movement of the displacement element relatively toward the housing element, gliding an inclined gliding surface of the displacement element on an inclined gliding surface of the housing element.

13. The method of claim 10, further comprising using an adjustment element to move the displacement element relatively toward the housing element along the first spatial direction.

14. The method of claim 1, wherein b) comprises bringing the tunable spacer from a non-deflected status into a deflected status, and a height of the tunable spacer in the deflected status is greater than a height of the tunable spacer the non-deflected status.

15. The method of claim 1, comprising keeping the tunable spacer between the first and second elements throughout a) to c).

16. The method of claim 1, wherein, during c), the tunable spacer is force-free.

17. The method of claim 1, wherein: a) comprises lifting the first element from the tunable spacer to at least partially remove the weight of the first element from the tunable spacer; and b) comprises steplessly adjusting the height of the tunable spacer.

18. The method of claim 17, wherein c) comprises settling the first element on the tunable spacer to put the weight of the first element on the tunable spacer.

19. The method of claim 18, further comprising, before a): determining the first location of the first element; and determining the second location of the first element.

20. The method of claim 1, wherein: a) comprises lifting the first element from the tunable spacer to at least partially remove the weight of the first element from the tunable spacer; b) comprises using a gear mechanism to adjust the height of the tunable spacer; and the gear mechanism comprises a part of the tunable spacer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the text that follows, the disclosure is explained in more detail on the basis of illustrative embodiments and with reference to the accompanying figures.

(2) FIG. 1A shows a schematic view of an embodiment of an EUV lithography apparatus;

(3) FIG. 1B shows a schematic view of an embodiment of a DUV lithography apparatus;

(4) FIG. 2 shows a schematic view of an embodiment of an optical system for the EUV lithography apparatus according to FIG. 1A or for the DUV lithography apparatus according to FIG. 1B;

(5) FIG. 3 shows a schematic view of an embodiment of a tunable spacer for the optical system according to FIG. 2;

(6) FIG. 4 shows a further schematic view of the tunable spacer according to FIG. 3;

(7) FIG. 5 shows a further schematic view of the tunable spacer according to FIG. 3;

(8) FIG. 6 shows a schematic perspective view of the tunable spacer according to FIG. 3;

(9) FIG. 7 shows a schematic perspective view of an embodiment of a housing element for the tunable spacer according to FIG. 3;

(10) FIG. 8 shows a schematic perspective view of an embodiment of a displacement element for the tunable spacer according to FIG. 3;

(11) FIG. 9 shows a schematic perspective partial view of the tunable spacer according to FIG. 3; and

(12) FIG. 10 shows a schematic block diagram of one embodiment of a method for adjusting a first element of the EUV lithography apparatus according to FIG. 1A or for the DUV lithography apparatus according to FIG. 1B toward a second element of the lithography apparatus.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(13) Identical elements or elements having an identical function have been provided with the same reference signs in the figures, unless indicated to the contrary. It should also be noted that the illustrations in the figures are not necessarily true to scale.

(14) FIG. 1A shows a schematic view of an EUV lithography apparatus 100A, which includes a beam shaping and illumination system 102 and a projection system 104. In this case, EUV stands for “extreme ultraviolet” and denotes a wavelength of the working light of between 0.1 nm and 30 nm. The beam shaping and illumination system 102 and the projection system 104 are respectively provided in a vacuum housing (not shown), each vacuum housing being evacuated with the aid of an evacuation device (not shown). The vacuum housings are surrounded by a machine room (not shown), in which drive devices for mechanically moving or setting optical elements are provided. Moreover, electrical controllers and the like can also be provided in this machine room.

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

(16) The beam shaping and illumination system 102 illustrated in FIG. 1A has five mirrors 110, 112, 114, 116, 118. After passing through the beam shaping and illumination system 102, the EUV radiation 108A is guided onto a photomask (called a reticle) 120. The photomask 120 is likewise embodied as a reflective optical element and can be arranged outside the systems 102, 104. Furthermore, the EUV radiation 108A can be directed onto the photomask 120 via a mirror 122. The photomask 120 has a structure which is imaged onto a wafer 124 or the like in a reduced fashion via the projection system 104.

(17) The projection system 104 (also referred to as 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 arranged symmetrically in relation to an optical axis 126 of the projection system 104. It should be noted that the number of mirrors M1 to M6 of the EUV lithography apparatus 100A is not restricted to the number represented. A greater or lesser number of mirrors M1 to M6 can also be provided. Furthermore, the mirrors M1 to M6 are generally curved on their front face for beam shaping.

(18) FIG. 1B shows a schematic view of a DUV lithography apparatus 100B, which includes a beam shaping and illumination system 102 and a projection system 104. In this case, DUV stands for “deep ultraviolet” and denotes a wavelength of the working light of between 30 nm and 250 nm. As has already been described with reference to FIG. 1A, the beam shaping and illumination system 102 and the projection system 104 can be arranged in a vacuum housing and/or surrounded by a machine room with corresponding drive devices.

(19) The DUV lithography apparatus 100B has a DUV light source 106B. By way of example, an ArF excimer laser that emits radiation 108B in the DUV range at 193 nm, for example, can be provided as the DUV light source 106B.

(20) The beam shaping and illumination system 102 illustrated in FIG. 1B guides the DUV radiation 108B onto a photomask 120. The photomask 120 is embodied as a transmissive optical element and can be arranged outside the systems 102, 104. The photomask 120 has a structure which is imaged onto a wafer 124 or the like in a reduced fashion via the projection system 104.

(21) The projection system 104 has a plurality of lens elements 128 and/or mirrors 130 for imaging the photomask 120 onto the wafer 124. In this case, individual lens elements 128 and/or mirrors 130 of the projection system 104 can be arranged symmetrically in relation to an optical axis 126 of the projection system 104. It should be noted that the number of lens elements 128 and mirrors 130 of the DUV lithography apparatus 100B is not restricted to the number represented. A greater or lesser number of lens elements 128 and/or mirrors 130 can also be provided. Furthermore, the mirrors 130 are generally curved on their front face for beam shaping.

(22) An air gap between the last lens element 128 and the wafer 124 can be replaced by a liquid medium 132 which has a refractive index of >1. The liquid medium 132 can be high-purity water, for example. Such a construction 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.

(23) FIG. 2 shows an optical system 200. The optical system 200 can be part of an EUV lithography apparatus 100A or of a DUV lithography apparatus 100B. For example, the optical system 200 can be part of a projection system 102 or can be a projection system 102, for example of an EUV lithography apparatus 100A. In the text below, the optical system 200 is explained only with reference to an EUV lithography apparatus 100A. However, the optical system 200 can also be used in a DUV lithography apparatus 100B.

(24) The optical system 200 includes a first element 202. The first element 202 can be, for example, an optical element, such as one of the mirrors 110, 112, 114, 116, 118, 122, 130, M1 to M6, one of the lens elements 128 or a stop. However, the first element 202 can also be a force frame, an adjusting element or actuator for aligning an optical element, an end stop of an optical element, part of an active vibration isolation system (AVIS), such as for suspension of a sensor frame, or similar.

(25) The optical system 200 moreover includes a second element 204. The second element 204 can be a base of the optical system 200. The base can also be designated as a fixed world of the optical system 200. For example, the second element 204 can also be an aforementioned force frame of the optical system 200 or of the EUV lithography apparatus 100A. In this case, the first element 202 can be, for example, an optical element as explained above, which is carried or supported by the second element 204.

(26) The first element 202 has in particular six degrees of freedom with respect to the second element 204, namely three translational degrees of freedom along an x direction x, a y direction y and a z direction z, respectively, and three rotational degrees of freedom about the x direction x, the y direction y and the z direction z, respectively. In other words, a position and an orientation of the first element 202 can be determined or described with the aid of the six degrees of freedom. The directions x, y, z can also be designated as spatial directions.

(27) The “position” of the first element 202 is to be understood in particular as its coordinates or the coordinates of a measurement point provided on the first element 202 with respect to the x direction x, the y direction y and the z direction z. The “orientation” of the first element 202 is to be understood in particular as its tilt with respect to the three spatial directions x, y, z. In other words, the first element 202 can be tilted about the x direction x, the y direction y and/or the z direction z. This gives the six degrees of freedom for the position and/or orientation of the first element 202. A “location” of the first element 202 includes both its position and its orientation.

(28) An interface 206 is provided between the first element 202 and the second element 204. The first element 202 is coupled to the second element 204 at the interface 206. A surface 208 of the first element 202 and a surface 210 of the second element 204 are assigned to the interface 206. The surfaces 208, 210 face towards each other.

(29) Before the optical system 200 is started up, for example before exposure operation, it is desirable to adapt the position and/or orientation of the first element 202. For this purpose, for example, the first element 202 can be adjusted or oriented in a coordinate system defined by the spatial directions x, y, z, or the first element 202 is adjusted or oriented relative to the second element 204.

(30) In the present case, “adjusting” can be understood as bringing the first element 202 from an actual position IL (shown in FIG. 2 with solid lines and labelled with the reference sign 202) to a nominal position SL (shown in FIG. 2 with broken lines and labelled with the reference signs 202′). The actual position IL can be measured, for example, and the nominal position SL can be calculated, for example, such as with the aid of a correction recipe.

(31) The adjustment of the first element 202 can be effected, for example, with the aid of spacers. For this purpose, desired thicknesses or heights of such spacer elements are first of all determined, for example with the aid of a virtual assembly model or with the aid of short-circuit measurements. A “short-circuit measurement” is to be understood in the present case as meaning that the optical system 200 is assembled completely with standard or nominal spacers and then measured.

(32) In order to avoid long processing times, for example on account of the grinding of the spacers, a modular system of spacers of very different heights or thicknesses is made available. The spacers are ground here with a precision of ±2 μm, in order to achieve the desired process tolerances. A plurality of spacers can be combined to form a spacer stack. On account of the small increments of 10 μm and the usual desire for a large adjustment range of up to 0.5 mm, it is desirable to make available a large number of spacers. For example, over 1000 spacers have to be kept in stock for a projection system 104 of the kind explained above. The complicated handling and the logistics of the spacers drive up the costs. Moreover, long processing times have to be expected. The production and cleaning of high-precision spacers is also very complex.

(33) In order to make adjustment easier in relation to known spacers, a tunable spacer 300 is provided at the interface 206. With the spacer 300 shown in FIG. 2, the position of the first element 202 in the z direction can be adjusted. A large number of spacers 300 of this kind can be provided, such that the position and/or orientation of the first element 202 can be adjusted with respect to the second element 204. A fastening element 212, for example a screw, can be guided through the spacer 300. The spacer 300 can be assigned a coordinate system formed by the three spatial directions x, y, z. That is to say, the spatial directions x, y, z are assigned to the spacer 300. The first element 202 has a weight G that rests on the spacer 300. In this way, the first element 202 loads the spacer 300 with its weight G.

(34) FIGS. 3 and 4 show an embodiment of the spacer 300. The spacer 300 includes a first housing element 302 and a second housing element 304. The housing elements 302, 304 can be of identical configuration. The housing elements 302, 304 can be positioned with mirror symmetry in relation to a plane of symmetry 306.

(35) The first housing element 302 includes a first gliding plane or first gliding surface 308, which is inclined at a first angle of inclination α1 relative to an outer face 310 of the first housing element 302. The angle of inclination α1 is can be smaller than 10°, for example 5° to 8°. Accordingly, the second housing element 304 has a second gliding plane or second gliding surface 312, which is inclined at a second angle of inclination α2 relative to an outer face 314 of the second housing element 304. The angles of inclination α1, α2 can be of the same size. Alternatively, the angles of inclination α1, α2 can also be of different size. The outer faces 310, 314 bear on the surfaces 208, 210 of the elements 202, 204. The angles of inclination α1, α2 can also be designated as wedge angles.

(36) The spacer 300 moreover includes a displacement element 316 arranged between the housing elements 302, 304 and linearly displaceable relative to the latter. The displacement element 316 is wedge-shaped. Therefore, the displacement element 316 can also be designated as a wedge element. The displacement element 316 can be configured with mirror symmetry in relation to the plane of symmetry 306.

(37) The displacement element 316 includes a first gliding plane or first gliding surface 318, which bears and can slide on the first gliding surface 308 of the first housing element 302. The displacement element 316 moreover includes a second gliding plane or second gliding surface 320, which bears and can slide on the second gliding surface 312 of the second housing element 304. The gliding surfaces 318, 320 are positioned with mirror symmetry in relation to the plane of symmetry 306.

(38) The first gliding surface 318 is inclined relative to the plane of symmetry 306 at a first angle of inclination β1, which can be equal to the first angle of inclination α1. The second gliding surface 320 is inclined relative to the plane of symmetry 306 at a second angle of inclination β2, which can be equal to the second angle of inclination α2. In the case where the angles of inclination α1, α2 are of different sizes, the angles of inclination β1, β2 are also of different sizes, although the first angles of inclination α1, β1 and the second angles of inclination α2, β2 are in each case of the same size. For example, the first angles of inclination α1, β1 or the second angles of inclination α2, β2 can also be equal to 0°, such that the corresponding gliding surfaces 308, 318 or 312, 320 are positioned parallel to the plane of symmetry 306. The angles of inclination β1, β2 can also be designated as wedge angles.

(39) The gliding surfaces 308, 312, 318, 320 are part of a gear mechanism 322 of the spacer 300. The gear mechanism 322 is designed to convert a linear movement of the displacement element 316 in a spatial direction, for example in the x direction x, into a linear movement of at least one of the housing elements 302, 304 in a spatial direction differing from the spatial direction in which the displacement element 316 is shifted, for example the z direction z. That is to say, in the orientation in FIG. 3, the gliding surfaces 308, 312, 318, 320 slide on each other during a linear shift of the displacement element 316 in the x direction x, as a result of which the housing elements 302, 304 move away from each other, viewed in the z direction z. In this way, a height h of the spacer 300, which is oriented parallel to the z direction z in the orientation of FIG. 3, can be adjusted. The height h can also be designated as a thickness. The linear movement of the displacement element 316 relative to the housing elements 302, 304 is illustrated in FIGS. 3 and 4 with the aid of an arrow 324.

(40) The spacer 300 can moreover include an optional spring element 326. The spring element 326 can be a cylindrical spring, such as a compression spring. The spring element 326 is positioned between the displacement element 316 and a fixed bearing 328. For example, the spring element 326 couples the displacement element 316 to the fixed bearing 328. The fixed bearing 328 can be, for example, part of the housing elements 302, 304 of the spacer 300.

(41) The spacer 300 can be brought from a non-deflected state Z1, shown in FIG. 3, to a deflected state Z2, shown in FIG. 4, and vice versa. The height h is greater in the deflected state Z2 than in the non-deflected state Z1. Between the states Z1, Z2, the spacer 300 can be brought steplessly to any desired number of intermediate states. As the spacer 300 is brought from the non-deflected state Z1 to the deflected state Z2, and vice versa, the gliding surface 308 slides on the gliding surface 318, and the gliding surface 312 slides on the gliding surface 320. In the non-deflected state Z1, the height is labelled with the reference sign h, and, in the deflected state, the height is labelled with the reference sign h′, wherein the height h′ is greater than the height h.

(42) As the spacer 300 is brought from the non-deflected state Z1 to the deflected state Z2, the spring element 326 is brought reversibly from an uncompressed or untensioned state Z10 to a compressed or tensioned state Z20. In the tensioned state Z20, the spring element 326 exerts a spring force F, such as a compressive force, on the displacement element 316, such that the displacement element 316 is pretensioned in the direction of the non-deflected state Z1.

(43) FIG. 5 shows a further schematic view of the spacer 300, wherein only half of the displacement element 316 is shown, and the second housing element 304 is not shown at all. The first housing element 302 is shown with hatching for better differentiation from the displacement element 316. As mentioned before, the displacement element 316 is moved linearly relative to the housing elements 302, 304 in order to adjust the height h. With the aid of the gear mechanism 322, a linear movement of the displacement element 316 along a spatial direction, for example along the x direction x, by a displacement path Δx, can be converted into a linear movement, i.e. a height change Δh, of the housing elements 302, 304 in another spatial direction, for example in the z direction z.

(44) In the geometry shown in FIG. 5, tan β1=(Δh/2)/Δx or tan α1=(Δh/2)/Δx. With a displacement path Δx of the displacement element 316 along the x direction x by 1 mm for example, and assuming an angle of inclination β1 of 5°, this gives the height change Δh=2 tan β1Δx=175 μm in the case where the displacement element 316 has two gliding surfaces 318, 320. The smaller the angle of inclination α1, α2, β1, β2, the less the height change Δh for a constant displacement path Δx. In the case where the displacement element 316 has only one gliding surface 318, 320, the height change Δh halves for the same displacement path Δx. The smaller the angle of inclination α1, α2, β1, β2, the smaller the adjustment increments that are to be realized.

(45) The shallow angle of inclination α1, α2, β1, β2 also increases the static friction between the displacement element 316 and the housing elements 302, 304. The spacer 300 is therefore self-locking. That is to say, the spacer 300 cannot be brought from the deflected state Z2 to the non-deflected state Z1 by application of forces to the outer faces 310, 314 of the housing elements 302, 304. Therefore, compared to a non-adjustable spacer, the spacer 300 is no less stiff and, moreover, has no lesser stability.

(46) FIG. 6 shows a specific design of the spacer 300 in a schematic perspective view. FIG. 9 shows a schematic perspective partial view of the spacer 300. The spacer 300 includes a perforation 330 which passes through the two housing elements 302, 304 and also the displacement element 316. The perforation 330 can have an elongate geometry, which can extend in the x direction x. That is to say, an extent of the perforation 330 along the x direction x is greater than its extent along the y direction y. The fastening element 212 can be guided through the perforation 330. In this way, the fastening element 212 does not need to be arranged next to the spacer 300, which could lead to a bending stress of the first element 202. The perforation 330 is provided substantially centrally on the spacer 300.

(47) The spacer 300 includes two adjustment elements 332, 334. The adjustment elements 332, 334 could be screws, such as cap screws. A first adjustment element 332 and a second adjustment element 334 are provided. The adjustment elements 332, 334 can be part of the gear mechanism 322. With the aid of the adjustment elements 332, 334, the displacement element 316 can be moved linearly along the displacement path Δx counter to the spring force F of the spring element 326, in order to bring the spacer 300 from the non-deflected state Z1 to the deflected state Z2. The adjustment elements 332, 334 can be actuated alternately.

(48) To bring the spacer 300 from the deflected state Z2 to the non-deflected state Z1, the adjustment elements 332, 334 are released again, as a result of which the spring element 326 again brings the spacer 300 automatically from the deflected state Z2 to the non-deflected state Z1.

(49) In the case where the spacer 300 has no spring element 326, the spacer 300 can also be brought from the deflected state Z2 to the non-deflected state Z1 by a striking action against the loosened adjustment elements 332, 334. Moreover, the spacer 300 can also alternatively include only one adjustment element 332, 334.

(50) The first housing element 302 shown in a schematic perspective view in FIG. 7 has a configuration identical to the second housing element 304. The first gliding surface 308 and the outer face 310 of the first housing element 302 are penetrated by a perforation 336. The perforation 336 is part of the perforation 330. Grooves 338, 340 for the adjustment elements 332, 334 are provided in the first gliding surface 308 on both sides of the perforation 336. Moreover, a receiving region 342 for the spring element 326 is provided on the first gliding surface 308. The receiving region 342 can be semi-cylindrical. The first housing element 302 can be produced from a metal material, for example from a steel alloy or an aluminium alloy.

(51) The first housing element 302 moreover includes a rear wall 344 with a perforation 346 through which the second adjustment element 334 is guided. The aforementioned fixed bearing 328 of the spring element 326 can be part of the rear wall 344. The first housing element 302 has a first guide rail 348, and a second guide rail 350 arranged parallel to and at a distance from the first guide rail 348. The guide rails 348, 350 can also be designated as guide surfaces or guide walls. As FIG. 6 shows, the second guide rail 350 of the first housing element 302 is guided internally on the first guide rail 348 of the second housing element 304. Accordingly, the second guide rail 350 of the second housing element 304 is guided internally on the first guide rail 348 of the first housing element 302. In this way, the housing elements 302, 304 cannot twist counter to each other.

(52) The displacement element 316 shown in a schematic perspective view in FIG. 8 likewise includes a perforation 352 which passes through the gliding surfaces 318, 320 and is part of the perforation 330. Moreover, the displacement element 316 has a first receiving portion 354 for the first adjustment element 332 and a second receiving portion 356 for the second adjustment element 334. The receiving portions 354, 356 can partially perforate the gliding surfaces 318, 320.

(53) Each receiving portion 354, 356 has a threaded bore (not shown) into which the respective adjustment element 332, 334 can be screwed. A receiving region 358, which is formed as a perforation, serves to receive the spring element 326. The displacement element 316 can be produced from a metal material, for example from a steel alloy or an aluminium alloy.

(54) The spacer 300 has many advantages over known spacers. The accuracy of the adjustment of the height h is not achieved through high-precision and therefore costly production, but with the aid on a non-sensitive adjustment mechanism in the form of the gear mechanism 322. It is not necessary to exchange the spacer 300 in order to adjust the height h. Rather, lateral access to the adjustment elements 332, 334 is sufficient to adjust the height h. With the spacer 300, it is possible to achieve at least the same adjustment accuracy, that is to say the graduation of the height h, as is possible with the aforementioned modular concept. The spacer 300 provides stiffness and stability that are no poorer than those of a known spacer stack.

(55) FIG. 10 shows a schematic block diagram of one embodiment of a method for adjusting the first element 202 toward the second element 204.

(56) In a step S1, the actual location IL of the first element is determined. After that, the nominal location SL of the first element 202 is determined in a step S2. In a step S3, the spacer 300 is unloaded. This can be done by lifting the first element 202 from the spacer 300. Consequently, the height h of the spacer 300 is adjusted in a step S4 in order to bring the first element 20 from the actual location IL into the nominal location SL. This can be done while leaving the spacer 300 sandwiched between the two elements 202, 204. Finally, the spacer 300 is loaded again in a step S5. For example, the spacer 300 is loaded with the weight G of the first element 202.

(57) Although the present disclosure has been described on the basis of illustrative embodiments, it is modifiable in diverse ways.

LIST OF REFERENCE SIGNS

(58) 100A EUV lithography apparatus 100B DUV lithography apparatus 102 beam shaping and illumination 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 wafer 126 optical axis 128 lens element 130 mirror 132 medium 200 optical system 202 element 202′ element 204 element 206 interface 208 surface 210 surface 212 fastening element 300 spacer 302 housing element 304 housing element 306 plane of symmetry 308 gliding surface 310 outer face 312 gliding surface 314 outer face 316 displacement element 318 gliding surface 320 gliding surface 322 gear mechanism 324 arrow 326 spring element 328 fixed bearing 330 perforation 332 adjustment element 334 adjustment element 336 perforation 338 groove 340 groove 342 receiving region 344 rear wall 346 perforation 348 guide rail 350 guide rail 352 perforation 354 receiving portion 356 receiving portion 358 receiving region F spring force G weight h height h′ height IL actual position M1 mirror M2 mirror M3 mirror M4 mirror M5 mirror M6 mirror SL nominal position S1 step S2 step S3 step S4 step S5 step x spatial direction y spatial direction z spatial direction Z1 state Z2 state Z10 state Z20 state α1 angle of inclination α2 angle of inclination β1 angle of inclination β2 angle of inclination Δh height change Δx displacement path