Faceted mirror for EUV projection lithography and illumination optical unit with same

Abstract

A facet mirror for EUV projection lithography has a plurality of facets for reflecting EUV illumination light. At least some of the facets are in the form of alignment facets and have a reflection surface, the edge contour of which is aligned along two alignment coordinates of an overall facet arrangement. The reflection surface of at least one of the alignment facets has a surface shape that exhibits different curvatures along two axes of curvature. The axes of curvature are tilted about a finite axis tilt angle relative to the alignment coordinates of the overall facet arrangement. The result is a facet mirror with increased EUV throughput, particularly for prolonged operation of a projection exposure apparatus that is equipped therewith.

Claims

1. A facet mirror, comprising: a plurality of facets configured to reflect EUV illumination light, wherein: at least some of the facets comprise alignment facets; the alignment facets comprise a reflection surface with an edge contour aligned along two alignment coordinates of an overall facet arrangement; the reflection surface of at least one of the alignment facets comprises a surface shape that exhibits different curvatures along two axes of curvature; the two axes of curvature are tilted about a finite axis tilt angle with respect to the alignment coordinates of the overall facet arrangement; and each of the alignment facets has a contiguous reflection surface.

2. The facet mirror of claim 1, wherein: the alignment facets comprise first and second alignment facets; the reflection surface of first and second alignment facets comprise surface shapes exhibiting different curvatures along two axes of curvature; and the axis tilt angles of the first and second alignment facets differ.

3. The facet mirror of claim 1, wherein the finite axis tilt angle is at least one degree.

4. The facet mirror of claim 1, wherein a greater radius of curvature of the reflection surface is infinite.

5. The facet mirror of claim 1, wherein both radii of curvature of the reflection surface are finite.

6. The facet mirror of claim 1, wherein: the alignment facets comprise first and second alignment facets; the reflection surface of first and second alignment facets comprise surface shapes exhibiting different curvatures along two axes of curvature; the axis tilt angles of the first and second alignment facets differ; and the finite axis tilt angle is at least one degree.

7. The facet mirror of claim 6, wherein a greater radius of curvature of the reflection surface is infinite.

8. The facet mirror of claim 6, wherein both radii of curvature of the reflection surface are finite.

9. The facet mirror of claim 1, wherein: the alignment facets comprise first and second alignment facets; the reflection surface of first and second alignment facets comprise surface shapes exhibiting different curvatures along two axes of curvature; the axis tilt angles of the first and second alignment facets differ; and a greater radius of curvature of the reflection surface is infinite.

10. The facet mirror of claim 9, wherein both radii of curvature of the reflection surface are finite.

11. The facet mirror of claim 1, wherein: the alignment facets comprise first and second alignment facets; the reflection surface of first and second alignment facets comprise surface shapes exhibiting different curvatures along two axes of curvature; the axis tilt angles of the first and second alignment facets differ; and both radii of curvature of the reflection surface are finite.

12. The facet mirror of claim 1, wherein a difference between the radii of curvature is between 20 mm and 60 mm.

13. The facet mirror of claim 1, wherein the radii of curvature are between 200 mm and 2000 mm.

14. An illumination optical unit, comprising: a facet mirror according to claim 1, wherein the illumination optical unit is configured to illuminate an object field with illumination light.

15. An illumination system, comprising: a light source; and an illumination optical unit comprising a facet mirror according to claim 1, wherein the illumination optical unit is configured to illuminate an object field with illumination light generated by the light source.

16. An optical system, comprising: an illumination optical unit comprising a facet mirror according to claim 1; and a projection optical unit, wherein the illumination optical unit is configured to illuminate an object field with illumination light, and the projection optical unit is configured to image the object field into an image field.

17. An apparatus, comprising: a light source; an illumination optical unit comprising a facet mirror according to claim 1; and a projection optical unit, wherein the illumination optical unit is configured to illuminate an object field with illumination light generated by the light source, the projection optical unit is configured to image the object field into an image field, and apparatus is a projection exposure apparatus.

18. The apparatus of claim 17, further comprising: an object holder comprising an object displacement drive configured to displace an object in the object field along an object displacement direction; and a wafer holder comprising a wafer displacement drive configured to displace a wafer in synchronization with the object displacement drive.

19. A method of using a projection exposure apparatus comprising an illumination optical unit and a projection optical unit, the method comprising: using the illumination optical unit to illuminate a lithography mask; and using the projection optical unit to project at least a portion of the illuminated lithography mask onto a light-sensitive material, wherein the illumination optical unit comprises a facet mirror according to claim 1.

20. A method of aligning a facet of a facet mirror, the facet mirror comprising a plurality of facets configured to reflect EUV illumination light, at least some of the facets being alignment facets which comprise a reflection surface with an edge contour aligned along two alignment coordinates of an overall facet arrangement, the reflection surface of a first alignment facet having a surface shape that exhibits different curvatures along two axes of curvature, the method comprising: aligning the two axes of curvature of the reflection surface of the first alignment facets by tilting the two axes of curvature about a finite axis tilt angle with respect to the alignment coordinates of the overall facet arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the disclosure will be described in more detail below with reference to the drawing, in which:

(2) FIG. 1 schematically illustrates a meridional section through a projection exposure apparatus for EUV projection lithography;

(3) FIGS. 2 and 3 illustrate arrangement variants of field facet mirrors, which can be configured with monolithic field facets, but can also have field facets that are in each case composed of a plurality of individual mirrors;

(4) FIG. 4 schematically illustrates a plan view of a pupil facet mirror, which, together with the field facet mirror, is part of an illumination optical unit of the projection exposure apparatus;

(5) FIG. 5 illustrates a variant of a pupil facet, which can be used in the pupil facet mirror in accordance with FIG. 4, wherein shown on the pupil facet is an edge contour of an illumination-light partial beam which impinges on the pupil facet via exactly one of the field facets and a specified illumination channel, wherein, in addition to the edge contour of the illumination-light partial beam, a field-dependent centroid profile of illumination-light subbeams is also illustrated which originate from different points on the respective field facet during the imaging of the light source;

(6) FIG. 6 shows a plan view of two adjacent field facets within a field facet arrangement in accordance with FIG. 3;

(7) FIG. 7 shows a section through one of the two field facets in accordance with FIG. 6 along the line VII-VII in FIG. 6;

(8) FIG. 8 shows a section through the field facet along the line VIII-VIII in FIG. 6;

(9) FIG. 9 shows an illustration that is similar to FIG. 5 of a further variant of a pupil facet, wherein the field-dependent centroid profile of the illumination-light subbeams, which originate from different points on the field facet, during the imaging of the light source is shown for an illumination channel which is guided over the same pupil facet, wherein the imaging is effected on the one hand using a conventional field facet and, on the other, with a tilted field facet reflection surface that has a toric design in accordance with the disclosure; and

(10) FIG. 10 shows, in an illustration that is similar to FIG. 9, the field-dependent centroid profiles of the illumination-light subbeams, which originate from different points on the field facet, for an illumination channel that is guided over a further pupil facet, wherein the imaging is again effected on the one hand with a conventional field facet and, on the other, with a tilted field facet reflection surface that has a toric design in accordance with the disclosure.

DETAILED DESCRIPTION

(11) FIG. 1 schematically shows a meridional section of a microlithographic projection exposure apparatus 1. Part of the projection exposure apparatus 1 is a light or radiation source 2. An illumination system 3 of the projection exposure apparatus 1 has an illumination optical unit 4 for exposing an illumination field in an object plane 6 that coincides with an object field 5. The illumination field can also be larger than the object field 5. In this case, an object in the form of a reticle 7, which is arranged in the object field 5 and held by an object or reticle holder 8, is exposed. The reticle 7 is also referred to as a lithography mask. The object holder 8 is displaceable along an object displacement direction by way of an object displacement drive 9. A projection optical unit 10, which is illustrated highly schematically, serves for imaging the object field 5 into an image field 11 in an image plane 12. A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 that is arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable parallel to the object displacement direction in synchronization with the object holder 8 by way of a wafer displacement drive 15.

(12) The radiation source 2 is an EUV radiation source with an emitted used radiation in the range between 5 nm and 30 nm. This radiation source can be a plasma source, for example a GDPP source (gas-discharge-produced plasma) or an LPP source (laser-produced plasma). A radiation source based on a synchrotron or on a free electron laser (FEL) is also usable as the radiation source 2. A person skilled in the art can find information relating to such a radiation source in U.S. Pat. No. 6,859,515 B2, for example. EUV radiation 16, emerging from the radiation source 2, in particular the used illumination light that illuminates the object field 5, is focused by a collector 17. A corresponding collector is known from EP 1 225 481 A. Downstream of the collector 17, the EUV radiation 16 propagates through an intermediate focal plane 18 before being incident on a field facet mirror 19.

(13) The field facet mirror 19 is a first facet mirror of the illumination optical unit 4. The field facet mirror 19 has a plurality of reflective field facets, which are not shown in FIG. 1. The field facet mirror 19 is arranged in a field plane of the illumination optical unit 4 which is optically conjugate to the object plane 6.

(14) The EUV radiation 16 will also be referred to below as illumination light or as imaging light.

(15) Downstream of the field facet mirror 19, the EUV radiation 16 is reflected by a pupil facet mirror 20. The pupil facet mirror 20 is a second facet mirror of the illumination optical unit 4. The pupil facet mirror 20 is arranged in a pupil plane of the illumination optical unit 4 which is optically conjugate to the intermediate focal plane 18 and to a pupil plane of the illumination optical unit 4 and of the projection optical unit 10 or coincides with this pupil plane. The pupil facet mirror 20 has a plurality of reflective pupil facets, which are not shown in FIG. 1. The pupil facets of the pupil facet mirror 20 and of a subsequent imaging optical assembly in the form of a transfer optical unit 21 having mirrors 22, 23 and 24, which are designated in the order of the beam path, are used to image the field facets of the field facet mirror 19 into the object field 5 such that they overlay one another. The last mirror 24 of the transfer optical unit 21 is a grazing incidence mirror. Depending on the configuration of the illumination optical unit 4, it is also possible to dispense with the transfer optical unit 21 entirely or in part.

(16) Illumination light 16, which is guided for example in the object plane 6 toward greater absolute x-values than the x-dimension of the object field 5, can be guided, using a corresponding optical unit (not illustrated), to a plurality of energy or dose sensors, one dose sensor 24a of which is schematically illustrated in FIG. 1. The dose sensor 24a is in signal connection with a central control device 24b in a manner that is not illustrated. The dose sensor 24a generates an input signal for controlling the light source 2 and/or the object displacement drive 9 and/or the wafer displacement drive 15. It is hereby possible to achieve dose adaptation of an exposure of the wafer 13 in the image field 11 first by adapting an output of the light source 2 and/or secondly by adapting a scanning speed.

(17) The control device 24b is in signal connection with tilt actuators for the field facets 25 of the field facet mirror 19, among others.

(18) To facilitate the description of positional relationships, a Cartesian xyz coordinate system is shown in FIG. 1 in the form of a global coordinate system for describing the positional relationships of components of the projection exposure apparatus 1 between the object plane 6 and the image plane 12. The x-axis in FIG. 1 extends perpendicular with respect to and into the drawing plane. The y-axis in FIG. 1 extends to the right and parallel with respect to the displacement direction of the object holder 8 and of the wafer holder 14. The z-axis in FIG. 1 extends downward, i.e. perpendicular to the object plane 6 and to the image plane 12.

(19) The x-dimension over the object field 5 or the image field 11 is also referred to as the field height. The object displacement direction extends parallel with respect to the y-axis.

(20) Local Cartesian xyz coordinate systems are shown in the other figures. The x-axes of the local coordinate systems extend parallel with respect to the x-axis of the global coordinate system in accordance with FIG. 1. The xy-planes of the local coordinate systems represent arrangement planes of the components which are respectively illustrated in the figure. The y- and z-axes of the local coordinate systems are correspondingly tilted by a specific angle about the respective x-axis.

(21) FIGS. 2 and 3 show examples of different facet arrangements for the field facet mirror 19. Each of the field facets 25 illustrated there can be constructed as an individual-mirror group from a plurality of individual mirrors, as is known for example from WO 2009/100 856 A1. Each of the individual-mirror groups then has the function of a facet of a field facet mirror, as is disclosed for example in U.S. Pat. No. 6,438,199 B1 or U.S. Pat. No. 6,658,084 B2.

(22) The field facets 25 can be configured to be tiltable between a plurality of tilt positions by way of an actuator.

(23) The field facet mirror 19 in accordance with FIG. 2 has a multiplicity of field facets 25 of curved configuration. These are arranged group-wise in field facet blocks 26 on a field facet carrier 27. Overall, the field facet mirror 19 in accordance with FIG. 2 has twenty-six field facet blocks 26, which are formed by grouping together 3, 5 or 10 of the field facets 25.

(24) Intermediate spaces 28 are located between the field facet blocks 26.

(25) The field facet mirror 19 in accordance with FIG. 3 has rectangular field facets 25, which in turn are arranged group-wise in field facet blocks 26, between which intermediate spaces 28 are located.

(26) FIG. 4 schematically shows a plan view of the pupil facet mirror 20. Pupil facets 29 of the pupil facet mirror 20 are arranged in the region of an illumination pupil of the illumination optical unit 4. The number of the pupil facets 29 in reality is greater than illustrated in FIG. 4. The number of the pupil facets 29 can in reality be greater than the number of the field facets 25 and can be many times the number of the field facets 25. The pupil facets 29 are arranged on a pupil facet carrier of the pupil facet mirror 20. A distribution of pupil facets 29, on which the illumination light 16 impinges by way of the field facets 25, within the illumination pupil specifies an actual illumination angle distribution in the object field 5.

(27) Each of the field facets 25 serves for transferring a portion of the illumination light 16, i.e. of an illumination-light partial beam 16.sub.i, from the light source 2 to one of the pupil facets 29.

(28) The description of illumination-light partial beams 16.sub.i below is based on the assumption that the associated field facet 25 is in each case lit in maximum fashion, i.e. over its entire reflection surface. In this case, an edge contour of the illumination-light partial beam 16.sub.i coincides with an edge contour of the illumination channel, which is why the illumination channels will also be designated 16.sub.i below. The respective illumination channel 16.sub.i represents one possible optical path of an illumination-light partial beam 16.sub.i, which lights the associated field facet 25 in maximum fashion, over the further components of the illumination optical unit 4.

(29) The transfer optical unit 21 has in each case one of the pupil facets 29 for each of the illumination channels 16.sub.i for transferring the illumination-light partial beam 16.sub.i from the field facet 25 to the object field 5.

(30) In each case one illumination-light partial beam 16.sub.i, of which FIG. 1 schematically illustrates two illumination-light partial beams 16.sub.i (i=1, . . . , N; N: number of the field facets), is guided between the light source 2 and the object field 5 via exactly one of the field facets 25 and via exactly one of the pupil facets 29 via in each case one illumination channel.

(31) FIG. 5 shows one of the pupil facets 29 that can be used in the pupil facet mirror 20. The pupil facet 29 in accordance with FIG. 5 does not have a circular edge contour, as illustrated in FIG. 4, but an approximately square edge contour with rounded corners. Such an edge contour, which can also be square or rectangular without rounded corners, makes it possible for the pupil facet carrier 30 to be populated relatively densely with the pupil facets 29.

(32) The illumination-light partial beam 16.sub.i impinges on the pupil facet 29 in accordance with FIG. 5 by way of an arch-shaped field facet 25 of the field facet mirror 19 in accordance with FIG. 2.

(33) In the arrangement illustrated in FIG. 5, an entire cross section of the illumination-light partial beam 16.sub.i is located on the pupil facet 29, with the result that the illumination-light partial beam 16.sub.i is not cut off at the edges by the edge of the pupil facet 29. An edge contour of the cross section of the illumination-light partial beam 16.sub.i on the pupil facet 29 has an approximately arch-shaped, bean-shaped or kidney-shaped form and can be understood as a convolution of the arch-shaped field facets 25 in accordance with FIG. 2 with a round source area of the light source 2. This convolution is produced owing to the fact that an image of the light source 2 is formed for different sections on the associated field facet 25, i.e. in a field-dependent manner, at different image sites and in addition generally at an image site that is located along the illumination channel 16.sub.i spaced apart from the pupil facet 29, i.e. upstream or downstream of the pupil facet 29 in the beam path.

(34) The arch-shaped edge contour of the illumination-light partial beam 16.sub.i on the pupil facet 29 represents a light spot of the illumination-light partial beam 16.sub.i.

(35) The dashes in the edge contour of the illumination-light partial beam 16.sub.i on the pupil facet 29 show three subbeams 16.sub.i.sup.1, 16.sub.i.sup.2 and 16.sub.i.sup.3. The illumination-light partial beam 16.sub.i is made up of a multiplicity of such subbeams 16.sub.i.sup.j. The illumination-light partial beam 16.sub.i on the respective pupil facet 29 can, if the optical parameters of the illumination are known, be calculated, for example by way of an optical design program, and is in this context also referred to as a point spread function.

(36) The illumination light 16 of these subbeams 16.sub.i.sup.1 to 16.sub.i.sup.3 originates from a left-hand edge point 25.sup.1, from a central point 25.sup.2 and from a right-hand edge point 25.sup.3 of the associated field facet 25. By way of example, FIG. 2 shows these points of origin 25.sup.1 to 25.sup.3 on one of the field facets 25.

(37) A field-dependent centroid profile 31.sub.i of all subbeams 16.sub.i.sup.j originating from the associated field facet 25 represents a core of an edge contour of the respective illumination-light partial beam 16.sub.i on each pupil facet 29. This centroid profile 31.sub.i is distinct for each illumination channel 16.sub.i and depends, among others, on the geometric profile of the illumination channel 16.sub.i between the light source 2 and the respective pupil facet 29 via the associated field facet 25.

(38) FIG. 5 here shows an idealized field-dependent centroid profile 31.sub.i.

(39) To influence an extent of an edge contour of the illumination-light partial beam 13.sub.i or an xy-extent of the respective field-dependent centroid profile 31.sub.i, reflection surfaces 32 of the field facets 25 are in the form of toric surfaces. This will be explained below with reference to FIGS. 6 to 8 using the example of rectangular field facets 25 in the manner of those in FIG. 3.

(40) A rectangular edge contour 33 of the field facets 25 is aligned along two alignment coordinates x and y of an overall facet arrangement that is illustrated by way of example in FIG. 3. The x-coordinate of this aligned edge contour 33 thus coincides with the x-coordinate of the overall facet arrangement. Similar is true for the y-coordinate.

(41) The facets to which this alignment applies will also be referred to below as alignment facets 25. The axes of curvature x, y of the toric reflection surfaces of the alignment facets 25 are in each case tilted with respect to the alignment coordinates x, y of the overall facet arrangement by a finite axis tilt angle.

(42) The axis of curvature x is here tilted relative to the alignment coordinate x about the alignment coordinate z by an axis tilt angle . The axis of curvature y is in turn tilted relative to the alignment coordinate y about the alignment coordinate z by the axis tilt angle . Since the coordinates of the axes of curvature x, y and the alignment coordinates xyz are Cartesian coordinates, the two angles and are in this case the same size.

(43) The axis of curvature x defines a curvature of the toric reflection surface 32 of the field facet 25 in the yz-plane (cf. FIG. 7). A radius of curvature of the reflection surface 32 in this yz-plane is designated R.sub.x.

(44) Accordingly, the axis of curvature y defines a curvature of the reflection surface 32 in the xz-plane. A radius of curvature of the reflection surface 32 in the xz-plane is designated R.sub.y.

(45) FIGS. 6 and 7 show the radii of curvature R.sub.x, R.sub.y in a highly schematic fashion. Other curvature conditions are also possible. Both R.sub.x and R.sub.y lie in the range between 200 mm and 2000 mm, for example in the range between 500 mm and 1500 mm, in the range between 800 mm and 1200 mm and in particular in the range of 1000 mm. The following always applies: R.sub.xR.sub.y. An eccentricity R=R.sub.xR.sub.y lies in the range between 10 mm and 200 mm, for example in the range between 15 mm and 100 mm, between 20 mm and 60 mm and in particular in the range around 40 mm. For R/R.sub.y, a percent range between 0.5% and 10%, in particular between 1% and 8%, between 2% and 6%, for example in the range around 4%, applies.

(46) It is also true that the smaller of the two radii of curvature R.sub.x, R.sub.y of the toric reflection surface 32 is finite. The other of the two radii of curvature R.sub.y, R.sub.x can be infinite, which results in a cylindrical reflection surface 32, or can be finite, which results in a toric reflection surface 32 having a reflection surface that is curved via two axes of curvature.

(47) A cylindrical surface or cylinder surface represents a special case of a toric surface and is likewise a toric surface within the meaning of this application.

(48) An effect of a toric reflection surface design of the alignment field facets 25 will be explained below with reference to FIGS. 9 and 10.

(49) FIGS. 9 and 10 show a further variant of a pupil facet 29, which is configured as a pupil facet having a hexagonal edge.

(50) FIG. 9 shows, on the reflection surface of the illustrated pupil facet 29, the field-dependent centroid profile 31.sub.i, 31.sub.i of the light source imaging for an illumination channel 16.sub.i. These two field-dependent centroid profiles 31.sub.i, 31.sub.i are present on the same pupil facet 29 and come about due to the imaging effect firstly of a conventional, non-tilted alignment field facet 25 (centroid profile 31.sub.i) and secondly due to an alignment field facet 25 (centroid profile 31.sub.i) that is tilted in accordance with the disclosure. These two centroid profiles 31.sub.i, 31.sub.i are shown in FIG. 9 as a schematic overlay, which comes about due to the effect both of the conventional alignment field facet 25 and the alignment field facet 25 that is tilted in accordance with the disclosure.

(51) On the basis of the imaging by way of the conventional alignment field facet 25, a centroid profile 31.sub.i with a maximum distance R.sub.i from a center Z of the reflection surface of the pupil facet mirror 29 is obtained. This distance value R.sub.i is described in FIG. 9 as the radius of a circumcircle around the center Z, into which the centroid profile 31.sub.i is inscribed. The imaging effect of the tilted alignment field facet 25 results in a field-dependent centroid profile 31.sub.i, which is tilted about the center Z of the pupil facet 29 and compressed at the same time. On the basis of the changed effect of the alignment field facet 25 which arises from the tilting, the centroid profile 31.sub.i with a smaller maximum distance R.sub.2 from the center Z of the reflection surface of the pupil facet mirror 29 is obtained. The above-mentioned compression of the centroid profile 31.sub.i as compared to the conventional centroid profile 31.sub.i has the effect that the maximum distance R.sub.2 of the field-dependent centroid profile 31.sub.i is reduced by approximately 25% as compared to the distance R.sub.1. As a result, firstly R.sub.2<R.sub.1, and secondly approximately: R.sub.2=0.75R.sub.1.

(52) FIG. 10 shows field-dependent centroid profiles 31.sub.j, 31.sub.j of an illumination-light beam of a further illumination channel 16.sub.j when imaging firstly by way of a conventional and tilted field facet 25 and secondly by way of an alignment field facet 25 having a toric reflection surface 32 that is tilted about the axis tilt angles , . The results are field-dependent centroid profiles 31.sub.j. The centroid profile associated with the conventional field facet 25 is designated 31.sub.j. The centroid profile 31.sub.j associated with the tilted alignment facet 25 is likewise tilted about the center Z of the associated pupil facet 29 and compressed at the same time.

(53) The effect of the compression even in the case of the illumination channel 16.sub.j in accordance with FIG. 10 is that a maximum distance R.sub.2 of the field-dependent centroid profile 31.sub.j from the center Z of the associated pupil facet 29 is reduced as compared to the distance R.sub.1. Again, R.sub.2<R.sub.1. Once again, approximately: R.sub.2=0.75R.sub.1.

(54) The tilt angles , in the centroid profiles illustrated in FIGS. 9 and 10 are in each case 6 degrees.

(55) In particular the compression of the centroid profiles 31.sub.i, 31.sub.j, as compared to the illumination-light partial beams guided using the conventional field facets, results in a constriction of the illumination-light partial beams 16.sub.i, 16.sub.j on the pupil facets 29, with the result that complete reflection of the partial beams 16.sub.i, 16.sub.j at the associated pupil facets 29 is facilitated without undesired light losses. Drifts of the partial beams 16.sub.i, 16.sub.j on the pupil facets 29 can be more easily tolerated. The compression of the centroid profiles 31.sub.i, 31.sub.j additionally has the result that a possible cutting-off behavior of illumination-light subbeams 16.sub.i.sup.n becomes less field-dependent and such a dependence is reduced also at the field edge and in particular beyond the field edges at the site of the arrangement of possible energy or dose sensors. Subsequent adjustment of the light source 2 as a reaction to measured intensity changes is thus simplified.

(56) When designing the field facet mirror 19 with the alignment facets, the tilt angles , of all alignment facets 25 are identical.

(57) In an alternative configuration, which is illustrated schematically in FIG. 6, the alignment tilt angles (and ) on the one hand and (and correspondingly ) on the other hand differ from one another. In the configuration in accordance with FIG. 6, , that is to say the angle between the guide axis x of the field facet 25 that is on the left in FIG. 6 and the alignment coordinate x, is greater than the angle between the axis of curvature x of the field facet 25 that is on the right in FIG. 6 and the alignment coordinate x.

(58) In the projection exposure using the projection exposure apparatus 1, at least part of the reticle 7 in the object field 5 is imaged onto a region of the light-sensitive layer on the wafer 13 in the image field 11 for lithographically producing a microstructured or nanostructured component, in particular a semiconductor component, for example a microchip. Here, the reticle 7 and the wafer 13 are continuously moved in the y-direction in time-synchronized fashion during the scanning operation.