DE102024201763A1 - Method for measuring an actual orientation of a reflection surface of an actuator-tiltable individual mirror and measuring device for carrying out the method - Google Patents

Abstract

To measure an actual orientation of a reflection surface of an actuator-tiltable useful individual mirror (18 _i ) of an individual mirror group of a facet mirror device, a deformation behavior of an individual mirror holder (35) on which the individual mirrors (18 _i ) of the individual mirror group are mounted is determined. One of the individual mirrors of the individual mirror group is specified as the individual measuring mirror (43). Measuring light (50) is guided from a measuring light source (51) across a measuring reflection surface of the individual measuring mirror (43) to a spatially resolving sensor (49) for measuring an actual orientation of the reflection surface of the individual measuring mirror (43). The actual orientation of the reflection surface of the individual useful mirror (18 _i ) to be measured is determined from the measured actual orientation of the reflection surface of the individual measuring mirror (43) and the determined deformation behavior of the individual mirror holder (35). This method is part of a correction method of the actual orientation of the reflection surface of the actuatable individual useful mirror (18 _i ). A measuring device (48) having at least one individual measuring mirror (43) and at least one spatially resolving sensor (49) is used to carry out the method. The measuring method can be used to specify and correct a reflection surface orientation of actuator-tiltable individual useful mirrors, which can be used in facet mirror devices of corresponding lithographic projection exposure systems, with sufficient precision.

Description

The invention relates to a method for measuring an actual orientation of a reflection surface of an actuator-tiltable individual useful mirror of an individual mirror group of a facet mirror device. The invention further relates to a method for correcting such an actual orientation, a measuring device for carrying out such a method, a correction device for carrying out such a method, an optical assembly with such a measuring device or with such a correction device, an illumination optics with such an optical assembly, an optical system with such an illumination optics, a projection exposure system with such an optical system, a manufacturing method for a micro- or nanostructured component using such a projection exposure system and a micro- or nanostructured component manufactured using this method.

The DE 10 2017 204 104 A1 discloses an EUV collector for use in an EUV projection exposure system. The DE 10 2017 212 622 A1 discloses a measuring device for determining a spatial position of an illumination light beam path of an EUV projection exposure system. The DE 10 2012 218 155 A1 discloses a device for coupling illumination radiation into an illumination optics. The US 8,958,053 B2 discloses a projection exposure apparatus and an alignment method. The US 2011/0122389 A1 discloses a light source, a projection exposure system and a method for producing a component.

It is an object of the present invention to provide a reflection surface orientation of actuator-tiltable individual mirrors, which can be used in facet mirror devices of corresponding lithographic projection exposure systems, with sufficient precision.

This object is achieved according to the invention by a measuring method having the features specified in claim 1.

The facet mirror device can be a facet mirror device of an illumination optics of a lithographic projection exposure system.

When used within such a facet mirror device, the individual useful mirror to be measured directs illumination light towards an object field.

The useful individual mirror can be a field facet and/or a pupil facet. Examples of this are given in the DE 10 2009 030 501 A1 The useful individual mirror can be an individual mirror, in particular designed as a micromirror, wherein several such individual mirrors can be assigned to one another to form a useful individual mirror group, e.g. in the form of a field facet and/or a pupil facet. An illumination optics that uses such individual mirrors can use at least one MEMS facet mirror device.

• - Durch eine Kalibrierungsmessung, bei der einer jeweiligen Ist-Orientierung der Reflexionsfläche des Mess-Einzelspiegels eine Ist-Orientierung der Reflexionsfläche des zu vermessenden Nutz-Einzelspiegels zugeordnet wird;
• - Eine Simulation eines Deformationsverhaltens der Einzelspiegel-Halterung;
• - Eine Berechnung eines Deformationsverhaltens der Einzelspiegel-Halterung, beispielsweise in Form einer Biegebalken-Deformation, insbesondere durch Einsatz numerischer Verfahren wie beispielsweise Finite Elemente.

The deformation behavior of the single mirror holder can be determined using measuring methods using at least one of the following variants:

• - By means of a calibration measurement in which an actual orientation of the reflection surface of the individual measuring mirror is assigned to an actual orientation of the reflection surface of the individual useful mirror to be measured;
• - A simulation of the deformation behavior of the single mirror mount;
• - A calculation of a deformation behavior of the single mirror holder, for example in the form of a bending beam deformation, in particular by using numerical methods such as finite elements.

As part of the measurement procedure, exactly one individual mirror from the individual mirror group can be specified as the individual measuring mirror. Alternatively, a majority of the individual mirrors from the individual mirror group can be specified as the individual measuring mirrors, for example two or three individual mirrors.

An orientation measurement according to the specified method enables the monitoring of a tilt or deformation of the individual mirrors of the individual mirror group attached to the individual mirror holder.

The respective actual orientation of the reflection surface of the measured individual useful mirror can result from actuator forces, for example from an individual mirror actuator, or from temperature changes of components of the facet mirror device. The cause of this can be, for example, a thermal imbalance between individual useful mirrors that are exposed to illumination light and individual mirrors that are not exposed to the illumination light. Such a thermal imbalance can in turn be the cause of thermal deformation of the individual mirror holder.

The orientation measurement of several useful individual mirrors of the individual mirror group according to claim 2 leads to a particularly meaningful measurement result. These several useful individual mirror orientations can be measured sequentially and/or in parallel. In particular, all useful individual mirrors of the individual mirror group can be measured with regard to their actual orientation.

A temperature detection according to claim 3 makes it possible to thermally calibrate the measuring method with regard to the temperature of the respective component being measured. This can be used as part of a temperature-dependent correction or compensation of corresponding actual orientations of the individual useful mirrors.

A correction method according to claim 4 uses the result of the measuring method to improve the precision of a specification of an illumination light guide over the respective individual useful mirror. In particular, an illumination setting, i.e. an illumination angle distribution and/or illumination intensity distribution of the illumination light over the object field, can then be precisely specified. The correction method can be used to control the actual orientation of the reflection surface of the at least one individual useful mirror and in particular of all individual useful mirrors of the respective individual mirror group.

A correction method with a basic adjustment according to claim 5 produces well reproducible starting conditions, in particular for the correction method. The measuring method and/or the correction method can be carried out as part of such a basic adjustment. The specified reference force that the individual mirror actuator exerts on the useful individual mirrors can be a minimum force. Such a minimum force can be determined as part of a calibration measurement.

Alternatively, the reference force can be a specified fraction of a maximum force that the individual mirror actuator can exert on the individual mirrors, for example half the maximum force. The maximum force can be determined as part of a calibration measurement.

A measuring device according to claim 6 has the advantages that have already been explained above with reference to the measuring method on the one hand and the correction method on the other. With the help of the spatially resolving sensor, an actual orientation of the individual measuring mirror can be measured with high precision. The spatially resolving sensor can be an array of sensor pixels. The spatially resolving sensor can be designed as a CMOS array, a CCD array or even a PSD (position sensitive device) detector. A measuring light source for generating measuring light that is detected with the spatially resolving sensor of the measuring device can be a useful light source of the projection exposure system, of which the useful individual mirror is a component. Alternatively, the measuring device can also have a separate measuring light source. As a rule, the facet mirror device has several individual mirror groups. In one variant, the facet mirror device can have exactly one individual mirror group.

In a further embodiment of the measuring device, an individual measuring mirror of the measuring device can also be assigned to several individual mirror groups, in particular those that are operatively connected to one another.

The advantages of a correction device according to claim 7 correspond to those already explained above in connection with the correction method.

The advantages of an optical assembly according to claim 8, an illumination optics according to claim 9, an optical system according to claims 10 or 11, a projection exposure system according to claim 12, a manufacturing method according to claim 13 and a micro- or nanostructured component according to claim 14 correspond to those already explained above with reference to the measuring method, the correction method and the measuring device. In particular, a highly integrated semiconductor component can be manufactured using the method, for example a microchip, in particular a memory chip.

• 1 schematisch eine Projektionsbelichtungsanlage für die EUV-Mikrolithographie, wobei eine Beleuchtungsoptik geschnitten und eine Projektionsoptik stark schematisch gezeigt ist;
• 2 eine Aufsicht auf einen Feldfacettenspiegel der Beleuchtungsoptik nach 1;
• 3 und 4 Aufsichten auf weitere Ausführungen eines Feldfacettenspiegels der Beleuchtungsoptik nach 1;
• 5 perspektivisch eine Ansicht einer weiteren Ausführung der Beleuchtungsoptik der Projektionsbelichtungsanlage;
• 6 in einem schematischen Querschnitt ein Facettenmodul des Feldfacettenspiegels mit mehreren Facetten bzw. mehreren zu Facetten gruppierbaren Einzelspiegeln, angeordnet auf einem Spiegelträger des Feldfacettenspiegels, wobei das Facettenmodul und der Spiegelträger bei den vorstehend dargestellten Ausführungen des Feldfacettenspiegels zum Einsatz kommen können;
• 7 eine Aufsicht auf das Facettenmodul nach 6, gesehen aus Blickrichtung VII in 6;
• 8 im Vergleich zu 6 stärker schematisch das Facettenmodul in einer Seitenansicht, wobei eine Facettenhalterung des Facettenmoduls in verschiedenen, übertrieben dargestellten Durchbiegungs-Situationen gezeigt ist;
• 9 in einer zu 8 ähnlichen Darstellung das Facettenmodul einschließlich einer Messeinrichtung zur Durchführung eines Verfahrens zur Vermessung einer Ist-Orientierung einer Reflexionsfläche eines aktorisch verkippbaren Nutz-Einzelspiegels, also einer Feldfacette bei der Ausführung der Feldfacettenspiegel nach den 2 bis 4 oder eines Einzelspiegels bei der Ausführung des Feldfacettenspiegels nach 5;
• 10 in einem Diagramm kumulierte Aktorkräfte, die auf eine Aktorik zur Verkippung der Nutz-Einzelspiegel des Feldfacettenspiegels bei verschiedenen, mit der Beleuchtungsoptik einstellbaren Beleuchtungssettings einwirken; und
• 11 in einem zu 10 vergleichbaren Diagramm, gemessene Verkippungen der Reflexionsfläche eines Mess-Einzelspiegels der Messeinrichtung bei den Beleuchtungssettings nach 10.

Embodiments of the invention are explained in more detail below with reference to the drawing, in which:

• 1 schematically shows a projection exposure system for EUV microlithography, with an illumination optics sectioned and a projection optics shown highly schematically;
• 2 a top view of a field facet mirror of the illumination optics according to 1 ;
• 3 and 4 Top views of further versions of a field facet mirror of the illumination optics according to 1 ;
• 5 a perspective view of another embodiment of the illumination optics of the projection exposure system;
• 6 in a schematic cross-section a facet module of the field facet mirror with several facets or several individual mirrors that can be grouped into facets, arranged on a mirror carrier of the field facet mirror, wherein the facet module and the mirror carrier can be used in the above-described designs of the field facet mirror;
• 7 a top view of the facet module after 6 , seen from direction VII in 6 ;
• 8 compared to 6 more schematically, the facet module in a side view, showing a facet holder of the facet module in various, exaggerated deflection situations;
• 9 in a 8 similar representation, the facet module including a measuring device for carrying out a method for measuring an actual orientation of a reflection surface of an actuator-tiltable individual useful mirror, i.e. a field facet when designing the field facet mirror according to the 2 to 4 or a single mirror when designing the field facet mirror according to 5 ;
• 10 in a diagram cumulative actuator forces acting on an actuator for tilting the useful individual mirrors of the field facet mirror in different lighting settings adjustable with the illumination optics; and
• 11 in one 10 comparable diagram, measured tilts of the reflection surface of a single measuring mirror of the measuring device in the lighting settings according to 10 .

1 shows a schematic of a projection exposure system 1 for EUV microlithography. An EUV radiation source serves as the light source 2. This can be an LPP (laser produced plasma) radiation source or a DPP (discharged produced plasma) radiation source. A synchrotron or a free-electron laser (FEL) can also be used as a possible light source. The light source 2 emits EUV useful radiation 3 with a wavelength in the range between 5 nm and 30 nm. The useful radiation 3 is also referred to below as illumination or imaging light.

The illumination light 3 emitted by the light source is first collected by a collector 4. Depending on the type of light source 2, this can be an ellipsoidal mirror or a nested collector. After the collector 4, the illumination light 3 passes through an intermediate focus in an intermediate focal plane 5 and then strikes a field facet mirror 6. Embodiments of the field facet mirror 6 are explained below. The illumination light 3 is reflected from the field facet mirror 6 to a pupil facet mirror 7. The illumination light beam is divided into a plurality of illumination channels via the facets of the field facet mirror 6 on the one hand and the pupil facet mirror 7 on the other, with each illumination channel being assigned exactly one facet pair with a field facet and a pupil facet. The respective field facet and/or the respective pupil facet of one of the illumination channels can in turn be constructed from a group of individual mirrors assigned to this facet, as will also be explained below.

A follow-up optics 8 arranged downstream of the pupil facet mirror 7 guides the illumination light 3, i.e. the light from all illumination channels, to an object field 9. The field facet mirror 6, the pupil facet mirror 7 and the follow-up optics 8 are components of an illumination optics 10 for illuminating an illumination field that coincides with the object field 9 and is therefore also referred to below as an object field. The object field 9 lies in an object plane 11 of a projection optics 12 of the projection exposure system 1 arranged downstream of the illumination optics 10. The shape of the object field 9 depends on the design of the illumination optics 10 on the one hand and the projection optics 12 on the other hand, which will be explained below.

For the entire projection exposure system 1 according to 1 A global Cartesian xyz coordinate system is used and in the 2 ff. a local Cartesian xyz coordinate system is used for individual components of the projection exposure system 1.

A structure arranged in the object field 9 on a reticle 12a, i.e. on a mask to be projected, is reduced by a reduction scale using the projection optics 12 and imaged onto an image field 13 in an image plane 14. The reticle 12a is carried by a reticle holder 12b.

The reduction scale for the projection optics is 12 4x. Other reduction scales, e.g. 5x, 6x, 8x or 10x, are also possible.

A wafer 13a is arranged at the location of the image field 13, onto which the structure of the reticle is transferred for producing a micro- or nanostructured component, for example a semiconductor chip. The wafer is carried by a wafer holder 13b. The reticle holder 12b can be displaced along the y-direction, which is also referred to as the object displacement direction, via a reticle displacement drive 12c. The wafer holder 13b can also be displaced along the y-direction in synchronization with the reticle displacement drive 12c. Depending on the design of the projection exposure system 1 as a scanner or stepper, this displacement can take place continuously and/or step by step.

The follow-up optics 8 between the pupil facet mirror 7 and the object field 9 has three further EUV mirrors 15, 16, 17. The last EUV mirror 17 in front of the object field 9 is designed as a grazing incidence mirror. In alternative designs of the illumination optics 10, the follow-up optics 8 can also have more or fewer mirrors or even be omitted entirely. In the latter case, the illumination light 3 is guided from the pupil facet mirror 7 directly to the object field 9.

To facilitate the representation of positional relationships, an xyz coordinate system is used below. In the 1 The x-direction runs perpendicular to the plane of the drawing into it. The y-direction runs in the 1 to the right and the z-direction runs in the 1 down. As far as in the 2 ff. a local Cartesian coordinate system is used, this spans the reflection surface of the component shown. The x-direction is then parallel to the x-direction in the 1 . An angular relationship of the y-direction of the individual reflection surface to the y-direction in the 1 depends on the orientation of the respective reflection surface.

2 shows the field facet mirror 6 in more detail. The field facet mirror 6 according to 2 has a field facet arrangement with curved field facets 18. These field facets 18 are arranged in a total of five columns S1, S2, S3, S4 and S5, which are 2 from left to right. In each of the five columns S1 to S5 there is a plurality of field facet groups 19, which are also referred to as field facet blocks or facet modules. The arrangement of the field facets 18 is determined by a mirror carrier in the form of a 2 The field facet arrangement is inscribed in the circular boundary of the carrier plate 20. A normal to the carrier plate 20 runs perpendicular to the xy plane. A boundary of a far field of the illumination light 3 coincides with this circular boundary. The arcuate field facets 18 of the field facet mirror 6 according to 2 all have the same area and the same ratio of width in the x-direction and height in the y-direction, i.e. they all have the same xy aspect ratio.

One of the facet modules 19 is in the 2 highlighted by a dashed line. Depending on the design of the field facet mirror 18, the facet modules 19 can each have the same number of field facets 18 or different numbers of field facets 18. A pupil facet of the pupil facet mirror 7 is assigned to the field facets 18 of the field facet mirror 6 via the respective illumination channel. Such a pupil facet can be designed as a monolithic facet or as a group of several individual mirrors.

3 shows a further embodiment of the field facet mirror 6, which instead of the field facet mirror 6 according to 2 can be used in the projection exposure system 1. Components and functions corresponding to those described above with reference to the 1 and 2 explained above bear the same reference numbers and will not be discussed in detail again.

The field facet mirror 6 after 3 has a total of four in columns S1, S2, S3, S4, which are in the 3 are numbered from left to right, arranged individual field facets 18. The two middle columns S2, S3 are separated from each other by a construction space 21, which runs in the y-direction and has a constant x-extension. The construction space 21 in turn corresponds to a far-field shading of the illumination light beam, which is structurally determined by a corresponding structure of the light source 2 and the collector 4. The four facet columns S1 to S4 each have a y-extension, which ensures that all four facet columns S1 to S4 lie within a circularly delimited far field 22 of the illumination light 3. The edge of the carrier plate 20 for the field facets 18 coincides with the edge of the far field 22.

The field facets 18 have a mutually congruent arc or partial ring shape with respect to a projection onto the xy plane, i.e. with respect to a main reflection plane of the field facet mirror 6, which corresponds to the shape with the field facet mirror according to 6 illuminable object field 9.

The object field 9 (see also 5 ) has an x/y aspect ratio of 13/1. The x/y aspect ratio of the field facets 18 can be greater than 13/1. Depending on the design, the x/y aspect ratio of the field facets 18 is, for example, 26/1 and is usually greater than 20/1.

Overall, the field facet mirror has 6 3 416 field facets 18. Alternative designs of such field facet mirrors 6, such as the field facet mirror 6 according to 2 , the number of field facets 18 can range from a few tens to, for example, a thousand.

The field facets 18 of the field facet mirror 6 according to 3 have an extension in the y-direction of approximately 3.4 mm. The extension of the field facets 18 in the y-direction is in particular greater than 2 mm. The extension of the field facets 18 in the x-direction varies, so that some of the field facets 18 have a larger and some of the field facets 18 of the field facet mirror 6 according to figure have a smaller x-extension. The field facets 18 of the field facet mirror 6 according to 3 Thus, in their projection onto an xy base plane of the field facet mirror, they differ in their size and, to the extent that individual field facet pairs can be converted into one another by rotation about an axis parallel to the z-axis, in their orientation.

The projection surfaces of the reflection surfaces of at least two of the field facets 18 onto the base plane of the field facet mirror 6, i.e. also the xy plane, differ due to their varying extension along the x-direction also in the arc angle that they sweep over. In other words, not all of the field facets 18 of the field facet mirror 6 have 3 the same azimuthal extension of their arc curvature.

The total of all 416 field facets 18 of the field facet mirror 6 according to 3 has a packing density of 73%. The packing density is defined as the sum of the area of all field facets 18 in relation to the total illuminated area on the carrier plate 20.

Along the columns Si, the arrangement of the field facets 18 of the field facet mirror 6 is 3 in turn divided into several facet modules 19, which in the 3 is not shown.

Designs of the field facet mirror 6 are also possible in which the projections of the reflection surfaces of at least two of the field facets 18 onto the xy base plane differ in their shape. For example, field facets 18 with different y-extensions can be used.

4 shows a further embodiment of a field facet mirror which can be used instead of the field facet mirror 6 in the illumination optics 10. Components and functions which correspond to those described above with reference to the 1 to 3 already explained, bear the same reference numbers and will not be discussed in detail again.

The field facet mirror 6 after 4 differs from the field facet mirror 6 according to the 2 and 3 in the shape and arrangement of the field facets 18. The field facets 18 are rectangular and each have the same x/y aspect ratio, which corresponds to the aspect ratio of the field facets 18 according to the 2 and 3 The field facets 18 according to 4 define a reflection surface of the field facet mirror 6 and are grouped into four columns S1, S2, S3 and S4. Within the columns S1 to S4, the field facets 18 are in turn divided into field facet modules 19 according to 2 Between the two middle facet columns S2, S3 and between centrally arranged facet rows, the facet arrangement of the field facet mirror 6 is 4 Intermediate spaces 23 in which no facets are arranged, since these areas of the far field of the light source 2 are shaded by holding spokes of a correspondingly shaped collector 4.

5 shows in a schematic and perspective arrangement a further embodiment of a field facet mirror 24 on the one hand and a pupil facet mirror 25 on the other hand. The field facet mirror 24 according to 5 can be used instead of the field facet mirrors explained above. Components and functions corresponding to those described above with reference to the 1 to 4 already explained, bear the same reference numbers and will not be discussed in detail again.

5 schematically illustrates a beam path of the illumination light 3 along an illumination channel 3 ₁ from an intermediate focus IF in the intermediate focus plane 5 to the object field 9. A field facet 26 ₁ of the field facet mirror 24 and a pupil facet 27 ₁ of the pupil facet mirror 25 are assigned to this illumination channel 3 _1. The field facet 26 ₁ is made up of a group of 18 individual mirrors ES with an overall arc-shaped envelope similar to the object field 9. The grouping of the individual mirrors ES in the field facet 26 ₁ can be carried out depending on an illumination angle distribution for the object field 9 that can be set via the illumination optics with the facet mirrors 24, 25, i.e. depending on an illumination setting of the illumination optics 10.

Via the actuator-adjustable tilt angles of the individual mirrors ES, four individual mirrors ES of the pupil facet mirror 25 are assigned to the field facet 26 ₁ via the illumination channel 3 ₁ , which form the pupil facet 27 ₁ of the pupil facet mirror 25 in the form of a 2 x 2 array. Via a corresponding actuator-based tilt setting, which in turn is dependent on the illumination setting, the individual mirrors ES of this pupil facet 27 ₁ are specified such that the object field 9 is illuminated via the illumination channel 3 ₁ .

Accordingly highlighted in the 5 on the field facet mirror 24 another facet 26 ₂ and another facet 27 ₂ , which a corresponding, further illumination channel 3 _2. By superimposing the illumination channels 3 _i on the object field 9, an illumination angle distribution and illumination intensity distribution on the object field 9 is created which is dependent on the respective individual mirror grouping to the field facets 26 _i and the pupil facets 27 _i , i.e. the respective illumination setting. This illumination setting can be specified in such a way that the same illumination angle distribution is present on the object field 9 regardless of the field. Alternatively, a field-dependent illumination setting can also be specified in which different illumination angle distributions are present defined across the object field. A specified illumination intensity distribution across the object field 9 can also be specified by appropriately assigning the field facets 26 _i to the pupil facets 27 _i via corresponding illumination channels 3 _i .

The two facet mirrors 24 and 25 can be constructed in the same way, in particular in the manner of MEMS mirrors, and each have a plurality of individual mirrors ES. These individual mirrors ES are in turn grouped into modules which, in terms of their basic structure, correspond to the facet modules 19 of the above-explained versions of the field facet mirror 6. In the following description of such a module, a module having a plurality of field facets is described; however, such a module can also have a plurality of individual mirrors ES or a plurality of monolithic pupil facets of a corresponding pupil facet mirror.

6 shows a schematic design of the facet module 19 in a cross-sectional view. The facet module 19 is supported by the mirror carrier 20 via a corresponding bearing with bearing points 31, 32. The mirror carrier 20 carries a plurality of such facet modules 19, as already explained above. Since the facet modules 19 are constructed in the same way, it is sufficient to describe one of these facet modules 19 below.

The facet module 19 has an actuator module 33 for the actuator tilting of the individual mirrors of the facet module 19, which, according to the above statements, can be monolithic field facets in the type of field facets 18, monolithic pupil facets or also individual mirrors ES.

The following description refers to the variants in which the individual mirrors are field facets 18. In the same way, an actuator tilting of monolithic pupil facets or also of individual mirrors can take place. These monolithic field facets, monolithic pupil facets and individual mirrors are referred to collectively below as the useful individual mirrors of the respective facet mirror device.

Shown in the 6 three actuator-tiltable field facets 18 ₁ , 18 ₂ and 18 ₃ . These are each held on a single mirror holder 35 of the actuator module 33 via a joint connection 34 _i .

The individual mirror holder 35 is designed as a holding plate with a passage opening at the location of the articulated connection 34 _i . The individual mirror holder 35 is mounted on a housing 38 of the actuator module 33 via bearing points 36, 37.

A base body of the respective field facet 18 _i is firmly connected to an actuator permanent magnet 40 _i via a respective facet or mirror pin 39 _i . The respective field facet 18 _i is also connected to the joint connection 34 _i via the facet pin 39 _i .

The actuator permanent magnets 40 _i are assigned to respective actuator electromagnets 41 _i , which are housed in the housing 38 of the actuator module 33.

By controlling and appropriately energizing the actuator electromagnets 41 _i, the actuator permanent magnets 40 _i of the respective field facets 18 _i can be deflected independently of each other, as shown in the 6 indicated by a double arrow 42 for the field facet 18 _1. A tilting of the field facet 18 i by a tilt angle drx about a tilt axis parallel to the x-axis and by a tilt angle dry about a tilt axis parallel to the y-axis can be specified in an independently controlled manner. In this way, the respective field facet 18 _i can be assigned to one of the pupil facets of the pupil facet mirror 7 via the respective illumination channel 3 _i in order to specify the respective illumination setting. In a corresponding manner, if individual mirrors ES are used instead of the field facets 18 _i , grouping assignments of these individual mirrors ES to the field facets 26 _i and, if applicable, to the pupil facets 27 _i can be made instead of the field facets 18 _i by appropriately controlled independent tilting of the individual mirrors ES in order to specify illumination channels 3 _i according to 5 be specified.

7 shows an embodiment of the facet module 19 and the actuator module 33 with a total of twelve field facets 18, which in a variant of the field facet mirror 6 according to 2 can be used.

Eleven of the twelve field facets 18 are individual useful mirrors for specifying corresponding illumination channels 3 _i . A twelfth facet, which is in the 7 highlighted at the very top represents a single measuring mirror 43 of a measuring device explained below.

8 shows the facet module 19 in a 6 similar representation, whereby the individual useful individual mirrors, for example the field facets 18 _i in the 8 are not shown in detail. Illustrated in the 8 two different bending situations of the holding plate of the single mirror holder 35. Shown in dashed lines is 8 a position 44 of the single mirror holder 35 that is not bent between the bearing points 36 and 37. The solid line in the 8 a bent position 45 of the individual mirror holder 35 between the bearing points 36, 37. Such a bent position can arise in particular due to accumulated actuator forces that the actuator electromagnets 41 of the actuator module 33 exert on the field facets 18 _i . Depending on the actuator principle used, corresponding actuator forces can also arise in other ways, for example in the form of capacitive actuator forces or in the form of actuator forces that are not transmitted without contact. Actuator variants that can be used are known, for example, from the DE 10 2012 224 022 A1 and the US 10,303,065 B2 .

8 further illustrates a change in directions of reference normals 46 on the holding plate of the single mirror holder 35 due to the respective positional situation 44 and 45. The reference normals 46 in the non-bent positional situation 44 are shown in dashed lines and the reference normals 47 in the bent positional situation 45 are shown in solid lines.

Due to the deflection of the individual mirror holder 35 in the deflected position 45, there is a significant deviation between the directions of the reference normals 46, 47 at the location of the corresponding useful individual mirror held by the individual mirror holder 35, particularly in the outer edge area of the individual mirror holder 45 adjacent to the outer bearing points 36, 37. Due to this deflection, an actual tilt angle of the respective useful individual mirror is influenced by a corresponding change in direction.

As the 8 illustrated, this difference ΔR of the directions between the normals 46 and 47 is dependent on the y-coordinate of a position of the respective useful individual mirror, for example the respective field facet 18 ₁ , on the individual mirror holder 35. A corresponding dependency also arises along the x-coordinate. The respective reference normals at the location of the measuring individual mirror 43 are highlighted by an index M, the position of which on the facet module 19 is selected such that there the sensitivity of the normal tilt ΔR to the deflection of the individual mirror holder 35 is as great as possible.

9 illustrates details of a measuring device 48 to which the measuring individual mirror 43 belongs. Components and functions corresponding to those described above with reference to the 1 to 8 and in particular with reference to the 7 and 8 already explained, bear the same reference numbers and will not be discussed again in detail.

In addition to the individual measuring mirror 43, the measuring device 48 also includes a spatially resolving sensor 49, which can be designed as a CMOS or CCD sensor pixel array or as a PSD detector. The spatially resolving sensor 49 is arranged in a measuring light beam path of measuring light 50, which is guided over the individual measuring mirror 43. The measuring light 50 can be the illumination light 3. The measuring light beam path is shown starting from the intermediate focus IF of the illumination light 3 in the intermediate focus plane 5.

Alternatively, the measuring device 48 can also have a measuring light source 51 separate from the light source, which in the 9 is also illustrated very schematically.

A position of an impact point A of the measuring light 50 on the spatially resolving sensor 49 is a measure of the direction difference ΔR (x, y) at the location of the individual measuring mirror 43 and thus a measure of a deformation, in particular of a deflection of the individual mirror holder 35 due to cumulative actuator forces which are exerted on the useful individual mirrors, i.e. in particular on the field facets 18 _i via the actuator module 33, for tilting.

The measuring device 48 is part of a correction device 52, which also includes a control/regulating device 53, which is in signal connection with the actuator module 33, which is shown in the 9 is not shown in detail.

The measuring device 48 can in principle also have at least one temperature sensor 54.

The field facet mirror 6, the pupil facet mirror 7, the field facet mirror 24 and the pupil facet mirror 25 are examples of a facet mirror device of an optical construction group to which the measuring device 48 or the correction device 52 belongs.

10 shows values of a cumulative actuation force F on the useful individual mirrors of each facet module 19, for example on the field facets 18 _i of the facet module 19 according to 6 , as a function of a respective lighting setting BS. Lighting settings BS that can be used here are, for example, an annular lighting setting, a dipole lighting setting (x-dipole, y-dipole) or a multipole lighting setting. A conventional lighting setting, in which a uniform lighting angle distribution is achieved within certain lighting angle limits, can also be used. Depending on the lighting setting BS, the field facets 18 _i of the facet module 19 are tilted to different degrees in total, resulting in a correspondingly different force effect that the actuator module 33 exerts via the actuator electromagnets 41 on the actuator permanent magnets 40 and via these on the individual mirror holder 35. The cumulative force F can vary by several orders of magnitude depending on the lighting setting BS.

11 shows a dependence of a deviation ΔA of the impact location A on the spatially resolving sensor 49 of the measuring device 48, again on the respective illumination setting BS, whereby these illumination settings BS are plotted in the same sequence as in the 10 . There is a very clear correlation between the cumulative force F for the respective illumination setting BS and the impact location offset ΔA. After a corresponding calibration, an impact location offset ΔA and thus a change in direction ΔR of a reference normal and thus a tilt change of the individual measuring mirror 43 can be predicted for the respective illumination setting BS, which can be used to correct tilt angle offsets of the individual useful mirrors 18 _i or ES of the respective facet module 19.

• Initial wird bei dem Messverfahren ein Deformationsverhalten der Einzelspiegel-Halterung 35 ermittelt. Dies kann durch eine analytische Simulation eines Deformationsverhaltens der Einzelspiegel-Halterung 35 und/oder durch eine Finite-Elemente-Rechnung und/oder durch eine Simulation des Deformationsverhaltens erfolgen.

An actual orientation of a reflection surface of the field facet mirror 18 ₂ , i.e. an example of an actuator-tiltable individual mirror of an individual mirror group of such a facet mirror device, can be measured using the measuring device 48 as follows:

• Initially, the measurement method determines a deformation behavior of the individual mirror holder 35. This can be done by an analytical simulation of a deformation behavior of the individual mirror holder 35 and/or by a finite element calculation and/or by a simulation of the deformation behavior.

To prepare the measuring process, one of the individual mirrors of the individual mirror group, i.e. in the example described above one of the field facets 18 _i of the facet module 19, is specified as the individual measuring mirror 43. A plurality of corresponding individual measuring mirrors 43 can also be specified and used in the further measuring process for measuring light guidance and measuring light detection.

The measuring light 50 is then guided from a measuring light source, which can be the light source 2 or the separate measuring light source 51, via a measuring reflection surface of the individual measuring mirror 43 to the spatially resolving sensor 49 for measuring a corresponding actual orientation of the measuring reflection surface of the individual measuring mirror 43.

From the measured actual orientation of the measuring reflection surface of the individual measuring mirror 43 and the determined deformation behavior, the actual orientations of the other reflection surfaces of the individual useful mirrors 18 _i of the facet module 19 can then be determined.

The deformation behavior of the individual mirror holder 35 can also be determined by a calibration measurement in which an actual orientation of the reflection surface of the useful individual mirror to be measured is assigned to a respective actual orientation of a measuring reflection surface of the measuring individual mirror 43.

By means of the temperature sensor 54 of the measuring device 48, a temperature of the individual mirror holder 35 and/or of the individual measuring mirror 43 and/or of at least one of the useful individual mirrors 18 _i of the facet module 19 can be detected and assigned to a measured actual orientation of the individual measuring mirror 43. In this way, a temperature influence on predetermined tilt angles of the useful individual mirrors can be reduced and possibly even completely eliminated.

The measuring method can be part of a method for correcting an actual orientation of a reflection surface of the actuatable individual useful mirror 18 _i or ES of the facet module 19. In this case, a target orientation of the corresponding reflection surface of the individual useful mirror 18 _i or ES is initially specified. After carrying out the measuring method described, a comparison of the determined actual orientation of the reflection surface of the individual useful mirror 18 _i or ES can then be carried out with the specified target orientation. Depending on the comparison result, the actuators of the individual useful mirror 18 _i or ES can then be controlled to bring the actual orientation closer to the target orientation as soon as the comparison results in an orientation difference between the target orientation and the actual orientation being greater than a specified tolerance value.

In preparation for the correction process, a basic adjustment of the respective facet mirror device 6, 7, 24, 25 can be carried out, in which an initial actual orientation of the individual useful mirrors 18 _i or ES is controlled by an actuator at an illumination angle distribution in which an individual mirror actuator, averaged over the individual useful mirrors 18 _i or ES of this facet mirror device and in particular of a considered facet module of the facet mirror device, integrally exerts a minimal force on the individual useful mirrors. Such a basic adjustment with the lowest cumulative actuator force on the individual useful mirrors reduces disruptive actuator influences on an initial tilt position of the individual useful mirrors.

After carrying out the orientation correction process in particular, a micro- or nanostructured component can be produced by means of the projection exposure system 1.

To produce a micro- or nanostructured component, the projection exposure system 1 is used as follows: First, the reticle and the wafer are prepared. A structure on the reticle is then projected onto a light-sensitive layer of the wafer using the projection exposure system 1. By developing the light-sensitive layer, a microstructure is then created on the wafer and thus the microstructured component.

The projection exposure system 1 is designed as a scanner. The reticle is continuously displaced in the y-direction during the projection exposure. Alternatively, a design as a stepper is also possible, in which the reticle is displaced step by step in the y-direction.

If the projection exposure system 1 is designed as a scanner, the scanning direction y runs parallel to the transverse dimension x of the object field 9.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 10 2017 204 104 A1 [0002]
• DE 10 2017 212 622 A1 [0002]
• DE 10 2012 218 155 A1 [0002]
• US 8,958,053 B2 [0002]
• US 2011/0122389 A1 [0002]
• DE 10 2009 030 501 A1 [0007]
• DE 10 2012 224 022 A1 [0060]
• US 10,303,065 B2 [0060]

Claims (14)

Method for measuring an actual orientation of a reflection surface of an actuator-tiltable useful individual mirror (18 _i ; ES) of an individual mirror group of a facet mirror device (6; 7; 24; 25), wherein the individual mirrors (18 _i ; ES) of the individual mirror group are mounted on a common individual mirror holder (35) with the following steps: - determining a deformation behavior of the individual mirror holder (35), - specifying at least one of the individual mirrors of the individual mirror group as an individual measuring mirror (43), - guiding measuring light (50) from a measuring light source (2; 51) over a measuring reflection surface of the individual measuring mirror (43) to a spatially resolving sensor (49) for measuring an actual orientation of the reflection surface of the individual measuring mirror (43), - determining the actual orientation of the reflection surface of the useful individual mirror to be measured (18 _i ; ES) from the measured actual orientation of the reflection surface of the individual measuring mirror (43) and the determined deformation behavior. procedure according to claim 1 , characterized in that the actual orientation of several useful individual mirrors (18 _i ; ES) of the individual mirror group is determined from the measured actual orientation of the reflection surface of the measuring individual mirror (43). procedure according to claim 1 or 2 , characterized in that a temperature of the individual mirror holder (35) and/or of the individual measuring mirror (43) and/or of at least one of the useful individual mirrors (18 _i ; ES) of the individual mirror group is detected and assigned to the measured actual orientation of the individual measuring mirror (43). Method for correcting an actual orientation of a reflection surface of an actuatable individual useful mirror (18 _i ; ES) of an individual mirror group of a facet mirror device (6; 7; 24; 25), with the following steps: - specification of a target orientation of the reflection surface of the individual useful mirror (18 _i ; ES), - carrying out the method according to one of the Claims 1 until 3 , - comparing the determined actual orientation of the reflection surface of the useful individual mirror (18 _i ; ES) with the specified target orientation, - controlling an actuator (41 _i ) of the useful individual mirror (18 _i ; ES) to approximate the actual orientation to the target orientation as soon as the comparison shows that an orientation difference between the target orientation and the actual orientation is greater than a specified tolerance value. correction procedure according to claim 4 when using the facet mirror device (6; 7; 24; 25) in an illumination optics (10), in which different illumination angle distributions of an illumination of an object field (9) by the illumination optics (10) can be predetermined by actuator-based tilting of the individual useful mirrors (18 _i ; ES), wherein for a basic adjustment of the facet mirror device (6; 7; 24; 25) an initial actual orientation of the individual useful mirrors (8 _i ; ES) is actuator-controlled at an illumination angle distribution in which an individual mirror actuator (41 _i ) integrally exerts a predetermined reference force on the individual useful mirrors (18 _i ; ES) averaged over the individual useful mirrors (18 _i ; ES) of the facet mirror device (6; 7; 24; 25). Measuring device (48) for carrying out a method according to one of the Claims 1 until 5 , - with at least one individual measuring mirror (43) as a component of an individual mirror group on a facet mirror device (6; 7; 24; 25), wherein at least one useful individual mirror (18 _i ; ES) belongs to the individual mirror group, - with at least one spatially resolving sensor (49), arranged in a measuring light beam path which is guided over the individual measuring mirror (43). Correction device for carrying out a method according to one of the Claims 4 or 5 , - with a measuring device (48) according to claim 6 , - with a control/regulating device (53) which is in signal connection with an actuator (41 _i ) for tilting the at least one useful individual mirror (18 _i ; ES) and with the spatially resolving sensor (49). Optical assembly with a measuring device (48) according to claim 6 or with a correction device (53) according to claim 7 , - with a facet mirror device (6; 7; 24; 25), - with an actuator (41 _i ) for tilting the at least one useful individual mirror (18 _i ; ES), which is in signal connection with the control/regulating device (53) of the measuring device (48) or the correction device (52). Illumination optics (10) with an optical assembly according to claim 8 , for illuminating an object field (9), in which an object (12a) to be imaged can be arranged, with illumination light (3). Optical system with an illumination optics according to claim 9 and with a projection optics (12) for imaging the object field (9) in an image field (13) in which a substrate (13a) can be arranged. Optical system with an illumination optics according to claim 9 and with a light source (2) for generating the illumination light (3). Projection exposure system with an optical system according to claim 10 and/or 11th Method for producing a structured component with the following method steps: - providing a reticle and a wafer as a substrate, - projecting a structure on the reticle onto a light-sensitive layer of the wafer with the aid of the projection exposure system (1) according to claim 12 , - Creating a micro- and/or nanostructure on the wafer. Structured component manufactured by a process according to claim 13 .

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