DE102018200956A1 - Optical element for beam guidance of imaging light in projection lithography - Google Patents

Abstract

An optical element (M10) is used for beam guidance of imaging light in projection lithography. The optical element (M10) has a base body (18) and at least one optical surface (19) carried by the base body (18). At least one compensating weight device (20) is attached to the main body (18). The balancing weight device (20) is used for weight compensation of a pass deformation of the optical surface (19) via a change in a mass distribution of the base body (18). A control device (31) is operatively connected to the compensating weight device (20) such that an influence of the compensating weight device (20) on the mass distribution of the main body (18) can be changed.

Description

The invention relates to an optical element for beam guidance of imaging light in projection lithography. Furthermore, the invention relates to a method for producing such an adjusted optical element, an imaging optical system with at least one such optical element, an optical system with such imaging optics, a projection exposure apparatus with such an optical system, a method for producing a micro- or nanostructured Component with such a projection exposure system and a manufactured with this method micro- or nanostructured component.

Such an optical element is known from the DE 10 2013 214 989 A1 , Imaging optics of the type mentioned above are known from the WO 2016/188934 A1 and the WO 2016/166080 A1 ,

It is an object of the invention to provide an optical element with the lowest possible pass deformation on site.

This object is achieved by an optical element having the features specified in claim 1.

According to the invention, a pass deformation of the optical surface controlled by a change in a mass distribution of a base body of the optical element is compensated, which can also be referred to as weight compensation. Thus, the weight of at least one balance weight of the balance weight device is used to change the shape of the optical surface of the optical element. The balancing weight represents an independent base body component. The change in the mass distribution can be brought about by adding / removing at least one balancing weight and / or by shifting at least one balancing weight of the balancing weight. The pass deformation to be compensated may be due to gravity and / or production. A production-related pass deformation may result, for example, due to deformations resulting from a blank production of the optical element due to a self-weight of the optical element and / or due to holding forces of the optical element in a holding frame. With regard to a gravitational pass deformation, it has been recognized that the requirements for the fit accuracy, that is to say the conformity of the shape of optical surfaces of the optical elements to the beam guidance of imaging light in projection lithography, are so high that a weight force which directly or indirectly affects the optical surface acts, especially the exact size of the weight at the site of the projection exposure system, the component of which is considered optical element can play a role. It was therefore recognized that it may be necessary to take into account a gravitational conditional deformation deformation of the optical surface, which is dependent in particular on the application location. The at least one balancing weight of the optical element can provide for a corresponding weight compensation, so that gravitational effects on the optical surface, particularly gravitational force differences and their influence on the pass between a Spiegel-manufacturing site on the one hand and a Spiegel-use site on the other can be compensated.

An embodiment according to claim 2 has been found to be particularly suitable. At the mirror back z. B. attach balancing weights without disturbing the optical surface. Balance weights can also be arranged peripherally on the main body of the optical element, in particular if the optical element is a lens.

In a balancing weight device according to claim 3, a change of a mass distribution of the base body via a change of a fluid level of the at least one fluid container can take place. The control device can control a fluid pump for this purpose. The fluid may be a liquid, such as water. Fluid pressure conduits used in such an embodiment may additionally be used to stiffen the optical element.

A fluid container according to claim 4 may be designed as a bellows container. By way of this it can be achieved that the fluid container as a whole always remains completely filled, but nevertheless, depending on the volume of the volume, can exert a different weight force on the basic body of the optical element. By means of such a bellows embodiment, an advantageous spring force can result, over which, as far as no pressure is exerted on the fluid present in the bellows, a fluid reflux from the fluid container is brought about by the bellows spring force.

Several fluid containers according to claim 5 allow a corresponding spatially resolved weight influence of the pass deformation of the optical surface. An arrangement of a plurality of fluid containers may be adapted to an expected symmetry of a gravitational and / or production-related pass deformation. The connection of the fluid container with each other makes it possible to fill both fluid containers via a common feed fluid channel. Control valves can in Feed fluid channel and / or arranged in the connecting fluid channel so that a level of the plurality of fluid containers can be specified independently.

An arrangement of the fluid container according to claim 6 has been found to be particularly suitable. In particular, in such an arrangement, the fluid container, a connecting fluid channel, if it is present, be designed as a loop.

A balance weight device according to claim 7 makes it possible to change the mass distribution of the base body via the displacement of the at least one balance weight. This shift can in particular be automated. In the active position of the balance weight whose weight acts on the other body of the optical element. In the normal position, the weight of the balance weight does not affect the body.

An electromagnet according to claim 8 allows a displacement of the at least one, then magnetically executed balance weight so that it is not mechanically connected in the operative position with other components of the balance weight device. As a result, an optimum power decoupling of the balance weight is given by the other balancing weight device, so that parasitic forces are avoided.

The balance weight device may comprise at least one Peltier balance weight unit wherein the change in mass distribution occurs via a controlled evaporation / condensation process of a Peltier fluid. This also makes it possible to change a mass distribution of the basic body via a mass displacement of the Peltier fluid.

The advantages of a manufacturing method for an adjusted optical element according to claim 9 correspond to those which have already been explained above in connection with the optical element. The production of the blank taking into account a negative deformation lead makes it possible to compensate for a pass deformation with the balance weight device, in which compared to a predetermined target shape of the optical surface either too low or too high an arrow height is determined. For example, in order to take account of a negative deformation lead during the production of the blank, it is possible to polish the optical surface under the action of a proportionate maximum mass, eg. B. under the action of half a maximum mass, done that can provide the total weight balance device available.

An attachment of at least one balance weight can be carried out before or after the blank is moved to the site of the installation for projection lithography. An adjustment step of the optical element within the respective assembly may also follow a compensation attachment step. The optical element may be part of a projection optical system and / or component of a lighting optical system of the projection exposure apparatus.

The advantages of an imaging optic according to claim 10, an optical system according to claim 11, a projection exposure apparatus according to claim 12, a manufacturing method for microstructured or nanostructured components according to claim 13 and a micro- or nanostructuring component according to claim 14 correspond to those described above with reference have already been explained on the optical element according to the invention and on the manufacturing method according to the invention for the adjusted optical element. In particular, a semiconductor component, for example a memory chip, can be produced using the projection exposure apparatus.

The light source may be an EUV light source. A DUV light source, for example a light source with a wavelength of 193 nm, can also be used as an alternative.

• 1 schematisch eine Projektionsbelichtungsanlage für die EUV-Mikrolithographie;
• 2 in einem Meridionalschnitt eine Ausführung einer abbildenden Optik, die als Projektionsobjektiv in der Projektionsbelichtungsanlage nach 1 einsetzbar ist, wobei ein Abbildungsstrahlengang für Hauptstrahlen und für einen oberen und einen unteren Komastrahl dreier ausgewählter Feldpunkte dargestellt ist;
• 3 Randkonturen genutzter Spiegelflächen von Spiegeln der abbildenden Optik nach 2;
• 4 eine rückseitige Ansicht eines Grundkörpers eines Spiegels der abbildenden Optik nach 2 mit einer dort angeordneten Ausgleichsgewichtseinrichtung zur Vorgabe einer veränderbaren Massenverteilung des Grundkörpers mit entsprechender Auswirkung auf die optische Fläche des Spiegels;
• 5 einen Schnitt gemäß Linie V-V in 4;
• 6 in einer zu 4 ähnlichen Darstellung einen Spiegel-Grundkörper mit einer weiteren Ausführung einer Ausgleichsgewichtseinrichtung;
• 7 einen Schnitt gemäß Linie VII-VII in 6;
• 8 stärker schematisch im Vergleich zu den 4 und 6 eine rückseitige Ansicht eines Grundkörpers eines Spiegels der abbildenden Optik nach 2 mit einer weiteren Ausführung einer Ausgleichsgewichtseinrichtung;
• 9 eine Seitenansicht gemäß Blickrichtung IX. in 8, wobei Ausgleichsgewichte der Ausgleichsgewichtseinrichtung mit einer Masse wiedergegeben sind, die zu einer Passedeformation der optischen Spiegelfläche des Spiegels aufgrund des Masseeinflusses der Ausgleichsgewichte führt, wobei die Passedeformation übertrieben dargestellt ist;
• 10 in einer zu 9 ähnlichen Darstellung den Grundkörper des Spiegels mit der optischen Spiegelfläche während der Herstellung des Spiegels, wobei Herstellungs-Ausgleichsgewichte mit der Rückseite des Spiegelkörpers verbunden sind, deren Gravitationseinfluss zu einem negativen Deformationsvorhalt bei der Herstellung des Spiegels führt;
• 11 einen mit Einsatz der Herstellungs-Ausgleichsgewichte nach 10 hergestellten Spiegel-Rohling mit weggelassenen Ausgleichsgewichten und hierdurch bedingter Passedeformation der Spiegelfläche, wobei die Passedeformation übertrieben dargestellt ist;
• 12 in einer zu 8 ähnlichen Darstellung einen Spiegel mit einer weiteren Ausführung einer Ausgleichgewichtseinrichtung mit mehreren Fluidbehältern mit veränderlichem Fassungsvolumen zur Vorgabe eines veränderlichen Einflusses auf eine Massenverteilung eines Spiegel-Grundkörpers;
• 13 eine Seitensicht gemäß Blickrichtung XIII in 12, wobei die Ausgleichsgewichtseinrichtung mit einem ersten, niedrigen Fülldruck der Fluidbehälter dargestellt ist;
• 14 in einer zu 13 ähnlichen Darstellung die Ausgleichsgewichtseinrichtung mit einem zweiten, höheren Fülldruck der Fluidbehälter;
• 15 eine innere Details preisgebende Seitenansicht einer Peltier-Ausgleichsgewichtseinheit einer weiteren Ausführung einer in Form eines geschlossenen Kreislaufs ausgestalteten Ausgleichsgewichtseinrichtung zur Vorgabe eines veränderlichen Einflusses auf eine Massenverteilung eines Grundkörpers eines optischen Elements, welche alternativ oder zusätzlich zu den vorstehend dargestellten Ausführungen zum Einsatz kommen kann; und
• 16 eine Anordnung von drei Peltier-Ausgleichsgewichtseinheiten nach 15 an einer Rückseite eines Grundkörpers eines Spiegels.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this show:

• 1 schematically a projection exposure system for EUV microlithography;
• 2 in a meridional section, an embodiment of an imaging optic, which follows as a projection objective in the projection exposure apparatus 1 is usable, wherein an imaging beam path for main beams and for an upper and a lower Komastrahl three selected field points is shown;
• 3 Edge contours of used mirror surfaces of mirrors of the imaging optics 2 ;
• 4 a back view of a main body of a mirror of the imaging optics 2 with a compensating weight device arranged there for specifying a variable mass distribution of the main body with a corresponding effect on the optical surface of the mirror;
• 5 a cut according to line V - V in 4 ;
• 6 in one too 4 similar representation a mirror base body with a further embodiment of a balance weight device;
• 7 a cut according to line VII - VII in 6 ;
• 8th more schematic compared to the 4 and 6 a back view of a main body of a mirror of the imaging optics 2 with a further embodiment of a balance weight device;
• 9 a side view according to the direction of view IX , in 8th wherein balancing weights of the balancing weight means are represented with a mass which results in a fitting deformation of the optical mirror surface of the mirror due to the mass influence of the balancing weights, the pass deformation being exaggerated;
• 10 in one too 9 similar representation of the base body of the mirror with the optical mirror surface during the manufacture of the mirror, wherein manufacturing balance weights are connected to the back of the mirror body whose gravitational influence leads to a negative deformation lead in the production of the mirror;
• 11 one with the use of the manufacturing balancing weights 10 manufactured mirror blank with omitted balancing weights and consequent pass deformation of the mirror surface, the pass deformation is exaggerated;
• 12 in one too 8th a similar representation, a mirror with a further embodiment of a balance weight device with a plurality of fluid containers with variable capacity to specify a variable influence on a mass distribution of a mirror base body;
• 13 a side view according to the viewing direction XIII in 12 wherein the balance weight means is shown with a first, low inflation pressure of the fluid containers;
• 14 in one too 13 similar representation, the balance weight device with a second, higher filling pressure of the fluid container;
• 15 an internal details disclosure side view of a Peltier balance weight unit of another embodiment of a designed in the form of a closed balance balancing weight means for specifying a variable influence on a mass distribution of a base body of an optical element, which can be used alternatively or in addition to the embodiments shown above; and
• 16 an arrangement of three Peltier balance weight units after 15 on a back of a base of a mirror.

A projection exposure machine 1 for microlithography has a light source 2 for illumination light or imaging light 3 , At the light source 2 it is an EUV light source that generates light in a wavelength range, for example between 5 nm and 30 nm, in particular between 5 nm and 15 nm. At the light source 2 it can be a plasma-based light source (laser-produced plasma (LPP), gas-generated plasma (GDP) or even a synchrotron-based light source, for example a free-electron laser (FEL) light source 2 it may in particular be a light source with a wavelength of 13.5 nm or a light source with a wavelength of 6.9 nm. Other EUV wavelengths are possible. In general, even arbitrary wavelengths, for example visible wavelengths or also other wavelengths which can be used in microlithography (for example DUV, deep ultraviolet) and for the suitable laser light sources and / or LED light sources are available (for example 365 nm, 248 nm) nm, 193 nm, 157 nm, 129 nm, 109 nm) for the in the projection exposure apparatus 1 led lighting light 3 possible. A beam path of the illumination light 3 is in the 1 shown very schematically.

For guiding the illumination light 3 from the light source 2 towards an object field 4 in an object plane 5 serves a lighting optics 6 , With a projection optics or imaging optics 7 becomes the object field 4 in a picture field 8th in an image plane 9 mapped with a given reduction scale.

To facilitate the description of the projection exposure apparatus 1 as well as the different versions of the projection optics 7 in the drawing, a Cartesian xyz coordinate system is given, from which the respective positional relationship of the components shown in the figures results. In the 1 runs the x Direction perpendicular to the plane of the drawing. The y Direction runs to the left and the z direction to the top.

The object field 4 and the picture box 8th are in the projection optics 7 bent or curved and executed in particular partially annular.

The projection optics 7 has a x - Measurement of the image field of 26 mm and a y-dimension of the image field 8th of 1.2 mm.

A radius of curvature of this field curvature can be 81 mm on the image side. A corresponding ring field radius of the image field is defined in FIG WO 2009/053023 A2 , A basic shape of a border contour of the object field 4 or the image field 8th is bent accordingly. Alternatively it is possible to use the object field 4 and the picture box 8th rectangular shape. The object field 4 and the picture box 8th have an xy aspect ratio greater than 1. The object field 4 So has a longer object field dimension in the x Direction and a shorter object field dimension in the y direction. These object field dimensions run along the field coordinates x and y ,

The object field 4 is accordingly spanned by the first Cartesian object field coordinate x and the second Cartesian object field coordinate y. The third Cartesian coordinate z perpendicular to these two object field coordinates x and y is hereinafter also referred to as normal coordinate.

For the projection optics 7 can that be in the 2 illustrated embodiment can be used. The optical design of the projection optics 7 after the 2 and 3 is known from the WO 2016/188934 A1 whose contents are fully referenced.

The picture plane 9 is in the projection optics 7 in the execution after 2 parallel to the object plane 5 arranged. Here, one is shown with the object field 4 coincident section of a reflection mask 10 , which is also called reticle. The reticle 10 is from a reticle holder 10a carried. The reticle holder 10a is powered by a reticle displacement drive 10b relocated.

The picture through the projection optics 7 takes place on the surface of a substrate 11 in the form of a wafer made by a substrate holder 12 will be carried. The substrate holder 12 is from a wafer or substrate displacement drive 12a relocated.

In the 1 is schematically between the reticle 10 and the projection optics 7 an incoming into this bundle of rays 13 of the illumination light 3 and between the projection optics 7 and the substrate 11 one from the projection optics 7 leaking radiation beam 14 of the illumination light 3 shown. An image field-side numerical aperture (NA) of the projection optics 7 is in the 1 not reproduced to scale.

The projection exposure machine 1 is the scanner type. Both the reticle 10 as well as the substrate 11 be during operation of the projection exposure system 1 in the y Direction scanned. Also a stepper type of the projection exposure system 1 in which between individual exposures of the substrate 11 a gradual shift of the reticle 10 and the substrate 11 in the y-direction is possible. These displacements are synchronized with each other by appropriate control of the displacement drives 10b and 12a ,

The 2 shows an example of the optical design of the projection optics 7 , The 2 shows the projection optics 7 in a meridional section, ie the beam path of the imaging light 3 in the yz plane. The projection optics 7 to 2 has a total of ten mirrors, in the order of the beam path of the individual beams 15 , starting from the object field 4 , With M1 to M10 are numbered. The mirror M1 to M10 are optical elements for beam guidance of the imaging light 3 in projection lithography. Depending on the design of the projection optics 7 instead of the mirrors or in addition to them, lenses can also be used as optical elements. The projection optics 7 Thus, it can be catoptric, catadioptric or even dioptric.

Shown in the 2 the beam path in each case three individual beams 15 , of three in the 2 to each other in the y Direction of spaced object field points. Shown are main rays 16 , so individual rays 15 passing through the center of a pupil in a pupil plane of the projection optics 7 run, and in each case an upper and a lower coma beam of these two object field points. Starting from the object field 4 close the main beams 16 with a normal to the object plane 5 an angle CRA of 5.2 °.

The object plane 5 lies parallel to the image plane 9 ,

Shown in the 2 Detail of the calculated reflection surfaces of the mirrors M1 to M10 , A subarea of these calculated reflection surfaces is used. Only this actually used area of the reflection surfaces is plus a supernatant in the real mirrors M1 to M10 actually present.

3 shows this actually used area of the reflection surfaces of the mirror M1 to M10 , The mirror M10 has a passage opening 17 to the passage of the imaging light 3 , the third last mirror M8 to the penultimate mirror M9 is reflected. The mirror M10 becomes the passage opening 17 around used reflectively. All other mirrors M1 to M9 have no passage opening and are used in a coherently coherent area reflective.

The mirror M1 to M10 are designed as freeform surfaces that can not be described by a rotationally symmetric function. There are also other versions of the projection optics 7 possible, where at least one of the mirrors M1 to M10 is designed as a rotationally symmetric asphere. An aspherical equation for such a rotationally symmetric asphere is known from US Pat DE 10 2010 029 050 A1 , Also all mirrors M1 to M10 may be embodied as such aspheres.

A free-form surface can be described by the following free-form surface equation (Equation 1): $$\begin{array}{l}Z=\frac{c_x{x}^2+{\mathrm{<figure-callout\; id="2"\; label="c\; y\; y"\; filenames="DE102018200956A1\_0002.png"\; state="\{\{state\}\}">c\; </figure-callout>}}_y{y}^{}{}^2}{1+\sqrt{1-\left(1+k_x\right){\left(c_{x}x\right)}^2-\left(1+k_y\right){\left(c_{y}y\right)}^2}}\hfill \\ \hfill \\ +{\mathrm{<figure-callout\; id="1x"\; label="C"\; filenames="DE102018200956A1\_0009.png"\; state="\{\{state\}\}">C</figure-callout>}}_{1}x+C_{2}y\hfill \\ +{\text{C}}_3{\text{x}}^2+{\text{<figure-callout id="4" label="C" filenames="DE102018200956A1\_0002.png,DE102018200956A1\_0003.png" state="{{state}}">C</figure-callout>}}_{\text{4}}\text{xy}+{\text{C}}_5{\text{<figure-callout id="2" label="y" filenames="DE102018200956A1\_0002.png" state="{{state}}">y</figure-callout>}}^2\hfill \\ +{\text{C}}_6{\text{x}}^3+...+{\text{C}}_9{\text{<figure-callout id="3" label="y" filenames="DE102018200956A1\_0002.png,DE102018200956A1\_0003.png" state="{{state}}">y</figure-callout>}}^3\hfill \\ +{\text{C}}_{\text{10}}{\text{x}}^4+...+{\text{C}}_{12}{\text{x}}^2{\text{<figure-callout id="2" label="y" filenames="DE102018200956A1\_0002.png" state="{{state}}">y</figure-callout>}}^2+...+{\text{C}}_{\text{14}}{\text{<figure-callout id="4" label="y" filenames="DE102018200956A1\_0002.png,DE102018200956A1\_0003.png" state="{{state}}">y</figure-callout>}}^4\hfill \\ +{\text{C}}_{\text{15}}{\text{x}}^4+...+{\text{C}}_{20}{\text{<figure-callout id="5" label="y" filenames="DE102018200956A1\_0002.png,DE102018200956A1\_0003.png" state="{{state}}">y</figure-callout>}}^5\hfill \\ +{\text{C}}_{\text{21}}{\text{x}}^{\text{6}}+...+{\text{C}}_{24}{\text{x}}^3{\text{<figure-callout id="3" label="y" filenames="DE102018200956A1\_0002.png,DE102018200956A1\_0003.png" state="{{state}}">y</figure-callout>}}^3+...+{\text{C}}_{27}{\text{<figure-callout id="6" label="y" filenames="DE102018200956A1\_0002.png" state="{{state}}">y</figure-callout>}}^6\hfill \\ +...\hfill \end{array}$$

• Z ist die Pfeilhöhe der Freiformfläche am Punkt x, y, wobei x² + y² = r². r ist hierbei der Abstand zur Referenzachse der Freiformflächengleichung
• (x = 0; y = 0).

For the parameters of this equation (1):

• Z is the arrow height of the freeform surface at point x, y, where x ² + y ² = r ² . Here r is the distance to the reference axis of the free-form surface equation
• (x = 0, y = 0).

In the free-form surface equation (1), C ₁ , C ₂ , C ₃ ... designate the coefficients of the free-form surface series expansion in the powers of x and y.

In the case of a conical base, c _x , c _{y is} a constant that corresponds to the vertex curvature of a corresponding asphere. So c _x = 1 / R _x and c _y = 1 / R _y . k _x and k _y each correspond to a conical constant of a corresponding asphere. The equation (1) thus describes a biconical freeform surface.

An alternatively possible free-form surface can be generated from a rotationally symmetrical reference surface. Such free-form surfaces for reflecting surfaces of the mirrors of projection optics of projection exposure apparatuses for microlithography are known from US Pat US 2007-0058269 A1 ,

Alternatively, freeform surfaces can also be described using two-dimensional spline surfaces. Examples include Bezier curves or nonuniform rational base splines (NURBS). For example, two-dimensional spline surfaces may be described by a network of points in an xy plane and associated z-values or by these points and their associated slopes. Depending on the particular type of spline surface, the complete surface is obtained by interpolation between the mesh points using, for example, polynomials or functions that have certain continuity and differentiability properties. Examples of this are analytical functions.

The used reflection surfaces of the mirrors M1 to M10 are carried by basic bodies. As far as in an embodiment of the projection optics, not shown 7 at least one lens as an optical element for beam guidance of the imaging light 3 is used, the lens body itself represents the main body of the optical element.

The main body 18 can be made of glass, ceramic or glass ceramic. The material of the basic body 18 may be tuned so that its thermal expansion coefficient at a selected operating temperature of the mirror M is very close to the value 0 and ideally exactly 0. An example of such a material is Zerodur ^®.

Based on 4 and 5 An exemplary embodiment will now be described by way of example with reference to the mirror M10 described.

4 shows an example of a mirror body 18 of the mirror M10 perspective. In this case, the viewing direction is from a mirror rear side, that is, from a side facing away from the reflective mirror surface. The optical surface used for reflection is z. B. in the 5 denoted by 19.

The mirror M10 has a balance weight device 20 on the main body 18 is appropriate. This balance weight device 20 is used for weight compensation of a pass deformation of the optical surface 19 about a change in a mass distribution of the body 18 , Such a compensating deformation to be compensated may be due to gravity and / or production. A gravitational pass deformation can result from the fact that the mirror M10 is produced at a place of manufacture at which a weight of the mirror M10 another is than at the place of use of the mirror in the production of semiconductor devices with the Projection exposure system 1 which includes the mirror M10 is.

The balance weight device 20 is at the body 18 on the back of the mirror facing away from the optical surface 21 appropriate.

The balance weight device 20 has a total of three with the mirror back 21 connected fluid container 22 . 23 . 24 , Also another number of such fluid containers 22 to 24 for example in the area between a fluid container and ten fluid containers is possible.

The three fluid containers 22 to 24 are threefold rotationally symmetrical about the passage opening 17 in the main body 18 of the mirror M10 attached around. This threefold rotational symmetry is particularly with respect to a centroid axis SP of the mirror M10 given. In the circumferential direction around the passage opening 17 is each of the three fluid containers 22 to 24 at the height of a depository 25 of the basic body 18 arranged. About the bearings 25 is the main body 18 in a bearing receptacle of a holding frame, not shown, of the mirror M10 stored.

Via a feed fluid channel 27 are the fluid containers 22 to 24 with a fluid pump 28 connected. The fluid pump 28 again stands with a fluid supply 29 in connection. Between the main body 18 and the fluid pump 28 runs the feed fluid channel 27 via a force decoupling unit 30 , which ensures that no unwanted power transmission from the fluid pump 28 over the feed fluid channel 27 on the main body 18 he follows.

The fluid pump 28 again stands with a control device 31 in signal connection. The control device 31 stands with the balance weight device 20 so in operative connection that an influence of the balancing weight device 20 on the mass distribution of the body 18 is changeable. Depending on the level of the fluid container 22 to 24 with fluid, which may be a liquid, for example, water or liquid nitrogen, exercises the respective fluid container 22 to 24 a predetermined weight on the other body 18 resulting in a deformation of the passe of the optical surface 19 on the opposite side of the main body 18 transfers.

About the specification of the level of the fluid container 22 to 24 Thus, a control of the influence of the balance weight device takes place 20 on the mass distribution of the body 18 with the control device 31 ,

In the connection fluid channel 26 is between each two adjacent the fluid container 22 to 24 one control valve each 32 arranged. Each of these three control valves 32 is in a manner not shown with the controller 31 in signal connection.

The fluid container 22 to 24 are based on the basic body 18 via outriggers 25a from. Such support boom 25a can be compared to the main body 18 be sprung and / or damped, so that in particular a vibration decoupling between the fluid containers 22 to 24 in the range of particular natural frequencies of the body 18 is guaranteed.

The fluid container 22 to 24 are connected to each other via a connecting fluid channel designed as a ring line 26 connected.

In the manufacture of an adjusted optical element according to the type of mirror M10 after the 4 and 5 the procedure is as follows:

First, a blank of the mirror M10 made in consideration of a negative Deformationsvorhaltes at a place of manufacture. The optical surface 19 is preformed so that it is only under the force of the partially, for example, half, filled with fluid, for example, with water, fluid container 22 to 24 the desired passport has. The predetermined gravitational influence of the balancing weight device with which initially the mirror blank is produced is less than a maximum gravitational influence. In this way, a negative deformation allowance is taken into account.

Subsequently, the thus prefabricated blank is spent at the site of the projection exposure system. There is an actual shape of the optical surface 19 of the mirror M10 measured and with one due to the design of the projection optics 7 predetermined target shape compared. Subsequently, via the control device 31 by driving the fluid pump 28 as well as the control valves 32 a level in the fluid containers 22 to 24 adapted so long, due to the mass influence of the then correspondingly changed masses of fluid containers 22 to 24 the actual shape of the optical surface 19 has approached the target shape within a predetermined tolerance range. Subsequently, the mirror is adjusted at its place of use in the projection exposure apparatus.

As far as z. B. a gravitational influence on the pass deformation by comparing the weight at the place of manufacture with the weight at the site can be determined, a default of levels of the fluid container 22 to 24 , So a specification of the influence of the balance weight device 20 on the mass distribution of the the body 18 , even before spitting the mirror M10 to the site of the projection exposure system 1 respectively.

Based on 6 and 7 Below is another embodiment of the mirror M10 with a balance weight device 33 explains that instead of the balance weight device 20 can be used. Components and functions corresponding to those described above with reference to FIGS 1 and 5 and in particular with reference to 4 and 5 already described, bear the same reference numbers and will not be discussed again in detail.

The balance weight device 33 has a plurality and in the illustrated embodiment, a total of six balancing weight units 34 ₁ , 34 ₂ , ... 34 ₆ , in the rear view to 6 clockwise around the opening 17 are numbered.

Each of the balance weight units 34 _i has a balance weight 35 which is controlled between one in the 7 shown active position in which the balance weight 35 in contact with the main body 18 stands, and a neutral position, not shown in the drawing, in which a weight influence of the balance weight 35 on the main body 18 is negligible, is relocatable. The balancing weight units 34 _i each have an electromagnet for this purpose 36 who has one in the 7 partially illustrated signal line 37 with the control device 31 is in signal connection. The respective electromagnets 36 the balance weight units 34 _i are again on the support frame of the mirror M10 assembled.

In the in the 7 shown active position of the balance weight 35 this is in a complementary to this in the body 18 trained balance weight admission 38 , By operation of the electromagnet 36 can the magnetic balance weight 35 from the balance weight absorption 38 in the 7 shifted upwards so that an influence of the balance weight 35 on the mass distribution of the body 18 is negligible.

Due to the change in the mass distribution by the balance weight device 20 , the level in the filling containers 22 to 24 depends, results in a corresponding, weight-related change in the shape of the optical surface 19 ,

The balancing weight units 34 _i are each in pairs and in turn dreizählig around the passage opening 17 arranged around, comparable to the arrangement of the fluid container 22 to 24 the execution after the 4 and 5 , In each case, a pair of balancing weight units 34 ₁ , 34 ₂ , 34 ₃ , 34 ₄ , 34 ₅ , 34 ₆ is at the location of one of the fluid container 22 to 24 arranged.

In the production of the mirror M10 with the balance weight device 33 in turn, by making first a blank of the optical surface 19 a negative deformation allowance is taken into account. The blank is in this case under the influence of, for example, manufacturing or polishing balance weights with less mass than the then during operation of the balance weight device 33 actually used balancing weights 35 polished. This can be a stroke of the effect of the balance weight device 33 around a nominal nominal shape for the optical surface 19 symmetrize, so that both small and too large arrow heights of the actual shape of the optical surface 19 at the site by action of the balance weight device 33 can be compensated. Corresponding polish balance weights may only be part of the mass of the balance weights 35 have, for example, half the mass of the balance weights 35 ,

Based on 8th to 11 Below is another embodiment of a balance weight device 39 described. Components and functions corresponding to those described above with reference to FIGS 1 to 7 and especially with reference to the 4 to 7 already described, bear the same reference numbers and will not be discussed again in detail.

The balance weight device 39 is exemplary again for the mirror M10 represented, in this case, no passage opening in the manner of the passage opening 17 of the embodiments described above.

At the balance weight device 39 come balancing weights 35 used, the free on the mirror back 21 can be positioned. Example positions for two such counterweights 35 on the mirror back 21 arise from the views of the 8th and 9 , Also a different number of such balance weights 35 , in the range, for example, between a balance weight 35 and ten balance weights 35 , can be used.

In the 9 to 11 is also a pass deformation of the optical surface 19 by a greatly exaggerated shape curve 40 indicated.

The 10 shows by way of example how under the influence of polish balancing weights 41 that can have half the mass, for example, than the during operation of the balance weight device 39 used balancing weights 35 first a blank polishing of the optical surface 19 of the mirror M10 takes place, the shape curve 40 a predetermined desired shape of the optical surface 19 At the end of the polishing process, it is now possible to use the heavier balance weights 35 Passage deformation in one direction (cf. 9 ) or by omitting the balance weights a pass deformation in the other direction (see. 11 ).

Based on 12 to 14 Below is another embodiment of a balance weight device 42 described, which can be used in place of the above-described balancing weights. Components and functions corresponding to those described below with reference to 1 to 11 and in particular on the basis of 4 to 11 already described, bear the same reference numbers and will not be discussed again in detail.

Instead of the fluid container 22 to 24 the balance weight device 20 has the balance weight device 42 three fluid containers 43 . 44 . 45 with variable capacity, designed as a bellows container. In the feed fluid channel 27 the balance weight device 42 is between the fluid pump 28 and the fluid container 44 a fluid pressure gauge 46 shown schematically.

The side view after 13 shows a situation "low fluid pressure". The bellows-fluid container are unfolded low, so that a correspondingly small amount of fluid in the fluid containers 43 to 45 is present. Accordingly, a small fluid weight acts on the induced change in the mass distribution of the body 18 on the shape of the optical surface 19 ,

14 shows the situation where a higher fluid pressure through the fluid pump 28 in the feed fluid channel 27 is initiated. Accordingly, the bellows fluid container 43 to 45 deployed and have, for example, an additional height extension .DELTA.L to the height of the fluid container compared to the height of the container at low fluid pressure after 13 has increased. The correspondingly larger, fluid-filled volume of the bellows fluid container 43 to 45 leads to a larger fluid weight, which leads to a change in the mass distribution of the base body and corresponding to a weight compensation of the pass deformation of the optical surface 19 leads.

A fluid pressure can after in the operating situation 13 at 1 in cash and in the operating situation 14 at 2 lie bar. At low fluid pressure after 13 arises, as far as this fluid pressure is adjusted starting from a higher fluid pressure, due to the restoring force of the bellows container 43 to 45 a reflux of the fluid from these containers 43 to 45 back into a fluid reservoir connected to the fluid pump 28 is in fluid communication.

Based on 15 and 16 Below is another embodiment of a balance weight device 47 explained. Components and functions corresponding to those described above with reference to FIGS 1 to 14 and in particular with reference to 4 to 14 already described, bear the same reference numbers and will not be discussed again in detail.

The balance weight device 47 has several and im in the 16 illustrated embodiment, three Peltier balancing weight units 48 . 49 and 50 , each of which has the same structure. In the 15 is exemplary the Peltier balance weight unit 48 shown.

The Peltier balance weight unit 48 is designed as a closed circulation system. It includes a Peltier element 51 , which with a schematically indicated power supply 52 connected is. A "warm" side of the Peltier element 51 (left in the 15 ) has a higher temperature T1 and a "cold" side of the Peltier element 51 (right in the 15 ) has a lower temperature T2 , The Peltier element 51 is in thermally conductive connection with a U-shaped, closed on both sides, so a total dense fluid channel 53 , which is a reservoir for a Peltier fluid 54 represents. With the Peltier fluid 54 it can be water.

Due to the U-shape of the fluid channel 53 is one in the 15 left leg of the fluid channel 53a with the tub side of the Peltier element 51 and a right thigh 53b of the fluid channel 53 with the cold side of the Peltier element 51 in thermally conductive connection.

Like in the 15 indicated schematically, can, controlled by the power supply 52 , in turn, with the control device 31 in a manner not shown is in signal communication, via an evaporation process in the left leg 53a of the fluid channel 53 and / or a condensation process in the right leg 53b of the fluid channel 53 a mass distribution of the Peltier fluid 54 between these two thighs 53a . 53b be selectively changed.

This results in a continuous change of a mass influence, in the appropriate place of the basic body 18 of the mirror M10 can act as exemplified in the 16 shown.

The Peltier balance weight units 48 to 50 are each about the warm side of the Peltier element 51 via a flexible hinge connection 55 with one of the three bearings 25 of the basic body 18 connected. The flexible joint 55 allows pivoting of the respective Peltier balance weight unit 48 around a schematic in the 16 illustrated axis S ₄₈ , S ₄₉ and S ₅₀ . These axes S ₄₈ , S ₄₉ , S ₅₀ are in the 16 indicated schematically and actually run perpendicular to the plane of the 16 , Accordingly, a point of action can be over which the cold side of the Peltier element 51 with the main body 18 in mechanical communication, depending on the pivoting angle about the axis S _48, S _49, S ₅₀ adjustable preset. A respective point of action or connection between the cold side of the Peltier element 51 and the body 18 is in the 16 highlighted in V ₄₈ , V ₄₉ and V ₅₀ .

About the Peltier balance weight unit 48 to 50 can be in each given action point a predetermined and continuously adjustable weight effect of the Peltier fluid 54 generate this point of action V _i , which in turn can be used for weight compensation of a pass deformation of the optical surface of the mirror M.

When performing the mirror M as a symmetrical ceramic mirror with a mass of 500 kg, a diameter of 90 cm and a thickness of 20 cm, a theoretical pass deformation, caused by a gravitational variation of 0.1% z. B. about 350 pm. Due to the weight compensation described above by means of balancing weight elements, this effect on z. B. about 13 pm reducible. This leaves after the compensation so less than 4% of the original pass deformation. Corresponding and comparable values result for an alternatively or additionally possible production-related pass deformation.

In general, a compensation of the pass deformation to a value of less than 10% of the original pass deformation can be achieved.

The projection exposure apparatus is used to produce a microstructured or nanostructured component 1 used as follows: First, the reflection mask 10 or the reticle and the substrate or the wafer 11 provided. Subsequently, a structure on the reticle 10 on a photosensitive layer of the wafer 11 using the projection exposure system 1 projected.

By developing the photosensitive layer, a micro or nanostructure is then formed on the wafer 11 and thus produces the microstructured component.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013214989 A1 [0002]
• WO 2016/188934 A1 [0002, 0026]
• WO 2016/166080 A1 [0002]
• WO 2009/053023 A2 [0024]
• DE 102010029050 A1 [0036]
• US 20070058269 A1 [0041]

Claims (14)

Optical element (M; M1 to M10) for beam guidance of imaging light (3) in projection lithography, - comprising a base body (18) and at least one optical surface (19) carried by the base body (18), characterized by at least one balance weight device (20; 33, 39, 42, 47) mounted on the base body (18) for compensating for a deformation of the optical surface (19) by changing a mass distribution of the base body (18), - a control device (31) connected to the balance weight device (20; 33; 39; 42; 47) is operatively connected such that an influence of the balancing weight device (20; 33; 39; 42; 47) on the mass distribution of the main body (18) is variable. Optical element after Claim 1 , characterized in that the optical element (M; M1 to M10) is designed as a mirror, wherein the at least one compensating weight device (20; 33; 39; 42; 47) is attached to the main body (18) at one of the optical surface (19). remote mirror back (21) is mounted. Optical element after Claim 1 or 2 , in that the compensating weight device (20; 42) has at least one fluid container (22 to 24; 43 to 45) arranged in the region of the main body (18), which can be connected to a fluid reservoir (29) via a feed fluid channel (27) is. Optical element after Claim 3 , characterized in that the fluid container (43 to 45) is designed with a variable capacity. Optical element after Claim 3 or 4 , characterized by a plurality of fluid containers (22 to 24, 43 to 45), which are arranged in the region of the base body (18), wherein at least two of the fluid container (22 to 24, 43 to 45) connected to each other via a connecting fluid channel (26) are. Optical element after Claim 5 , characterized in that the fluid containers (22 to 24, 43 to 45) are arranged multiple rotationally symmetrical with respect to a center of gravity axis (SP) of the optical element (M10) in the region of the base body (18). Optical element according to one of Claims 1 to 6 , characterized in that the compensating weight device (33; 39) has at least one compensating weight unit (34) with at least one compensating weight (35) which can be displaced via the control device (31) between a neutral position and an operative position. Optical element after Claim 7 , characterized in that the balance weight (35) is held in the neutral position via an electromagnet (36) which is in signal communication with the control device (31). Method for producing an adjusted optical element (M; M1 to M10) according to one of Claims 1 to 8th with the following steps: - producing a blank of the optical element (M; M1 to M10) with predetermined weight influence of the counterbalancing weight device (20; 33; 39; 42; 47) which is less than a maximum weight influence to take account of a negative deformation pre-camber; controlling the influence of the balancing weight device (20; 33; 39; 42; 47) on the mass distribution of the base body (18) with the control device (31) for compensating a pass deformation of the optical Surface (19). Imaging optics (7) with at least one optical element (M1 to M10) according to one of Claims 1 to 8th for imaging an object field (4), in which an object (10) to be imaged can be arranged, in an image field (8), in which a substrate (11) can be arranged. Optical system - with an imaging optic Claim 8 , - with an illumination optical system (6) for illuminating the object field (4) with illumination light (3) of a light source (2). Projection exposure system with an optical system after Claim 11 and a light source (2) for generating the illumination light (3). A method of fabricating a patterned device comprising the steps of: providing a reticle (10) and a wafer (11), projecting a pattern on the reticle (10) onto a photosensitive layer of the wafer (11) using the projection exposure apparatus Claim 12 , - Generating a micro or nanostructure on the wafer (11). Structured component produced by a method according to Claim 13 ,

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