Optical arrangement with frame component

Abstract

The invention relates to an optical arrangement, in particular a projection lens, comprising: at least one mount component (2) to which an optical element (1), preferably a lens or a mirror, is particularly permanently attached. The optical arrangement comprises at least one further mount component (4) to which the at least one mount component (2) is detachably attached, wherein the further mount component (4) and / or the mount component (2) has at least one hollow shaft cone (8) and / or at least one prism receptacle.

Description

Background of the invention

[0001] The invention relates to an optical arrangement, in particular a projection lens, comprising: at least one mount component to which an optical element, preferably a lens or a mirror, is in particular permanently attached.

[0002] Optical elements, for example transmissive optical elements such as lenses or the like, are typically permanently attached to a metallic frame component. For permanent attachment, the optical elements are usually glued into the respective frame component. The bonding and other manufacturing processes of the optical elements and frame components create tolerances. Since the optical elements often have to be arranged in series, the individual frame components are adjusted to one another. Adjustment can be achieved by the tried and tested "tapping" method. When "tapping" the frame components usually lie on top of one another due to their own weight and the positions of the frame components and thus of the optical elements relative to one another are recorded using a measuring system (e.g. a coordinate measuring machine or a dial indicator). By tapping on the edge of the upper frame component, it overcomes the static friction and slides slightly.The "tapping" process continues until the measuring system indicates a perfect alignment of the individual socket components relative to each other. The socket components are then secured in this alignment or position using screws or clamps, for example.

[0003] A problem with adjusting the mount components arises when individual optical elements need to be replaced at the customer's site and the high-precision measuring system is unavailable. Adjustment by tapping also takes too long and unnecessarily increases the downtime of the optical assembly, for example, a projection lens in a projection exposure system in which the optical element is operated. Object of the invention

[0004] The object of the invention is to provide an optical arrangement, in particular a projection lens, which enables repeatable, precise positioning of optical elements or frame components even without the availability of a measuring system. Subject of the invention

[0005] This object is achieved by an optical arrangement of the type mentioned at the outset, which has at least one further frame component to which the at least one frame component is detachably fastened, wherein the further frame component and / or the frame component has at least one hollow shaft cone and / or at least one prism receptacle.

[0006] To solve the problem of precisely positioning the mount component(s) without the use of a measuring system, it is proposed to releasably attach each mount component to another mount component. The other mount component is fixed in the optical assembly, for example, in a projection lens, and is typically adjusted by "tapping" and connected to or fixed to a series of other mount components of the optical assembly.

[0007] The hollow shaft cone acts like a tool change interface, as is known from machine tools, and has a repeatability of typically approximately 3µm. When the frame component to which the optical element is attached is detachably attached to the additional frame component, the frame component can therefore be positioned with high repeatability using the hollow shaft cone. The same applies if the additional frame component has one or more prism mounts, which also have a high repeatability. Using the changeover interface provided by the hollow shaft cone or the prism mounts, frame components with different optical elements or different optical assemblies can be detachably attached to the additional frame component as often as required.

[0008] In one embodiment, in a fastening position the socket component rests against an axial contact surface of the other socket component, or vice versa, wherein the hollow shaft cone and / or the prism receptacle is / are elastically expanded in the fastening position. The hollow shaft cone is based on the operating principle of a cone, such as a steep cone receptacle. A steep cone centers very well, but does not define the Z height, i.e. the position in the axial direction. A hollow shaft cone is basically a hollow steep cone. If the cone of the socket component (see below) is pressed further into the hollow shaft cone after centering, the latter deforms elastically within a certain range. Within this elastic play of the hollow shaft cone, the cone of the socket component is pressed onto a defined Z support, i.e. against an axial contact surface of the other socket component.A further mounting component with a receptacle in the form of a hollow shaft cone can therefore determine the center as well as the z-height of the mounting component and thus of the optical element with repeatable accuracy. The at least one prism receptacle can also expand elastically when the further mounting component is attached to the mounting component, allowing the mounting component to rest against the axial contact surface of the further mounting component in the attached position and thus be positioned with repeatable accuracy in the Z-direction.

[0009] In both cases, the socket component is typically moved into an initial position for fastening, in which the socket component rests against the other socket component but is spaced axially from the axial contact surface of the other socket component. During fastening, the socket component is moved from the initial position into the fastening position, whereby a force is exerted on the socket component in the axial direction. This force causes the hollow shaft cone and / or the prism receptacle to expand elastically until the socket component rests against the contact surface of the other socket component. The role of the socket component and the other socket component can also be reversed, depending on whether the other socket component or the socket component has the hollow shaft cone or the prism receptacle.

[0010] In one embodiment, the socket component has a conical section which bears against a conical section of the hollow shaft cone of the further socket component for centering the socket component, or vice versa. As described above, the socket component is centered on the further socket component by means of the hollow shaft cone. The further socket component can, for example, be designed in the manner of a sleeve or the like. If the socket component is brought into contact with the conical section of the further socket component in a contact position, the socket component initially does not reach the axial contact surface of the further socket component, i.e. a gap is formed between the socket component and the further socket component.

[0011] In a further development of this embodiment, the conical section of the hollow shaft cone is designed to be elastically expandable. As described above, by applying an axially acting force, the conical section of the socket component can be pressed from its initial position further into the conical section of the hollow shaft cone of the further socket component in order to elastically expand this or the cone of the hollow shaft cone so that the socket component reaches the axial contact surface.

[0012] As a rule, it is sufficient for elastic expansion if the conical section of the additional socket component has a comparatively small thickness in the radial direction, which allows for radial expansion of the conical section. The conical section can be made of the same material as the rest of the additional socket component, but it is also possible for the conical section to be made of a material that is more easily elastically deformable than the rest of the additional socket component. The conical section or the additional socket component can be made of a metallic material, for example.

[0013] In a further development, the hollow shaft cone, preferably the conical section of the hollow shaft cone, comprises a prism mount. With the help of the prism mount, in addition to aligning the center of the socket component via the hollow shaft cone, the rotational position of the socket component in relation to the Z axis or the axial direction can be specified with repeatable accuracy. Typically, both the prism mount and the hollow shaft cone are designed to be elastically expandable so that the Z position of the socket component is also clearly and repeatably determined by contact with the axial contact surface. In this way, the position of the socket component in all three spatial directions x, y, z can be clearly and repeatably defined.

[0014] In a further embodiment, the further socket component and / or the socket component has / have two spaced-apart hollow shaft cones, wherein the conical section of one of the two hollow shaft cones preferably has a reduced diameter along a spacing direction between the two hollow shaft cones. In this case, the conical section of the hollow shaft cone is typically cut off or flattened on two opposite sides that run transversely to the spacing direction of the two hollow shaft cones.

[0015] In this embodiment, one of the two hollow shaft cones serves to fix the further socket component in its x and y position relative to the socket component, or vice versa. The second hollow shaft cone, spaced apart from the first, serves to precisely specify the rotational position of the socket component or of the further socket component with respect to the Z axis or the axial direction. In this case, it is advantageous if one of the two hollow shaft cones has a conical section that is not rotationally symmetrical, but has a reduced diameter on two opposite sides that run transversely to a spacing direction or to an imaginary connecting line between the two hollow shaft cones, because the conical section is cut off or removed.In the event that the distance between the centers of the two hollow shaft cones of the further socket component does not exactly match the distance between the centers of the two conical sections of the socket component (or vice versa), the hollow shaft cone with the diameter reduced in the direction of the distance serves in the manner of an elongated hole, ie to compensate for tolerances.

[0016] In an alternative embodiment, the further frame component or the frame component has at least three prism receptacles, which are preferably arranged uniformly in the circumferential direction on the further frame component. In this embodiment, the further frame component does not have a hollow shaft cone; rather, the repeatable positioning of the frame component is achieved by the at least three prism receptacles, which - particularly in the case of a uniform arrangement of the prism receptacles at the edge of the further frame component - center the frame component and thus the optical element. In the event that the further frame component has three prism receptacles, these can be arranged in the circumferential direction, for example, in a 120° arrangement.

[0017] In a further development, the at least one prism holder for the elastic expansion has two prism parts that can move relative to one another. The two prism parts each have a contact surface for the socket component. The angle between the two contact surfaces is increased by applying an axial force, which elastically pushes the two prism parts apart. In this way, the prism holder deforms elastically, and an axial gap between the socket component and the further socket component is reduced until the socket component rests against the axial contact surface of the further socket component.

[0018] In a further development, the mounting component or the additional mounting component has at least one preferably spherical or cylindrical contact contour that rests against the two prism parts of the prism mount. The contact contour rests against the two prism parts or their contact surfaces. During attachment, the contact contour is pressed axially into the prism mount, which deforms elastically, or the two prism parts deflect laterally, until the mounting component rests against the axial contact surface of the additional mounting component.

[0019] In a further embodiment, the socket component is releasably attached to the further socket component by means of at least one clamping screw acting in the axial direction. The clamping screw makes it possible to apply a force in the axial direction to the socket component and move it into the fastening position, whereby the hollow shaft cone or the prism receptacle expands elastically in order to bring the socket component into contact with the axial contact surface of the further socket component. It is understood that the socket component can also be pressed against the further socket component in a manner other than by a clamping screw in order to achieve contact of the socket component against the axial contact surface.

[0020] In a further embodiment, the mount component has an adjustment ring to which the optical element is preferably attached by adhesive bonding, wherein the adjustment ring is preferably releasably attached to a base body of the mount component by means of at least one adjustment screw. The adjustment ring can be adjusted in the factory, i.e., with a measuring system present, by "tapping" and releasably attached to the base body of the mount component by means of one or more adjustment screws. It is understood that the releasable connection can also be realized in other ways.

[0021] In a further embodiment, the frame component and / or the further frame component have a friction-reducing coating, preferably a DLC ("diamond-like carbon") coating. The friction-reducing coating is typically limited to a respective area of ​​the frame component or the further frame component where friction occurs due to the movement from the starting position to the fastening position. The friction-reducing coating is therefore typically applied to the contact surface of the conical section of the frame component or the further frame component and / or to the bearing surfaces of the prism receptacles or to the contact contour for the prism receptacles.

[0022] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details essential to the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention. drawing

[0023] Exemplary embodiments are shown in the schematic drawing and are explained in the following description. It shows Fig. 1 a schematic representation of a DUV lithography system with an illumination device and a projection lens, Fig. 2 a schematic sectional view of a socket component which is detachably attached to another socket component which has a hollow shaft cone, Fig. 3 a schematic perspective view of a frame component which is detachably attached to another frame component which has three prism receptacles, Fig. 4 a schematic sectional view of one of the prism receptacles and a contact contour of the frame component of Fig. 3, Fig. 5 is a schematic sectional view of a socket component which is detachably attached to another socket component which has two hollow shaft cones, Fig. 6 a plan view of the top side of the further socket component of Fig. 5 with the two hollow shaft cones, as well as Fig. 7 a plan view of the underside of the socket component of Fig. 5 with two conical sections formed at recesses.

[0024] In the following description of the drawings, identical reference symbols are used for identical or functionally identical components.

[0025] Fig. 1 shows a schematic view of a DUV projection exposure system 100, which includes a beam shaping and illumination device 102 and a projection lens 104. DUV stands for "deep ultraviolet" (DUV) and denotes a wavelength of the working light between 30 nm and 370 nm. The DUV projection exposure system 100 has a DUV light source 106. The DUV light source 106 can be, for example, an ArF excimer laser, which emits radiation 108 in the DUV range at, for example, 193 nm.

[0026] The Fig. The beam-shaping and illumination device 102 shown in Figure 1 directs the DUV radiation 108 onto a photomask 120. The photomask 120 is designed as a transmissive optical element and can be arranged outside the beam-shaping and illumination device 102 and the projection lens 104. The photomask 120 has a structure that is imaged in a reduced size onto a wafer 124 or the like by means of the projection lens 104.

[0027] The projection lens 104 has a plurality of lenses 128 and / or mirrors 130 for imaging the photomask 120 onto the wafer 124. Individual lenses 128, 140 and / or mirrors 130 of the projection lens 104 can be arranged symmetrically to the optical axis 126 of the projection lens 104. It should be noted that the number of lenses and mirrors of the DUV projection exposure system 100 is not limited to the number shown. More or fewer lenses and / or mirrors can also be provided. Furthermore, the mirrors are typically curved at their front side for beam shaping.

[0028] An air gap between a final lens 128 and the wafer 124 can be replaced by a liquid medium 132 having a refractive index > 1. The liquid medium 132 can be, for example, ultrapure water. Such a setup is also referred to as immersion lithography and features increased photolithographic resolution.

[0029] Fig. 2 shows an optical element in the form of a lens 1, which in the example shown is one of the lenses 128 of the projection lens 104 of Fig. 1. The lens 1 is permanently attached to a mount component 2 via an adhesive 3. The mount component 2 is detachably attached to another mount component 4, which is designed in the manner of a sleeve. The other mount component 4 is fixedly arranged in the projection lens 104 and firmly connected thereto, as well as being aligned with the other mount components of the projection lens 104 by "tapping."

[0030] The frame component 2 with the lens 1 has an adjustment ring 5, into which the lens 1 is glued by means of the adhesive 3. The adjustment ring 5 is releasably attached to an annular base body 6 of the frame component 2 by means of adjustment screws 7. The adjustment ring 5 was measured in the factory using a measuring system and is adjusted to the base body 6 of the frame component 2 by "tapping."

[0031] The socket component 2 is in the Fig. 2, the optical element 1 is detachably attached to the further mounting component 4 via a hollow shaft cone interface. Such an interface has proven itself in machine tools and can also be used as an interface for a mounting component 2 of an optical element 1 to enable repeatable positioning of the optical element 1 with a positioning accuracy in the order of a few micrometers.

[0032] For this purpose, the further mounting component 4 has a hollow shaft cone 8, which comprises a base section 9 and a conical section 10. The mounting component 2 also has a conical section 11, which is used to center the mounting component 4 on the conical section 10 of the hollow shaft cone 8 of the further mounting component 4. If the mounting component 2 is inserted with the conical section 11 of the base body 6 into the further mounting component 4 or into the hollow shaft cone 8, its conical contact surface rests against the conical contact surface of the conical section 10 of the hollow shaft cone 8, whereby the mounting component 2 is centered with respect to an axial direction that coincides with the optical axis 126 of the projection lens 104.

[0033] Unlike in Fig. 1, the socket component 2, more precisely a bottom side 11a of the conical section 11 of the base body 6, is in an initial position in which the socket component 2 is placed on the further socket component 4, not in contact with a top side 9a of the bottom section 9 of the hollow shaft cone 8, since there is an axial gap between the two.

[0034] In order to close the gap and in this way to ensure that the underside 11a of the conical section 11 of the socket component 2 comes into axial contact with the upper side 9a of the base section 9 of the hollow shaft cone 8, the conical section 10 of the hollow shaft cone 8 is designed to be elastically expandable: If the socket component 2 is pressed further into the hollow shaft cone 8 by means of clamping screws 12 or by other external forces, the conical section 10 of the hollow shaft cone 8 expands elastically radially outwards and the socket component 2 reaches its Fig. 2. In the fastening position B, the socket component 2 rests on the upper side 9a of the base section 9 of the hollow shaft cone 8, which forms a defined support for the socket component 2 in the axial direction, which corresponds to the Z direction of an XYZ coordinate system.

[0035] In the manner described above, the frame component 2 with the lens 1 is positioned clearly and with repeatable accuracy in all three spatial directions X, Y, and Z. This process, i.e., the detachable attachment to the additional frame component 4, can now be performed as often as desired with a wide variety of assemblies or frame components 2 with any optical elements. This process does not require the presence of a measuring system and can therefore also be performed at the customer's site.

[0036] Fig. 3 shows a socket component 2, which is also detachably connected to another socket component 4 via an exchange interface. In contrast to Fig. 2 has the exchange interface of the further socket component 4 in Fig. 3 does not have a hollow shaft cone 8, but rather three prism receptacles 13a-c, which are arranged at equal intervals around the circumference of the second socket component 4. The socket component 2 with the Fig. 2, also has three cylindrical contact contours 14a-c arranged at equal distances in the circumferential direction. The contact contours 14a-c rest on contact surfaces of two prism parts 15a,b of the respective prism receptacles 13a-c, as is exemplified for the first prism receptacle 13a in Fig. 4. By placing the three contact contours 14a-c on the two contact surfaces of the three prism receptacles 13a-c, the frame component 2 is centered, so that the center of the frame component 2 is aligned with the optical axis 126 of the projection lens 104 of Fig. 1 matches.

[0037] The underside 11a of the Fig. 2 cylindrically shaped base body 11 of the socket component 2 does not rest on the top side 4a of the second socket component 4 in a starting position not shown in the picture, but rather there is an air gap between the top side 4a of the further socket component 4 and the underside 9a of the socket component 2. By pressing the socket component 2 into the prism receptacles 13a-c, these are elastically deformed and thereby expanded. In the example shown, the two prism parts 15a,b, between which a groove is formed, are elastically expanded, i.e. the angle between the two bearing surfaces of the prism parts 15a,b for the contact contour 14a increases, whereby a bottom side 6a of the base body 6 of the socket component 2 is brought into contact with the top side 4a of the further socket component 4, which serves as an axial contact surface. In this way, the socket component 2 can also be positioned with repeatable accuracy in all three spatial directions X, Y, Z.

[0038] It is also possible to Fig. 2 shown hollow shaft cone 8 with a prism mount to enable an exact rotational alignment of the lens 1 or the mount component 2 relative to the optical axis 126 of the projection lens 104. In this case, the hollow shaft cone 8 aligns the center of the mount component 2 concentrically to the optical axis 126 of the projection lens 104 in the manner described above. The prism mount (not shown in the image), which as in Fig. 3 is arranged on the edge of the further frame component 4, enables a precise, repeatable rotational or angular alignment of the frame component 2 about the optical axis 126 of the projection lens 104. As in connection with Fig. 2, Fig. 3 and Fig. 4, in this case too, for example, with the aid of clamping screws 12, an axial contact of the underside 11a of the socket component 2 on the upper side 4a of the further socket component 4 can be achieved in order to position the socket component 2 with repeatable accuracy in the Z direction.

[0039] Since frictional forces occur during the elastic expansion of the hollow shaft cone 8 or the prism receptacles 13a-c, it is advantageous if the frame component 2 and / or the further frame component 4 is provided with a friction-reducing coating, e.g. with a DLC coating, at least in the areas in which friction occurs.

[0040] It is also possible to attach an optical element 1 in the form of a mirror to the frame component 2 instead of a lens, as shown in Fig. 5. In the example shown, the mounting component 2 is a mirror module, such as is used in a projection lens of a semiconductor technology system in the form of an EUV lithography system. In this case, the mirror 1 can be detachably connected to the mounting component 2 in the form of the mirror module.

[0041] The frame component 2 with the mirror 1 is detachably attached to a further frame component 4, which can be a central module, for example in the form of a support frame or the like. For this purpose, the further frame component 4 has two hollow shaft cones 8, 8a, which are designed to be elastically expandable and are attached to a Fig. 6 shown top side of the further socket component 4 are arranged spaced apart from each other. The hollow shaft cones 8, 8a, more precisely the conical sections 10, 10a of the two hollow shaft cones 8, 8a running along the outer circumference, are inserted into recesses in the socket component 2 (see also Fig. 7) are inserted, which have two conical sections 11, 11a, and brought into contact with an axial contact surface of the further socket component 4 in the manner described above. In this way, the socket component 2 can be positioned with repeatable accuracy in all three spatial directions X, Y, Z and aligned in a desired angular position in the Z direction.

[0042] As in Fig. 6, the second hollow shaft cone 8a has a conical section 10a, which has a reduced diameter along a spacing direction or along a connecting line between the two hollow shaft cones 8, 8a in order to act in the manner of an elongated hole for tolerance compensation. The reduced diameter of the second hollow shaft cone 8a is Fig. 6 is realized in that the conical section 10a of the second hollow shaft cone 8a is cut off on two opposite sides, which run transversely to the spacing direction of the two hollow shaft cones, as shown in Fig. 6 can be seen.

Claims

[1] Optical arrangement (104), in particular projection lens, comprising: at least one frame component (2) to which an optical element (1), preferably a lens or a mirror, is in particular permanently attached, characterized by at least one further socket component (4) to which the at least one socket component (2) is detachably fastened, wherein the further socket component (4) and / or the socket component (2) has at least one hollow shaft cone (8, 8a) and / or at least one prism receptacle (13a-c). [2] Optical arrangement according to claim 1, in which in a fastening position (B) the frame component (2) rests against an axial contact surface (9a, 4a) of the further frame component (4), or vice versa, wherein the hollow shaft cone (8, 8a) and / or the prism receptacle (13a-c) is / are elastically widened in the fastening position (B). [3] Optical arrangement according to claim 1 or 2, wherein the frame component (2) has a conical section (11, 11a) which, for centering the frame component (2), bears against a conical section (10, 10a) of the hollow shaft cone (8, 8a) of the further frame component (4), or vice versa. [4] Optical arrangement according to claim 3, wherein the conical section (10) of the hollow shaft cone (8, 8a) is designed to be elastically expandable. [5] Optical arrangement according to claim 3 or 4, in which the hollow shaft cone (8), preferably the conical section (10) of the hollow shaft cone (8), has a prism receptacle. [6] Optical arrangement according to one of claims 3 to 5, in which the further frame component (4) and / or the frame component (2) has two hollow shaft cones (8, 8a) spaced apart from one another, wherein preferably the conical section (10a) of one of the two hollow shaft cones (8a) has a reduced diameter along a spacing direction of the two hollow shaft cones (8, 8a). [7] Optical arrangement according to claim 1 or 2, wherein the further frame component (4) or the frame component (2) has at least three prism receptacles (13a-c), which are preferably arranged uniformly distributed in the circumferential direction on the further frame component (4). [8] Optical arrangement according to one of claims 2 to 7, in which the at least one prism receptacle (13a-c) for the elastic expansion has two prism parts (15a,b) which are movable relative to one another. [9] Optical arrangement according to claim 8, in which the frame component (2) or the further frame component (4) has at least one preferably spherical or cylindrical contact contour (14a-c) which bears against the two prism parts (15a,b) of the prism receptacle (13a-c). [10] Optical arrangement according to one of the preceding claims, in which the frame component (2) is detachably fastened to the further frame component (4) by means of at least one clamping screw (12) acting in the axial direction (z). [11] Optical arrangement according to one of the preceding claims, in which the frame component (2) has an adjustment ring (5) to which the optical element (1) is permanently fastened, preferably by an adhesive bond (3), wherein the adjustment ring (5) is preferably detachably fastened to a base body (6) of the frame component (2) by means of at least one adjustment screw (7). [12] Optical arrangement according to one of the preceding claims, in which the frame component (2) and / or the further frame component (4) has a friction-reducing coating, preferably a DLC coating.

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