Memsmicro-mirror unit and its manufacture

Abstract

This invention relates to a method for manufacturing a MEMS micromirror unit (100) used in a projection illumination system (1) for photolithography, and the MEMS micromirror unit (100) manufactured according to the method. The invention also relates to a system for semiconductor technology having a corresponding MEMS micromirror unit (100) and an electronic component manufactured using such a system. The MEMS micromirror unit (100) includes a MEMS mirror array assembly (110) having a MEMS mirror array structure (111) and a bonding structure (115), an interface element (120) for securing the MEMS micromirror unit (100) to a higher-level assembly, a bonding structure (125) interacting with it in a form-fitting manner, and at least one stop surface (121, 121'). The manufacturing process includes the following steps: a) measuring the position and orientation of the MEMS mirror array structure (111) relative to the bonding structure (115); b) adjusting the relative position and / or orientation of the bonding structure (125) and at least one stop surface (121, 121') of the interface element (120) such that after the MEMS mirror array assembly (110) and the interface element (120) are bonded via the bonding structure (115, 125), the relative position and orientation of the MEMS mirror array structure (111) and at least one stop surface (121, 121') correspond to a predetermined position and orientation.

Description

[0001] This application claims priority to German patent application 10 2023 123 889.2, filed on September 5, 2023. The contents of that German patent application are incorporated herein by reference. Technical Field

[0002] This invention relates to a method for manufacturing a MEMS micromirror unit for use in a semiconductor technology device, and to a MEMS micromirror unit for use in a semiconductor technology device. The invention also relates to a semiconductor technology device having a corresponding MEMS micromirror unit, and to an electronic component manufactured using such a device. Background Technology

[0003] In the prior art, equipment used in semiconductor technology is understood as equipment used to manufacture or test microstructured components or components required for this purpose. An example of such equipment is a photolithography projection exposure apparatus.

[0004] Photolithography is used to produce microstructured components, such as integrated circuits. The projection exposure equipment used in this process includes an illumination system and a projection system. The image of a mask (also called a mask master) illuminated by the illumination system is projected onto a substrate (such as a silicon wafer) to reduce the size of the former. The substrate is coated with a photosensitive layer and arranged in the image plane of the projection system. The projection system is used to transfer the mask structure onto the photosensitive coating of the substrate.

[0005] In illumination systems, particularly for projection exposure equipment designed for the EUV range (i.e., exposure wavelengths from 5 nm to 30 nm), two faceted mirrors are typically arranged in the beam path between the actual exposure radiation source and the mask to be illuminated. These mirrors allow for radiation homogenization in a manner substantially equivalent to that of a fly-eye condenser. The faceted mirror closer to the exposure radiation source in the beam path is typically a so-called field faceted mirror, while the other faceted mirror is a so-called pupil faceted mirror.

[0006] In order to produce different intensity and / or incident angle distributions during mask illumination, it is known that at least one of two faceted mirrors (particularly the facets of a field faceted mirror) is formed by one or more individually electromechanically pivotable micromirrors. The same is disclosed accordingly, for example, in WO 2012 / 130768 A2.

[0007] In order to obtain small-sized individual micromirrors, the known approach is to form micromirror arrays as so-called MEMS mirror arrays, which are mirror arrays made of microelectromechanical systems (MEMS).

[0008] In a MEMS mirror array, multiple small mirror elements are each mounted individually movable relative to a common base. For each mirror element, at least one actuator is provided, enabling adjustment of the mirror element along separately predefined degrees of freedom. The mirror elements are typically pivotable about two axes that are perpendicular to each other and parallel to the base; in this case, sufficient actuators are provided to allow the mirror elements to pivot precisely about these axes independently of each other. Sensors can also be provided for individual mirror elements, enabling determination of the mirror element's position relative to the base, thereby allowing monitoring of mirror alignment. A particularly advantageous embodiment of the mirrors in a MEMS mirror array is described in DE 10 2015 204 874 A1.

[0009] A method for fabricating micromirrors or MEMS mirror arrays comprising multiple such micromirrors is disclosed in DE 10 2015 220 018 A1, along with further details relating to possible configurations of the micromirrors.

[0010] To form the faceted reflectors of the projection exposure device, multiple MEMS mirror arrays are fixed to a higher-level component in a dense planar grid arrangement. For this purpose, the MEMS mirror array is designed as a MEMS micromirror unit (“micromirror unit”, MMU), which, in addition to the actual MEMS mirror array, also has an interface element through which the unit can be fixed to the higher-level component.

[0011] In order for MEMS mirror arrays to be arranged at relatively close intervals to achieve the desired purpose, and to have the required precise position and alignment in the inserted and fixed states of the assembly, the individual mirror elements of the MEMS micromirror unit must be positioned and aligned with high precision relative to their interface elements. The problem addressed by this invention is to provide a method for manufacturing a MEMS micromirror unit and a MEMS micromirror unit that meets these requirements.

[0012] This problem is solved by the method according to claim 1 and the MEMS micromirror unit according to claim 12. The dependent claims relate to advantageous improvements. Summary of the Invention

[0013] Therefore, the present invention relates to a method for manufacturing a MEMS micromirror unit for a semiconductor technology device, the MEMS micromirror unit comprising a MEMS mirror array assembly having a MEMS mirror array structure and a bonding structure disposed on a side opposite to the MEMS mirror array structure, and an interface element for fixing the MEMS micromirror unit to a higher-level assembly, the interface element having a bonding structure that interacts with the bonding structure of the MEMS mirror array assembly in an interlocking manner and at least one abutting surface for positioning and / or aligning the MEMS micromirror unit relative to the higher-level assembly, the method comprising the following steps:

[0014] a) Measure the relative position and orientation of the MEMS mirror array structure with respect to the bonding structure of the MEMS mirror array assembly;

[0015] b) Adapting the bonding structure of the interface element and the relative position and / or orientation of at least one adjacent surface such that once the MEMS mirror array assembly and the interface element have been bonded by the bonding structure, the relative position and / or orientation of the MEMS mirror array structure and at least one adjacent surface corresponds to a predetermined position and orientation.

[0016] Furthermore, the present invention relates to a MEMS micromirror unit for use in a device for semiconductor technology, comprising: a MEMS mirror array assembly having a MEMS mirror array structure and a bonding structure disposed on a side opposite to the MEMS mirror array structure; and an interface element for securing the MEMS micromirror unit to a higher-level assembly, the interface element having a bonding structure that interacts with the bonding structure of the MEMS mirror array assembly in an interlocking manner and at least one abutting surface for positioning and / or aligning the MEMS micromirror unit relative to the higher-level assembly, wherein the MEMS micromirror unit is manufactured according to the present invention.

[0017] The present invention also relates to an apparatus for semiconductor technology comprising at least one MEMS micromirror unit according to the invention, the MEMS micromirror unit being used to deflect radiation employed by the apparatus, for example, for exposing an object. The invention also extends to electronic components manufactured using suitable semiconductor technology equipment, wherein the components preferably comprise structures in the micrometer and / or nanometer range.

[0018] In the context of this invention, "apparatus for semiconductor technology" means any apparatus that can be used to manufacture or test microstructured components or components required for this purpose. This particularly covers inspection apparatus and metrology systems, in addition to photolithography projection exposure apparatus. In the case of inspection apparatus for masks or wafers, the variability of illumination can be increased, for example by means of one or more MEMS micromirror units, which can result in higher contrast or entirely new image representation of the mask or wafer surface, which is advantageous for mask or wafer inspection. The same applies to metrology systems that can be used to measure masks, wafers, or any other optical elements (especially mirrors), in which case increased variability of illumination can improve measurement results.

[0019] This invention is based on the understanding that merely reducing permissible tolerances when manufacturing individual components of a MEMS micromirror unit and connecting these components does not, or at least cannot easily, achieve the precision required for using such a MEMS micromirror unit in devices for semiconductor technology—namely, the position and orientation of individual mirror elements relative to the adjacent surfaces of an interface element used to define the position and alignment relative to the higher-level components of the entire MEMS micromirror unit. To address this problem, this invention provides combining an actual MEMS mirror array structure with possible other components to form a MEMS mirror array assembly, which includes a defined bonding structure on the side facing away from the MEMS mirror array structure. If the appropriate components are available, the position and orientation of the MEMS mirror array structure can be accurately measured relative to the bonding structure. Using the position and orientation information obtained from this measurement as a basis, the interface elements can then be adjusted in such a way that, after the MEMS mirror array assembly and the interface elements are joined at the joint structure provided for this purpose, their interlocking interactions (and thus accurate position and orientation) produce a predetermined position and orientation of the MEMS mirror array structure relative to those adjacent surfaces on the interface elements with sufficient precision. These adjacent surfaces are used to at least partially fix the position and orientation of the MEMS micromirror units relative to the upper-level components.

[0020] The relative position and / or orientation of the interface element's engagement structure and at least one adjacent surface can be adjusted by modifying the engagement structure of the interface element. For this purpose, the surface of the interface element used for form-fitting can be appropriately modified, for example, by machining. Specifically, for this purpose, the interface element in its initial state can be a blank, where the surface in question has not yet been designed or has only been preliminarily designed, so that the surface ultimately needed and desired for form-fitting can be produced purely by machining, for example, using a CNC milling machine.

[0021] As an alternative or supplement, the mating structure of the interface element and the relative position and / or orientation of at least one of the at least one adjacent surface can also be adapted (e.g., by machining). This also allows defining the position and orientation of the adjacent surface relative to the mating structure of the interface element, and, after the MEMS mirror array assembly is mated, also relative to the MEMS mirror array structure. To allow for adaptation by machining, it is preferable that the interface element blank is configured such that the basic region of the adjacent surface has sufficient material excess.

[0022] The interface element can preferably be formed in two parts. In this case, the main element of the interface element forms a bonding structure for connection to the MEMS mirror array assembly. A compensation element forms at least one adjacent surface of the interface element, and this compensation element can be fixed to the main element in a predetermined orientation and position—at least partially predetermined by, for example, appropriate shaping. The adaptation of the relative position and / or orientation of the bonding structure of the interface element and at least one adjacent surface can be achieved by processing the compensation element alone.

[0023] If the compensation element has a geometrically simple shape, the process of adapting the required compensation element is generally easy to perform. For example, the compensation element can be a compensation sleeve whose inner or outer contour (for connection to the main element or for contact with a higher-level assembly) is fixedly predetermined, while other corresponding contours can be modified. Needless to say, this also applies to the end face of the compensation sleeve, which can also represent the adjacent surface. The combination of the main element and the compensation element, relative to each other in a predetermined position and / or orientation, then forms the interface element provided according to the invention. In this case, it is irrelevant whether the main element and the compensation element are initially joined together or whether the main element is joined to the MEMS mirror array assembly in the first step and only subsequently attached to the compensation element.

[0024] In view of the two-part embodiments of the interface element described above, it should also be noted that when a component corresponding to the main component is connected to or integrated with the MEMS mirror array assembly, the area for connecting to the component corresponding to the compensation element is subsequently measured and adapted based on the measurement before the component corresponding to the compensation element is attached. The component corresponding to the main component should be considered as part of the MEMS mirror array assembly, and the component corresponding to the compensation element is the actual interface element.

[0025] The relative position and / or orientation of the interface element's bonding structure and at least one adjacent surface can be adapted in at least two, preferably three, translational degrees of freedom and / or at least two, preferably two, rotational degrees of freedom. In this way, the position can preferably be adapted in the direction and / or perpendicular to the base region of the MEMS mirror array structure. Alternatively or additionally, the tilt of the MEMS mirror array structure relative to the interface element can preferably also be varied. In other words, the relative orientation should be affected by rotation about two axes extending parallel to the base region of the MEMS mirror array structure.

[0026] The number and configuration of adjacent surfaces on the interface element are preferably selected such that as few degrees of freedom as possible are retained when inserted into a higher-level component, preferably one degree of freedom (specifically, a translational degree of freedom for insertion or subsequent removal of the MEMS micromirror unit) or two degrees of freedom (plus, for example, a rotational degree of freedom about the first translational degree of freedom). The degrees of freedom that might be retained immediately after insertion can then be blocked by suitable securing devices. In particular, suitable securing can be achieved through force fit and / or form fit (e.g., by threaded connection).

[0027] The joining structure of the MEMS mirror array assembly and interface element is preferably configured to be self-centering. As a result, when the MEMS mirror array assembly and interface element are joined, it ensures that the relative position and / or attitude affected by self-centering can be achieved with high precision, which also benefits the accuracy of the relative attitude of the MEMS mirror array structure and at least one adjacent surface. The joining structure also preferably includes a travel stop for the degree of freedom in the direction of the self-centering axis. In this case, high positional accuracy is also achieved in this direction.

[0028] For example, the bonding structure of a MEMS mirror array assembly may include a cylindrical protrusion. In this case, the bonding structure of the interface element may include a corresponding cylindrical receptacle, which, as described above, can be adapted if necessary. Furthermore, the base region at the free end of the protrusion and / or the surface from which the protrusion projects may take the form of a travel stop. The travel stop then predetermines the degree of engagement between the two bonding structures during bonding.

[0029] The actual engagement of the MEMS mirror array assembly and interface elements is preferably achieved through force fitting or integral bonding.

[0030] In particular, shrinkage fits can be used as a joining process if the joining structures have a suitable form. Here, two joining structures are manufactured relative to each other for an interference fit, and one joining structure is heated to engage, causing the interference fit to temporarily become a transition fit or clearance fit, in which the parts to be joined can slide into each other. This reverts to an interference fit after cooling, meaning a force-fit connection. If a press-fit connection is to have an airtight construction, an indium insert can be placed between the surfaces provided for forming the press fit.

[0031] If the intention is to create cohesive connections, the MEMS mirror array assembly and interface element are preferably joined by welding. If the contact area between the MEMS mirror array assembly and the interface element does not provide any surface on the MEMS mirror array assembly and / or the interface element made of a weldable material, the MEMS mirror array assembly and / or the interface element may have a weldable coating, particularly a metallic coating, provided in the relevant area.

[0032] In addition to the MEMS mirror array structure and bonding structure, the MEMS mirror array assembly may also include: at least one substrate having at least one application-specific integrated circuit (ASIC); redistribution elements for converting the MEMS mirror array structure contacts into those contacts (typically larger contacts) that can be inserted into or soldered with control and power cables; and / or spacer elements, preferably for forming cavities, particularly for housing electronic components. The specified elements—typically also like the MEMS mirror array structure—may be fabricated on a silicon-based substrate. The connections between elements are preferably highly thermally conductive, allowing heat dissipation from the MEMS mirror array structure via the MEMS mirror array assembly. The defined bonding structure is preferably integrally formed with the elements of the MEMS mirror array assembly furthest from the MEMS mirror array structure. In this way, separate bonding structure elements can be omitted.

[0033] Each element of a MEMS mirror array assembly, as well as the connection between two adjacent elements, is subject to tolerances that generally exceed the requirements for use in devices for semiconductor technology, but can be adequately compensated for by the method according to the invention.

[0034] The interface element preferably has a basic cylindrical or truncated conical shape, wherein at least one adjacent surface is preferably at least partially formed by the basic shape. Such a configuration of the interface element has proven advantageous.

[0035] To explain the MEMS micromirror unit according to the present invention, refer to the above statement.

[0036] The proof of a MEMS micromirror unit produced by the method according to the invention can be provided based on a comparative examination of at least two MEMS micromirror units. If two examined MEMS micromirror units with identical structures have, in principle, the same (i.e., within what is considered permissible tolerance) relative positions and orientations of the MEMS mirror array structure and at least one adjacent surface, but the contact surfaces between the two components of the MEMS micromirror unit that affect this position and orientation exhibit differences beyond conventional tolerances, then it can be assumed that the contact surfaces in question have been adapted according to the method according to the invention.

[0037] Referring to the foregoing statements, the semiconductor technology apparatus according to the present invention is used to explain its application. In particular, the apparatus may be a photolithography projection exposure apparatus. In this case, at least one MEMS micromirror unit is preferably arranged within the illumination system. Attached Figure Description

[0038] The invention will now be described by way of example with reference to the accompanying drawings, in which:

[0039] Figure 1 : A schematic diagram of a photolithography projection exposure apparatus including a MEMS micromirror unit according to the present invention is shown;

[0040] Figures 2a-2c : A schematic diagram of a first exemplary embodiment of the manufacturing method according to the present invention is shown;

[0041] Figure 3 : Shown according to Figures 2a-2c A schematic diagram of the interface components manufactured during the process of the method;

[0042] Figures 4a-4c : A schematic diagram illustrating a second exemplary embodiment of the manufacturing method according to the present invention; and

[0043] Figure 5 It shows something similar to Figures 4a-4c A schematic diagram of an alternative starting point for the manufacturing method according to the present invention. Detailed Implementation

[0044] Figure 1 A schematic meridional section is shown through a photolithography projection exposure apparatus 1, an example of a device used in semiconductor technology. In this case, the projection exposure apparatus 1 includes an illumination system 10 and a projection system 20.

[0045] The illumination system 10 illuminates the object field 11 in the object plane or mask master plane 12. For this purpose, the illumination system 10 includes an exposure radiation source 13, which, in the illustrated exemplary embodiment, emits illumination radiation containing light in the EUV range, specifically having wavelengths between 5 nm and 30 nm. The exposure radiation source 13 can be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge-generated plasma) source. It can also be a synchrotron-based radiation source. The exposure radiation source 13 can also be a free-electron laser (FEL).

[0046] The illumination radiation emitted from the exposure radiation source 13 is initially focused into the concentrator 14. The concentrator 14 may be a concentrator having one or more elliptical and / or hyperboloidal reflective surfaces. The illumination radiation may be incident on at least one reflective surface of the concentrator 14 at grazing incidence (GI) (i.e., at an angle of incidence greater than 45°) or normal incidence (NI) (i.e., at an angle of incidence less than 45°). The concentrator 14 may be structured and / or coated, on the one hand to optimize its reflectivity to the radiation used, and on the other hand to suppress intrusive light.

[0047] Downstream of the light collector 14, the illumination radiation propagates through the intermediate focal point in the intermediate focal plane 15. If the illumination system 10 is constructed with a modular design, the intermediate focal plane 15 can, in principle, be used to separate (including structurally separate) the illumination system 10 into a radiation source module and an illumination optics unit 16, described below, which includes an exposure radiation source 13 and a light collector 14. In the case of such separation, the radiation source module and the illumination optics unit 16 together form the modularly constructed illumination system 10.

[0048] The illumination optics unit 16 includes a deflector 17. The deflector 17 may be a planar deflector, or alternatively a mirror with a beam-affecting effect beyond a pure deflection effect. Alternatively or additionally, the deflector 17 may be implemented as a spectral filter that separates the wavelength of the illumination radiation used from the intrusive light having a wavelength that deviates from it.

[0049] Deflector 17 is used to deflect radiation emitted from exposure radiation source 13 to first faceted mirror 18. If, as in the present case, the first faceted mirror 18 is arranged in a plane of illumination optics unit 16, which serves as a field plane optically conjugate with mask master plane 12, then the faceted mirror is also called a field faceted mirror.

[0050] The first faceted reflector 18 comprises a plurality of micromirrors 18', each of which can be individually pivoted about two mutually perpendicular axes for the purpose of controllable terrain faceting. Each facet is preferably provided with an orientation sensor (not shown) for determining the orientation of the micromirror 18'. Thus, the first faceted reflector 18 is a microelectromechanical system (MEMS system), as described, for example, in DE 10 2008 009 600 A1.

[0051] The second faceted mirror 19 is arranged downstream of the first faceted mirror 18 in the beam path of the illumination optics unit 16, resulting in a double-faceted system, the basic principle of which is also known as a fly-eye integrator. If the second faceted mirror 19 (as in the illustrated exemplary embodiment) is arranged in the pupil plane of the illumination optics unit 16, it is also called a pupil faceted mirror. However, the second faceted mirror 19 may also be arranged at a distance from the pupil plane of the illumination optics unit 16, thus the specular reflector is produced by a combination of the first and second faceted mirrors 18, 19, as described, for example, in US 2006 / 0132747 A1, EP1 614 008 B1, and US 6,573,978.

[0052] The second faceted mirror 19 does not, in principle, need to be composed of pivotable micromirrors. Instead, it may comprise individual facets formed by a single mirror or a manageable number of mirrors (significantly larger than the micromirrors), which are either stationary or tiltable only between two defined end positions. However, as shown, the second faceted mirror 19 may also provide a microelectromechanical system with multiple micromirrors 19', each of which can individually pivot about two mutually perpendicular axes, and each micromirror 19' preferably includes an orientation sensor.

[0053] The individual facets of the first faceted mirror 18 are imaged into the object field 11 by means of the second faceted mirror 19, which is typically only an approximate image. The second faceted mirror 19 may be the final beam-shaping mirror, or in fact the final mirror reflecting the illumination radiation in the beam path upstream of the object field 11.

[0054] In each case, one facet of the second faceted mirror 19 is assigned to exactly one facet of the first faceted mirror 18 to form an illumination channel for illuminating the object field 11. This can in particular result in illumination according to Köhler's principle.

[0055] For the purpose of illuminating the object field 11, the facets of the first faceted mirror 18 are superimposed on each other through the corresponding facets of the second faceted mirror 19 to form an image. Here, the illumination of the object field 11 is as uniform as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0056] By selecting the illumination channel used (which can be achieved without problems through the proper setting of the micromirrors 18' of the first faceted mirror 18), the intensity distribution in the entrance pupil of the projection system 20, as described below, can still be set. This intensity distribution is also referred to as the illumination setting. Incidentally, it may be advantageous here to arrange the second faceted mirror 19 imprecisely in a plane optically conjugate with the pupil plane of the projection system 20. In particular, the pupil faceted mirror 19 may be arranged tilted relative to the pupil plane of the projection system 20, for example, as described in DE 10 2017 220 586 A1.

[0057] However, in such Figure 1 In the arrangement of components of the illumination optical unit 16 shown, the second faceted mirror 19 is arranged in the region conjugate with the entrance pupil of the projection system 20. The deflecting mirror 17 and the two faceted mirrors 18, 19 are arranged to be tilted relative to the object plane 12 and relative to each other in each case.

[0058] In an alternative embodiment (not shown) of the illumination optics unit 16, a transmission optics unit comprising one or more mirrors may be additionally provided in the beam path between the second faceted mirror 19 and the object field 11. The transmission optics unit may specifically include one or two normal incident mirrors (NI mirrors) and / or one or two grazing incident mirrors (GI mirrors). Using the additional transmission optics unit, different orientations of the incident pupils of the tangential and sagittal beam paths of the projection system 20 described below can be particularly considered.

[0059] Alternatively, it can be omitted Figure 1 The deflector 17 shown is used for this purpose. For this purpose, the faceted mirrors 18 and 19 should be properly arranged relative to the radiation source 13 and the light collector 14.

[0060] The object field 11 in the mask master plane 12 is transferred to the image field 21 in the image plane 22 by means of the projection system 20.

[0061] For this purpose, the projection system 20 includes multiple reflectors M i They are numbered sequentially according to their arrangement in the beam path of the projection exposure device 1.

[0062] exist Figure 1 In the example shown, the projection system 20 includes six reflectors M1 to M6. It can also have four, eight, ten, twelve, or any other number of reflectors M1. iAlternatives are also possible. The penultimate reflector M5 and the last reflector M6 each have a channel opening for illumination radiation, thus the projection system 20 shown is a double-shielded optical unit. The projection system 20 has an image-side numerical aperture greater than 0.3, or it can be greater than 0.6, for example, it can be 0.7 or 0.75.

[0063] Mirror M i The reflecting surface can be a free-form surface without a rotational symmetry axis. However, the reflecting mirror M... i The reflective surface can also be alternatively designed as an aspherical surface with exactly one axis of rotational symmetry of its shape. Just like the reflector in illumination optics unit 16, reflector M... i Highly reflective coatings for illumination radiation can be used. These reflective coatings can be designed as multilayer coatings, particularly with alternating layers of molybdenum and silicon.

[0064] The projection system 20 has a large object-image shift in the y-direction between the y-coordinate of the center of the object field 11 and the y-coordinate of the center of the image field 21. This object-image shift in the y-direction can have a magnitude approximately the same as the z-distance between the object plane 12 and the image plane 22.

[0065] In particular, the projection system 20 can be designed to be deformable, that is, it has different imaging scales β, especially in the x and y directions. x β y The two imaging scales β of the projection system 20 x β y Preferably (β) x , β y = (+ / -0.25, / +-0.125). An imaging scale β of 0.25 here corresponds to a reduction with a ratio of 4:1, while an imaging scale β of 0.125 results in a reduction with a ratio of 8:1. A positive sign in the case of imaging scale β means imaging without image inversion; a negative sign indicates imaging with image inversion.

[0066] Other imaging scales are also possible. An imaging scale β with the same sign and the same absolute size in both the x and y directions. x β y That's also possible.

[0067] The number of intermediate image planes in the x and y directions of the beam path between object field 11 and image field 21 may be the same or different, depending on the embodiment of projection system 20. Examples of projection systems 20 with different numbers of such intermediate images in the x and y directions are known from US 2018 / 0074303 A1.

[0068] Specifically, the projection system 20 may include concentric entrance pupils. These can be accessible, or they may be inaccessible.

[0069] A mask master 30 (also referred to as a mask), arranged in the object field 11, is exposed by the illumination system 10 and transferred onto the image plane 21 by the projection system 20. The mask master 30 is held by a mask master holder 31. The mask master holder 31 can be displaced in the scanning direction, in particular, by a mask master displacement driver 32. In the exemplary embodiment shown, the scanning direction extends in the y-direction.

[0070] The structure on the mask master 30 is imaged onto the photosensitive layer of the wafer 35, which is arranged in the image field 21 region of the image plane 22. The wafer 35 is held by a wafer holder 36. The wafer holder 36 can be moved by a wafer displacement driver 37, particularly in the y-direction. The displacement of the mask master 30, first by the mask master displacement driver 32, and the displacement of the wafer 35, secondarily by the wafer displacement driver 37, can be synchronized with each other.

[0071] Figure 1 The projection exposure apparatus 1 or its illumination system 10 shown (the above description substantially reflects known prior art) is characterized in that the first and / or second faceted reflectors 18, 19 are each composed of a plurality of MEMS micromirror units 100 according to the invention (see Figures 2 to 4), wherein each MEMS micromirror unit 100 includes a plurality of micromirrors 18', 19'. Individual MEMS micromirror units 100 are fixed to a higher-level assembly to collectively form... Figure 1 The faceted mirrors 18 and 19 are schematically depicted. In addition to mechanical fixation, the upper-level assembly also provides any necessary connections to the individual MEMS micromirror units 100, such as to control electronics and / or cooling circuits.

[0072] Figures 2a-2c A first exemplary embodiment of the MEMS micromirror unit 100 according to the present invention is schematically shown, as can be... Figure 1 The method used, and in particular the method of manufacturing thereof according to the present invention.

[0073] Firstly, according to Figure 2c The structure of the MEMS micromirror unit 100 is described in detail.

[0074] MEMS micromirror unit 100 includes MEMS mirror array assembly 110 and interface element 120 fixedly connected thereto.

[0075] The actual MEMS mirror array structure 111, including multiple micromirrors 18', 19', is part of the MEMS mirror array assembly 110. In the exemplary embodiment shown, 12 × 12 = 144 micromirrors 18', 19' are arranged in a grid-like manner in a common plane 111'. In this case, the MEMS mirror array structure 111 also includes all actuators and sensors required for the individual pivoting of each micromirror 18', 19', as described above.

[0076] MEMS mirror array structure 111 is arranged on a redistribution element 113 made of multilayer ceramic with metallic redistribution planes between the ceramic layers, such as high-temperature multilayer ceramic (“high-temperature co-fired ceramic”, HTCC). A silicon-based substrate 112 with application-specific integrated circuits (ASICs) is also disposed between the redistribution element 113 and the MEMS mirror array structure 111. Using the redistribution substrate 113, the electrical contacts of the MEMS mirror array structure 111 and the ASICs provided for operation are converted into electrical contacts that can, for example, connect electrical control and power supply lines. Furthermore, the redistribution substrate 113 imparts structural integrity to the MEMS mirror array structure 111 and the substrate 112 with the ASICs, which themselves may not possess sufficient structural integrity.

[0077] Spacer element 114 is fixedly connected to redistribution element 113 and together with redistribution element 113 forms an inner cavity (not shown), in which, for example, connectors for additional integrated circuits or control and power lines for the MEMS mirror array structure 111 can be arranged. Additionally, cooling lines can be guided within the cavity for heat dissipation, particularly from the MEMS mirror array structure 111. For this purpose, the MEMS mirror array structure 111, the substrate 112 with application-specific integrated circuits, the redistribution element 113, and spacer element 114 should be configured thermally conductively and connected such that heat generated at the MEMS mirror array structure 111 can be conducted to the cavity and from there to the optionally present cooling lines.

[0078] The bonding structure 115 is integrally formed with the spacer element 114 and serves as the element furthest from the MEMS mirror array structure 111 in the MEMS mirror array assembly 110. In this case, the bonding structure 115 takes the form of a cylindrical protrusion 116, wherein the protrusion 116, protruding from the surface 117 of the spacer element 114, acts as a travel stop. A feedthrough 118 is provided in the cylindrical protrusion 116, through which power supply lines and control lines can be guided into the cavity formed by the spacer element 114 and the rewiring element 113.

[0079] Interface element 120 is fixed to the bonding structure 115 of MEMS mirror array assembly 110. In principle, the rotationally symmetric interface element 120 is shown only in cross-section in all figures to show its internal structure and its interaction with MEMS mirror array assembly 110.

[0080] The interface element 120, made of metal, has a generally truncated conical shape. In this case, the side of the frustum-shaped region of the interface element 120 serves as an abutment surface 121, through which the MEMS micromirror unit 100 can be interlocked into the conical receptacle of the upper-level component. After insertion into this conical receptacle, the MEMS micromirror unit 100 retains one degree of freedom, specifically rotational freedom about the longitudinal axis 122 of the interface element 120. To secure the MEMS micromirror unit 100 within the conical receptacle, the free end of the interface element 120 is provided with a threaded region 123, which supports the interface element 120 within the receptacle, creating a force fit at the abutment surface 121, which also suppresses the aforementioned two degrees of freedom.

[0081] At the opposite end of the threaded region 123, the interface element 120 includes a engagement structure 125 corresponding to the engagement structure 115 on the MEMS mirror array assembly 110. The engagement structure 125 includes a cylindrical receiving portion 126 adapted to accommodate an oversized cylindrical protrusion 116, and a travel stop 127 abutting against the travel stop 117 in the assembled state of the MEMS micromirror unit 110. To connect the interface element 120 and the MEMS mirror array assembly 110, the former is heated so that it subsequently retracts onto the cylindrical protrusion 116 of the MEMS mirror array assembly 110. In this case, the engagement structures 117, 127 are self-centering, specifically around the axis of the cylindrical protrusion 116. If the two travel stops 117 and 127 come into contact during this process, the degree of freedom in the axial direction of the cylindrical projection 116 is also restricted, and only the angular position of the interface element 120 relative to the MEMS mirror array assembly 110 about the longitudinal axis 122 of the interface element 120 remains undetermined. However, this angular position can also be specified and precisely maintained by appropriate markings on the interface element 120 and the MEMS mirror array assembly 110.

[0082] The interface element 120 is hollow, allowing power and control lines to pass through without any problems.

[0083] In order for the MEMS micromirror unit 100 to be used as part of the faceted mirrors 18, 19 in a photolithography projection exposure apparatus, particularly for EUV projection exposure apparatus, the orientation and position of the individual micromirrors 18', 19' relative to the adjacent surface 121 on the interface element must meet the corresponding specifications within a narrow tolerance range. Therefore, in the case of some projection exposure apparatuses, the position of the micromirrors 18', 19' in the plane 111' may deviate from the position specification relative to the adjacent surface 121 by, for example, a maximum of 10 μm. Here, the tilt angle of the plane 111' relative to the adjacent surface 121 should deviate from the target by, for example, a maximum of 0.2°.

[0084] In order to Figure 2c These specifications are achieved in the case of the MEMS micromirror unit 100 shown, which has been fabricated using the method according to the invention, as follows. Figures 2a-2c As shown.

[0085] exist Figure 2a In the initial state of the method according to the invention shown, the MEMS mirror array assembly 110 is fully present, i.e., the individual elements 111-114 are fully bonded together. The interface element 120 is in the form of a blank 120', wherein, in particular, the adjacent surface 121 is fully fabricated, but the bonding region 125 still has a certain amount of excess material.

[0086] In the first step of this method ( Figure 2a In this study, the position and orientation of the MEMS mirror array structure 111 relative to the bonding structure 115 of the MEMS mirror array assembly 110 are measured with high precision. For the orientation and position thus established, all deviations from the ideal assembly that may occur during the production and bonding of the individual elements 111-114 of the MEMS mirror array assembly 110 are taken into account.

[0087] Subsequently, measurements of the MEMS mirror array assembly 110 are used to determine how the bonding structure 125 on the interface element 120 should be designed so that, once the MEMS mirror array assembly 110 and the interface element 120 are properly bonded together, the desired orientation and position of the MEMS mirror array structure 111 relative to the adjacent surface 121 are accurately obtained.

[0088] exist Figure 2b In the image, the design of the engagement structure 125 for the interface element 120 on the blank 120' is shown in dashed lines on the left. Based on this design, the blank 120' can be machined—for example, using a CNC milling machine—so that, as a result, the interface element 120 with the desired design is available.

[0089] As already described, the interface element 120 prepared in this manner can then be coupled to the MEMS mirror array assembly 110, making the MEMS micromirror unit 100 available, wherein the specifications relating to the attitude and position of the MEMS mirror array structure 111 relative to the adjacent surface 121 are met with the required precision.

[0090] For purely illustrative purposes, in Figures 2a-2c In the exemplary embodiment shown, there is actually no need to compensate for position and orientation deviations, which is why the assembly structure 125 of the interface element 120 and the final design appear symmetrical. To clarify the situation according to... Figures 2a-2c In the exemplary embodiments, large position and attitude deviations can also be compensated. Figure 3 The design for establishing the bonding structure 125 is depicted using dashed lines and for MEMS mirror array assembly 110 (not shown here). This bonding structure 125 serves not only to compensate for the lack of connection between the MEMS mirror array assembly 110 and the bonding structure 115 of the MEMS mirror array structure 111 (not shown here) in three degrees of freedom (specifically in plane 111' (see...)). Figure 2a Small positional deviations (and perpendicular to it) are also used to compensate for the two rotational degrees of freedom (specifically about the plane 111' (see...) Figure 2a The attitude deviation of the two rotation axes in the equation.

[0091] Figures 4a-4c A second exemplary embodiment of the method according to the invention and a second exemplary embodiment of the MEMS micromirror unit 100 according to the invention are shown. The exemplary embodiments are largely consistent with those from... Figures 2a-2c The embodiments are the same, which is why refer to the explanation given there, and the differences between the two exemplary embodiments will be discussed below only.

[0092] According to Figures 4a-4c In an exemplary embodiment, the interface element 120 is implemented as two parts. Therefore, the interface element 120 includes a main element 128 (which is shown in cross-section only in principle) and a compensation element 129 (see [link to example]) that is initially separate from the main element 128. Figure 4a ).

[0093] The main component 128 has a basic cylindrical shape and a joining structure 125 is provided at its end. This joining structure 125 is in the initial state ( Figure 4a The engagement structure 116 of the MEMS mirror array assembly 110 is fully adapted to it, meaning that the engagement structure 125 can be connected to the engagement structure 116 of the MEMS mirror array assembly 110 by force engagement only through a shrink fit. Furthermore, the threaded area 123 for fixing to the upper-level assembly is located at the other end.

[0094] The compensating element 129 is designed as a compensating sleeve, with its outer sheath set as the subsequent adjacent surface 121; however, its inner radius is smaller than the decisive outer radius of the main element 128.

[0095] In a similar way Figure 2a After measuring the MEMS mirror array assembly 110, a target design for the compensation element 129 is then established. This is followed by the correct assembly of the main element 128 and the compensation element 129 to form the interface element 120, and then the interface element 120 is coupled to the MEMS mirror array assembly 110. Figure 4c The MEMS micromirror unit 100 shown has two adjacent surfaces 121, 121', which can interact with a suitable receiving portion of the upper-level component to ensure the predetermined attitude and position of the MEMS mirror array structure 111 relative to the upper-level component.

[0096] Figure 4b The left-hand side shows the compensating element 129 as the blank 129', where the established target design is depicted using dashed lines. It is evident that only the inner contour and end faces of the compensating element 129 need to be processed here to achieve the target design. In particular, the outer sheath, which serves as the abutment surface 121, does not need to be processed and can be used, for example, for clamping the blank 129 in a CNC milling machine and / or adjusting lathe. Figure 4b The right side depicts the fully processed compensation element 129.

[0097] In order to accomplish such Figure 4a The MEMS micromirror unit 100 shown initially attaches the compensation element 129 to the main element 128 by integral bonding, particularly by welding or thermal bonding, to create a contractile fit between the two elements 128, 129 made of metal. Maintaining the correct angular position of the compensation element 129 relative to the main element 128 can be ensured by appropriate markings on the two elements 128, 129. Subsequently, the interface element 120 assembled in this manner is securely connected to the MEMS mirror array assembly 111 by contracting it onto the bonding structure 115, where the correct angular position can again be ensured by appropriate markings.

[0098] Figure 5 A third exemplary embodiment of the method according to the invention is shown, which largely corresponds to the method according to... Figures 4a-4c The second exemplary embodiment is why the explanation above is referenced.

[0099] Figure 5 Only with Figure 2a and Figure 4aThe initial state of the method according to the invention is shown in a corresponding manner. According to... Figure 4a In the exemplary embodiment, the main element 129 assigned to the interface element 120 is now connected to the spacer element 114 in its initial state and is therefore part of the MEMS mirror array assembly 110. Thus, the main element 129 forms the bonding structure 115 of the MEMS mirror array assembly 110, whose relative position and orientation can be measured relative to the MEMS mirror array structure 111. Figure 5 In an alternative to the separate formation of the main element 129 depicted, the main element 129 may be integrated with the spacer element 114.

[0100] In this case, only the compensation element 129 (which only forms) Figure 4a A portion of the interface element 120 is used as the interface element 120. In the exemplary embodiment shown, the inner diameter of the interface element 120 is fitted to the cylindrical shape of the main element 129 with a clearance fit or transition fit. However, the outer diameter is significantly oversized relative to the receiving portion of the upper-level component provided for the MEMS micromirror unit 100, so appropriate machining based on the performed measurements allows for the production of adjacent surfaces 121, 121' suitable for compensating for any attitude and position errors, and as Figure 4c As illustrated in the example. Therefore, Figure 5 The blank 120' of the interface element 120 or the blank 129' of the compensation element 129 is depicted. Figure 4b The manufacturing process described in the figure is different; only the outer contour is modified in the blanks 129' and 120' instead of the inner contour, so as to achieve the desired compensation element 129 or interface element 120.

[0101] Subsequently, the interface element 120 can be inserted into the MEMS mirror array assembly 110 and, in particular, integrally connected to the main element 129 forming the joint structure 115 by soldering and in the correct angular position that can be ensured by appropriate marking.

[0102] At the end of the manufacturing method according to the invention outlined above, from according to Figure 5 Starting with the MEMS mirror array assembly 110 and interface element 120, as... Figure 4c The MEMS micromirror unit 100 shown is illustrated.

Claims

1. A method for manufacturing a MEMS micromirror unit (100) for use in semiconductor technology devices, the MEMS micromirror unit (100) comprising: MEMS mirror array assembly (110), the MEMS mirror array assembly (110) having a MEMS mirror array structure (111) and a bonding structure (115) disposed on a side opposite to the MEMS mirror array structure (111); and an interface element (120) for fixing the MEMS micromirror unit (100) to a higher-level assembly, the interface element having a bonding structure (125) and at least one adjacent surface (121, 121'), the bonding structure (125) interacting with the bonding structure (115) of the MEMS mirror array assembly (110) in an interlocking manner, the at least one adjacent surface (121, 121') for positioning and / or aligning the MEMS micromirror unit (110) relative to the higher-level assembly, the method comprising the following steps: a) Measure the relative position and orientation of the MEMS mirror array structure (111) with respect to the bonding structure (115) of the MEMS mirror array assembly (110); b) Adapting the relative position and / or orientation of the bonding structure (125) of the interface element (120) and the at least one adjacent surface (121, 121') such that once the MEMS mirror array assembly (110) and the interface element (120) have been bonded by the bonding structure (115, 125), the relative position and / or orientation of the MEMS mirror array structure (111) and the at least one adjacent surface (121, 121') corresponds to a predetermined position and orientation.

2. The method according to claim 1, Its features are, The relative position and / or orientation of the interface element (120) and the at least one adjacent surface (121, 121') are adapted by adapting the interface element (120) to the engagement structure (125).

3. The method according to claim 1 or 2, Its features are, The relative position and / or orientation of the interface element (120) and the engagement structure (125) and the at least one adjacent surface (121, 121') are adapted by adapting the at least one adjacent surface (121, 121').

4. The method according to claim 3, Its features are, The interface element (120) is implemented in two parts, wherein the main element (128) includes the bonding structure (125) for connection to the MEMS mirror array assembly (110) and a compensation element (129), the compensation element (129) being able to be fixed to the main element (128) in a predetermined orientation and position and forming the at least one adjacent surface (121, 121'), wherein the relative position and / or orientation of the bonding structure (125) and the at least one adjacent surface (121, 121') of the interface element (120) is adapted by processing the compensation element (129) before fixing it to the main element (128).

5. The method according to any one of the preceding claims, Its features are, The relative positions and / or orientations of the interface element (120)’s engagement structure (125) and the at least one adjacent surface (121, 121') are adapted in at least two, preferably three, translational degrees of freedom and / or at least two, preferably two, rotational degrees of freedom.

6. The method according to any one of the preceding claims, Its features are, The number and configuration of the adjacent surfaces (121, 121') on the interface element (120) are selected such that no more than two degrees of freedom are retained when inserted into the superior assembly, and these are preferably blocked by suitable fixing devices.

7. The method according to any one of the preceding claims, Its features are, The joining structures (115, 125) of the MEMS mirror array assembly (110) and the interface element (120) are configured to be self-centering, wherein the joining structures (115, 125) preferably include travel stops for degrees of freedom in the direction of the self-centering axis.

8. The method according to any one of the preceding claims, Its features are, The engagement structure (115) of the MEMS mirror array assembly (110) includes a cylindrical protrusion (116), the base region of which and / or the protrusion (116) from its protruding surface (117) are preferably formed as a travel stop.

9. The method according to any one of the preceding claims, Its features are, The MEMS mirror array assembly (110) and the interface element (120) are joined at the joining structure (115, 125) by press fit, preferably by shrink fit, or by integral joining, preferably by welding.

10. The method according to any one of the preceding claims, Its features are, In addition to the MEMS mirror array structure (111) and the bonding structure (115), the MEMS mirror array assembly (11) also includes a substrate (112) having at least one application-specific integrated circuit, a redistribution element (113) and / or a spacer element (114), wherein the defined bonding structure (115) is preferably integrally formed with the elements (111-114) of the MEMS mirror array assembly (110) furthest from the MEMS mirror array structure (110).

11. The method according to any one of the preceding claims, Its features are, The interface element (120) has a basic shape of cylindrical or truncated cone, wherein at least one adjacent surface (121, 121') is preferably formed at least partially by the basic shape.

12. A MEMS micromirror unit (100) for use in semiconductor technology devices, comprising: MEMS mirror array assembly (110), the MEMS mirror array assembly having a MEMS mirror array structure (111) and a bonding structure (115) disposed on a side opposite to the MEMS mirror array structure (111); and an interface element (120) for fixing the MEMS micromirror unit (100) to a higher-level assembly, the interface element having a bonding structure (125) and at least one adjacent surface (121, 121'), the bonding structure (125) interacting with the bonding structure (115) of the MEMS mirror array assembly (110) in an interlocking manner, the at least one adjacent surface (121, 121') for positioning and / or aligning the MEMS micromirror unit (100) relative to the higher-level assembly. Its features are, The MEMS micromirror unit (100) is manufactured according to any one of the preceding claims.

13. An apparatus for semiconductor technology, comprising at least one MEMS micromirror unit (100) according to claim 12 for deflecting radiation used by said apparatus.

14. The device according to claim 13, Its features are, The device is a photolithography projection exposure device (1), wherein at least one MEMS micromirror unit (100) is preferably disposed in the illumination system (10).

15. An electronic component, Its features are, The component is manufactured using a semiconductor technology apparatus according to claim 14, wherein the component preferably comprises a structure in the micrometer and / or nanometer range.

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