Microelectromechanically movable element and system

Abstract

The invention relates to a microelectromechanically movable element (103) for use in a microelectromechanical system (100) and to a corresponding microelectromechanical system (100), in particular for use in systems for semiconductor technology. The microelectromechanically movable element (103) comprises a base plate (104), on the side of which facing away from the base structure (101) a mirror plate (105) having a curvature geometry is arranged, wherein the mirror plate (105) is connected to the base plate (104) via a pedestal (106), wherein the geometries of the contact points (107, 108) between the pedestal (106) and the mirror plate (105) on the one hand and the pedestal (106) and the base plate (104) on the other hand are different. The microelectromechanical system (100) comprises an element (103) which can be moved microelectromechanically at least with respect to a base structure (101) in at least one degree of freedom by at least one actuator (102), wherein the microelectromechanically movable element (103) is designed according to the invention.

Description

micro-electro-mechanically movable element and system

[0001] The present application claims priority from German patent application 10 2024 205 025.3, filed on May 29, 2024. The content of that German patent application is incorporated into the present application text by reference.

[0002] The invention relates to a micro-electro-mechanically movable element for use in a micro-electro-mechanical system and a corresponding micro-electro-mechanical system, in particular for use in semiconductor technology equipment.

[0003] In the prior art, semiconductor technology equipment refers to equipment used for the production or testing of microstructured devices or the components required for their manufacture. An example of such equipment is a projection exposure system for photolithography.

[0004] Photolithography is used to manufacture microstructured components, such as integrated circuits. The projection exposure system used comprises an illumination system and a projection system. The image of a mask (also called a reticulum) illuminated by the illumination system is projected in a reduced size onto a substrate, such as a silicon wafer, coated with a photosensitive layer and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0005] In lighting systems, especially projection exposure systems designed for the EUV range, i.e., for exposure wavelengths from 5 nm (or possibly 2 nm) to 30 nm, but also for the DUV range with exposure wavelengths of, for example, 193 nm, two faceted mirrors are usually arranged in the beam path between the actual exposure radiation source and the mask to be illuminated. The faceted mirror that is closer to the source of the light source in the beam path is often a so-called field faceted mirror, the other a so-called pupil faceted mirror.

[0006] To produce different intensity and / or angle of incidence distributions when illuminating the mask, it is known to form the facets of at least one of the two faceted mirrors – in particular those of the field faceted mirror – from one or more individually electromechanically pivotable micromirrors. A corresponding method is disclosed, for example, in WO 2012 / 130768 A2.

[0007] In order to achieve a small size for the individual micromirrors, it is known to form groups of micromirrors in the form of a so-called MEMS mirror array, namely a mirror array made of micro-electro-mechanical systems (MEMS).

[0008] Micro-electro-mechanical systems (MEMS) are small components that combine micromechanical structures and electronic elements on a single chip. MEMS can be manufactured using integrated circuits, similar to microchips. A MEMS essentially comprises a basic structure on which movable elements, controlled relative to the basic structure, are arranged.

[0009] A MEMS mirror array contains a large number of small Mirror elements can each be moved individually relative to one The mirror elements are mounted on a common basic structure. At least one actuator is provided for each mirror element, allowing it to be adjusted along a predefined degree of freedom. Often, the mirror elements can be pivoted about two axes perpendicular to each other and parallel to the base. In such cases, sufficient actuators are provided to allow the mirror element to be pivoted independently about these axes. Sensors can also be provided for the individual mirror elements to determine their position relative to the base, thus enabling monitoring of the mirrors' alignment. A particularly advantageous embodiment for the mirrors of a MEMS mirror array is described in DE 10 2015 204 874 A1.

[0010] A method for manufacturing a micromirror or a MEMS mirror array comprising a plurality of such micromirrors is disclosed - together with further details on a possible embodiment of the micromirror - in DE 10 2015 220 018 Al .

[0011] In particular, when the reflective surface of the mirror elements is not planar but curvature to achieve desired optical properties, it is known to manufacture the mirror elements in two parts. The reflective surface is formed by a mirror plate provided with a suitable reflective coating, while the connection to the base structure and the actuator is made via a base plate that is generally flat. The mirror plate and base plate, which are generally manufactured separately, are firmly joined together, usually by gluing.

[0012] It has been shown that the mechanically sound connection between the mirror plate and the base plate has a negative effect. This can influence the curvature of the mirror plate, which can also result in deviations from the desired optical properties of the mirror element.

[0013] The object of the present invention is to create a micro-electro-mechanically movable element and a micro-electromechanical system in which the disadvantages known from the prior art no longer occur or only occur to a reduced extent.

[0014] This problem is solved by a micro-electro-mechanically movable element according to claim 1 and a micro-electro-mechanical system according to claim 11. Advantageous further developments are the subject of the dependent claims.

[0015] Accordingly, the invention relates to a micro-electro-mechanically movable element for use in a micro-electro-mechanical system with a basic structure (102) and at least one actuator for moving the element relative to the basic structure in at least one degree of freedom, wherein the element comprises a base plate on the side of which facing away from the basic structure a mirror plate with a curvature geometry is arranged, and wherein the mirror plate is connected to the base plate via a pedestal, wherein the geometry of the contact points between pedestal and mirror plate as well as between pedestal and base plate are different.

[0016] Furthermore, the invention relates to a micro-electro-mechanical system comprising an element that is micro-electro-mechanically movable relative to a basic structure in at least one degree of freedom by at least one actuator, wherein the micro-electro-mechanically movable element is designed according to the invention.

[0017] First, some terms used in connection with the invention will be explained:

[0018] A "plate" is a component that is basically spread out in a plane and consists of a rigid material. The extent of the plate in the plane is regularly many times greater, often even by at least an order of magnitude (i.e., by at least a factor of 10), than the thickness of the plate.

[0019] A "plate with curvature geometry" is a rigid component with essentially constant thickness, whose curvature is reflected on the two main surfaces of the plate. This can be illustrated with a plate that is initially flat, into which a curvature is subsequently introduced (e.g., by bending): in this case, one main surface of the plate takes on a concave shape, and the other main surface of the plate takes on a convex shape.

[0020] The invention recognizes that by arranging a pedestal between the mirror plate and the base plate of a micro-electro-mechanically movable element, in which the geometry of the contact points between the pedestal and mirror plate, as well as between the pedestal and base plate, differs, a sufficiently strong connection between the mirror plate and the base plate can be created, while simultaneously the contact surface between the pedestal and mirror plate can be designed in such a way that negative effects of the contact point on the curvature geometry of the mirror plate are reduced. The geometry of the contact point between the pedestal and the base plate can be optimized for the strongest possible connection between the pedestal and the base plate.

[0021] The latter is particularly relevant if the pedestal is formed in one piece with the mirror plate, e.g. The pedestal is formed by being grown directly alongside the mirror plate during its production. At the time the pedestal is grown, the mirror plate is typically in a flat initial state before the curvature geometry is subsequently introduced. The effect of the pedestal, which is formed integrally with the mirror plate, should be minimized. The connection between the integrally formed pedestal and the base plate is then made later by a material bond, particularly by adhesive bonding. For this purpose, the pedestal is preferably designed with an optimized surface for material bonding at the contact area intended for contact with the base plate. The material bond can be formed in any desired manner; alternatively to adhesive bonding, for example, it can also be achieved by bonding, soldering, or fusing.

[0022] However, it is also possible to manufacture the pedestal as a single piece with the base plate – for example, by suitable welding – in which case the connection to the mirror plate is achieved by a fabric joint. Alternatively, the pedestal can be manufactured as a separate component, which is then connected to both the mirror plate and the base plate by a fabric joint.

[0023] To accommodate the different geometries of the contact points, it can be provided that the extent of the contact point between the pedestal and the base plate is larger in at least one direction than the extent of the contact point between the pedestal and the mirror plate. The larger extent of the contact point creates a larger contact area for any potential material bond between the base plate and the pedestal. Furthermore, the contact point between the base plate and the pedestal is more moment-resistant due to its larger extent. Conversely, the extent of the contact point between the pedestal and the mirror plate can be kept smaller. which reduces the negative effects on the curvature geometry of the mirror plate.

[0024] Alternatively or additionally, the contact area between the pedestal and the base plate can be larger than the contact area between the pedestal and the mirror plate. The larger contact area between the pedestal and the base plate ensures the strength and, if necessary, the stiffness of the connection between the pedestal and the base plate, while the relatively smaller contact area between the pedestal and the mirror plate reduces their negative effects on the curvature geometry of the mirror plate.

[0025] The contact surface of the interface between the pedestal and the mirror plate can have more than one closed edge. In other words, the contact point in question does not have to be a single continuous surface within a single outer edge, but can also have, for example, cutouts, etc.

[0026] In particular, the contact area of ​​the contact point between the pedestal and the mirror plate can also comprise several unconnected surface sections. These surface sections or sub-surfaces can be arranged at a distance from one another.

[0027] In a preferred embodiment, the contact surface of the contact point between the pedestal and the mirror plate can be annular, or the surface segments of the contact surface can be ring-segmented. The ring shape includes not only circular but also elliptical forms. A corresponding design of the contact surface of the contact point between the pedestal and the mirror plate is particularly suitable for simple (i.e., in one dimension) and double (i.e., in two dimensions) applications. Curved mirror plates are advantageous in terms of dimensions, whereby the specific design of the ring (segment) shape can be optimized with regard to the actual curvature geometry of the mirror plate, e.g. by FEM analysis.

[0028] As already mentioned, it is preferred if the pedestal is formed integrally with the mirror plate, with the curvature geometry preferably being incorporated into the mirror plate after the integral formation of the pedestal. Due to the integral design, the contact area between the pedestal and the mirror plate can generally be smaller compared to a contact area for a material bond, while still ensuring a sufficiently strong connection.

[0029] In particular, the pedestal can be bonded to the base plate using a liquid adhesive. If the pedestal is not integral with the mirror plate, for example, because the pedestal is integral with the base plate, the pedestal can alternatively or additionally be bonded to the mirror plate using a liquid adhesive.

[0030] The mirror plate can be made at least mostly of monocrystalline silicon and / or the base plate of polycrystalline silicon or another material. The dimensions of the mirror plate and / or the base plate are preferably between 0.5 mm x 0.5 mm and 5 mm x 5 mm, more preferably 1 mm x 1 mm.

[0031] For an explanation of the micro-electro-mechanical system according to the invention, reference is made to the preceding statements.

[0032] The micro-electro-mechanical system is preferably a micromirror, preferably as part of a MEMS mirror array, with a surface area opposite the The basic structure comprises at least one, preferably two, preferably rotationally movable, mirror element. The micro-electro-mechanical system can preferably be configured for use in a semiconductor technology system, in particular a protection exposure system.

[0033] The invention will now be described by way of example with reference to advantageous embodiments and the accompanying drawings. These show: Figure 1: a schematic representation of a projection exposure system for photolithography comprising a micro-electro-mechanical system according to the invention; Figure 2: a schematic representation of the micro-electro-mechanical system according to the invention from Figure 1; and Figure 3a-d: schematic representations of alternative embodiments of the micro-electro-mechanical system according to Figure 2.

[0034] Figure 1 shows a schematic meridional section of a projection exposure system 1 for photolithography as an example of a system for semiconductor technology. The projection exposure system 1 comprises an illumination system 10 and a projection system 20.

[0035] The lighting system 10 illuminates an object field 11 in an object plane or reticulum plane 12. The lighting system 10 comprises an exposure radiation source 13, which in the illustrated embodiment emits illumination radiation comprising at least useful light in the EUV range, i.e., in particular with a wavelength between 5 nm and 30 nm. The exposure radiation source 13 can be a plasma source, for example an LPP source (Laser Produced Plasma, plasma generated by a laser) or a DPP source (Gas Discharge Produced Plasma, plasma generated by gas discharge). It can also be a synchrotron-based radiation source. The exposure radiation source 13 can also be a free-electron laser (FEL).

[0036] The illumination radiation emanating from the light source 13 is first focused in a collector 14. The collector 14 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 14 can be illuminated with grazing incidence (Gl), i.e., with angles of incidence greater than 45°, or with normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 14 can be structured and / or coated, on the one hand to optimize its reflectivity for the useful radiation and on the other hand to suppress stray light.

[0037] After the collector 14, the illumination radiation propagates through an intermediate focus in an intermediate focal plane 15. If the illumination system 10 is to be constructed in a modular manner, the intermediate focal plane 15 can, in principle, be used for the separation – including structural separation – of the illumination system 10 into a radiation source module, comprising the exposure radiation source 13 and the collector 14, and the illumination optics 16 described below. With such a separation, the radiation source module and the illumination optics 16 then together form a modularly constructed illumination system 10.

[0038] The lighting optics 16 include a deflecting mirror 17. The deflecting mirror 17 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 17 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation from stray light of a different wavelength.

[0039] The deflecting mirror 17 deflects the radiation from the illumination radiation source 13 onto a first faceted mirror 18. If the first faceted mirror 18 is arranged – as in the present case – in a plane of the illumination optics 16 that is optically conjugate to the reticular plane 12 as the field plane, it is also referred to as a field faceted mirror.

[0040] The first faceted mirror 18 comprises a plurality of micromirrors 18' that can be individually pivoted about two mutually perpendicular axes for the controllable formation of facets, each preferably equipped with an orientation sensor (not shown) for determining the orientation of the micromirror 18'. The first faceted mirror 18 is thus a microelectromechanical system (MEMS system), as described, for example, in DE 10 2008 009 600 A1.

[0041] In the beam path of the illumination optics 16, a second faceted mirror 19 is arranged downstream of the first faceted mirror 18, resulting in a double-faceted system, the basic principle of which is also known as a honeycomb condenser (Fly's Eye Integrator). If the second faceted mirror 19 is arranged in a pupil plane of the illumination optics 16 – as in the illustrated embodiment – ​​it is also referred to as a pupil faceted mirror. The second faceted mirror However, 19 can also be arranged at a distance from a pupil plane of the illumination optics 16, whereby the combination of the first and the second faceted mirrors 18, 19 results in a specular reflector, as described, for example, in US 2006 / 0132747 Al, EP 1 614 008 Bl and US 6,573,978.

[0042] The second faceted mirror 19 need not be constructed from pivotable micromirrors, but can instead comprise individual facets formed from one or a manageable number of mirrors that are significantly larger than micromirrors, and which are either fixed or tiltable only between two defined end positions. However, as shown, it is also possible to provide the second faceted mirror 19 with a microelectromechanical system comprising a plurality of micromirrors 19' that are individually pivotable about two axes perpendicular to each other, each preferably comprising an orientation sensor.

[0043] With the aid of the second faceted mirror 19, the individual facets of the first faceted mirror 18 are projected onto the object field 11, although this is regularly only an approximate projection. The second faceted mirror 19 can be the last beam-forming or even the last mirror for the illumination radiation in the beam path before the object field 11.

[0044] Each of the facets of the second faceted mirror 19 is assigned to exactly one of the facets of the first faceted mirror 18 to form an illumination channel for illuminating the object field 11. This can result in illumination according to Köhler's principle.

[0045] The facets of the first faceted mirror 18 are each imaged superimposed on a corresponding facet of the second faceted mirror 19 to illuminate the object field 11. The illumination of the object field 11 is as homogeneous as possible. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0046] By selecting the illumination channels ultimately used, which is easily achieved by appropriately adjusting the micromirrors 18' of the first faceted mirror 18, the intensity distribution in the entrance pupil of the projection system 20 described below can also be adjusted. This intensity distribution is also referred to as the illumination setting. Furthermore, it can be advantageous not to arrange the second faceted mirror 19 exactly in a plane that is optically conjugate to a pupil plane of the projection system 20. In particular, the pupil faceted mirror 19 can be tilted relative to a pupil plane of the projection system 20, as described, for example, in DE 10 2017 220 586 A1.

[0047] In the arrangement of the components of the illumination optics 16 shown in Figure 1, the second faceted mirror 19 is arranged in a surface conjugated to the entrance pupil of the projection system 20. Deflection mirror 17 and the two faceted mirrors 18, 19 are each tilted relative to both the object plane 12 and to each other.

[0048] In an alternative embodiment of the illumination optics 16, not shown, a transmission optic comprising one or more Mirrors may be provided. The transmission optics may, in particular, comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (Gl mirrors, grazing incidence mirrors). With an additional transmission optic, different positions of the entrance pupil for the tangential and sagittal beam paths of the projection system 20 described below can be taken into account.

[0049] Alternatively, it is possible to dispense with the deflecting mirror 17 shown in Figure 1, in which case the faceted mirrors 18, 19 must be arranged appropriately opposite the radiation source 13 and the collector 14.

[0050] Using the projection system 20, the object field 11 in the reticulum plane 12 is transferred to the image field 21 in the image plane 22.

[0051] The projection system 20 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1. The mirrors Mi are optical elements 25.

[0052] In the example shown in Figure 1, the projection system 20 comprises six mirrors Mx to M6 as optical elements 25. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage for the illumination radiation, making the projection system 20 a doubly obscured optical system. The projection system 20 has an image-side numerical aperture that is greater than 0.3 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0053] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can also be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 16, can have highly reflective coatings for the illumination radiation. These reflective coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0054] The projection system 20 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 11 and a y-coordinate of the center of the image field 21. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 12 and the image plane 22.

[0055] The projection system 20 can in particular be anamorphic, i.e. it has in particular different image scales β. x , ß y in the x and y directions. The two image scales ß x , ß y of the projection system 20 are preferably located at (ß x , ß y ) = ( + 0.25, / + - 0.125) . A magnification β of 0.25 corresponds to a reduction in the ratio of 4:1, while a magnification β of 0.125 results in a reduction in the ratio of 8:1. A positive sign for the magnification β indicates a magnification without image inversion, a negative sign indicates a magnification with image inversion.

[0056] Other magnification ratios are also possible. Magnification ratios with the same sign and those with the same absolute value are also possible. x , ß y In the x and y directions, adjustments are possible.

[0057] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 11 and the image field 21 can be the same or different, depending on the design of the 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 Al.

[0058] Projection system 20 can, in particular, have a homocentric entrance pupil. This may be accessible. However, it may also be inaccessible.

[0059] A reticle 30 (also called a mask) arranged in the object field 11 is exposed by the lighting system 10 and transferred to the image plane 21 by the projection system 20. The reticle 30 is held by a reticle holder 31. The reticle holder 31 can be moved, particularly in a scanning direction, by means of a reticle displacement drive 32. In the illustrated embodiment, the scanning direction is in the y-direction.

[0060] The reticule 30 can have an aspect ratio between 1:1 and 1:3, preferably between 1:1 and 1:2, and particularly preferably 1:1 or 1:2. The reticule 30 can be substantially rectangular and is preferably 5 to 7 inches (12.70 to 17.78 cm) long and wide, more preferably 6 inches (15.24 cm) long and wide. Alternatively, the reticule 30 can be 5 to 7 inches (12.70 to 17.78 cm) long and It should be 10 to 14 inches (25.40 to 35.56 cm) wide, and preferably 6 inches (15.24 cm) long and 12 inches (30.48 cm) wide.

[0061] A structure on the reticulum 30 is imaged onto a light-sensitive layer of a wafer 35 located in the image plane 22 within the image field 21. The wafer 35 is held by a wafer holder 36. The wafer holder 36 is The wafer 35 can be displaced, in particular along the y-direction, via a wafer displacement drive 37. The displacement of the reticule 30 via the reticule displacement drive 32 and of the wafer 35 via the wafer displacement drive 37 can be synchronized with each other.

[0062] The projection exposure system 1 shown in Figure 1, or its projection system 20, the above description of which essentially reflects known prior art, is characterized in that the first and second faceted mirrors 18, 19 are MEMS mirror arrays with micro-electro-mechanical systems 100 according to the invention, one micro-electro-mechanical system 100 of which is shown schematically in Figure 2 as an example.

[0063] Figure 2 shows a sectional view of a micro-electro-mechanical system 100, which is part of a MEMS mirror array. Therefore, parts of other adjacent micro-electro-mechanical systems 100' are also shown. The micro-electro-mechanical system 100 comprises a basic structure 101 common to the other micro-electro-mechanical systems 100', on which element 103 is arranged to be movable, namely pivotable about two degrees of freedom. Actuators 102 are provided for moving element 103, namely for pivoting it about the two degrees of freedom, thus making element 103 a movable micro-electro-mechanical element 103. Since the movable micro-electro-mechanical element 103 is located on the top side, e.g., If, with the aid of a suitable coating, it is designed to be reflective, element 103 can also be referred to as a mirror element.

[0064] Element 103 comprises a flat base plate 104, which serves as the connection to the base structure 101 and on which parts of the actuators 102 are also arranged. A pedestal 106 is attached to this base plate 104. Mirror plate 105. The mirror plate 105 has a curvature geometry adapted to the desired optical properties of the micro-electro-mechanical system 100.

[0065] The pedestal 106 has a first contact point 108 to the mirror element 105 and a second contact point 107 to the base plate 104.

[0066] The connection between mirror plate 105 and pedestal 106 at the contact point 108 is created by forming the pedestal 106 onto the mirror plate 105 in one piece. The pedestal 106 was thus grown onto the mirror plate 105 during its manufacture. At the time the pedestal 106 was grown, the mirror plate 105 was still flat; the curvature geometry was only introduced into the mirror plate 105 after the pedestal 106 had been grown.

[0067] The connection between base plate 104 and pedestal 106 is subsequently made by material closure, in the present embodiment namely by gluing with suitable adhesive.

[0068] As can be seen from the enlarged view and the sectional view in Figure 2, the geometry of the pedestal 106 in the area of ​​the contact point 108 with the mirror plate 105 differs from that in the area of ​​the contact point 107 with the base plate 104. The contact point 108 is optimized to have as little adverse an impact as possible on the curvature geometry of the mirror plate 105, which, for example, can be doubly curved. Due to the one-piece design of the pedestal 106 with the mirror plate 105, a fairly strong connection between the pedestal 105 and the mirror plate 105 can be assumed, while the contact point 107 is optimized for the best possible material bond with the base plate 104.

[0069] In the illustrated embodiment, both contact points 107, 108 are circular, with the area of ​​the contact surface 107' at contact point 107 between pedestal 106 and base plate 104 being significantly larger than the area of ​​the comparable contact surface 108' at contact point 108 between pedestal 106 and mirror plate 104. Furthermore, the extent of contact point 107 in all directions is greater than the extent of contact point 108.

[0070] Figure 3 shows various alternative embodiments (a) to (d), particularly of the pedestal 106. The illustration is limited to the enlarged and sectional view shown in Figure 2, as the micro-electro-mechanical system 100 is otherwise identical in construction to that shown in Figure 2. The contact surface 107' at the contact point 107 between the pedestal 106 and the base plate 104 is also designed analogously to the embodiment in Figure 2, so reference is made to the preceding descriptions in this regard.

[0071] In the embodiment shown in Figure 3a, the contact point 108 between the pedestal 106 and the mirror plate 105 is designed in an annular shape. Thus, the contact surface 108' of the contact point 108 in question has two closed edges 109, one on the inside and one on the outside of the annular contact surface 108'.

[0072] In the embodiment shown in Figure 3b, the contact point 108 between the pedestal 106 and the mirror plate 105 is designed in the shape of a ring segment. The contact surface 108' of this contact point 108 subsequently comprises several, in this example four, unconnected surface sections 110, each of which is delimited by a closed edge 109.

[0073] In the embodiments shown in Figures 3c and 4d, the contact points 108 between the pedestal 106 and the mirror plate 105j are each adapted to the curvature geometry of the mirror plate 105. In embodiment (c), the mirror plate 105 is still doubly curved, but the curvature in one direction is less than in the other. To minimize the impact on this curvature geometry, the contact surface 108' at the contact point 108 is elliptically shaped, meaning that its extent in one direction is greater than in the other. In embodiment variant ( d) a complex curvature geometry is provided for the mirror plate 105, for which the star-shaped design of the contact surface 108 ' of the contact point 108 between pedestal 106 and mirror plate 105 shown was found to be advantageous.

[0074] In all the embodiments described above, the dimensions of base plate 104 and mirror plate 105 are each 1 mm x 1 mm. The mirror plate 105, and thus also the pedestal 106 formed integrally with it, are made mostly of monocrystalline silicon, while the base plate 104 and the other parts of the movable element 103 are made of polycrystalline silicon. The mirror plate 105 is provided with a reflective coating (not shown) on the side facing away from the pedestal 106.

Claims

Patent claims 1. Micro-electro-mechanically movable element (103) for use in a micro-electro-mechanical system (100) with a basic structure (101) and at least one actuator (102) for the movement of the element (103) relative to the basic structure (101) in at least one degree of freedom, wherein the element (103) comprises a base plate (104) on the side of which facing away from the basic structure (101) a mirror plate (105) with a curvature geometry is arranged, characterized in that the mirror plate (105) is connected to the base plate (104) via a pedestal (106), wherein the geometry of the contact points (107, 108) between pedestal (106) and mirror plate (105) as well as between pedestal (106) and base plate (104) are different.

2. Element according to claim 1, characterized in that the extent of the contact point (107) between pedestal (106) and base plate (106) is larger in at least one direction than the extent of the contact point (108) between pedestal (106) and mirror plate (105).

3. Element according to one of the preceding claims, characterized in that the area of ​​the contact surface (107') of the contact point (107) between pedestal (106) and base plate (106) is larger than the area (108') of the contact surface (108') of the contact point (108) between pedestal (106) and mirror plate (105).

4. Element according to one of the preceding claims, characterized in that the contact surface (108') of the contact point (108) between The pedestal (106) and mirror plate (105) have more than one enclosed edge (109).

5. Element according to one of the preceding claims, characterized in that the contact surface (108') of the contact point (108) between pedestal (106) and mirror plate (105) comprises several mutually unconnected surface sections (110).

6. Element according to one of the preceding claims, characterized in that the contact surface (108') of the contact point (108) between pedestal (106) and mirror plate (105) is annular or the surface sections (110) of the contact surface (108') are annular segment-shaped.

7. Element according to one of the preceding claims, characterized in that the pedestal (106) is formed integrally with the mirror plate (105), wherein the curvature geometry is preferably introduced into the mirror plate (105) after the integral formation of the pedestal (106).

8. Element according to one of the preceding claims, characterized in that the pedestal (106) is connected to the base plate (104) and / or the mirror plate (105) by means of a liquid adhesive.

9. Element according to one of the preceding claims, characterized in that the mirror plate (105) is at least largely made of monocrystalline silicon and / or the base plate (104) is made of polycrystalline silicon.

10. Element according to one of the preceding claims, characterized in that the dimensions of the mirror plate (105) and / or the base plate (104) are between 0.5 mm x 0.5 mm and 5 mm x 5 mm, preferably 1 mm x 1 mm.

11. Micro-electro-mechanical system (100) comprising an element (103) that is micro-electro-mechanically movable relative to a basic structure (101) in at least one degree of freedom by at least one actuator (102), characterized in that the micro-electro-mechanically movable element (103) is configured according to one of claims 1 to 10.

12. Micro-electro-mechanical system according to claim 11, characterized in that the micro-electro-mechanical system (100) is a micromirror, preferably as part of a MEMS mirror array, with a mirror element (103) movable relative to the basic structure (101) by at least one, preferably two, preferably rotational, degrees of freedom.

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