Micro-electromechanical system with fixation

Abstract

The invention relates to a micro-electromechanical system (100) comprising at least one element (101) which can be moved in at least one degree of freedom relative to a base structure (102) in a micro-electromechanical manner by means of at least one actuator (103), such as an element which can be used in projection exposure systems for photolithography in particular. The micro-electromechanical system (100) is characterized in that at least one removable fixation (200) is provided which is an integral part of the micro-electromechanical system (100) at least in the starting state and by means of which at least one element (101) is fixed in at least one degree of freedom of the element (101) relative to the base structure (102) and / or another element (101).

Description

Micro-electro-mechanical system with fixation

[0001] The invention relates to a micro-electro-mechanical system comprising an element which can be moved micro-electro-mechanically in at least one degree of freedom relative to at least one basic structure by at least one actuator, as can be used in particular in systems for semiconductor technology.

[0002] In the state of the art, semiconductor technology systems refer to systems used to manufacture or test microstructured devices or the components required for them. An example of such a system is a projection exposure system for photolithography.

[0003] 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 reticle) illuminated by the illumination system is projected in a reduced size by the projection system onto a substrate coated with a light-sensitive layer and arranged in the image plane of the projection system, for example a silicon wafer, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0004] In illumination systems, especially projection exposure systems designed for the EUV range, i.e., for exposure wavelengths from 5 nm to 30 nm, two facet mirrors are usually arranged in the beam path between the actual exposure radiation source and the mask to be illuminated. The facet mirror located closer to the exposure radiation source in the beam path is One is often a so-called field facet mirror, the other is a so-called pupil facet mirror.

[0005] In order to be able 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 facet mirrors—in particular those of the field facet mirror—from one or more electromechanically individually pivotable micromirrors. A corresponding method is disclosed, for example, in WO 2012 / 130768 A2.

[0006] In order to achieve a small size of 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).

[0007] Micro-electro-mechanical systems are small components that combine micromechanical structures and electronic elements in a single chip. MEMS can be manufactured in a similar way to microchips with integrated circuits. A MEMS essentially comprises a basic structure on which controllably movable elements are arranged.

[0008] In a MEMS mirror array, a large number of small mirror elements are mounted on a common base structure, each of which is individually movable. At least one actuator is provided for each mirror element, with which the mirror element can be adjusted along a predetermined degree of freedom. The mirror elements are often pivotable about two axes running perpendicular to each other and parallel to the base, with sufficient actuators being provided to pivot the mirror element independently of each other about these axes. Sensors can also be provided for the individual mirror elements, with which The position of the mirror element relative to the base can be determined in order to monitor the alignment of the mirrors. A particularly advantageous embodiment for the mirrors of a MEMS mirror array is described in DE 10 2015 204 874 A1.

[0009] A method for producing a micromirror or a MEMS mirror array comprising a plurality of such micromirrors is disclosed - together with further details on a possible design of the micromirror - in DE 10 2015 220 018 A1.

[0010] In micro-electro-mechanical systems such as MEMS mirror arrays, where the weight of the individual moving elements is unfavorable in relation to the strength of the electro-mechanical structure connecting these elements, there is a risk that vibrations or even deliberate movements of the micro-electro-mechanical system, as can occur, for example, during coating or installation of micro-electro-mechanical systems in higher-level assemblies or during transport, may cause permanent damage to a micro-electro-mechanical system or at least to individual elements or their connections. Reinforcing the electro-mechanical structure connecting the individual moving elements is generally not an option, as this would limit the functionality of the electro-mechanical structure.

[0011] The object of the present invention is to create a micro-electro-mechanical system in which this risk is at least reduced.

[0012] This object is achieved by a micro-electro-mechanical system according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0013] Accordingly, the invention relates to a micro-electro-mechanical system comprising an element which is micro-electro-mechanically movable in at least one degree of freedom relative to a basic structure by at least one actuator, wherein at least one removable fixing means is provided which is an integral part of the micro-electro-mechanical system at least in the initial state and with which at least one element is fixed relative to the basic structure and / or another element in at least one degree of freedom of the element.

[0014] As is already clear from the above wording, the term "initial state" in the context of the present invention refers to a state of the micro-electro-mechanical system in which the fixation is (still) a component of the micro-electro-mechanical system. Consequently, the fixation has not yet been removed in the initial state.

[0015] The invention has recognized that the problems known from the prior art can be solved by providing a fixation which is integrated into the micro-electro-mechanical system at least in its initial state and with which an element which is fundamentally movable relative to the basic structure is at least initially fixed. Such a fixation prevents unintentional movement of the element relative to the basic structure, which could lead to damage to the generally delicate mechanics between the element and the basic structure or to components arranged on or at the micro-electro-mechanical system. In particular, this prevents damage to micro-electro-mechanical systems, as can occur in the prior art due to vibrations during transport or installation of the micro-electro-mechanical system in a higher-level assembly.By integrating the fixation into the micro-electro-mechanical system, the risk of... Damage to the device or individual elements due to improper attachment of an external fixation device is minimized. It may be sufficient to restrict only some of the existing degrees of freedom through fixation. However, it is preferred if the fixation restricts all degrees of freedom of the element.

[0016] The fixation can act between an element to be fixed and the base structure. However, it is also possible that the fixation restricts and / or prevents relative movement between two elements of the micro-electro-mechanical system, which usually results in the movement of one of the elements relative to the base structure being fixed in at least one degree of freedom.

[0017] It is preferred if the at least one fixation is reversibly removable. In other words, the fixation should be capable of being restored if necessary after it has been removed. This offers the advantage, for example, that the functionality of the micro-electro-mechanical system can first be fully tested after manufacture before the fixation is subsequently restored in order to protect the micro-electro-mechanical system from damage during transport and / or during installation in a higher-level assembly.

[0018] The at least one fixation can be force-fitting and / or form-fitting.

[0019] In the case of a form-fitting fixation, there may be, for example, a material bridge between the element to be fixed and the base structure and / or another element, which must be removed to release the fixation. The material bridge can be formed with the element to be fixed, the base structure and / or the other element, materially bonded. be connected to the element to be fixed, the basic structure and / or the further element, or be achieved by an interlocking design of the element to be fixed, the basic structure and / or the further element and a fixing element. Of course, any combination of the above is also conceivable. For example, the connection of the fixing to the element to be fixed can be designed differently than the connection of the fixing to the basic structure.

[0020] With force-locking, at least one force acts on the element to be fixed in order to hold it in a predetermined position. In addition to mechanical forces acting on the element to be fixed, other forces, such as magnetic or electrostatic forces, can also act on the element to be fixed and secure it.

[0021] A combination of force-locking and form-locking fixation is also possible.

[0022] The fixation can be a play fixation, i.e. the element to be fixed can move despite existing fixation even in a fundamentally fixed degree of freedom to a certain extent, however predetermined by the fixation. Appropriate play fixation can be sufficient to protect the micro-electro-mechanical system from damage, e.g. in the event of vibrations. At the same time, the play fixation, especially if it can only be removed irreversibly, can make it possible to check the basic functionality of the micro-electro-mechanical system, namely whether actuators and / or sensors for an element fixed only by play fixation basically function.

[0023] Particularly in conjunction with a play fixation, but possibly also independently thereof, the at least one element to be fixed can be moved or held by at least one actuator into a position in which the element rests against the at least one fixation. In this case, the at least one actuator actively participates in the fixation of the element.

[0024] The fixation can preferably be designed in such a way that, in addition to the function of fixing an element, it also serves as a shield, for example against stray vapor, plasma, electric fields, ions and / or radiation. Depending on the design of the fixation, the space between the movable element(s) and the basic structure can be protected in particular. Depending on when the fixation is provided in the manufacturing process of the micro-electro-mechanical system, the shielding effect of the fixation can already be utilized during the subsequent manufacturing steps of the micro-electro-mechanical system. In addition to possible shielding, an already existing fixation of one or more elements can also be helpful in other ways in subsequent manufacturing steps, for example.Steps for coating elements that are already fundamentally movable at this point, which is still possible with greater precision given existing fixation.

[0025] The at least one fixation can be removed by mechanical breaking, severing by heat or particle beam, selective etching of material, and / or demagnetization, e.g., thermally, of magnetically interacting regions. These are generally irreversible processes, which then also irreversibly remove the fixation.

[0026] Alternatively or additionally, at least one fixation can be removed by changing the position, orientation and / or shape of the fixation. If the change to be made is reversible, the fixation can generally be restored if necessary. The change in the fixation can be effected in particular electrically, piezoelectrically, electrostatically, magnetically, pneumatically, hydraulically and / or thermally. The fixation can in particular be moved translationally and / or rotationally.

[0027] At least one of the fixations is preferably designed for the joint fixation of at least two elements. It is, of course, also possible for more than two elements to be fixed by a common fixation.

[0028] The micro-electro-mechanical system can, in particular, be a MEMS mirror array with a plurality of movable mirror elements arranged on the base structure. The mirror elements, which can be arranged, for example, in a grid pattern on the base structure, are generally movable by at least one, usually two, degrees of freedom, whereby these degrees of freedom are usually rotational. The individual mirror elements can then generally be individually pivoted about two mutually perpendicular axes.

[0029] The micro-electro-mechanical system or the MEMS mirror array are preferably designed especially for use in semiconductor technology systems. In this context, a "semiconductor technology system" refers to any system that can be used to manufacture or test microstructured components or the components required for them. In addition to projection exposure systems for photolithography, this also includes inspection systems and Metrology systems. In inspection systems for masks or wafers, one or more MEMS micromirror units can be used, for example, to increase the variability of the illumination. This can result in higher-contrast or entirely new images of the surface of a mask or wafer, which can be advantageous for the inspection of the mask or wafer. A similar situation also applies to metrology systems with which masks, wafers, or other optical elements, such as mirrors, can be measured. Increased variability in the illumination can improve the measurement results.

[0030] Further preferably, the micro-electro-mechanical system is designed to be suitable for use in EUV projection exposure systems.

[0031] The invention will now be described by way of example using advantageous embodiments with reference to the accompanying drawings. They show: Figure 1: a schematic representation of a projection exposure system for photolithography comprising MEMS mirror array modules according to the invention; Figure 2a, b: a schematic representation of a first embodiment of a micro-electro-mechanical system according to the invention in two embodiment variants; Figure 3a, b: a schematic representation of a second embodiment of a micro-electro-mechanical system according to the invention in two states; Figure 4a-c: a schematic representation of a third embodiment of a micro- electro-mechanical system in three versions; Figure 5a, b: a schematic representation of a fourth embodiment of a micro-electro-mechanical system according to the invention in two embodiment variants; Figure 6a-c: a schematic representation of a fifth embodiment of a micro-electro-mechanical system according to the invention in three embodiment variants; Figure 7: a schematic representation of a sixth embodiment of a micro-electro-mechanical system according to the invention; Figure 8a-d: a schematic representation of a seventh embodiment of a micro-electro-mechanical system according to the invention in four embodiment variants; Figure 9a, b: a schematic representation of an eighth embodiment of a micro-electro-mechanical system according to the invention in two states; Figure 10a, b: a schematic representation of a ninth embodiment of a micro-electro-mechanical system according to the invention in two embodiments; and Figure 11a, b: a schematic representation of a tenth embodiment of a micro-electro-mechanical system according to the invention in two embodiment variants.

[0032] 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.

[0033] With the help of the illumination system 10, an object field 11 in an object plane or reticle plane 12 is illuminated. The illumination system 10 comprises an exposure radiation source 13 which, in the illustrated embodiment, emits illumination radiation at least comprising 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 with the aid of a laser) or a DPP source (gas discharge produced plasma, plasma generated by means of gas discharge). It can also be a synchrotron-based radiation source. The exposure radiation source 13 can also be a free-electron laser (FEL).

[0034] The illumination radiation emanating from the exposure radiation source 13 is first bundled in a collector 14. The collector 14 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 14 can be exposed to the illumination radiation at grazing incidence (Gl), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at 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.

[0035] After the collector 14, the illumination radiation propagates through an intermediate focus in an intermediate focal plane 15. If the illumination system 10 is constructed in a modular design, the intermediate focal plane 15 can in principle be used for the - also 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 illumination optics 16 then together form a modular illumination system 10.

[0036] The illumination optics 16 comprises a deflecting mirror 17. The deflecting mirror 17 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 17 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation from stray light of a different wavelength.

[0037] The deflecting mirror 17 deflects the radiation originating from the exposure radiation source 13 onto a first facet mirror 18. If the first facet mirror 18 is arranged—as in the present case—in a plane of the illumination optics 16 that is optically conjugated to the reticle plane 12 as a field plane, it is also referred to as a field facet mirror.

[0038] The first facet mirror 18 comprises a plurality of micromirrors 18' which can be individually pivoted about two mutually perpendicular axes for the controllable formation of facets, which are each preferably equipped with an orientation sensor (not shown) for determining the orientation of the micromirror 18'. The first facet mirror 18 is therefore a micro-electro-mechanical system (MEMS), as is also described, for example, in DE 10 2008 009 600 A1.

[0039] In the beam path of the illumination optics 16, a second facet mirror 19 is arranged downstream of the first facet mirror 18, resulting in a double-faceted system, the basic principle of which is also referred to as a honeycomb condenser (fly's eye integrator). If the second facet mirror 19 - as in the illustrated embodiment - is arranged in a pupil plane of the illumination optics 16, it is also referred to as a pupil facet mirror. However, the second facet mirror 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 facet mirror 18, 19 results in a specular reflector, as is the case, for example. in US 2006 / 0132747 A1, EP 1 614 008 B1 and US 6,573,978.

[0040] The second facet mirror 19 does not necessarily have to 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, which are either fixed or can only be tilted between two defined end positions. However, as shown, it is also possible to provide the second facet mirror 19 with a micro-electro-mechanical system with a plurality of micromirrors 19' that can each be individually pivoted about two axes running perpendicular to one another, each preferably comprising an orientation sensor.

[0041] By means of the second facet mirror 19, the individual facets of the first facet mirror 18 are imaged into the object field 11, whereby this is usually only a approximate imaging. The second facet mirror 19 can be the last beam-forming mirror or actually the last mirror for the illuminating radiation in the beam path in front of the object field 11.

[0042] Each facet of the second facet mirror 19 is assigned to exactly one of the facets of the first facet mirror 18 to form an illumination channel for illuminating the object field 11. This can, in particular, result in illumination according to the Köhler principle.

[0043] The facets of the first facet mirror 18 are each imaged by an associated facet of the second facet mirror 19, superimposed on one another, to illuminate the object field 11. The illumination of the object field 11 is as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0044] By selecting the illumination channels ultimately used, which is easily possible by suitable adjustment of the micromirrors 18' of the first facet 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. In this case, it can also be advantageous not to arrange the second facet mirror 19 exactly in a plane which is optically conjugate to a pupil plane of the projection system 20. In particular, the pupil facet mirror 19 can be arranged tilted relative to a pupil plane of the projection system 20, as is described, for example, in DE 10 2017 220 586 A1.

[0045] In the arrangement of the components of the illumination optics 16 shown in Figure 1, the second facet mirror 19 is arranged on a surface conjugated to the entrance pupil of the projection system 20. Deflecting mirror 17 and the two facet mirrors 18, 19 are tilted both relative to the object plane 12 and relative to each other.

[0046] In an alternative, not-shown embodiment of the illumination optics 16, a transmission optics comprising one or more mirrors can be provided in the beam path between the second facet mirror 19 and the object field 11. The transmission optics can, 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, gracing incidence mirrors). With an additional transmission optics, 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.

[0047] Alternatively, it is possible to dispense with the deflection mirror 17 shown in Figure 1, for which purpose the facet mirrors 18, 19 are then to be suitably arranged opposite the radiation source 13 and the collector 14.

[0048] With the help of the projection system 20, the object field 11 in the reticle plane 12 is transferred to the image field 21 in the image plane 22.

[0049] For this purpose, 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.

[0050] In the example shown in Figure 1, the projection system 20 comprises six mirrors Mx to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation, thus making the projection system 20 shown a doubly obscured optics. 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.

[0051] The reflection surfaces of the mirrors M ± can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can also be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection 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.

[0052] 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.

[0053] The projection system 20 can in particular be anamorphic, ie it has in particular different image scales ß x , ß y in the x- and y-direction. The two magnifications ß x , ß y of the projection system 20 are preferably (ß x , ß y ) = ( + / - 0.25, / + - 0. 125) . A magnification ß of 0.25 corresponds to a A reduction in the ratio 4:1, while a magnification ratio ß of 0.125 results in a reduction in the ratio 8:1. A positive sign for the magnification ratio ß means an image without image inversion, a negative sign means an image with image inversion.

[0054] Other magnifications are also possible, including identical and absolutely identical magnifications ß x , ß y in x and y directions are possible.

[0055] 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 A1.

[0056] The projection system 20 can, in particular, have a homocentric entrance pupil. This can be accessible. But it can also be inaccessible.

[0057] A reticle 30 (also called a mask) arranged in the object field 11 is illuminated by the illumination 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 displaced, in particular in a scanning direction, via a reticle displacement drive 32. In the illustrated embodiment, the scanning direction runs in the y-direction.

[0058] A structure on the reticle 30 is imaged onto a light-sensitive layer of a wafer 35 arranged in the region of the image field 21 in the image plane 22. The wafer 35 is held by a wafer holder 36. The wafer holder 36 is can be displaced, in particular along the y-direction, via a wafer displacement drive 37. The displacement of the reticle 30, on the one hand, via the reticle displacement drive 32, and the wafer 35, on the other hand, via the wafer displacement drive 37, can be synchronized with each other.

[0059] The projection exposure system 1 shown in Figure 1 and its illumination system 10, the above description of which essentially reflects known prior art, is characterized in that the first and / or second facet mirrors 18, 19 each comprise a plurality of micro-electro-mechanical systems 100 according to the invention, each of which is designed as a MEMS mirror array module 100 and each comprises a plurality of micromirrors 18', 19'. The individual MEMS mirror array modules 100 are mounted on a higher-level assembly to jointly form the facet mirrors 18, 19 sketched in Figure 1. The basic structure of the MEMS mirror array modules 100 is known from the prior art.

[0060] The micro-electro-mechanical systems 100 or MEMS mirror array modules 100 used in the projection exposure system 1 according to Figure 1 are designed according to the invention at least temporarily before the final commissioning of the projection exposure system 1 and in particular in the period between the start of production of the micro-electro-mechanical systems 100 and their final use in the projection exposure system 1.

[0061] Since the basic structure and the manufacture of micro-electro-mechanical systems 100 and in particular MEMS mirror array modules 100 or their individual elements 101 or mirror elements 101 is known from the prior art (cf., for example, WO 2012 / 130768 A2, DE 10 2015 204 874 A1 or DE 10 2015 220 018 A1), only the special features of the invention will be discussed below. For these purposes, it is It is sufficient to assume that the micro-electro-mechanical system 100 has at least one element 101 which is micro-electro-mechanically movable relative to a basic structure 102 in at least one degree of freedom by at least one actuator 103. In the exemplary embodiments shown in Figures 2 to 10, the elements 101 are movable about two rotational degrees of freedom, namely, in the various side views, about an axis perpendicular to the plane of the page and an axis in the plane of the page, parallel to the basic structure 102. In some of Figures 2 to 10, one or more actuators 103 are shown in the form of interlocking lamellae 104. In these figures in particular, a representation of the mechanical connection 105 between element(s) 101 and basic structure 102 is generally omitted.

[0062] In Figure 2, two embodiments of the invention are outlined, in which the micro-electro-mechanical system 100, in the respectively illustrated initial state of the micro-electro-mechanical system 100, has a fixation 200 as an integral component, with which the mobility of one element 101 is completely restricted (cf. Figure 2a) or of the two elements 101 at least with regard to the rotational degree of freedom about the respective axis perpendicular to the plane of the sheet.

[0063] The fixation 200 is in each case a form-fitting fixation 200. In the exemplary embodiment according to Figure 2a, an intermediate layer 201 was realized during the manufacture of the micro-electromechanical system 100. This intermediate layer firmly connects the element 101 to the base structure 102 via the lamellae 104 of the actuator 103. This intermediate layer can be removed by selective etching to irreversibly release the fixation.

[0064] In the embodiment according to Figure 2a, a web 202 is provided between the two adjacent elements 101, with which a relative movement of the two elements 101 to one another is prevented, whereby the mobility with respect to the basic structure 102 is at least restricted (namely by the rotational degree of freedom about the respective axis perpendicular to the sheet plane of the elements 101). To remove the web 202, it must be removed, e.g. by selective etching, severing by heat or particle beam, or by mechanical breaking. If the web 202 is materially bonded to the elements 101, the material bond can also be deactivated, e.g. thermally, whereupon the web 202 can then be removed.

[0065] In the embodiment according to Figure 3, a mass 203 extending between the lamellae 104 of the actuators 103 of the elements 101 is provided as a fixation 200 (see Figure 3a). The mass 203 is solid at normal temperatures, in particular at room temperature and / or temperatures up to 35°C, but changes its state of aggregation at higher temperatures which are, however, not critical for the actual micro-electro-mechanical system 100. For example, the mass 203 can liquefy at suitable temperatures and flow into a cavity 110 provided for this purpose in the basic structure 102 (see Figure 3b). During subsequent cooling, the mass 203 solidifies again, but is no longer located between the lamellae 104 of the actuator 103 and can therefore no longer block it. The fixation 200 of the elements 101 is thus removed. The mass 203 can be removed if necessary after completion of the micro-electro-mechanical system 100 and possibly.Tests of the system 100 are introduced.

[0066] Alternatively, the mass 203 can be evaporated or sublimated with a suitable material selection and adjusted temperatures. Selective removal of the mass 203, for example by etching, is also possible. A cavity 110 in the Basic structure 102 is then no longer required.

[0067] The mass 203 can be, for example, wax, carbon or metal.

[0068] In the embodiment shown in Figure 4, the element 101 is fixed relative to the base structure 102 of the micro-electro-mechanical system 100, or adjacent elements 101 are fixed relative to one another by a magnetically generated frictional connection. For this purpose, the elements 101 have suitable magnetic regions 204. By generating a suitable magnetic field, the elements 101 can then be moved into a predetermined position and held there.

[0069] In the embodiment shown in Figure 4a, the required magnetic field is generated by an electromagnet 205. Upon activation, the element 101 is pivoted into the position shown in the figure and held there permanently until the electromagnet 205 is deactivated again. By subsequently reactivating the electromagnet 205, the fixation 200 can also be restored. Thus, the fixation 200 is reversibly removable in this embodiment.

[0070] The embodiment in Figure 4b is fundamentally comparable to that in Figure 4a, with the sole difference that a permanent magnet 206 is provided instead of an electromagnet 205. To remove the fixation 200, the permanent magnet 206 and / or the magnetic regions 204 on the elements 101 must be thermally deactivated. The removal of the fixation 200 is then irreversible.

[0071] The latter also applies to the embodiment according to Figure 4c, in which the individual elements 101 each have several magnetic regions 204, which interact with magnetic regions of adjacent elements 101 in order to prevent relative movement of two adjacent elements 101, or at least to be limited. Furthermore, an external permanent magnet 207 can be provided, with the magnetic field of which at least the element 101 adjacent to the permanent magnet 207 can be further fixed. To release the fixation 200, thermal deactivation of the magnetic regions 204 and / or removal of the permanent magnet 207 is required.

[0072] In the embodiment according to Figure 5, electrically, in particular piezoelectrically adjustable holding arms 208 are provided. In the embodiment according to Figure 5a, two holding arms 208 are provided, which extend along opposite edges of the element 101. The right-hand holding arm 208 in the plan view (Figure 5a, top) and the side view (Figure 5a, bottom) is shown in its holding position, while the left-hand holding arm 208 is shown in the released position. If both holding arms 208 are brought into the holding position, the element 101 is fixed in the illustrated position relative to the base structure 102 by frictional engagement.

[0073] As indicated in the top view in Figure 5a, the holding arms 208 are continuous in the direction of the longitudinal extent along the edge of the element 101 and thus offer protection against the penetration of particles into the area between the element 101 and the basic structure 102. In addition to the actual fixing function - particularly if the lever arms 208 are already provided during the manufacturing process of the micro-electro-mechanical system 100 - the actuator 103 can be effectively protected against unwanted material application, for example when sputtering a coating onto the element 101.

[0074] Figure 5b shows a variant of Figure 5a, in which the holding arm 208 in its holding position engages in a groove 111 provided for this purpose. As a result, the element 101 can already be fixed relative to the base structure 102 by a single holding arm 208.

[0075] Figure 6 shows further embodiments which are similar to the embodiment of Figure 5, since they also comprise one or more adjustable holding arms 208.

[0076] The embodiment shown in Figure 6a is functionally identical to that shown in Figure 5a, which is why reference is made to the above explanations in this regard. However, in the embodiment shown in Figure 6a, the holding arms 208 comprise a parallelogram guide, so that the contact surface of the holding arms 208 intended for contact with the element 101 maintains a predetermined orientation regardless of the angular position of the holding arms 208.

[0077] A comparable mechanism is also provided in the embodiment shown in Figure 6b. However, in this case, the holding arms 208 do not engage laterally on the element 101 in the holding position, but rather form a stop for some of the slats 104 of the actuator 103 (see Figure 6a, right holding arm 208), which fixes the actuator 103 and thus the element 101. In the released position of the holding arms 208, the movement of the actuator 103 and thus of the element 101 is not restricted (see Figure 6b, left holding arm 208).

[0078] In the embodiment according to Figure 6b, an electrically operable expansion element 209 is provided for fixing 200. In the activated state (Figure 6b, right), this expansion element rests against the slats 104 of the actuator 103, thus fixing the actuator and the element 101. In the released state (Figure 6a, left), the expansion element 209 moves far enough away from the slats 104 that the actuator 103 can move freely.

[0079] Figure 7 shows an embodiment fundamentally comparable to the embodiments of Figures 5 and 6. Instead of a holding arm 208 pivotable about an axis perpendicular to the respective plane of the page in the side view or a spreading element 209 expandable about such an axis, the embodiment in Figure 7 shows a holding element 210 which can be pivoted about an axis perpendicular to the plane of the page in the plan view (Figure 7, right).

[0080] The holding arms 208, spreading elements 209, or holding elements 210 can be actively moved; for this purpose, they can, for example, be suitably piezoelectrically designed to be moved by applying voltage. However, it is also possible for the holding arms 208, spreading elements 209, or holding elements 210 to be actuated by interaction with the respective element 101 or the lamellae 104 of the actuator 103, with which they are intended to cooperate for fixation.

[0081] In the embodiment according to Figure 7, the holding element 210 is attracted, for example, by an electrostatic interaction between the holding element 210 and the element 101, the translational degrees of freedom of which are limited by the mechanical connection 105, in such a way that the support designed as a torsion bar 211 is twisted to such an extent that the holding element 210 rests against the element 101 and thus fixes it.

[0082] If necessary, something similar can also be realized in the embodiments according to Figures 5 and 6.

[0083] In the embodiments according to Figure 8, the fixation 200 is actuated pneumatically or hydraulically.

[0084] In the embodiments in Figures 8a and 8b, a holding punch 212 is moved pneumatically or hydraulically in the direction indicated by the arrow 90 by pneumatically or hydraulically applying pressure to a pressure chamber 214 in the base structure 102 on the side facing away from the holding punch 212, which pressure chamber is separated by a flexible membrane 213, so that the membrane 213 is deformed in the direction of the holding punch 212, whereby the holding punch 212 resting on the membrane 213 is raised so far that it rests against one or more elements 101 and thus fixes them (cf. Figures 8a, 8b, each on the right). If the pressure is released, the holding punch 212 sinks accordingly (cf. Figures 8a, 8b, each on the left). The position of the holding stamps 212 shown in Figures 8a and 8b is only exemplary.

[0085] The holding pins 212 in the embodiment according to Figure 8a are designed to interact with a single element 101 and to fix it in place if necessary. The holding pins 212 in Figure 8b can simultaneously bear against two or more adjacent elements 101.

[0086] In the embodiment according to Figure 8c, the holding plunger 212 is fixedly arranged on the membrane 213, which is arranged exposed on the upper side of the base structure 102. By applying pressure to the pressure chamber 214 (cf. Figure 8c, initial state on the left, final state on the right), the membrane 213 is deformed, so that the holding plunger 212 is pivoted as indicated by the arrow 91 and brought into contact with the element 101 or the actuator 103, which then fixes them. By releasing the pressure, the element 101 or the actuator 103 is released again.

[0087] In the embodiment according to Figure 8d, the membrane 213 is arranged directly between the lamellae 104 of the actuator 103 and expands when the Pressure chamber 214 is pressurized in such a way that relative movement of the slats 104 to one another and thus the actuator 103 as a whole are blocked. As a result, the element 101 is also fixed, but can be released again by releasing the pressure.

[0088] The membrane 213 can preferably be arranged and designed in such a way that the fixation achieved via the membrane 213 and optionally a holding stamp 212 is released as soon as the micro-electro-mechanical system 100 is in a vacuum, which is regularly the case when used in the field of systems for semiconductor technology.

[0089] For the embodiment according to Figure 9, it should first be noted that the mechanical connection 105 of element 101 to the base structure 102 is designed to be spring-elastic. By operating the actuator 103 on one side or on two opposite sides in opposite directions, the element 101 can be pivoted about two rotational degrees of freedom, namely by "pulling" the actuator 103 together on one side through suitable, e.g., magnetic, interaction of the slats 104 and, if necessary, "pushing it apart" on the opposite side. This is known from the prior art.

[0090] In the embodiment according to Figure 9, stops 215 are provided which do not limit the basic functionality of the micro-electro-mechanical system 100 and in particular the pivoting of the element 101 by the actuator 103.

[0091] If the actuator 103 - unlike in normal operation - is now controlled in such a way that it "contracts" over its entire surface, a translational movement occurs in which the element 101 approaches the basic structure. Stops 215 are designed such that, in this case, the actuator 103, its slats 104, or stop elements (not shown) provided separately for this purpose on the element 101 bear against them, thereby securing the element 101 relative to the base structure 102. Here, too, the design and arrangement of the stops 215 are shown only as examples. In particular, the stops 215 can be arranged closer to the center.

[0092] Figure 10 shows further exemplary embodiments in which movable flaps 216 are provided for fixing 200 the element 101 or the actuator 103 and its slats 104. The flaps 216 can basically be designed to be operable in a manner comparable to the holding arms 208 described in connection with Figures 5 and 6, so that reference is made to the relevant explanations. The flaps 216 can also be designed as back-vapor protection, i.e. the surfaces and elements located behind the closed flaps 216 can be protected from material application - for example, even during the manufacturing process of the micro-electro-mechanical system 100, provided the flaps 216 are already provided at this time.

[0093] Figure 11 shows a further embodiment of a micro-electro-mechanical system 100 according to the invention. In this micro-electro-mechanical system 100, the basic structure 102 has openings 106 through which the punches 221 of a punch element 220 can be guided. The punches 221, in the fully inserted state, rest against the elements 101 and thus fix them (cf. Figures 11a and b, left-hand illustration in each case). To release the fixation thus achieved, it is sufficient to change the position of the punch element 220 or the punches 221, for example, by manually pulling out the punch element 220 (cf. Figures 11a and b, right-hand illustration in each case). The punch element 220 can also be completely removed. For repeated fixing, the stamps 221 of the stamp element 220 must be reinserted through the openings 106 or brought into contact with the elements 101.

[0094] In the embodiment shown in Figure 11a, a stamp 221 is guided through a central opening 106 relative to an element 101 and can thus block the mechanical connection 105 between element(s) 101 and basic structure 102.

[0095] In the embodiment according to Figure 11b, the openings 106 are each arranged in the area between the elements 101, so that a punch 221 passed through such an opening 106 rests against several, usually two or four, elements 101 and can thus block them.

[0096] In particular, the embodiments according to Figures 5 to 11, with suitable control and / or design of the elements used for fixation 200, generally enable reversibly removable fixation. Thus, the fixation 200 of the element(s) 101 can be released as needed, for example, to perform a functional test of the actuators 103 of the micro-electro-mechanical system 101, and then reattached.

Claims

Patent claims 1. Micro-electro-mechanical system (100) comprising an element (101) which is micro-electro-mechanically movable in at least one degree of freedom relative to at least one basic structure (102) by at least one actuator (103), characterized in that at least one removable fixing means (200) is provided which, at least in the initial state, is an integral component of the micro-electro-mechanical system (100) and with which at least one element (101) is fixed relative to the basic structure (102) and / or a further element (101) in at least one degree of freedom of the element (101).

2. Device according to claim 1, characterized in that at least one fixation (200) is reversibly removable.

3. Device according to one of the preceding claims, characterized in that at least one fixation (200) acts in a force-fitting and / or form-fitting manner.

4. Device according to one of the preceding claims, characterized in that the fixing (200) is a play fixing.

5. Device according to one of the preceding claims, characterized in that the at least one element (101) is moved and / or held by the at least one actuator (103) into a position for bearing against the at least one fixing means (200).

6. Device according to one of the preceding claims, characterized in that the at least one fixing (200) serves as a shield against Scattered vapor, plasma, electric fields, ions and / or radiation.

7. Device according to one of the preceding claims, characterized in that at least one fixation (200) is removable by mechanical breaking, severing by heat or particle beam, selective etching of material and / or demagnetization of magnetically interacting regions.

8. Device according to one of the preceding claims, characterized in that at least one fixation (200) is removable by changing the position, orientation and / or shape of the fixation (200), wherein the change in the fixation (200) is preferably effected electrically, piezoelectrically, magnetically, pneumatically, hydraulically and / or thermally.

9. Device according to one of the preceding claims, characterized in that at least one fixing means (200) is designed for the joint fixing of at least two elements (101).

10. Device according to one of the preceding claims, characterized in that the micro-electro-mechanical system (100) is a MEMS mirror array with a plurality of mirror elements (101) which are movable on a base structure (102) by at least one, preferably two, preferably rotational, degrees of freedom.

11. Device according to one of the preceding claims, characterized in that at least one fixation (200) is integrated into the micro-electro-mechanical system (100) in such a way that it even before completion of the micro-electro-mechanical System (100) has a fixing effect on at least one element (101).

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