Microelectromechanical loudspeaker having a

Abstract

A microelectromechanical loudspeaker (100) comprises a substrate (110) having a substrate surface (111), a housing (130) arranged on the substrate, and a cavity (140) delimited by the housing and the substrate. The loudspeaker (100) further comprises a translation device (150) which is arranged in the cavity so as to be deflectable and movable in a predetermined direction of movement (x) and which comprises: an assembly of fin structures (160) arranged next to each other in the direction of movement; and a bracket structure (151) connecting the fin structures to each other; and a drive device (170) designed to deflect the translation device in the direction of movement, comprising a plurality of drive units (172), each of which consists of an actuator electrode (180) and a stator electrode (173.1, 173.2), the actuators and stator electrodes associated with the drive units being designed to deflect the translation device in the direction of movement, an electrostatic force that accelerates the translation device in the direction of movement is generated when the respective different potentials are applied. At least a portion of the movable drive electrode is arranged on the support structure.

Description

Technical Field

[0001] The invention relates to a micro-electromechanical loudspeaker with a large-area force field. Background Art

[0002] The main goal or challenge of MEMS-based loudspeakers is to achieve the highest possible SPL (Sound Pressure Level). A high SPL is accompanied by a high displaced air volume. At the same time, for cost reasons, the chip area should be kept as small as possible, so that the characteristic variable SPL / chip area needs to be optimized or increased.

[0003] Most of the current MEMS speakers are implemented as planar structures, in which a vibrating membrane is excited so that the displacement and / or compression of the fluid is carried out perpendicular to the membrane plane. Typically, the excitation of such a membrane is carried out by means of a piezoelectric or electrostatic effect. For example, such an embodiment is disclosed in US2021297787. Due to the limitation of the maximum deflection of the membrane, these systems have the following disadvantages: the displacement of a high fluid volume is accompanied by a large surface of the membrane and therefore the area of ​​the MEMS element. Another limitation of the displaceable air volume is caused by the membrane that is connected or clamped to the substrate material in a circumferential manner. Due to this circumferential clamping, the deflection amplitude of the membrane on the surface of the membrane is different (in the clamped edge area, the deflection is almost zero, while it is typically the largest in the middle of the membrane). Such an uneven deflection of the membrane surface additionally reduces the displaced air volume and further increases the harmonic sound distortion (THD).

[0004] In US2021297787, the following structure of the membrane is proposed: the structure reduces the uneven deflection to a certain part or increases the area with the maximum deflection by arranging a torsionally rigid "diaphragm plate" in the middle of the membrane, which is embedded in the membrane in a circumferential manner and actually acts as an actuator. In general, a corresponding MEMS loudspeaker with such a planar structure or membrane has a fluid-like acting surface, which is in principle smaller than the chip surface. In other words, an increase in the air volume to be displaced is necessarily accompanied by an increase in the chip surface.

[0005] Therefore, in the prior art, the following design is proposed: the design does not have a single membrane that vibrates in the vertical direction, but has multiple laterally or horizontally movable elements that extend in the vertical direction. The advantage here is that the displaced volume of the fluid not only scales in proportion to the chip surface, but can also be influenced by means of the vertical dimension. The vertical installation and multiplication of the membrane multiplies the surface on which the fluid acts and can be significantly larger than the actual chip surface. For example, MEMS speakers based on this basic design are disclosed in WO 2021 / 144400, WO002021223886 or DE 10 2019 203 914 and in Kaiser et al.'s Microsystems and Nanoengineering (2019).

[0006] WO002021223886 describes a design in which a separation of an active drive structure and a passive displacement structure is proposed, wherein the two structures are arranged one above the other (for example, as a wafer stack). In other words, in this document, the two structures (drive and displacer) are located in the same area. Here, the two structures can be mechanically connected to each other via a coupling element, so that a deflection in the active structure leads to a movement of the passive displacer structure. The proposed drive structure is a typical comb structure (comb-like electrode structure interlaced with each other), for example, which utilizes electrostatic attraction.

[0007] From WO22117197, a microfluidic structural element with a vertical displacement element is known, which is driven by means of an electric scattering field. There, the displacement element is clamped laterally on both sides. Here, the electric scattering field is constructed by electrodes, which are arranged not only on the lower side of the cover substrate but also on the upper side of the base substrate. That is, the electrodes are oriented toward the displacement structure located between them and have a spacing to the displacement element that is as small as possible. That is, the displacement element is located in the scattering field of the electrode on the end face side (the upper and lower sides of the displacement element), and the scattering field or electric field between the electrodes has a directional component perpendicular to the surface of the electrode and therefore parallel to the extension direction of the displacement element, and a directional component along the deflection of the displacement element. When the displacement element is electrically controlled, the individual displacement elements are subjected to electrostatic forces (acting on the upper and lower sides of the displacement structure), which lead to a lateral deflection of the displacement element (caused by the scattering field portion in the deflection direction of the displacement element). In contrast to the embodiment from WO002021223886, the displacement element here does not constitute a passive displacement structure but is actively actuated with an alternating voltage.

[0008] Disadvantages of this displacer design or drive design, in addition to the high technical barriers for industrial implementation, are the small maximum deflection of the displacer element, which lies in the range of a few micrometers (due to the principle, this deflection can only have a maximum of half the spacing of the fixed electrodes). Due to this small deflection, for a high SPL, not only a plurality of vertically arranged displacer elements with a small spacing to one another (high periodicity) but also a displacer element with a high vertical extension are required. These two requirements together lead to high requirements on the design (specifications and tolerances) of the displacer element, which make technical feasibility problematic.

[0009] The small deflection of the vertical displacement structure from WO22117197 is also based in particular on the following basis: the area of ​​the electric field in which a force can be exerted on the movable membrane or displacement structure is significantly limited. This also significantly limits the force used for deflection. The limitation of the force field (and thus the driving force) acting on the displacement structure is based on the following basis: only the upper side and the lower side (end face side) of the vertically oriented (a few micrometers thin) displacement element are located in the force field (electric field). In other words, the very thin, a few micrometers wide end face side of the vertically placed displacement element (membrane) located in the limited force field of the fixed opposing electrodes is (so to speak) "responsible" for the deflection or driving force of the entire membrane. Compared with the overall extension of the membrane / displacement structure to be deflected, the area of ​​the end face side is very small and therefore the driving force is also very small. Or in other words, the area of ​​the electric field in which the membrane that can be deflected laterally is located is small and therefore the possible driving force is also small. Too low a driving force results in a smaller deflection (and thus in a reduced output power of the loudspeaker) or in stringent specifications with regard to the stiffness or mass of the displacement structure to be deflected. These increased requirements are inevitably accompanied by increased risks with regard to industrial feasibility. Summary of the invention

[0010] The object underlying the invention may therefore be to provide an actuator structure for a MEMS-based loudspeaker concept with a vertically oriented and laterally deflectable displacement structure having a high surface utilization for generating a force field over a large area, taking into account technical manufacturability or reduced process complexity. This object is achieved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the respective dependent claims.

[0011] A micro-electromechanical loudspeaker is described, which comprises a substrate having a substrate surface, a housing arranged on the substrate, a cavity bounded by the housing and the substrate, a translation device arranged in the cavity so as to be deflectable and movable in a predetermined direction of movement parallel to the substrate surface, the translation device comprising a component consisting of a plurality of movable fin structures arranged side by side in the direction of movement, the movable fin structures dividing the cavity into a plurality of sections that are fluidically independent of one another, and a support structure connecting the movable fin structures to one another. In addition, the micro-electromechanical loudspeaker comprises a drive device configured to deflect the translation device in the direction of movement, the drive device comprising a plurality of drive units, the drive units each comprising at least one actuator electrode mechanically connected to the translation device and at least one stator electrode mechanically connected to the housing and / or the substrate, wherein the actuator electrode and the stator electrode respectively assigned to the drive unit are configured to generate an electrostatic force that accelerates the translation device in the direction of movement when respectively acted upon with different potentials. In this case, at least a portion of the movable drive electrodes is arranged on the support structure. By arranging the drive electrodes on the support structure, a higher area utilization can be achieved for generating a large-area force field and the driving force of the displacement structure can be increased. Thus, the active chip surface necessary for air displacement can be better utilized with the proposed embodiment of the actuator structure.

[0012] In one embodiment, a non-movable fin structure, which is arranged on a substrate or a housing, is arranged between two directly adjacent movable fin structures. Here, a gas volume which can be compressed by the movement of the movable fin structure in the movement direction is formed between the movable fin structure and the non-movable fin structure directly adjacent to them. This embodiment enables a particularly simple construction of the MEMS loudspeaker.

[0013] In another embodiment, two translation devices that move in opposite directions are arranged in the cavity, each of which has a movable support structure and a plurality of movable fin structures arranged on the respective support structure. The movable fin structures of the two translation devices are arranged alternately in the direction of movement, so that a gas volume that can be compressed by the relative movement of the respective fin structures is formed between the movable fin structure of the first translation device and the movable fin structure of the second translation device. With these measures, particularly large gas volumes can be displaced. This increases the efficiency of the MEMS loudspeaker.

[0014] In another specific embodiment, it is provided that a part of the actuator electrode is arranged on the top and / or bottom of at least one movable fin structure. As a result, the area available for the drive electrodes can be increased.

[0015] In another embodiment, the housing comprises a frame structure which laterally surrounds the cavity, wherein the movable support structure is designed in the form of a frame in which the movable fin structure is clamped laterally. In this case, at least a portion of the actuator electrodes is arranged on the end face side of the support structure. Finally, the stator electrodes assigned to the respective actuator electrodes are arranged on the inner side of the frame structure which is arranged opposite the respective end face side of the support structure. This makes it possible to increase the area available for the drive electrodes.

[0016] In another embodiment, the housing comprises a frame structure which laterally surrounds the cavity, wherein the movable support structure is designed in the form of a frame in which the movable fin structure is clamped laterally. In addition, at least a portion of the actuator electrodes is arranged on the outer side of the side wall of the support structure. Here, the stator electrodes assigned to the respective actuator electrodes are arranged on the inner side of the frame structure which is arranged opposite the respective side wall of the support structure. This also increases the area available for the drive electrodes.

[0017] In another embodiment, the housing comprises a frame structure which laterally surrounds the cavity, in which the movable fin structure is clamped laterally. In this case, the movable support structure connects the movable fin structures arranged side by side in the direction of movement to one another in the middle region of the fin structures. With this embodiment, the gas volume of the cavity can be increased.

[0018] In another embodiment, it is provided that at least a portion of the movable fin structure on the upper side and / or the lower side has a lateral extension which extends in the direction of movement and each has a plurality of actuator electrodes arranged side by side in the direction of movement. By means of such a lateral extension and the associated increase in the surface available for the arrangement of the actuator electrodes, the number of drive units can be increased. This results in a higher drive force.

[0019] In another embodiment, the actuator electrode and the stator electrode respectively assigned to the actuator electrode each have a plurality of track-shaped structures extending in the direction of movement, wherein the track-shaped structures of the actuator electrode and the track-shaped structures of the stator electrode are interlaced in a comb-like manner. This can significantly increase the effective electrode surface of the drive electrode. Overall, this generates a higher drive force.

[0020] In another embodiment, the actuator electrodes and the stator electrodes are each designed to be planar and are arranged opposite one another, separated from one another by a defined gap. With the aid of this planar design of the drive electrodes and their non-intersecting arrangement, relatively large stroke movements of the translation device can be achieved.

[0021] In another embodiment, the actuator electrodes and the stator electrodes are arranged side by side in the direction of movement and form two mutually interlaced crenellations. The electric field available for the movable electrodes is significantly increased by means of the crenellated, mutually interlaced electrode structure. The increase in the area of ​​the electric field leads to a significant increase in the driving force.

[0022] In another embodiment, it is provided that the actuator electrodes and the stator electrodes assigned thereto are each designed in the form of a plurality of electrode plates, which are arranged one above the other in a direction perpendicular to the substrate surface and extend parallel to the substrate surface. In this case, the electrode plates of the actuator electrodes and the electrode plates of the stator electrodes are arranged alternately in a direction perpendicular to the substrate plane and are each connected to one another via their own connecting structures. With such a meander-shaped electrode assembly, a particularly high increase in the area of ​​the force field is achieved, which is accompanied by a significant increase in the drive force.

[0023] In another embodiment, it is provided that at least a portion of the actuator electrodes each include a two-dimensional arrangement of male electrodes extending in the direction of movement and connected to one another via a connecting structure. In this case, the stator electrodes assigned to the respective actuator electrodes each include an assembly of correspondingly shaped hole electrodes, wherein each hole electrode is designed to receive the male electrode assigned to it. A further significant area increase of the force field is achieved by further segmenting the electrode structure perpendicular to the substrate surface. This achieves a further increase in the driving force.

[0024] In another embodiment, it is provided that the punch electrodes each have a cross-sectional profile with an extension extending perpendicularly to the direction of movement. In this case, the hole electrode associated with the punch electrode has a cross-sectional profile adapted to the cross-sectional profile of the punch electrode. With the aid of such an extension, the effective electrode surface can be significantly increased. This is accompanied by a significant increase in the force field and therefore also in the generated driving force.

[0025] In another embodiment, it is provided that the cross-sectional profile of the punch electrode is designed in the form of a double T-bracket or in a cross shape. These two cross-sectional profiles are accompanied by a significant increase in the electrode surface and thus allow a significant increase in the force field and the drive force that can be achieved thereby. At the same time, these cross-sectional profiles can be realized particularly easily with the aid of the method used to produce the microelectronic mechanical structure.

[0026] Finally, in another embodiment, it is provided that the support structure comprises a displacement support, which connects the movable fin structures of the translation device to one another, and a drive support mechanically connected to the displacement support, which connects the actuator electrodes of the translation device to one another. The spatial separation of the displacement structure and the drive structure allows a particularly efficient drive device to be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be described in more detail below with reference to the accompanying drawings. It is shown here:

[0028] Figure 1 Schematic cross section along the direction of movement through a MEMS loudspeaker with an extended arrangement of actuator electrodes and stator electrodes,

[0029] Figure 2 From Figure 1 Schematic top view of a MEMS speaker,

[0030] Figure 3 Schematically passing through a plane perpendicular to the direction of motion Figure 1 Cross section of a MEMS speaker,

[0031] Figure 4 Schematic top view of a MEMS loudspeaker according to another embodiment, in which one of the support structures connects the individual movable fin structures to one another in their central region,

[0032] Figure 5 Schematic cross section of a MEMS loudspeaker according to another embodiment, the MEMS loudspeaker having two oppositely driven movable fin structures, Figure 6 Schematic top view of a MEMS speaker having two mutually

[0033] The translation device moves in the opposite direction,

[0034] Figure 7 Schematic cross section through a MEMS loudspeaker according to another embodiment, in which

[0035] In another embodiment, the movable fin has a transversely extended structure. Figure 8 From Figure 7 Schematic top view of a MEMS speaker,

[0036] Fig. 9 Schematic cross section through a MEMS loudspeaker according to another embodiment, in which

[0037] In another embodiment, the side of the support structure is also used to place the actuator electrodes. Fig.10 From Fig. 9 Schematic top view of a MEMS speaker,

[0038] Fig.11 Schematic cross section through a MEMS loudspeaker according to another embodiment, in which

[0039] In another embodiment, the drive electrodes are interlaced in a crenellated pattern.

[0040] Fig.12 Schematic cross section through a MEMS loudspeaker according to another embodiment, in which

[0041] In another embodiment, the driving electrodes have a track-like structure that intersects with each other. Fig.13 A schematic perspective view of a drive unit of another embodiment of a MEMS loudspeaker,

[0042] In this further embodiment, the drive electrode has electrodes arranged one above the other in a stack.

[0043] Plates,

[0044] Fig.14 Two oppositely disposed plate-shaped actuator electrodes and associated plate-shaped stator electrodes

[0045] Schematic top view of the assembly consisting of a driven drive support, Fig.15 A schematic perspective view of a further drive unit in which the

[0046] The actuator electrode has a male electrode extending in the direction of motion, while the stator electrode has a corresponding

[0047] a hole electrode shaped to receive the male electrode, Fig.16 By having from Fig.15 Two oppositely driven drive supports of a plurality of drive units

[0048] A schematic top view of the components of the rack,

[0049] Fig.17 Schematic diagram of a plurality of convex electrodes of the actuator electrode, each having a rectangular profile,

[0050] The punch electrode engages in a correspondingly shaped hole electrode of the associated stator electrode, and Fig.18 The schematic diagram of a plurality of actuator electrodes each has a profile in the form of a double T-shaped bracket, which engages in a correspondingly shaped hole electrode of the associated stator electrode. DETAILED DESCRIPTION

[0051] The design described here provides an actuator structure or translation device for a MEMS-based loudspeaker design, which has a vertically oriented and laterally deflectable displacement structure, which has a high area utilization for generating a large-area force field. The entire actuator structure has a large-area electric field in the sum of all substructures, that is, a surface perpendicular to the electric field, which is parallel to the direction of movement of the membrane or the displacement structure, in which the associated counter-electrodes are subjected to electrostatic forces. The translation device for generating a large-area force field (which does not necessarily have to be continuous) is not accompanied by an increase in the chip area, or only slightly. Rather, the proposed configuration of the actuator structure makes the best possible use of the active chip surface required for air displacement.

[0052] Furthermore, the feasibility or simplicity of the manufacturing process in terms of process technology is ensured by providing in one embodiment a largely planar design of the actuator structure. A design that can be realized using a planar, layer-deposition-based technology is advantageous over a design that requires a technology with a necessary, deep structure.

[0053] The actuator concept proposed here, which consists of an actuator arrangement or a translation device and an actuator method, maximizes the entire, combined area of ​​the electric field. This refers to the part of the electric field that has a field direction parallel to the direction of movement, since only this part of the electric field is available for electrostatic forces in the direction of movement. In this case, a surface is to be understood as a surface perpendicular to the electric field lines. The maximization of the relevant area of ​​the force field is achieved by a multiple arrangement of the drive structure consisting of fixed electrodes (stator electrodes) and movable electrodes (actuator electrodes).

[0054] Exemplary MEMS structures are described below in which the actuator concept according to the invention is implemented in different ways, which has a large-area actuator arrangement for a large-area force field. The described MEMS loudspeaker concept has fins that are extendable in the vertical direction and can be moved laterally, or fin structures, which serve as displacement elements for displacing air.

[0055] In the following embodiments, the immovable electrode for generating an electrostatic field (electroscattering field) is exemplarily fixedly arranged on a cover wafer or a base wafer, while the movable electrode is mechanically connected to a movable fin structure and generates an alternating electric field that interacts with the electrostatic field. However, in principle, this arrangement can be configured in the opposite way, wherein the movable electrode mechanically connected to the fin structure is used to generate the electrostatic field, while the immovable electrode fixedly arranged on the cover wafer or the base wafer generates the alternating electric field.

[0056] Figure 1 The MEMS loudspeaker 100 is shown in cross section with two laterally movable fin structures 160 . 2 , 160 . 3 which have a relative movement with respect to a fixed wall or fin structure.

[0057] The dashed box schematically illustrates the drive principle with two fixed drive electrodes (stator electrodes) 173.1, 173.2, each charged with a different potential, for generating an electric field in which a movable drive electrode (actuator electrode) 180, which is mechanically connected to the movable fin structure 160 at the end face, is subjected to a transversely directed force along or against the direction of movement x. In this case, an alternating potential acts on the movable actuator electrode 180, so that the electrode 180 is subjected to a directionally defined, transversely directed force in the electrostatic (scattering) field of the fixed stator electrodes 173.1, 173.2. Each actuator electrode 180 together with its associated stator electrode 173.1, 173.2 forms a respective separate drive unit 172.5, 172.6.

[0058] In addition to this electrode assembly, a support structure 151 is provided which serves as a frame or shuttle and moves with the fin structure 160. In the present embodiment, the support structure 151 has the shape of a frame in which the movable fin structure 160 is clamped laterally.

[0059] In this case, additional movable electrodes 180 are arranged on the upper side 154 and the lower side 155 of the support structure 151, which together with the immovable electrodes 173.1, 173.2 arranged opposite each other on the surface 111 of the substrate wafer 110 and on the lower side 132 of the cover structure (cover wafer) 130 form additional drive units 172.1, 172.2. In this case, the additional drive units 172.1, 172.2 achieve an increase in the area of ​​the force field.

[0060] Figure 2 Shown from Figure 1A planar cross-section of the MEMS loudspeaker parallel to the substrate surface 111 at the height of the stator electrodes 173.1, 173.2 arranged on the cover structure. It can be seen here that the frame-like shape of the support structure 151 includes two longitudinal sections 159.1, 159.2 oriented in the direction of movement x and two transverse sections 159.3, 159.4 extending transversely to the direction of movement x. Here, the support structure 151 is arranged in a cavity 140, which is laterally surrounded by a frame structure 135 (which constitutes a chip frame of the housing 130), and the support structure is fastened to the housing 130 and in particular the frame structure 135 and / or to the substrate 110 in a deflectable manner in the direction of movement x by a suitable elastic spring structure (not shown here). Here, the fin structure 160 1 Up to 160 5 is clamped between the two longitudinal sections 159.1, 159.2, wherein the outer fin structure 160 1 and 160 5 At the same time, the cross-sections 159.3, 159.4 of the support structure 151 are formed. The fin structures 160.1 to 160.5 divide the cavity 140 into four mutually independent sub-cavities 141. In each of these sub-cavities 141, a fixed wall 123 is arranged, which is constructed in the form of a fin structure that is mechanically clamped between the base 111 and the cover structure 131 and divides the corresponding sub-cavity 141 into two fluidically independent sub-volumes 141.1, 141.2. Due to this arrangement, when the translation device 150 moves along the movement direction x in the sub-volume 141.1 that is reduced by this movement, a compression of the gas volume arranged therein occurs, while in the respectively complementary sub-volume 141.2, an expansion of the gas volume contained therein occurs at the same time, and vice versa. In the opposite movement of the translation device 151, the previously compressed gas volume expands, while the previously expanded gas volume is compressed. When the gas volume is compressed, the corresponding gas escapes through the ventilation openings 102, 103 assigned to the corresponding subvolumes 141.1, 141.2 within the base 111 or the cover structure 131. In the opposite case, when the gas volume is expanded, the gas flows into the corresponding subvolumes 141.1, 141.2 through the corresponding ventilation openings 102, 103.

[0061] exist Figure 3 Shown in Figure 1 and 2 A cross-section of the MEMS speaker in a second sectional plane extending along the ventilation opening 102 and at Figure 21 and 173.1, 173.2. As indicated here, the gap between the actuator electrode 180 arranged on the upper side 154 of the support structure 151 and the fin structure 160 and the stator electrodes 173.1, 173.2 arranged on the lower side 132 of the cover structure 131 preferably has the smallest possible width in order to achieve the best possible fluid separation of adjacent sub-volumes. In addition, a small gap width enables a better electrostatic interaction between the respectively complementary drive electrodes, which is accompanied by a higher force effect.

[0062] In addition, from Figure 3 It can be seen that the cover structure 131 can have suitable reinforcement structures 134 in the region of the ventilation opening 102 , which increase the stability of the MEMS structure.

[0063] The MEMS speaker 100 Figure 2 As an alternative to the structural type shown in , in which the movable fin structure 160 is clamped in a frame-like support structure 151 , a translation device 150 with an internal support structure 151 can also be realized. For this purpose, Figure 4 A corresponding embodiment is shown, in which it can be seen that the support structure 151 arranged in the middle area of ​​the cavity 140 and connecting the fin structures 160 to each other is mechanically connected to the relevant fin structure in the middle section of the movable fin structure 160. In addition, it can be seen that the individual fin structures 160 are clamped in the frame structure 135. In order to realize the relative movement of the fin structure relative to the rigid frame structure 135, the relevant fin structure 160 must have a sufficiently high elasticity at least in the section directly adjacent to the frame structure 135. However, alternatively, it is also feasible to mechanically connect the movable fin structure 160 to the frame structure 135 by a special elastic coupling element (not shown here). In another alternative embodiment, the fin structure can also be constructed without a direct mechanical connection to the frame structure 135. In this case, the support structure 151 can be mechanically fastened to the housing 130 (especially the frame structure 135) and / or on the substrate 110 by means of a suitable elastic coupling element.

[0064] If also from Figure 4It can be seen that in this embodiment, the immovable fin structure 12, which is respectively arranged between two directly adjacent movable fin structures 160, is constructed in two parts, wherein each of the two sections 123.1, 123.2 separated from each other by the support structure 151 is fastened to the frame structure 135 on one side. In the case where the support structure 151 does not extend over the entire height of the movable fin structure, the immovable fin structures 123.1, 123.2 can also be connected to each other via an intermediate section not shown here. In this case, the immovable fin structure can have a suitable opening (not shown here) for the support structure 151.

[0065] exist Figure 4 The embodiment variant shown in Figure 2 The essential difference between the embodiments shown in the drawings is essentially the internal support structure or shuttle structure 151. Here, the fin structure 160 is not incorporated into the frame-like support structure 151 on both sides, but directly into the frame structure 135 (chip frame). The internal support structure 151 does not have to be constructed over the entire height (e.g. from the Figure 2 More precisely, the support structure 135 can be designed only as a mechanical coupling structure, which is mechanically attached to the fin structure 160 at the end face and thus mechanically couples the fin structures 160 to each other. Here, in addition to the force field in the end face region of the fin structure 160, the area for generating the force field is increased by using the area of ​​the support structure 151 by arranging a further drive unit 172.1.

[0066] Figure 5 Shown through Figure 4 A cross section of a MEMS loudspeaker structure 100 is shown. It can be seen here that the function of the functional unit constructed between two directly adjacent movable fin structures 160 is basically the same as that in Figure 2 The first embodiment shown in FIG.

[0067] In the previous embodiments, the compression of the individual gas volumes was always carried out by the movement of the movable fin structure relative to the fixed fin structure used as a rigid wall, while in Figure 5 In the embodiment shown in , the corresponding gas volume is achieved by the opposite movement of two independently deflectable translation devices 150.1, 150.2. Figure 4 1 with an inner support structure 151 , wherein however no fixed walls are introduced here, but rather two adjacent fin structures 160 are moved relative to one another.

[0068] As from Figure 6 (said Figure 6 Shown from Figure 5 In a planar section of the MEMS loudspeaker 100 parallel to the substrate surface 111 at the height of the stator electrodes 173.1, 173.2 arranged on the cover structure, it can be seen that the movable fin structures 160.1, 160.3, 160.5, 160.7 and 160.9 are assigned to the first translation device 150.1 and are connected to each other via the first support structure 151.1, while the movable fin structures 160.2, 160.4, 160.6, 160.8 and 160.10 are assigned to the second translation device 150.2 and are connected to each other via the second support structure 151.2. This arrangement produces an offset of the two translation devices 150.1, 150.2 in the movement direction x. Here, the two support structures 151.1, 151.2 are mechanically decoupled from each other in order to achieve opposite movements of the two translation devices 150.1, 150.2. For this purpose, the movable fin structures 160.2, 160.4, 160.6, 160.8 and 160.10 have suitable cutouts or openings 163 through which the support structure 151.1 of the first translation device 150.1 protrudes. Similarly, the movable fin structures 160.3, 160.5, 160.7 and 160.9 have corresponding cutouts or openings 163 through which the support structure 151.2 of the second translation device 150.2 protrudes.

[0069] In order to ensure sufficient movement of the two translation devices, the fin structures 160.1 to 160.10 can be designed elastically. In this case, this elasticity can be particularly strongly reflected in the outer section of the fin structure adjacent to the frame structure 135. However, it is also possible to mechanically connect the movable fin structure 160 to the frame structure 135 by means of a special elastic coupling element (not shown here). In another alternative embodiment, the fin structure 160 can also be designed without a direct mechanical connection to the frame structure 135. In this case, the support structure 151 can be mechanically fastened to the housing 130 (especially to the frame structure 135) and / or to the substrate 110 by means of suitable elastic coupling elements (not shown here).

[0070] In order to be able to further increase the driving force, it can be sensible to increase the area of ​​the force field achieved by the drive electrodes. This can be advantageously achieved by increasing the number of drive electrodes. If there is no more sufficient free area for placing the electrodes on the translation device, the movable fin structure and / or the movable support structure can be equipped with a lateral expansion structure. For this purpose, Figure 7 Shown with Figure 2A cross section of an expanded configuration of the embodiment described in connection therewith. Here, the movable fin structures 160.1 to 160.5 have additional planes on their upper and lower sides, in which corresponding transverse expansion structures 164 are constructed. Here, by appropriately structuring the additional planes on the end faces of the fin structures 160.1 to 160.5, a type of front top is respectively realized, on which the electrodes are arranged in a planar manner. Now, with the help of these measures, the planar configuration of the force field can be significantly increased. As can be seen from Figure 7 It can be seen that the lateral extension 164.1 on the upper side of the fin structures 160.1 to 160.5 can extend in the direction of movement x, while the lateral extension on the lower side of the fin structures 160.1 to 160.5 extends in the opposite direction. In this way, the symmetry of the partial volume sections can be maintained.

[0071] exist Figure 8 Shown in Figure 7 A plane cross section of the MEMS speaker 100 parallel to the substrate surface 111 at the height of the stator electrodes 173.1, 173.2 arranged on the cover structure. Figure 7 The section plane of is indicated by means of a dot-dash line. It can be seen here that a significant increase in the overall electrode surface is achieved by the lateral expansion 164 , in particular in the regions above and below the subvolume 141 .

[0072] Fig. 9 Another possible embodiment of a MEMS loudspeaker 100 is shown, in which the side surfaces of the frame structure 135 and the support structure 151 are utilized to increase the force field. As can be seen in this cross-sectional view of the MEMS loudspeaker 100, the side walls 156 of the support structure 151 along the movement direction x and the inner side 136 of the frame structure 135 opposite thereto can be constructed with alternating electrode assemblies 173.1, 173.2, 180, so that these surfaces 136, 156 also contribute to the increase in the area of ​​the force field.

[0073] exist Fig.10 Shown in Fig. 9 A plane cross section of the MEMS speaker 100 parallel to the substrate surface 111 at the height of the stator electrodes 173.1, 173.2 arranged on the cover structure 131. Here, the dot-dash line illustrates Fig. 9It can be seen here that the actuator electrodes 180 arranged on the two side walls 156.1, 156.2 of the frame-like support structure 135 and the stator electrodes 173.1, 173.2 arranged opposite them on the two inner sides 136.3, 136.4 of the frame structure 135 respectively form corresponding drive units 172.3, which are preferably arranged along the entire length of the side walls 156.1, 156.2 of the frame-like support structure 151.

[0074] Additionally or alternatively, the side faces 156.1, 156.2 of the support structure 151 on the end face with respect to the movement direction x can also be designed as electrodes of a parallel plate capacitor. By applying a corresponding potential to the electrodes, an attractive force can be generated on each of the two end faces. Fig.10 4, which each include an actuator electrode 180 arranged on an end face 157.1, 157.2 of the support structure 151 and a stator electrode 173 arranged on the inner side 136.1, 136.2 of the frame structure 135 facing one of the respective end faces 157.1, 157.2.

[0075] exist Fig.11 An alternative configuration of electrodes is shown in , which is used to further increase the electric field in terms of area, in which the drive electrodes are interlaced in a crenelated manner. In the previously described embodiment, the MEMS loudspeaker has a planar electrode structure. Due to the planar configuration of the drive electrodes 180, 173 in the direction of movement x, the available electric (scattering) field from the corresponding counter-electrode between the corresponding actuator electrode and the stator electrode is only very weak, because the electric field depends in particular on the distance from the movable electrode to the fixed electrode. By means of Fig.11 The crenellated, interlaced electrode structure shown in the Figure significantly increases the electric field (field lines parallel to the direction of movement in the region of the movable electrode) available to the movable actuator electrode 180. Basically, the crenellated configuration of the electrodes (fixed and movable) can be combined with all the previously shown options.

[0076] In order to maximize the driving force of the MEMS loudspeaker, the force field achieved between the complementary driving electrodes can be increased in area by a special configuration of these electrodes. Fig.12, a modified drive unit is shown by way of example, in which the effective electrode surface is increased by the fact that complementary electrodes (fixed and movable) 173, 180 have rail-like structures 174, 181 which are interlaced in a comb-like manner. The direction of movement x in this cross-sectional drawing is in the drawing plane, so that the electrode structure 172.1 formed by the actuator electrode 180 and the stator electrode 173 can also be regarded as a rail (or "railway").

[0077] The design of electrodes interlaced in a comb-like manner can also be realized by means of an electrode structure arranged parallel to the substrate surface 111. The following figures show further exemplary MEMS structures within the meaning of the present invention. Here, the actuator design according to the present invention should also be implemented with an actuator arrangement configured in a large area for a force field that is as large as possible. As has already been described, Figures 1 to 11 In this connection, the drive or actuator device is intended to drive one or more displacement elements independent of this, which have a fin structure extending in the vertical direction and can be deflected in the direction of movement x and can be moved laterally. In this case, the design described below focuses on the configuration of the drive. The fin structure used as a displacement element can be supplemented in the subsequent embodiments in a manner similar to the previously described embodiments.

[0078] Here, in Fig.13 The arrangement shown in can involve, for example, Figure 2 or a more advantageous configuration of the drive device 170 shown in 4. Here, the basic principle is to Figure 2 The electrode structure used in principle in or 4 is multiplied perpendicularly to the direction of movement x (here vertically), so that in combination with the segmentation of the individual drive electrodes 173, 180 along the direction of movement x, the product of the sum of all forces generated by the drive in the direction of movement x can be achieved. This advantage can be used particularly well when the drive device 170 is spatially separated from the actual displacement structure 160. The force transmission is achieved by the displacement support 152 used as a shuttle for the movable displacement element 160, which is mechanically attached on the one hand to the drive support 153, which is also used as a shuttle for the actuator electrode 180, and on the other hand to the individual movable fin structure 160 used as a displacement element. The drive support 153 concentrates the tensile forces of all drive units fastened thereto on the displacement support 152 and realizes correction over its entire lateral extension.

[0079] The drive principle here corresponds to Figure 1The drive unit 172.1 described in connection therewith (marked by a dashed frame). In this case, each drive unit 172 preferably comprises two fixed electrodes (stator electrodes) 173.1, 173.2 for generating an electric field and a movable electrode (actuator electrode) 180, which is subjected to a transversely directed force in the electric field and transmits the force to a movable fin structure mechanically connected on the end face. In contrast to the described embodiments, in Figure 2 The fin structure 160 (displacer element) mechanically connected at the end face is replaced by a structure used as drive support 153 which is movable bidirectionally between the two stator poles 173 . 1 , 173 . 2 .

[0080] The previously described arrangement is now improved to the extent that the drive unit consisting of the actuator electrode 180 and the stator electrode 173 is multiplied vertically in type. This generates a meander structure perpendicular to the direction of movement x, which is directly accompanied by an increase in the area of ​​the force field. This results in the generation of Fig.13 2D comb actuator shown in . Multiplication can be achieved technically by means of the layer stacking customary in semiconductor production, for example by means of a sequence of polysilicon deposition, trenches, sacrificial oxide, oxide structures, polysilicon, etc.

[0081] As from Fig.13 It can be seen that each stator electrode 173.1, 173.2 has electrode plates 176 arranged one above the other in the vertical direction z, which are mechanically and electrically connected to one another by means of connecting structures 177 arranged between them. The actuator electrode 180 also has electrode plates 184 arranged one above the other, which are mechanically and electrically connected to one another by means of connecting structures 186 arranged between them. In this case, the electrode plates 177, 184 are arranged offset relative to one another in the vertical direction z, so that the electrode plates 184 of the actuator electrode 180 can move back and forth between the electrode plates 176 of the stator electrodes 173.1, 173.2 in the direction of movement x.

[0082] In addition, if Fig.13 It can be seen that stator electrodes 173.1, 173.2 can each be segmented in the middle in a suitable manner so that a connection structure 186 of actuator electrode 180 can be moved unhindered in movement direction x between two segments 175.1, 175.2 of stator electrodes 173.1, 173.2.

[0083] In addition, if Fig.13It can be seen that actuator electrode 180 is fastened together with further actuator electrodes to a common drive support 153 which is mechanically connected to a displacement support 152 located above or below it, for example by means of a suitable coupling structure 158 (indicated here only by means of a dashed line).

[0084] Fig.14 A top view of an embodiment with two drive supports 153.1, 153.2 that move in opposite directions is shown. Each of the drive supports 153.1, 153.2 is mechanically connected to a corresponding displacement support (also not shown here) via a coupling structure 158, not shown here. The two drive supports 153.1, 153.2 can be suspended by a suitable spring structure 190 in the chip frame, wherein a potential can also be generated at the actuator electrode 180 via the spring structure 190. The two drive supports 152.1, 152.2 each include two sections 159.1, 159.2 extending in the direction of movement x, between which the actuator electrode 180 is clamped accordingly. In the following exemplary embodiment, the actuator electrode 180 has a plurality of electrode plates 184 that are electrically connected to each other and are arranged in a manner similar to that of the actuator electrode 180. Fig.13 As indicated by dashed lines, electrode plates 184 of actuator electrode 180 each extend between electrode plates 176 of stator electrodes 173 . 1 , 173 . 2 , which are also designed in a vertical arrangement of a plurality of electrode plates.

[0085] Fig.15 Another embodiment that is particularly advantageous in terms of increasing the area of ​​the force field is described intuitively. Fig.13 The electrode arrangement structure of the stator electrode 173 is further segmented perpendicular to the vertical multiplication direction z. The stator hole electrode 178 is generated by the vertical connection 177 between the electrode plates 176 of the stator electrode 173. Complementarily, the electrode plates 184 of the actuator electrode 180 are connected perpendicularly to the movement direction x and perpendicularly from Fig.13 The segmentation of the multiplication direction z produces a suitable actuator electrode protrusion 185, which can be electrostatically bidirectionally sunk into the corresponding electrode hole 178 of the complementary stator electrode 173. This results in a 3D comb actuator 172, which can provide multiple times the force of a conventional in-plane comb actuator. In addition, this structure basically brings the following technical potential at the same time: the force generated thereby can be further increased by reducing the horizontal and vertical electrode gaps (F~1 / d) between the protrusion electrode 185 and the hole electrode 178.

[0086] Fig.16A plan view perpendicular to the direction of movement x (left) and four cross sections (right) show a system with two mutually oppositely moving axes, each with a plurality of axes from Fig.15 The configuration of the drive device 170 of the drive support 153.1, 153.2 of the drive unit 172. The vertical sequence of the electrode structures enables a two-period interleaving of the drive shuttle structure, so that bidirectionality can be implemented by two opposite, movable drive supports (shuttles) 153.1, 15.2 within the drive plane. In this case, the suspension of the drive supports 152.1, 152.2 can be carried out by a suitable spring structure 190 in the chip frame, wherein a potential can also be generated at the actuator electrode 180 via the spring structure 190.

[0087] Fig.17 The figure shows the driving electrodes in the form of male electrodes and hole electrodes. Fig.15 and 16 Here, the advantages of the special configuration shown in Fig.16 Detailed illustration of a second cross section of FIG. 1 , in which the male electrode 185 is arranged inside the hole electrode 178. Fig.16 The electrode unit cell (marked with a dotted line) is Fig.14 , the corresponding electrode areas of the embodiment shown in FIG. Fig.14 The loss of the horizontal electrode surface with width E in the 2D comb actuator with the accompanying vertical segmentation is overcompensated by the growth of the vertical electrode surface with height F, since the section F is larger than the section E. This leads to a further increase in the force area. It can also be seen here that the higher the relevant electrode is designed, the larger the effective electrode area of ​​the punch electrode 185 and the associated hole electrode 178. Depending on the design and technical possibilities, this effect can be further increased if the width of the vertical gap between the vertical side walls of the punch electrode 185 and the hole electrode 178 and the vertical webs between the hole electrodes 178 are reduced.

[0088] exist Fig.18, an additional possibility for increasing the driving force is illustrated by way of example. Here, the effective area of ​​the force field is increased by shaping the profile of the punch electrode 185 through an additional plane so that a new surface for the effective force field is generated. Here, for example, an additional effective electrode surface can be generated between two complementary drive electrodes by means of a meander-like interlacing of the punch electrode 184 and the hole electrode 178. In the present example, the punch electrode 185 of the actuator electrode 180 has a cross-sectional profile in the form of a double T-bracket. The hole electrode 178 to which the stator electrode 173 belongs has a cross-sectional profile that is correspondingly adapted to the punch electrode 185. However, in principle, differently shaped cross-sectional profiles of the electrodes are also possible, by means of which the effective electrode surface and, in association therewith, the electric field between the complementary drive electrodes can be increased in a suitable manner.

[0089] Compared with conventional in-plane comb drives, Figures 13 to 18 The design concept for increasing the effective electrode surface, which is illustrated in Figure 1, enables significantly higher forces to be provided per chip surface. In an embodiment with only two repetitions of the proposed actuator plane, the segmented electrode structure provides between 65% and 135% higher forces per chip surface than a standard comb drive. Fig.13 and 15 The embodiment of the invention achieves a further multiplication of the surface area for generating the force field per chip surface by technical improvements to achieve horizontal or vertical gaps and reduce the structure width, actuator layer thickness and web width. In contrast, conventional in-plane comb drives are not considered to have this technical evolution potential, because an increase in the comb layer thickness (actuator and stator) is usually accompanied by an increase in the gap.

[0090] Although the present invention has been illustrated and described in more detail through preferred embodiments, the present invention is not limited by the disclosed embodiments. More specifically, those skilled in the art can also derive other variations therefrom without departing from the protection scope of the present invention.

Claims

1. A micro-electromechanical loudspeaker (100), comprising: - a substrate (110) having a substrate surface (111), - a housing (130) arranged on said substrate (110), - a cavity (140) delimited by the housing (130) and the base (110), - a translation device (150) arranged in the cavity (140) so as to be pivotally movable in a predetermined direction of movement (x) parallel to the base surface (111), the translation device comprising a component consisting of a plurality of movable fin structures (160) arranged side by side in the direction of movement (x), the movable fin structures dividing the cavity (140) into a plurality of fluidically independent sections, and the translation device comprising a support structure (151) connecting the movable fin structures (160) to one another, - a drive device (170) which is configured to deflect the translation device (150) in the movement direction (x), the drive device comprising a plurality of drive units (172), each of which is composed of at least one actuator electrode (180) mechanically connected to the translation device (150) and at least one stator electrode (173.1, 173.2) mechanically connected to the housing (130) and / or the substrate (110), wherein the actuator electrode and the stator electrode (180, 173.1, 173.2) respectively assigned to the drive unit (172) are configured to generate an electrostatic force for accelerating the translation device (150) in the movement direction (x) when being loaded with different potentials, Wherein, at least a portion of the movable driving electrode (180) is arranged on the support structure (151).

2. The micro-electromechanical loudspeaker (100) according to claim 1, in, An immovable fin structure (123) arranged on the base (110) and / or the housing (130) is respectively provided between two directly adjacent movable fin structures (160), wherein a gas volume that can be compressed by the movement of the movable fin structure (160) in a movement direction (x) is respectively formed between the movable fin structure (160) and the immovable fin structure (123) directly adjacent to the movable fin structure.

3. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, Two translation devices (150.1, 150.2) that move in opposite directions to each other are arranged in the cavity (140), each of the translation devices having a movable support structure (150.1, 150.2) and a plurality of movable fin structures (160) arranged on the corresponding support structure (151.1, 151.2). In which, the movable fin structures (160) of the two translation devices (150.1, 150.2) are arranged alternately in the movement direction (x), so that a gas volume that can be compressed by the relative movement of the corresponding fin structures (160) is formed between the movable fin structure (160) of the first translation device (150.1) and the movable fin structure (160) of the second translation device (150.2).

4. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, A portion of the actuator electrode (180) is arranged on an upper side (161) and / or an underside (162) of at least one movable fin structure (160).

5. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The housing (130) includes a frame structure (135) that laterally surrounds the cavity (140). wherein the movable support structure (151) is constructed in the form of a frame, and the movable fin structure (160) is clamped laterally in the frame, wherein at least a portion of the actuator electrode (180) is arranged on an end surface (157.1, 157.2) of the support structure (151), and The stator electrodes (173.1, 173.2) assigned to the respective actuator electrodes (180) are arranged on inner sides (136.1, 136.2) of the frame structure (135) which are arranged opposite the respective end faces (157.1, 157.2) of the support structure (151).

6. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The housing (130) includes a frame structure (135) that laterally surrounds the cavity (140). The movable support structure (151) is constructed in the form of a frame, and the movable fin structure (160) is clamped transversely in the frame. wherein at least a portion of the actuator electrode (180) is arranged on the outer side of the side wall (156.1, 156.2) of the support structure (151), and The stator electrodes (173.1, 173.2) assigned to the respective actuator electrodes (180) are arranged on inner sides (136.3, 136.4) of the frame structure (135) which are arranged opposite the respective side walls (156.1, 156.2) of the support structure (151).

7. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The housing (130) comprises a frame structure (135) laterally surrounding the cavity (140), the movable fin structure (160) being laterally clamped in the frame structure, and The movable support structure (151) connects the movable fin structures (160) arranged side by side in the movement direction (x) to one another in the middle region of the fin structures (160).

8. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, At least a portion of the movable fin structure (160) has a lateral expansion structure (164) on the upper side and / or the lower side (161, 162), which extends in the movement direction (x) and each has a plurality of actuator electrodes (180) arranged side by side in the movement direction (x).

9. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The actuator electrode (180) and the stator electrodes (173.1, 173.2) respectively assigned to the actuator electrode each have a plurality of track-shaped structures (181, 174) extending in the direction of movement (x). The track-shaped structure (181) of the actuator electrode (180) and the track-shaped structure (174) of the stator electrode are interlaced in a comb-like manner.

10. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The actuator electrode (180) and the stator electrodes (173.1, 173.2) are each of planar design and are arranged opposite one another, separated from one another by a defined gap.

11. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The actuator electrode (180) and the stator electrodes (173.1, 173.2) are respectively arranged side by side in the movement direction (x) and form two mutually staggered castellations.

12. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The actuator electrode (180) and the stator electrodes (173.1, 173.2) assigned to the actuator electrode are each constructed in the form of a plurality of electrode plates (184, 176) arranged one above the other in a direction (z) perpendicular to the substrate surface (111) and extending parallel to the substrate surface (111). The electrode plates (184) of the actuator electrodes (180) and the electrode plates (176) of the stator electrodes (173.1, 173.2) are alternately arranged in a direction (z) perpendicular to the base plane (103) and are connected to each other via their own connection structures (186, 177).

13. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, At least a portion of the actuator electrodes (180) respectively comprises a two-dimensional arrangement of male electrodes (185) extending in the direction of movement (x) and connected to each other by a connecting structure (186), and The stator electrodes (173.1, 173.2) assigned to the respective actuator electrode (180) each comprise a component of correspondingly shaped hole electrodes (177), wherein each hole electrode (177) is designed to receive a punch electrode (185) assigned thereto.

14. The micro-electromechanical loudspeaker (100) according to claim 13, in, The male electrodes (185) each have a cross-sectional profile having an extension (187) extending perpendicularly to the direction of movement (x), and The hole electrode (177) assigned to the punch electrode (185) has a cross-sectional profile that is adapted to the cross-sectional profile of the punch electrode (186).

15. The micro-electromechanical loudspeaker (100) according to claim 14, in, The cross-sectional profile of the punch electrode (185) is designed in the form of a double T-bracket or in a cross shape.

16. The micro-electromechanical loudspeaker (100) according to any one of the preceding claims, in, The support structure (151) includes a displacement support (152) that interconnects the movable fin structures (160) of the translation device (150) and a drive support (153) that is mechanically connected to the displacement support (152), and the drive support interconnects the actuator electrodes (180) of the translation device (150).

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