MEMS TRANSDUCER, IN PARTICULAR FOR INTERACTING WITH A FLUID

Abstract

A MEMS transducer interacting with a fluid. The MEMS transistor includes: a layer stack of at least three MEMS layer structures in a layer sequence, an active MEMS layer structure being formed between a lower MEMS layer structure and an upper MEMS layer structure; at least one lamella formed in the active MEMS layer structure and deflectable laterally for interacting with the fluid; and a drive device for deflecting the movable lamella in a lateral direction perpendicular to the layer sequence, with a lower and/or upper electrode structure, which is formed adjacent to the active MEMS layer structure on the lower and/or upper MEMS layer structure. For applying an electrical voltage to the upper and/or lower electrode structure, a through-connection of the upper or lower MEMS layer structure is provided, which is electrically conductively connected to a contact element formed in the active MEMS layer structure.

Claims

1. A MEMS transducer for interacting with a fluid, comprising: a layer stack of at least three MEMS layer structures arranged one above the other in a layer sequence, an active MEMS layer structure of the layer stack being formed between a lower MEMS layer structure of the layer stack and an upper MEMS layer structure of the layer stack; at least one lamella which is formed in the active MEMS layer structure and is deflectable laterally at least in sections for interacting with the fluid; and a drive device configured to deflect the lamella at least in sections in a lateral direction perpendicular to the layer sequence, with a lower and/or upper electrode structure, which is formed adjacent to the active MEMS layer structure on the lower MEMS layer and/or upper MEMS layer structure; wherein, for applying an electrical voltage to the upper and/or lower electrode structure, a through-connection of the upper or lower MEMS layer structure is provided, which is electrically conductively connected to at least one contact element formed in the active MEMS layer structure, the at least one contact element being mechanically connected to the upper and the lower MEMS layer structure and being electrically conductively connected to at least one drive electrode of the upper and/or the lower electrode structure and being insulated from a substrate of the upper and lower MEMS layer structures in a region outside the through-connection.

2. The MEMS transducer according to claim 1, wherein the at least one lamella is laterally movably guided at least in sections in an active region of the active MEMS layer structure, the at least one contact element being formed in a frame region bordering the active region at an edge of the active region.

3. The MEMS transducer according to claim 2, wherein the at least one lamella is mechanically connected to the upper and the lower MEMS layer structure at opposite support points in the frame region and is electrically insulated from the upper and the lower MEMS layer at the support points.

4. The MEMS transducer according to claim 2, wherein at least one fixed support wall is formed in the active region of the active MEMS layer structure and is mechanically connected to the upper and the lower MEMS layer structure.

5. The MEMS transducer according to claim 4, wherein the support wall divides the active region into subregions.

6. The MEMS transducer according to claim 1, wherein the at at least one contact element is mechanically and electrically conductively connected to a stamp of the through-connection and, outside the through-connection, is mechanically connected to the upper and/or lower MEMS layer structure in at least one contact region spaced apart from the through-connection in a lateral direction.

7. The MEMS transducer according to claim 6, wherein the at least one contact element has at least one cutout, the cutout spacing apart and electrically insulating the contact element from the upper and/or lower MEMS layer structure in a portion located between the through-connection and the at least one contact region.

8. The MEMS transducer according to claim 1, wherein the at least one contact element has a substantially H-shaped or Y-shaped cross-sectional shape.

9. The MEMS transducer according to claim 1, wherein the at least one contact element is connected in the region outside the through-connection at least in sections to a conductive path layer which is flush with the upper and/or lower MEMS layer structure and is electrically insulated from the substrate of the upper or lower MEMS layer structure by an insulation layer.

10. The MEMS transducer according to claim 1, wherein the at least one contact element is electrically conductively connected to a lower drive electrode of the lower electrode structure and an upper drive electrode of the upper electrode structure.

11. The MEMS transducer according to claim 1, wherein the at least one contact element includes at least one first contact element, which is electrically conductively connected to a lower drive electrode of the lower electrode structure, at least one second contact element, which is electrically conductively connected to an upper drive electrode of the upper electrode structure, and a third contact element, which is electrically conductively connected to a further upper drive electrode and a further lower drive electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a cross-sectional view of an active region of a MEMS transducer with a plurality of movable lamellae for interacting with a fluid, according to an example embodiment of the present invention.

[0032] FIG. 2 shows the MEMS transducer in a sectional view in the main extension plane, according to an example embodiment of the present invention.

[0033] FIG. 3 is a first cross-sectional view of a support point formed in a frame region of an active MEMS layer structure for connecting a movable lamella of the MEMS transducer, according to an example embodiment of the present invention.

[0034] FIG. 4 is a second cross-sectional view of the support point of FIG. 3 in a drawing plane perpendicular to FIG. 3.

[0035] FIG. 5 shows a contact element between a through-connection in the upper MEMS layer structure and a lower drive electrode of a lower electrode structure, according to an example embodiment of the present invention.

[0036] FIG. 6 shows a contact element between a through-connection in the upper MEMS layer structure and a lower and an upper drive electrode, in particular for applying an electrical potential to movable lamellae, according to an example embodiment of the present invention.

[0037] FIG. 7 shows a contact element between a through-connection in the upper MEMS layer structure and a lower drive electrode of a lower electrode structure in an alternative embodiment to FIG. 5, according to an example embodiment of the present invention.

[0038] FIG. 8 shows a contact element between a through-connection in the upper MEMS layer structure and an upper drive electrode of an upper electrode structure, according to an example embodiment of the present invention.

[0039] FIG. 9 shows a support wall formed in the active region of the active MEMS layer structure, according to an example embodiment of the present invention.

[0040] Identical or corresponding elements are provided with the same reference signs in all figures.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0041] The figures show a MEMS transducer 1 that can be produced by means of wafer bonding, in particular fusion bonding, from a layer structure of three MEMS layer structures 100, 200, 300 provided with conductive paths and/or insulation layers.

[0042] The figures illustrate exemplary embodiments in which a through-connection 310 is provided in an upper MEMS layer structure 300 by way of example. It is to be understood that this is to be interpreted in a non-restrictive manner and, in particular, that correspondingly inverted arrangements in which the through-connection 310 is provided in a lower MEMS layer structure 100 can be taken directly and equivalently from the present disclosure.

[0043] FIG. 1 shows a cross-section of an active region 1000 of the MEMS transducer 1 with an active MEMS layer structure 200 arranged between a lower MEMS layer structure 100 and an upper MEMS layer structure 300.

[0044] In the active MEMS layer structure 200, a plurality of lamellae 210 arranged in parallel with one another is formed, which are controllable and deflectable by means of electrical potentials UB1, UB2, UL, UT1, UT2. The lamellae 210 are movable in the lateral direction 500 at least in sections in the main extension plane of the MEMS transducer 1. The lamellae 210 are anchored at their ends in a frame region 1500, cf. in particular FIGS. 2 to 4, which borders the active region 1000 at the edge.

[0045] The lower MEMS layer structure 100 forms a base structure and the upper MEMS layer structure 300 forms a cover structure for a cavity in which the movable lamellae 210 are arranged. For interacting with a fluid, in particular for sound generation, through-openings 110, 310 are introduced into the lower MEMS layer structure 100 or into the upper MEMS layer structure 300.

[0046] A drive device 400 for controlling the movable lamellae 210 comprises upper drive electrodes 350, 390 of first and second upper electrode arrangements 320, 330 and lower drive electrodes 150, 190 of first and second lower electrode arrangements 120, 130 for applying the alternating electric fields, in particular the electric potentials UB1, UB2, UL, UT1, UT2. The lower drive electrodes 150 of the first lower electrode arrangement 120 and of the second lower electrode arrangement 130 are electrically insulated from one another in the lateral direction 500 by lower isolation regions 160. Correspondingly, the upper drive electrodes 350 of the first upper electrode arrangement 320 and the second upper electrode arrangement 330 are electrically insulated from one another in the lateral direction 500 by upper isolation regions 360. An upper substrate 380, for example made of silicon, of the upper MEMS layer structure 300 is electrically insulated from the upper electrode arrangements 320, 330 in the layer sequence direction by an upper insulation layer 370. Correspondingly, a lower substrate 180 of the lower MEMS layer structure 100 is electrically insulated from the lower electrode arrangements 120, 130 in the layer sequence direction by a lower insulation layer 170.

[0047] The drive electrodes 150, 190, 350, 390 of the upper and/or lower electrode arrangements 120, 130, 320, 330 are designed, for example, as highly doped polycrystalline silicon structures and can preferably be produced by means of layer deposition.

[0048] FIG. 2 shows the MEMS transducer 1 with the active region 1000 in a sectional view, the drawing plane shown corresponding to the main extension plane of the MEMS transducer 1. The lower, upper, and active MEMS layer structures 100, 200, 300 are connected to one another at the edges in a wafer bonding region 1800. The active region 1000 is surrounded by the frame region 1500, which is separated from the wafer bonding region 1800 by a peripheral isolation gap 1700.

[0049] The potentials UB1, UB2, UL, UT1, UT2 are supplied via contact elements 600, which are shown in cross-section in particular in FIGS. 5 to 8. The sectional planes shown in FIGS. 1, 3 to 6, and 8 are denoted by Roman numerals in FIG. 2.

[0050] FIGS. 3 and 4 show the anchoring of the live lamellae 210 at a support point in the frame region 1500. The lamellae 210 are mechanically connected to an upper conductive path layer 391 and to a lower conductive path layer 191, which are respectively electrically insulated from the substrates 380, 180 of the upper and lower MEMS layer structure 300, 100 by upper and lower insulation layers 391, 191. The lamellae 210 are clamped between the upper and the lower MEMS layer structure 300, 100 and anchored at their opposite ends in the frame region 150. In the vertical direction 501, the lamellae 210 have a reduced structural height in order to ensure mobility of the lamellae 210 and sufficient electrical isolation from the upper and/or lower electrode arrangements 120, 130, 320, 330 or from the upper and the lower MEMS layer structure 300, 100.

[0051] FIGS. 5 to 8 show contact elements 600 for supplying the electrical potentials UB1, UB2, UL, UT1, UT2. Each contact element 600 is connected to a through-connection 381, which is designed as a through-silicon via, in the substrate 380 of the upper MEMS layer structure 300. The through-connection 391 has a stamp 383 which is electrically insulated from the substrate 380 by a peripheral isolation 382 and provided with a metallization 384 on the upper side of the upper MEMS layer structure 300 for applying an electrical potential UB1, UB2, UL, UT1, UT2.

[0052] The contact elements 600 are formed in the active MEMS layer structure 200 and are directly connected to the stamp 383, in particular by means of wafer bonding. The contact elements 600 provide mechanical support for the stamp 383 and are connected, for this purpose, at least to the lower MEMS layer structure 100, cf. in particular FIG. 5, indirectly via intermediate conductive path layers 191, in particular made of polycrystalline silicon, and insulation layers 170. The contact elements 600 and the substrates 180, 380 of the upper and lower MEMS layer structures 100, 300 are electrically insulated from one another and can be grounded accordingly.

[0053] The first electrical potentials UB1, UB2 are supplied via first contact elements 601, as shown by way of example in FIGS. 5 and 7. The first contact element 601 is electrically conductively connected to a lower drive electrode 150 of the lower electrode arrangement 120, 130.

[0054] FIG. 5 shows an embodiment in which the first contact element 601 has an I-shaped cross-section. FIG. 5 also shows the region where the lower drive electrode 150 passes through the frame region 1500 into the active region 1000 of the MEMS transducer 1. A frame element 700 of the frame region 1500 is indirectly connected to the upper MEMS layer structure 100 via an upper conductive path layer 391, which is electrically insulated from the substrate 380 by an insulation layer 370. The frame element 700 has a structural height so that an insulating gap is formed between the lower drive electrode 150 and the frame element 700. The frame element 700 can thus in particular be at a different electrical potential than the lower drive electrode 150.

[0055] FIG. 7 shows an alternative embodiment with a substantially H-shaped cross-section. Here, the first contact element 601 is mechanically and electrically conductively connected to the stamp 383 of the through-connection 381 and, outside the through-connection 383, is connected at a plurality of points to upper and lower conductive path layers 391, 191 of the upper and lower MEMS layer structures 300, 100 and to the lower drive electrode 150. The upper and the lower conductive path layer 391, 191 and the lower drive electrode 150 are electrically insulated from the substrates 380, 180 of the upper and lower MEMS layer structures 300, 100 by upper and lower insulation layers 370, 170. For increasing the stability of the layer structure, the first contact element 601 designed to contact the lower drive electrode 150 is mechanically connected to the upper and lower MEMS layer structures 300, 100 in a contact region 2000, which is spaced apart from the through-connection 383 in the lateral direction 500. The first contact element 601 has cutouts 610, 620, which space apart and electrically insulate the first contact element 601 from the upper and/or lower MEMS layer structure 300, 200 in the region portion located between the through-connection 381 and the contact region 2000.

[0056] For supplying second potentials UT1, UT2 to the upper drive electrodes 350, second contact elements 602 are provided, an exemplary embodiment of the second contact element 602 being shown in FIG. 8. In contrast to the embodiment shown in FIG. 7, the second contact element 602 is electrically conductively connected to the upper drive electrode 350 in the contact region 2000 and is mechanically supported there on a region of a lower conductive path layer 191 that is stripped through an insulation layer 170. The second contact element 602 also has the cutouts 610, 620 in order to ensure electrical isolation of the second contact element 602 in the region between the through-connection 381 and the contact region 2000.

[0057] The live upper drive electrode 350 passing through the frame region 1500 into the active region 1000 of the MEMS transducer 1 is also shown in FIG. 8. Here, the frame element 700 of the frame portion 1500 is indirectly connected to the lower MEMS layer structure 100 via a lower conductive path layer 191 which is electrically insulated from the substrate 180 of the lower MEMS layer structure 100 by an insulation layer 170, wherein an insulating gap is formed between the upper drive electrode 350 and the frame element 700. The frame element 700 can thus in particular be at a different electrical potential than the upper drive electrode 350.

[0058] For supplying a third potential UL to the upper and lower drive electrodes 390, 190, third contact elements 603 are provided, which are shown in an exemplary embodiment in FIG. 6. In contrast to the embodiments shown in FIGS. 7 and 8, the third contact element 603 is mechanically and electrically conductively connected in the contact region 2000 to further upper and lower drive electrodes 390, 190, in particular for applying a voltage to the lamellae 210.

[0059] FIG. 9 shows a portion of the active region 1000 of the MEMS transducer 1 in cross-section. A fixed support wall 8000 is formed in the active MEMS layer structure 200 of the active region 1000, is mechanically connected directly, for example by means of wafer bonding, to the upper and the lower MEMS layer structure 300, 100 and divides the active region 1000 into subregions. The support wall 800 in particular serves as a spacer in order to ensure a substantially constant distance between the upper and lower MEMS layer structures 300, 100 in the active region 1000.