Search

US-12617671-B2 - Micromechanical sensor element

US12617671B2US 12617671 B2US12617671 B2US 12617671B2US-12617671-B2

Abstract

A micromechanical sensor element includes a substrate, a first structure movably arranged on the substrate, a second structure movably arranged on the substrate and an electrode arrangement, situated on the substrate in a fixed manner, which includes at least one first electrode. The movably arranged structures are coupled with each other by at least one coupling element in such a way that, upon a deflection of the first movably arranged structure along a first direction, the second movably arranged structure undergoes a deflection along an opposite direction. The first electrode includes a plurality of electrode surfaces. The movably arranged structures each include a plurality of movable electrode surfaces. The substrate-fixed electrode surfaces and the movable electrode surfaces engage with each other. The movable electrode surfaces are each situated on sides of the electrode surfaces of the substrate-fixed electrode arrangement facing away from the movably arranged structures.

Inventors

  • Jochen Reinmuth

Assignees

  • ROBERT BOSCH GMBH

Dates

Publication Date
20260505
Application Date
20211029
Priority Date
20201109

Claims (13)

  1. 1 . A micromechanical sensor element, comprising: a substrate; a first movably arranged structure movably arranged on the substrate; a second movably arranged structure movably arranged on the substrate; and a substrate-fixed electrode arrangement situated on the substrate in a fixed manner, the substrate-fixed electrode arrangement including at least one first electrode; wherein: the first movably arranged structure and the second movably arranged structure are coupled with each other by coupling elements in such a way that, upon a deflection of the first movably arranged structure along a first direction running in parallel to the substrate, a portion of the second movably arranged structure undergoes a deflection along an opposite direction; the at least one first electrode includes a plurality of electrode surfaces; the first movably arranged structure includes a plurality of first movable electrode surfaces, and the second movably arranged structure includes a plurality of second movable electrode surfaces; the plurality of electrode surfaces of the substrate-fixed electrode arrangement and the first and second movable electrode surfaces of the first and second movably arranged structures engage with each other; the first movable electrode surfaces of the first movably arranged structure and the second movable electrode surfaces of the second movably arranged structure being each situated on sides of the plurality of electrode surfaces of the substrate-fixed electrode arrangement facing away from the first and second movably arranged structures, wherein: the at least one first electrode includes a first electrode section and a second electrode section; the first electrode section and the second electrode section are connected to the substrate via a shared first anchor point, wherein a displacement of the shared first anchor point relative to another anchor point results in distances between electrode surfaces of the first electrode section and the first movable electrode surfaces increasing, while distances between electrode surfaces of the second electrode section and the second movable electrode surfaces decrease; the first electrode section faces the first movably arranged structure, and the second electrode section faces the second movably arranged structure.
  2. 2 . The micromechanical sensor element as recited in claim 1 , wherein the plurality of electrode surfaces of the substrate-fixed electrode arrangement are situated to run perpendicularly to the first direction, and the plurality of electrode surfaces of the substrate-fixed electrode arrangement being situated to run in parallel to the movable electrode surfaces.
  3. 3 . The micromechanical sensor element as recited in claim 1 , wherein a first anchor point of the at least one first electrode fixedly situated on the substrate is situated outside an area of the substrate which encompasses the at least one first electrode.
  4. 4 . The micromechanical sensor element as recited in claim 1 , wherein: each of the coupling elements is a lever spring element, each lever spring element including a lever subelement and a respective first, a respective second and a respective third spring subelement; each lever subelement is connected to the substrate by the respective first spring subelement and via an anchor point; each lever subelement is connected to the first movably arranged structure by the respective second spring subelement and to the second movably arranged structure by the respective third spring subelement; each lever spring element is situated in such a way that at least one respective first lever subelement is situated to run along the first direction in a non-deflected state, and at least one respective second lever subelement is situated to run along a second direction running perpendicularly to the first direction in a non-deflected state; each lever spring element is configured in such a way that the respective first lever subelement is tilted in a plane spanned by the first direction and the second direction when an acceleration acts along the second direction, and the respective second lever subelement is tilted in the plane when an acceleration acts along the first direction; the substrate-fixed electrode arrangement includes at least the at least one first electrode configured to detect deflections of the first movably arranged structure and the second movably arranged structure along the first direction, and including at least one second electrode configured to detect deflections of the first movably arranged structure and the second movably arranged structure along the second direction.
  5. 5 . The micromechanical sensor element as recited in claim 4 , wherein: the at least one first electrode and the at least one second electrode each include a first electrode section and a second electrode section; the first electrode section and the second electrode section of the first electrode are connected to the substrate via a shared first anchor point, and the first electrode section and the second electrode section of the at least one second electrode are connected to the substrate via a shared second anchor point; the first electrode sections of the at least one first and second electrodes each faces the first movably arranged structure, and the second electrode sections of the at least one first and second electrodes each face the second movably arranged structure; the first and second electrode sections of the at least one first and second electrode each include a plurality of electrode surfaces situated perpendicularly to a plane spanned by the first direction and the second direction; the electrode surfaces of each of the first electrode sections of the at least one first and second electrode are situated to run in parallel to the electrode surfaces of the second electrode sections of the at least one first and second electrodes, the first movably arranged structure including a plurality of first movable electrode surfaces, and the second movably arranged structure including a plurality of second movable electrode surfaces; the plurality of electrode surfaces of the substrate-fixed electrode arrangement and the first and second movable electrode surfaces of the first and second movably arranged structures engage with each other and are situated to run in parallel to each other; the first movable electrode surfaces of the first movably arranged structure and the second movable electrode surfaces of the second movably arranged structure being each situated on sides of the plurality of electrode surfaces of the substrate-fixed electrode arrangement facing away from the movably arranged structures.
  6. 6 . The micromechanical sensor element as recited in claim 1 , further comprising: a third electrode situated in a fixed manner, wherein the third electrode is situated in relation to the first and second movably arranged structures in such a way that a distance between the third electrode and each of the first and second movably arranged structures is smaller than a distance between the at least one first electrode and the first and second movably arranged structures upon a deflection of the first and second movably arranged structures along the first direction.
  7. 7 . The micromechanical sensor element as recited in claim 1 , wherein: the first movably arranged structure and the second movably arranged structure are coupled with each other and to the substrate by four lever spring elements, the electrode arrangement includes four electrodes which each include a first electrode section facing the first movably arranged structure and a second electrode section facing the second movably arranged structure, which are each connected to the substrate via shared anchor points; the electrode sections each include a plurality of electrode surfaces; the electrode surfaces of the at least one first electrode and a third electrode being situated to run in parallel to each other, and the electrode surfaces of a second electrode and a fourth electrode being situated to run in parallel to each other, the plurality of electrode surfaces of the substrate-fixed electrode arrangement and the movable electrode surfaces of the movably arranged structures engaging with each other and being situated to run in parallel to each other; the first movably arranged structure includes a plurality of third movable electrode surfaces, and the second movably arranged structure includes a plurality of fourth movable electrode surfaces; the first and third movable electrode surfaces of the first movably arranged structure and the second and fourth movable electrode surfaces of the second movably arranged structure are each situated on sides of the plurality of electrode surfaces of the substrate-fixed electrode arrangement facing away from the first and second movably arranged structures, the lever spring elements being designed in such a way that the first and second moveably arranged structures move away from the third electrode and/or from the fourth electrode upon a deflection in a direction of the at least one first electrode and/or in a direction of the second electrode.
  8. 8 . The micromechanical sensor element as recited in claim 1 , wherein the substrate-fixed electrode arrangement includes at least one axis of symmetry running within a plane spanned by the first direction and the second direction.
  9. 9 . The micromechanical sensor element as recited in claim 1 , wherein an arrangement of the first and second movably arranged structures and the substrate-fixed electrode arrangement includes at least one axis of symmetry running within a plane spanned by the first direction and the second direction.
  10. 10 . The micromechanical sensor element as recited in claim 5 , wherein an arrangement of the anchor point and the shared first and shared second anchor points includes at least one axis of symmetry running within a plane spanned by the first direction and the second direction.
  11. 11 . The micromechanical sensor element as recited in claim 1 , wherein the first and second movably arranged structures are situated and coupled with each other in such a way that deflection amplitudes of the first and second movably arranged structures are of the same size when an acceleration acts perpendicularly to the electrode surfaces.
  12. 12 . The micromechanical sensor element as recited in claim 7 , wherein the first, second, third, and fourth electrodes are each situated in areas of the lever spring elements, at least in sections.
  13. 13 . The micromechanical sensor element as recited in claim 1 , wherein anchor points of the first and second movably arranged structures and the substrate-fixed electrode arrangement are situated in surroundings of a center of gravity of the micromechanical sensor element.

Description

CROSS REFERENCE The present application claims the benefit under 35 U.S.C. § 119 of German Patent Application No. 102020214019.7 filed on Nov. 9, 2020, which is expressly incorporated herein by reference in its entirety. FIELD The present invention relates to a micromechanical sensor element. BACKGROUND INFORMATION Some conventional micromechanical systems (MEMS) are available, with the aid of which a movement of a seismic mass may be verified. MEMS of this type may be designed, for example, as acceleration sensors or as rotation rate sensors. At least one seismic mass is usually freely movable suspended via a spring on a substrate. Movable electrodes are formed at the seismic mass. Anchored electrodes are formed on the substrate, which form capacitances together with the movable electrodes of the seismic mass. By a measurement of a capacitance, a position of the movable mass perpendicular to the electrode surfaces may be determined. Two oppositely working symmetrical electrode pairs are usually provided opposite the movable mass. A change in position or an absolute position of the seismic mass may be very accurately determined via an electronic circuit from a differential signal of the capacitances formed thereby. A disadvantage of an arrangement of this type is, for example, that the substrate may bend due to a soldering operation when manufacturing the acceleration sensor and due to external influences. Since the seismic mass and the electrodes are not suspended at the same point on the substrate, this bending results in a displacement of the seismic mass relative to the fixed electrodes, which may not be differentiated from a present acceleration. An undesirable spurious signal thus occurs. To reduce this effect, for example, anchorings of the fixed electrodes and the movable mass may be moved as close as possible toward each other, which requires an additional complexity and an additional use of space. For example, additional layers, which are associated with additional costs, are often necessary in the process, or nonlinearities must be taken into account, with unfavorable electrode arrangements resulting therefrom. Since the fixed electrodes must be electrically insulated from the movable electrodes, the anchorings may not be situated arbitrarily close to each other. The anchorings must furthermore be made smaller, the closer they are moved toward each other, and thus have an unstable design. SUMMARY An object of the present invention is to provide an improved micromechanical sensor element, which is insensitive to a substrate bending and whose manufacture is easier to implement. This object is achieved by a micromechanical sensor element in accordance with an example embodiment of the present invention. Advantageous refinements of the present invention are disclosed herein. In accordance with an example embodiment of the present invention, a micromechanical sensor element includes a substrate, a first structure movably arranged on the substrate, a second structure movably arranged on the substrate and an electrode arrangement, situated on the substrate in a fixed manner, which includes at least one first electrode. The first movably arranged structure and the second movably arranged structure are coupled with each other by at least one coupling element in such a way that, upon a deflection of the first movably arranged structure along a first direction running in parallel to the substrate, the second movably arranged structure undergoes a deflection along an opposite direction. The first electrode includes a plurality of electrode surfaces. The first movably arranged structure includes a plurality of first movable electrode surfaces, and the second movably arranged structure includes a plurality of second movable electrode surfaces. The electrode surfaces of the substrate-fixed electrode arrangement and the movable electrode surfaces of the movably arranged structures engage with each other. The first movable electrode surfaces of the first movably arranged structure and the second movable electrode surfaces of the second movably arranged structure are each situated on sides of the electrode surfaces of the substrate-fixed electrode arrangement facing away from the movably arranged structures. Due to the arrangement of the elements of the micromechanical sensor element, the first movable structure and the second movable structure are coupled with each other in such a way that the first movable electrode surfaces and the second movable electrode surfaces move together with a component perpendicular to the movable electrode surfaces in the direction of the substrate-fixed electrode surfaces upon a present acceleration, by means of which the active acceleration is detectable. In accordance with an example embodiment of the present invention, it is advantageous that a displacement of an anchor point of the substrate-fixed electrode relative to an anchor point of the movable structures in a direction com