阅读说明：本技术 用于与流体的体积流相互作用的mems换能器及其制造方法 (MEMS transducer for interaction with a volume flow of a fluid and method of manufacturing the same ) 是由 哈拉尔德·申克 霍尔格·康拉德 于 2018-04-20 设计创作，主要内容包括：一种用于与流体的体积流相互作用的MEMS换能器,包括衬底,该衬底包括具有具有形成多个衬底平面的多个层的层堆叠并且在层堆叠内包括腔。MEMS换能器包括连接到腔内的衬底的机电换能器,并且在多个衬底平面的至少一个移动平面内包括可变形的元件,在移动平面内的可变形元件的变形和流体的体积流因果相关。MEMS换能器包括在层堆叠的层内布置电子电路,该电子电路连接到机电换能器并且被配置为提供在可变形元件的变形和电信号之间的转换。(A MEMS transducer for interacting with a volumetric flow of a fluid includes a substrate including a layer stack having a plurality of layers forming a plurality of substrate planes and including a cavity within the layer stack. The MEMS transducer includes an electromechanical transducer connected to a substrate within the cavity and includes a deformable element in at least one plane of movement of the plurality of substrate planes, deformation of the deformable element in the plane of movement causally related to the volumetric flow of the fluid. The MEMS transducer includes an electronic circuit disposed within the layers of the layer stack, the electronic circuit being connected to the electromechanical transducer and configured to provide conversion between deformation of the deformable element and an electrical signal.)

1. A MEMS transducer for interacting with a volumetric flow (12) of a fluid, comprising:

a substrate (14) comprising a layer stack having a plurality of layers (32a-32b,34a-34b,36) forming a plurality of substrate planes and comprising a cavity (16) within the layer stack;

an electromechanical transducer (18; 18a-18f) connected to a substrate (14) within the cavity (16) and comprising an element (22; 22a-22 f; 30; 40; 150; 160) deformable in at least one plane of movement of the plurality of substrate planes, a deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) in the plane of movement being causally related to a volumetric flow (12) of the fluid;

an electronic circuit (17; 17a-17b) arranged within a layer (32a-32b) of the layer stack, the electronic circuit (17; 17a-17b) being connected to the electromechanical transducer (18; 18a-18f) and being configured to provide conversion between deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) and an electrical signal.

2. A MEMS transducer as claimed In claim 1, wherein the electronic circuitry (17; 17a-17b) is configured to couple an electrical control signal (In) ₁) Into the deformable element (22; 22a-22 f; 30, of a nitrogen-containing gas; 40; 150; 160) or to move the deformable element (22; 22a-22 f; 30, of a nitrogen-containing gas; 40; 150; 160) is converted into an electrical output signal (Out) ₂)。

3. A MEMS transducer as claimed in claim 2, wherein the electronic circuitry (17; 17a-17b) comprises at least one of: for applying the control signal (In) ₁) Is converted into said control signal (Out) ₁) For converting said electrical output signal (In) ₁) Is converted into said electrical output signal (Out) ₁) A digital version of the analog-to-digital converter of (a) the signal decoder, the processor, the semiconductor memory, the wireless communication interface for near field communication and the mobile radio interface.

4. A MEMS transducer as claimed In claim 2 or 3, wherein the electronic circuit (17; 17a-17b) is configured to convert the electrical control signal (In) into a deflection of the deformable element (22; 22a-22 f; 30; 40; 150; 160) and comprises a switching amplifier configured to provide a digital pulse width modulated control signal to the deformable element (22; 22a-22 f; 30; 40; 150; 160).

5. MEMS transducer according to any of claims 2 to 4, wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is a first deformable element (22; 22a-22 f; 30; 40; 150; 160), the MEMS transducer comprising at least a second deformable element (22; 22a-22 f; 30; 40; 150; 160), the electronic circuit (17; 17a-17b) being configured to convert the electrical control signal (In) into a deflection of the first and second deformable elements (22; 22a-22 f; 30; 40; 150; 160) or to convert a deformation of the first and second deformable elements (22; 22a-22 f; 30; 40; 150; 160) into the electrical output signal (Out) ₂)。

6. A MEMS transducer as claimed in any preceding claim wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is actively formed and configured to interact with the volumetric flow (12); or a plate element (62; 62a-62c) connected to the deformable element (22; 22a-22 f; 30; 40; 150; 160) is configured to be rigid and to interact with the volume flow (12).

7. A MEMS transducer as claimed in any of the preceding claims, wherein the layers (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged are arranged in a direction perpendicular to the plane of movement.

8. A MEMS transducer as claimed in any preceding claim wherein the layer (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged is electrically connected to the outside of the MEMS transducer, or is the outside of the MEMS transducer, and is in contact with a lead assembly.

9. A MEMS transducer as claimed in any of the preceding claims, wherein the layer (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged is a first cover layer, the electronic circuitry (17; 17a-17b) is a first electronic circuitry (17a), and wherein a second electronic circuitry (17b) is arranged in a second cover layer of the substrate (14).

10. A MEMS transducer as claimed in claim 9, wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is arranged between the first electronic circuit (17a) and the second electronic circuit (17b) at least some of the time during deformation.

11. The MEMS transducer according to claim 9 or 10, wherein the second electronic circuit (17b) is connected to the electromechanical transducer (18; 18a-18f) or to the first electronic circuit (17a) and is configured to provide a function related to the deformable element (22; 22a-22 f; 30; 40; 150; 160) to supplement the first electronic circuit (17 a).

12. A MEMS transducer as claimed in any of the preceding claims, wherein the layer stack comprises an adjustment layer (27), the adjustment layer (27) comprising at a first layer main side (29a) a first electronic pattern (31a) with a first distance grating (33a) and at an oppositely positioned second layer main side (29b) a second electronic pattern (31b) with a second distance grating (33b), the first and second electronic structures being connected to each other in the adjustment layer.

13. A MEMS transducer as claimed in claim 12, wherein the adjustment layer (27) is the stacked cap layer and the electronic circuitry (17; 17a-17b) is at least partially arranged in the adjustment layer (27), or the adjustment layer (27) is only the stacked cap layer electrically configured as adjustment layer.

14. A MEMS transducer as claimed in any of the preceding claims, wherein the layer (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged comprises a functional element (21) connected to the electronic circuitry (17; 17a-17b), the electronic circuitry (17; 17a-17b) being configured to control or evaluate the functional element (21).

15. A MEMS transducer as claimed in any of the preceding claims, wherein the layer (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged is a first cap layer, the electronic circuitry (17; 17a-17b) being a first electronic circuitry (17a), and wherein a second electronic circuitry (17b) and a functional element (21) are arranged in a second cap layer of the substrate (14), the second electronic circuitry (17b) being connected to the functional element (21) and being configured to control or evaluate the functional element (21).

16. A MEMS transducer as claimed in claim 14 or 15, wherein the functional element (21) comprises at least one of: a sensor, an actuator, a wireless communication interface, a light source, a memory component, a processor, and a navigation receiver.

17. A MEMS transducer as claimed in claim 16, wherein the functional element (21) comprises at least one of a MEMS sensor and a MEMS actuator.

18. A MEMS transducer as claimed in any of the preceding claims, wherein the electronic circuitry (17; 17a-17b) is arranged in a cover layer of the substrate (14), and wherein a gas sensing functionality is additionally arranged in the cover layer, the cover layer comprising an opening (26a) configured to allow the fluid flow (12) to pass, the gas sensing functionality being configured to sensorially interact with the fluid flow (12).

19. A MEMS transducer as claimed in claim 18, wherein the opening is surrounded by the gas sensing function (21) in the cover layer.

20. A MEMS transducer as claimed in claim 18, wherein the gas sensing function (21) at least partially protrudes into the opening (26 a).

21. A MEMS transducer as claimed in any of the preceding claims, wherein the layer (32a-32b) in which the electronic circuitry (17; 17a-17b) is arranged is a first substrate layer, and wherein the electronic circuitry (17; 17a-17b) is at least partly arranged in an adjacent second substrate layer.

22. A MEMS transducer as claimed in any preceding claim wherein the electronic circuit (17; 17a-17b) is arranged in a direction perpendicular to the plane of movement and the position of the electronic circuit (17; 17a-17b) corresponds to the position at which the deformable element (22; 22a-22 f; 30; 40; 150; 160) is at least partially located during deformation when the position of the electronic circuit (17; 17a-17b) extends into the plane of movement.

23. A MEMS transducer as claimed in any preceding claim, wherein the electromechanical transducer (18; 18a-18f) is configured to be responsive to electrical control (Out ) of the electronic circuit (17; 17a-17b) ₁) Causing fluid movement within the cavity (16), and/or in response to fluid movement within the cavity (16), responsively transferring fluid to the electronic circuitry (17; 17a-17b) provides an electrical signal (Out) ₂)。

24. A MEMS transducer as claimed in any preceding claim comprising: a plurality of electromechanical transducers (18; 18a-18 f); a first and a second deformable element (22; 22a-22 f; 30; 40; 150; 160) comprising a beam structure (30), the first and second deformable elements (22; 22a-22 f; 30; 40; 150; 160) being configured to be curvilinear along an axial direction of the beam structure (30); a first partial cavity (42a,42b) adjoining the opening (26) of the substrate (14) is arranged between the beam structure (30) of the first electromechanical transducer (18b,18d) and the beam structure (30) of the second electromechanical transducer (18c,18 e).

25. A MEMS transducer as claimed in any preceding claim comprising:

a plurality of electromechanical transducers (18; 18a-18f), the electromechanical transducers (18; 18a-18f) being connected to the substrate (14) and each of the electromechanical transducers (18; 18a-18f) comprising an element (22; 22a-22 f; 30; 40; 150; 160) deformable in a transverse direction of movement (24);

a first partial cavity (42a,42b) arranged between the first electromechanical transducer (18b,18d) and the second electromechanical transducer (18c,18e), a second partial cavity (38a,38b) arranged between the second electromechanical transducer (18b,18d) and the third electromechanical transducer (18a,18 c).

26. The MEMS transducer as recited in claim 25, wherein the first and second electromechanical transducers (18b,18d) are configured to change the volume of the first local cavity at a first frequency, the first and third electromechanical transducers (18b,18d, 18a,18c) being configured to change the volume of the second local cavity at a second frequency.

27. A MEMS transducer as claimed in any of claims 25 or 26, wherein the substrate (14) comprises a plurality of openings connected to a plurality of local cavities of the cavity (16), the volume of each local cavity being influenced by the deflection state of at least one element deformable in the lateral direction of movement, two adjacent local volumes of a local cavity being able to increase or decrease in a complementary manner during a first time interval and a second time interval.

28. The MEMS transducer as recited in any one of claims 25 to 27, wherein the deformable elements (22; 22a-22 f; 30; 40; 150; 160) of the first, second and third electromechanical transducers (18b,18d, 18c,18e, 18a,18c) each comprise a beam actuator (30), each of the beam actuators (30) comprising a first end and a second end, the beam actuator (30) of the first electromechanical transducer (18b,18d) being connected to the substrate (14) at the first and second ends, the beam actuator of the second or third electromechanical transducer (18c,18e, 18c) being connected to the substrate (14) in a central region of the beam actuator.

29. A MEMS transducer as claimed in any of claims 25 to 28, wherein the substrate (14) comprises a plurality of openings (26) connected to a plurality of local cavities (42a-42b,38a-38c) of the cavity (16), the volume of each local cavity (42a-42b,38a-38c) being influenced by a deflection state of at least one element (22; 22a-22 f; 30; 40; 150; 160) deformable in a transverse direction of movement (24), wherein a value based on the deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) and on a sound pressure level obtained from the local cavity (42a-42b,38a-38c) exhibits a phase difference with a value of the sound pressure level flowing out of or into the respective local cavity (42a-42b,38a-38c), 38a-38c), which can be described as a function; the frequency of the volume flow (12) describes a frequency-dependent course of the pressure within the fluid.

30. A MEMS transducer as claimed in any preceding claim, wherein the electromechanical transducer (18; 18a-18f) comprises a plurality of deformable elements (22; 22a-22 f; 30; 40; 150; 160) connected at least indirectly in an axial direction (y) of the electromechanical transducer (18; 18a-18f), the elements being configured to influence the volume of the first and second partial cavity portions (96a,96b), respectively.

31. The MEMS transducer as recited in claim 30, wherein the electromechanical transducer (18; 18a-18f) is configured to cause fluid movement within the first partial cavity portion (96a) and the second partial cavity portion (96b) in response to electrical control (129a), the deformable element (22; 22a-22 f; 30; 40; 150; 160) being configured to change the volume of the first partial cavity portion (96a) and the second partial cavity portion (96b) at different frequencies.

32. A MEMS transducer as claimed in any preceding claim, wherein the deformable elements (22; 22a-22 f; 30; 40; 150; 160) are arranged in non-contact with a layer (32a-32b) of the substrate (14), the layer (32a-32b) defining the cavity (16) parallel to the plane of movement, or wherein a low friction layer is arranged between the deformable elements (22; 22a-22 f; 30; 40; 150; 160) and the layer (32a-32b) defining the cavity (16) parallel to the plane of movement.

33. A MEMS transducer as claimed in any preceding claim, wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is configured as a bimorph comprising an actuation direction (59, 59') along which the deformable element (22; 22a-22 f; 30; 40; 150; 160) is deflected by application of a voltage.

34. A MEMS transducer as claimed in claim 33, wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) comprises a first beam section (30a), a second beam section (30b) and a third beam section (30c) arranged in order along the axial direction (y) according to a first beam section (30a), a second beam section (30b) and a third beam section (30c), each beam section comprising opposite actuation directions (59a-59 c).

35. The MEMS transducer according to claim 34, wherein the electromechanical transducer (18; 18a-18f) comprises a first and a second deformable element (22; 22a-22 f; 30; 40; 150; 160), the outer beam section (30a,30c) of the first deformable element (22; 22a-22 f; 30; 40; 150; 160) and the outer beam section (30a,30c) of the second deformable element (22; 22a-22 f; 30; 40; 150; 160) being at least indirectly connected to each other.

36. A MEMS transducer as claimed in any preceding claim wherein the substrate (14) comprises an anchor element (84);

wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is connected to the anchoring element (84) in a central region (30b) of the axial extension direction (y) of the deformable element (22; 22a-22 f; 30; 40; 150; 160); or

Wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) is connected to another deformable element at an outer beam section (30a,30c) via the anchoring element (84).

37. A MEMS transducer as claimed in any preceding claim wherein the deformable element (22; 22a-22 f; 30; 40; 150; 160) comprises a beam structure fixedly clamped at first and second ends.

38. A MEMS transducer as claimed in any preceding claim wherein the cavity (16) comprises an opening (26) in the substrate (14), the opening (26) being arranged perpendicular to the lateral direction of movement (24) such that the volume flow (12) flows out of the cavity (16) or into the cavity (16) perpendicular to the lateral direction of movement (24) based on deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160).

39. A MEMS transducer as claimed in any preceding claim, wherein the deformable element is arranged adjacent the opening (26).

40. A MEMS transducer as claimed in any preceding claim wherein the MEMS transducer is configured as one of a MEMS pump, MEMS speaker, MEMS microphone, MEMS valve and MEMS dosage system.

41. A device comprising a MEMS transducer according to any of the preceding claims, wherein the MEMS transducer is configured as a MEMS speaker, the device being configured as a mobile music reproduction device or a headset.

42. A system comprising a MEMS transducer according to any of claims 1 to 38, wherein the MEMS transducer is configured as a MEMS speaker and is designed to reproduce an acoustic signal based on an output signal.

43. The system of claim 42, wherein the system is configured as a general translator or a navigation assistance system.

44. A semiconductor layer comprising at a first layer main side (29a) a first electronic pattern (31a) with a first distance grating (33a) and at an oppositely positioned second layer main side (29b) a second electronic pattern (31b) with a second distance grating (33b), the first and second electronic patterns (31a,31b) being electrically connected to each other.

45. A MEMS layer stack comprising a semiconductor layer according to claim 44 and comprising a circuit layer having an electronic circuit (17), the electronic circuit (17) comprising a first distance grating (33 a);

wherein the electronic circuit (17) is connected to the first electronic structure such that the electronic circuit (17) is accessible via the second layer main side (29 b).

46. The MEMS layer stack of claim 45, wherein the MEMS layer stack forms a MEMS transducer for interacting with a volumetric flow (12) of a fluid, the MEMS layer stack comprising:

a substrate (14) comprising a layer stack having a plurality of layers (32a-32b,34a-34b,36) forming a plurality of substrate planes and comprising a cavity (16) within the layer stack;

an electromechanical transducer (18; 18a-18f) connected to a substrate (14) within the cavity (16) and comprising an element (22; 22a-22 f; 30; 40; 150; 160) deformable in at least one plane of movement of the plurality of substrate planes, a deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) in the plane of movement being causally related to a volumetric flow (12) of the fluid;

wherein the electronic circuit (17) is connected to the electromechanical transducer (18; 18a-18f) via the semiconductor layer;

wherein the electronic circuit (17; 17a-17b) is configured to provide conversion between deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) and an electrical signal.

47. A health assistance system (220), comprising:

sensor means (35) for sensing a vital function of a body (37) and outputting a sensor signal (39) based on the sensed vital function;

processing means (41) for processing the sensor signal (39) and for providing an output signal (43) based on the processing; and

a headset (200) comprising a MEMS transducer according to any of the claims 1 to 38, configured as a speaker and comprising a wireless communication interface for receiving the output signal (43), and configured to reproduce an acoustic signal based on the output signal (43).

48. The health assistance system of claim 47, wherein the headset is formed as an in-ear headset.

49. A method of providing a MEMS transducer for interacting with a volumetric flow (12) of a fluid, comprising:

providing a substrate (14), the substrate (14) comprising a layer stack having a plurality of layers (32a-32b,34a-34b,36) forming a plurality of substrate planes, and comprising a cavity (16) within the layer stack;

-generating an electromechanical transducer (18; 18a-18f) within the substrate (14) such that the electromechanical transducer (18; 18a-18f) is connected to the substrate (14) within the cavity (16), and the electromechanical transducer (18; 18a-18f) comprises an element (22; 22a-22 f; 30; 40; 150; 160) deformable in at least one plane of movement of the plurality of substrate planes, a deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) within the plane of movement being causally related to a volumetric flow (12) of the fluid;

arranging an electronic circuit (17; 17a-17b) within a layer (32a-32b) of the layer stack such that the electronic circuit (17; 17a-17b) is connected to the electromechanical transducer (18; 18a-18f) and is configured to provide conversion between deformation of the deformable element (22; 22a-22 f; 30; 40; 150; 160) and an electrical signal.

50. A method of providing a semiconductor layer, comprising:

arranging a first electronic pattern (31a) at the first layer main side (29a) such that the first electronic structure comprises a first distance grating (33 a);

arranging a second electronic pattern (31b) at the oppositely located second layer main side (29b) such that the first electronic structure comprises a second distance grating (33 b); and

connecting the first and second electronic patterns (31a,31b) to each other.

Technical Field

The present invention relates to a MEMS transducer, such as a MEMS speaker, a MEMS microphone or a MEMS pump, for interacting with a volumetric flow of a fluid, and in particular to a MEMS transducer comprising an integrated electronic circuit. The invention also relates to a device comprising such a MEMS transducer, and to a method of producing a MEMS transducer. In addition, the present invention relates to an on-chip MEMS-CMOS (complementary metal oxide semiconductor) speaker system.

Background

In addition to being able to be miniaturized, one of the key points of MEMS (micro-electro-mechanical systems) technology is in particular the low-cost production potential with a medium-high number of parts. Electro-acoustic MEMS loudspeakers are currently being commercialized to a small extent. Almost without exception, MEMS speakers each contain a diaphragm that deflects in a quasi-static or resonant manner through selected physical principles of action. Here, the manner in which the deflection is linear or non-linear depends on the applied electrical signal (current or voltage). The signal includes a temporal variation that is transferred to a temporal variation of the diaphragm deflection. The reciprocating motion of the diaphragm is acoustically transmitted to the surrounding fluid, which for purposes of simplicity and not limitation will be assumed hereinafter to be air.

In some cases, the diaphragm is actuated in only one direction. The restoring force is then provided by the mechanical spring action as the diaphragm deflects. In other cases, the diaphragm is actuated in two directions so that the diaphragm can exhibit very low stiffness.

For actuating the membrane, the principle of using electrostatic, piezoelectric, electromagnetic, electrodynamic or magnetostrictive action is described. An overview of MEMS acoustic transducers based on the principle is found, for example, in [1 ].

Electrostatically operated transducers are based on the force generated between two planar electrodes to which different potentials are applied. In the simplest case, this arrangement corresponds to a plate capacitor, wherein one of the two plates is suspended movably. For practical implementation, the movable electrode is configured as a diaphragm, thereby avoiding acoustic short-circuits. When a voltage is applied, the membrane will warp towards the counter electrode. In a particular embodiment, the membrane is operated in a so-called touch mode. Here, for example, as described in [2], the diaphragm touches the lower electrode, which has been coated with a thin insulator layer to avoid short-circuiting. The contact area is determined by the magnitude of the applied voltage and therefore exhibits a time variation that depends on the time course of said voltage. The oscillations that can thus be generated are used to produce sound. In principle, under classical electrostatic settings, the membrane can be attracted only in the direction of the electrodes. The restoring force may be determined at least in part by the stiffness of the diaphragm and must be large enough to be able to transmit higher frequencies in the audible sound range.

On the other hand, at a given voltage, the deflection of the diaphragm may decrease as the stiffness level increases. To avoid this problem, a method has been developed which involves a very flexible membrane that can be controlled by an upper electrode and a lower electrode, thus deflecting it in both directions, as described in [3 ]. The loudspeaker uses a total of two such diaphragms suspended in a chamber including an inlet and an outlet and otherwise closed as with a micro-pump.

Piezoelectrically operated transducers utilize the inverse piezoelectric effect. The applied voltage causes mechanical stress in the solid. In the MEMS technology, a material such as PZT (lead zirconium titanate), AlN (aluminum nitride), or ZnO (zinc oxide) is generally used. The material is usually applied as a functional layer to the membrane and patterned so that the membrane can deflect and/or cause vibrations depending on the voltage applied to the functional layer. The piezoelectric functional layer has the disadvantage that it cannot be operated in a hysteresis-free manner. Furthermore, the integration of ceramic functional layers is complicated and, due to the lack of CMOS (complementary metal oxide semiconductor) compatibility in the case of PZT and ZnO, integration is only possible under strict contamination control, even in the need of a separate clean room environment.

Electromagnetically operated transducers are based on the forces to which soft magnetic materials are subjected in non-stationary magnetic fields (gradients). In order to put this principle into practice, in addition to the soft magnetic material, permanent magnets and coils are required, by means of which the position gradient of the magnetic field can be controlled temporally via an electric current. For example, soft magnetic materials are integrated into the diaphragm. For example, as described in [4], all other components can be used in the assembly. This arrangement is bulky, complex and does not seem to scale reasonably to large numbers.

Electrically operated transducers use lorentz forces. The method is widely spread in macro loudspeakers and has been adopted in some MEMS loudspeakers. The magnetic field is generated by a permanent magnet. The coil through which the current flows is placed within the magnetic field. Typically, the coils are integrated into the diaphragm by depositing and patterning a metal layer, and the permanent magnets are added as external components to the assembly. The complexity and limitations associated with the integration of all components in MEMS technology represent significant drawbacks similar to electromagnetically operated transducers.

A magnetostrictive transducer is based on the contraction or expansion of a functional layer under the application of a magnetic field. For example, vanadium permadur is positively magnetostrictive, i.e., exhibits expansion under the application of a magnetic field. With suitable arrangements, the contraction can be used to generate a diaphragm vibration. In [1]]Middle, vanadium non-stick layer (Fe) ₄₉Co ₄₉V ₂) Deposition on SiO via a chromium adhesive layer ₂(silica) as a magnetostrictive functional layer. The external magnetic field can be obtained via a micro-pancake coil, which is realized by electrodeposited copper. The disadvantages found are similar to those of the two principles of action described above in terms of complexity and limitations of integration.

A feature common to the classical and the most widely used variants described above is the use of a diaphragm that can cause vibrations, which variants will be supplemented below by specific modifications that have been examined due to specific drawbacks of the classical diaphragm principle.

The flexible membrane may also comprise higher modes in the audible sound range and may therefore cause parasitic vibrations, which will reduce the acoustic quality (harmonic distortion), see [1 ]. Thus, in order to avoid or reduce said effect, plates with a significantly higher hardness level are used. Such a plate is connected to the chip via a very flexible suspension, which also avoids acoustic short-circuits, see [5 ].

A further modification consists of a segmented membrane which has been employed with the magnetostrictive transducer described above. This corresponds to a particular topographical solution to the problem of shrinkage or expansion of the functional layer in two directions. In particular, the arrangement consists of several deflectable bending beams. According to [1], the arrangement can be considered acoustically closed for a beam pitch of less than or equal to 3 μm. By dimensioning the individual beams accordingly in dependence on the resonance frequency and the distance between the beams, a relatively high acoustic bandwidth can be achieved and the process of sound level can be adapted or optimized on the basis of the vibration frequency.

In Neumann et al [6], a method is followed that uses multiple small partial diaphragms instead of a single large diaphragm. The resonance frequency of each partial diaphragm is sufficiently high that quasi-static deflection can occur in the audible sound range. Thus, in particular, digital operation of the loudspeaker can be achieved.

In summary, it can be concluded that known electrostatically operated membrane loudspeakers comprise a relatively small deflection as long as the drive voltage is moderate in terms of integration. For example, according to [3]The electrostatic diaphragm speaker of Kim et al can be used as a reference. The area of each of the two membranes is 2x2mm ². In each case, the upper and lower electrodes were mounted at a distance of 7.5 μm, respectively. Depending on the geometry of the membrane and the increase in stiffness of the membrane with increasing deflection, the deflection is usually limited to 1/3 to 1/2 of the electrode distance due to the so-called pull-in effect. If a higher value of 1/2 is assumed, the result of the deflection is 7.5 μm/2, i.e. in both one direction and the other. The volume of displacement can be estimated by assuming that it corresponds to the volume of the deflected rigid plate, which is half the maximum deflection of the diaphragm.

For example, the result is:

ΔV≈(2x2mm ²)x50％*(2x7.5μm)/2＝15x10 ^-3mm ³(formula 1)

And/or

Δ V/activation area (active area) ═ Δ V/A ═ Δ V/4mm ²＝3.75x10 ^-3mm (formula 2)

A general problem in the production of miniaturized membrane loudspeakers is the realization of a flattening process of the sound pressure as a function of frequency. The achievable sound pressure is proportional to the radiation impedance and the velocity of the diaphragm. From a macroscopic point of view, the diaphragm diameter can be compared to the acoustic wavelength. Here, the real case is that the radiation impedance is proportional to the frequency, see [6]]. High quality loudspeakers are often designed to resonate f ₀Below the audible sound range (for multi-path speakers the respective resonance frequency is below the corresponding down-edge frequency of the electrical filter). Thus for f > f ₀The speed of the diaphragm is proportional to 1/f. In general, the frequency-dependent result of the sound pressure p is an expression p ∈ 1. Thus, with the above (simplified) considerations, the course of the sound pressure results is completely flat.

Once the diameter of the source/diaphragm is much smaller than the wavelength of the acoustic wave to be generated, it can be assumed that the radiation impedance exhibits a quadratic dependence on frequency, e.g. [7 ]]The method as described in (1). This is given for MEMS loudspeakers with a membrane of the order of millimeters. If f > f is assumed as described above ₀Then the correlation p oc f will lead to the course of the sound pressure. Low frequencies are reproduced at a considerably lower sound pressure than high frequencies. In quasi-static operation, the diaphragm velocity is proportional to f. Then, what causes the sound pressure process is the correlation p ^ f ³It is even more detrimental to low frequencies

Miniature multifunction systems for human-computer or human-machine interaction have different levels of integration.

Level 1: hybrid integration of printed circuit boards

The sensors, actuators and electronic circuits produced on different substrates are combined on a shared wiring support (here a printed circuit board).

And 2, stage: system-in-package

Within a particular housing, at least two chips are combined to form a system. Sometimes, inter-chip bonding is also used for this purpose. Silicon-based wiring supports (so-called "interposer technology") are also often used.

And 3, level: wafer level hybrid integration and monolithic integration

Sensors, actuators and electronic circuits, which are produced in part on different wafers, are interconnected elsewhere at the wafer level. Individual chips of the bonded wafer stack are removed from the stack by a corresponding dicing process. By monolithic integration, sensors, actuators and electronic circuits can be realized on a wafer. In both cases, the electrical connection of the components is realized by integrated conductors or through-chip connections ("through-silicon vias", abbreviated as TSVs).

One example of a highly advanced hybrid integrated sensor/actuator system (level 1) is the so-called audible (hearable) product. Today, the following components have been provided in the form of in-ear headphones: a speaker (produced by precision machining), a rechargeable battery, a memory chip, a CPU, red and infrared sensors, a temperature sensor, an optical touch sensor, a microphone, a 3-axis acceleration sensor, a 3-axis magnetic field sensor, and a 3-axis position sensor. Today, companies such as Bragi (hereinafter "Dash"), Samsung, Motorola, and Sony have used this "system in package" approach to audible products.

One example of a highly advanced system-in-package sensor system (level 2) is the so-called 9-axis sensor. Here, for example, a 3-axis acceleration sensor and a 3-axis position sensor are implemented on one silicon chip, a 3-axis magnetic field sensor is implemented on a second silicon chip, and an electronic circuit is implemented on a third chip, which are housed in a shared package. The supplier of such a system is, for example, InvenSense (MPU-9150).

Examples of monolithically integrated sensor systems are single-axis or multi-axis gyroscopes, or acceleration sensors, pressure sensors and magnetic field sensors, wherein the sensor elements and the electronic functions are each implemented in a single chip.

Monolithic integration offers major advantages in terms of structural size. In the case of hybrid integration of printed circuit boards, a separate housing is required for each component, whereas in the case of system-in-package, a relatively large housing is required, in particular when several individual chips are combined, said additional requirements with respect to space being dispensed with in monolithic integration. In addition, the manufacturing costs are significantly reduced, particularly in the case of a large number of parts, due to the elimination of complex hybrid placement techniques.

In the case of miniature sound generating (microspeaker) or sound sensing (microphone) MEMS components, which are to be addressed here, monolithic integration including circuitry or other actuator or sensor related elements is nowadays severely limited. On the one hand, the reason for this is the mode of operation of the MEMS microphone or loudspeaker. In both cases, it is necessary to form a relatively large membrane in the chip surface. The chip surfaces on the top and bottom sides are mainly required for the air flow induced during the movement of the membrane. Thus, no significant amount of chip surface area is available for integrating other functions. First, the substantially possible enlargement of the chip surface conflicts with a disproportionately reduced yield with chip surface area. On the other hand, the manufacturing process is often not directly compatible with that of CMOS circuits, which increases the complexity of the overall process. Thus, for both reasons, today, other functions are implemented with acoustic components on one or more separate chips, and the entire system is consolidated via hybrid integrated/system-in-package.

At the same time, the mounting space of the MEMS transducer needs to be kept to a minimum in order to be able to be used in portable devices such as headsets, in particular so-called in-ear headsets.

Accordingly, an improved MEMS transducer concept with a high level of efficiency while requiring little mounting space is desired.

Disclosure of Invention

It is therefore an object of the present invention to provide a MEMS transducer and a method of producing the same, which can be influenced by a volume flow with a high level of efficiency of the volume flow and/or can be influenced by a volume flow with a low level of efficiency, which fulfill these functions while requiring little installation space.

This object is achieved by the subject matter of the independent claims.

The core idea of the invention is to recognize that the above-mentioned objects can be achieved in that the volume flow of the fluid can be influenced in a particularly effective manner by an element that is deformable in the plane of movement (in-plane) and/or that such an element can be deflected in a particularly effective manner. This enables a large surface area of the deformable element which can interact with the volume flow at the same time with a small chip surface size, so that overall a highly efficient MEMS transducer device with a high level of efficiency is obtained. In addition, it has been recognized that integrating electronic circuitry for operating the MEMS into the layers of the layer stack would make these semiconductor surfaces, which were not otherwise used, useful for electronic circuitry, resulting in the device requiring little mounting space.

According to an embodiment, a MEMS transducer for interacting with a volumetric flow of a fluid comprises a substrate comprising a layer stack having a plurality of layers. The substrate includes a cavity within the layer stack. The layers form a plurality of substrate planes. The MEMS transducer includes an electromechanical transducer connected to the substrate within the cavity and including a deformable element in at least one plane of movement of the plurality of substrate planes. The deformation of the deformable element in the plane of movement is causally related to the volumetric flow of the fluid. The MEMS transducer further comprises electronic circuitry arranged within the layers of the layer stack. The electronic circuit is connected to the electromechanical transducer and is configured to provide conversion between deformation of the deformable element and an electrical signal.

According to other embodiments, a device comprises the MEMS transducer described, configured as a MEMS speaker, configured as a mobile music reproduction device or as a headset.

According to other embodiments, the health assistance system comprises a sensor device for sensing a vital function of the body and outputting a sensor signal based on the sensed vital function. The health assistance system comprises processing means for processing the sensor signal and providing an output signal based on said processing, and comprises a headset comprising the described MEMS transducer. The MEMS transducer is configured as a speaker and includes a wireless communication interface for receiving the output signal and is configured to reproduce the acoustic signal based thereon.

According to other embodiments, a method of providing a MEMS transducer for interacting with a volumetric flow of a fluid includes providing a substrate comprising a layer stack having a plurality of layers forming a plurality of substrate planes and including a cavity within the layer stack. The method includes generating an electromechanical transducer within a substrate such that the electromechanical transducer is connected to the substrate within a cavity, and including a deformable element within at least one plane of movement of a plurality of substrate planes, deformation of the deformable element within the plane of movement causally correlating with a volumetric flow of a fluid. The method further includes arranging an electronic circuit within the layers of the layer stack such that the electronic circuit is connected to the electromechanical transducer and configured to provide conversion between deformation of the deformable element and an electrical signal.

Further advantageous embodiments form the subject of the dependent claims.

Drawings

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic perspective view of a MEMS transducer according to an embodiment;

fig. 2a shows a schematic perspective view of a MEMS transducer comprising a plurality of electromechanical transducers according to an embodiment;

FIG. 2b shows a schematic top view of the MEMS transducer of FIG. 2a in accordance with an embodiment;

FIG. 2c shows a schematic perspective view of the MEMS transducer of FIG. 2a, wherein the electromechanical transducers each exhibit a deformed state of the deformable element, in accordance with an embodiment;

figure 3 shows a schematic perspective view of a deformable element configured as a bimorph according to an embodiment;

figure 4a shows a schematic perspective view of a deformable element comprising three bimorph structures according to an embodiment;

fig. 4b shows a schematic perspective view of the deformable element based on fig. 4a in a deflected state according to an embodiment;

fig. 4c shows a schematic top view of an arrangement of two deformable elements arranged adjacent to each other according to an embodiment;

fig. 5 shows a schematic top view of a MEMS transducer according to an embodiment, wherein the electromechanical transducers each comprise a modified configuration compared to the configuration of the MEMS transducer of fig. 2 a;

fig. 6a shows a schematic top view of an electromechanical transducer according to an embodiment, wherein a spring element formed along a straight line is arranged between a plate element and a deformable element;

fig. 6b shows a schematic top view of an electromechanical transducer according to an embodiment, wherein the spring element is arranged at an angle of less than 90 ° with respect to the deflectable end of the deformable element;

fig. 6c shows a schematic top view of an electromechanical transducer according to an embodiment, wherein the spring elements are arranged at an angle of more than 90 °;

fig. 6d shows a schematic top view of an electromechanical transducer according to an embodiment, wherein the substrate comprises a spring element adjacent to the deformable element;

fig. 6e shows a schematic top view of an electromechanical transducer according to an embodiment, wherein the plate element comprises a recess;

fig. 7a shows a schematic top view of a deformable element connected to a plate element according to an embodiment;

FIG. 7b shows a schematic top view of a configuration in which a deformable element is fixedly clamped and formed between substrates according to an embodiment;

fig. 7c shows a schematic top view of a configuration of an electromechanical transducer according to an embodiment, wherein the deformable element comprises a depression in a central region;

fig. 7d shows a schematic top view of a configuration of an electromechanical transducer, wherein the first deformable element and the second deformable element are arranged parallel to each other;

FIG. 8a shows a schematic perspective view of a MEMS transducer according to an embodiment, wherein the deformable elements are alternately connected to the substrate and the anchor elements, respectively;

FIG. 8b shows a schematic top view of the MEMS transducer of FIG. 8a in accordance with an embodiment;

FIG. 8c shows a schematic perspective view of the MEMS transducer of FIG. 8a in a deflected state, in accordance with an embodiment;

FIG. 8d shows a schematic top view of the MEMS transducer of FIG. 8b in a deflected state in accordance with an embodiment;

FIG. 9 shows a schematic perspective view of a stack comprising three MEMS transducers according to an embodiment;

FIG. 10 is a schematic perspective top view of a portion of a MEMS transducer having a deformable element disposed between sides of a substrate according to an embodiment;

fig. 11a shows a schematic top view of a part of a MEMS transducer according to an embodiment, wherein the electromechanical transducer is arranged in an inclined manner with respect to a lateral direction of the substrate;

FIG. 11b shows a schematic top view of a portion of a MEMS transducer that can be used as a pump according to an embodiment;

FIG. 12a shows a schematic top view of a portion of a MEMS transducer that may be used as a MEMS pump, for example, in a first state;

FIG. 12b shows the MEMS transducer of FIG. 12a in a second state;

fig. 13 shows a schematic view of two deformable elements connected to each other along a transverse extension direction according to an embodiment;

FIG. 14 shows a schematic diagram of a stack including two MEMS transducers connected to each other and sharing a layer according to an embodiment;

fig. 15 shows a schematic cross-sectional side view of a deformable element comprising two layers spaced from and connected to each other via a connecting element according to an embodiment;

FIG. 16 shows a schematic top view of a deformable element arranged adjacent to an electrode according to an embodiment;

FIG. 17a shows a schematic perspective view of a MEMS transducer in accordance with a further embodiment from a first side;

FIG. 17b shows a schematic view of the MEMS transducer of FIG. 17a from a second side;

FIG. 17c shows a schematic perspective view of a MEMS transducer according to the view of FIG. 17a according to a further embodiment, wherein the openings are designed such that a grid web can be arranged;

FIG. 18a shows a schematic perspective view of a MEMS transducer according to an embodiment, wherein the functional elements are arranged adjacent to the electronic circuitry;

FIG. 18b shows a schematic perspective view of a modified MEMS transducer compared to the MEMS transducer of FIG. 18a, wherein openings are arranged in the cap layer according to an embodiment;

fig. 19a shows a schematic diagram of a layer for adapting a distance grating according to an embodiment;

FIG. 19b shows a schematic diagram of the use of a tuning layer according to an embodiment;

FIG. 20 shows a schematic block diagram of a MEMS system according to an embodiment;

fig. 21a shows a device according to an embodiment;

FIG. 21b shows a schematic block diagram of yet another system that may be configured as a general translator and/or navigation aid system, in accordance with embodiments;

FIG. 22 shows a schematic diagram of a health assistance system according to an embodiment;

FIG. 23 shows a schematic top view of a MEMS transducer including a plurality of electromechanical transducers including a beam element clamped on one side, in accordance with an embodiment; and

fig. 24 shows a schematic top view of a MEMS transducer according to an embodiment, comprising a plurality of electromechanical transducers comprising beam elements clamped on both sides.

Detailed Description

Before embodiments of the invention are explained in detail below with reference to the drawings, it should be noted that elements, objects and/or structures that are identical or functionally equivalent or equivalent in the various figures are provided with the same reference numerals, so that the descriptions of the elements given in the different embodiments can be interchanged and/or applied to one another.

Reference will be made below to MEMS (micro-electro-mechanical systems) transducers. The MEMS transducer may include one or more electro-active components that cause a change in a mechanical component based on an applied electrical quantity (current, voltage, charge, etc.). The change may involve, for example, deformation, temperature increase or generation of tension in the mechanical component. Alternatively or additionally, mechanical influences exerted on the component, such as deformation, temperature increase or generation of tension, may result in an electrical signal or electrical information (voltage, current, charge, etc.) that may be detected at the electrical terminals of the component. Some materials or components exhibit interchangeability, which means that effects can be interchanged. For example, piezoelectric materials can have an inverse piezoelectric effect (deformation based on an applied electrical signal) and a piezoelectric effect (providing charge based on deformation).

Some embodiments described below relate to fully integrated and highly miniaturized systems for human/computer, or human/machine, interface applications and interactions, including applications in the field of "personal assistants". The acoustic interface here is the focus of attention. Embodiments relate to the integration of MEMS and CMOS.

Some of the following embodiments relate to the fact that: the deformable element of the electromechanical transducer is configured to interact with a volumetric flow of the fluid. The interaction may comprise, for example, deformation of the deformable element, which is caused by an electrical control signal that causes movement, displacement, compression or decompression of the fluid. Alternatively or additionally, the volumetric flow of the fluid may deform the deformable element such that information about the presence, characteristics (pressure, flow rate, etc.) or some other information (e.g., temperature) of the fluid may be obtained based on the interaction between the volumetric flow and the deformable element. This means that the deformation of the deformable element in the transverse direction of movement has a causal relationship with the volumetric flow of the fluid. For example, MEMS can be produced in silicon technology. The electromechanical transducer may comprise a deformable element and other elements, such as electrodes and/or electrical terminals. The deformable element may be configured to deform (macroscopically) in a lateral direction of movement, i.e. the element or region may be movable in the lateral direction of movement. For example, the element or region may be a beam end or a central region of a beam structure. From a microscopic point of view, deformation of the deformable element in a transverse direction of movement causes deformation of the deformable element perpendicular to the transverse direction of movement. The embodiments described below relate to macroscopic angles.