MEMS device with tmd structure

Abstract

A MEMS device is disclosed, the MEMS device having a TMD structure. The MEMS device (10) comprises: a suspended electrode structure (12; 13) anchored to a substrate (14), the MEMS device (10) having a MEMS resonance mode; and a TMD (tuned mass damper) structure (16), wherein a portion of the suspended electrode structure (12; 13) is arranged to form the TMD structure (16) having a TMD spring element (16-2) and a TMD mass element (16-1) for providing a TMD resonance mode that counteracts the MEMS resonance mode.

Description

Technical Field

[0001] Embodiments of this disclosure relate to MEMS devices (MEMS = Microelectromechanical Systems) having a TMD (tuned mass damper) structure. More specifically, embodiments relate to the field of MEMS microphones using a tuned mass damper (TMD) for resonant mode control. Background Technology

[0002] In the fields of mobile devices, home automation (such as smart homes) and automobiles, it is becoming increasingly important to use MEMS-based devices to sense environmental parameters (such as sound, noise, temperature, gas, etc.) in the ambient atmosphere.

[0003] For example, due to the asymmetry of sensor arrangement, MEMS sensors may generate net external vibrations or resonances when reading out MEMS sensor signals. Furthermore, in audio microphone applications of MEMS sensors, various undesirable MEMS resonance modes can be observed, possibly due to mechanical interactions between different elements and components of the MEMS microphone. These undesirable resonance modes can affect the operating characteristics of the MEMS sensor.

[0004] Therefore, in the field of MEMS sensors (such as MEMS microphones), there is a need to realize MEMS sensors with improved operating characteristics (e.g., improved noise performance and improved resonance performance). Summary of the Invention

[0005] According to an embodiment, a MEMS device includes: a suspended electrode structure anchored to a substrate, the MEMS device having a MEMS resonant mode; and a TMD (tuned mass damping) structure, wherein an integral portion of the suspended electrode structure is arranged to form a TMD structure having a TMD spring element and a TMD mass element for providing a TMD resonant mode that cancels out the MEMS resonant mode.

[0006] The TMD structure (TMD = Tuned Mass Damping) is realized by using the suspended electrode structure of a MEMS device.

[0007] According to the concept of this invention for MEMS devices, undesirable MEMS resonant modes can be reduced by using a TMD (Tuned Mass Damping) structure (TMD = Tuned Mass Damping) in the suspended electrode structure of the MEMS device. A portion of the suspended electrode structure itself is arranged to at least partially or completely form a TMD spring element and a TMD mass element within the TMD structure. Therefore, the TMD structure is an integral part of the suspended electrode structure. The elasticity (flexibility) of the TMD spring element and the mass of the TMD mass element can be set to cancel out MEMS resonant modes by the TMD resonant modes of the TMD structure.

[0008] In the case where the MEMS device is implemented as an audio MEMS microphone, the MEMS device includes a first suspended electrode and a second suspended electrode, which are spaced apart from each other and at least partially opposite to each other, and both the first and second suspended electrodes are anchored to a substrate. The first electrode is a deflectable film element, and the second electrode is a static counter electrode (stator or backplate), wherein the TMD structure is an integral part of the movable film element and / or the static counter electrode. Attached Figure Description

[0009] The embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings, in which:

[0010] Figure 1a An exemplary illustration shows the displacement (deflection) process of the stator of a membrane structure and MEMS device (e.g., a MEMS microphone) in response to an acoustic input signal or acoustic excitation as a function of frequency;

[0011] Figure 1b An exemplary illustration shows the process of the output voltage of a MEMS device responding to an acoustic input signal as a function of frequency;

[0012] Figure 2a A schematic cross-sectional view of a MEMS device with a TMD structure according to an embodiment is shown.

[0013] Figure 2b A schematic diagram of a spring-mass-damper system obtained from a MEMS device having an integrally formed TMD structure according to an embodiment is shown.

[0014] Figure 3 A schematic cross-sectional view of a packaged MEMS microphone with a TMD structure according to an embodiment is shown;

[0015] Figure 4 A schematic diagram of the resulting mass-spring-damper system of a MEMS microphone having a TMD structure as part of the stator according to an embodiment is shown.

[0016] Figure 5a A schematic plan view (top view) of the stator of a MEMS device having a TMD structure according to an embodiment is shown.

[0017] Figure 5b An enlarged plan view of the TMD structure in the stator of a MEMS device according to an embodiment is shown;

[0018] Figures 6a to 6b A schematic diagram of the oscillation of a TMD structure in the stator of a MEMS device according to an embodiment is shown;

[0019] Figure 7A schematic diagram of the resulting spring-mass-damper system of a MEMS microphone having a TMD structure as part of a membrane element according to an embodiment is shown.

[0020] Figures 8a to 8c Schematic cross-sectional views of different embodiments of a TMD structure as part of a membrane in a MEMS device are shown, according to an example.

[0021] Figure 9a Typical dimensions of relevant components of a MEMS device 10 having a TMD structure 16 according to an embodiment are shown; and

[0022] Figure 9b A schematic diagram of the oscillation of a TMD structure in the stator of a MEMS device according to an embodiment is shown.

[0023] In the following description, embodiments are discussed in further detail with the aid of the accompanying drawings, wherein in the drawings and description, the same elements and components having the same function and / or the same technical or physical effect are given the same reference numerals or identified by the same names. Therefore, the descriptions of these elements and their functions shown in different embodiments are interchangeable or can be applied to each other in different embodiments. Detailed Implementation

[0024] In the following description, embodiments are discussed in detail; however, it should be understood that the embodiments provide many applicable concepts that can be embodied in a variety of semiconductor devices. The specific embodiments discussed are merely illustrative of particular ways of forming and using the concepts and do not limit the scope of the embodiments. In the following description of the embodiments, the same or similar elements having the same function are associated with the same reference numerals or the same names, and the description of these elements will not be repeated for each embodiment. Furthermore, features of the different embodiments described below can be combined with each other unless otherwise specifically stated.

[0025] It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Conversely, when an element is referred to as "directly" connected, "connected," or "coupled," there are no intermediate elements. Other terms used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," "on" vs. "directly on," etc.).

[0026] For ease of description of different embodiments, some figures include a Cartesian coordinate system x, y, z, where the xy plane corresponds to, i.e., parallel to, the first main surface region of the substrate (=reference plane=xy plane), where the direction perpendicularly upward relative to the reference plane (xy plane) corresponds to the "+z" direction, and where the direction perpendicularly downward relative to the reference plane (xy plane) corresponds to the "-z" direction. In the following description, the term "lateral" means a direction parallel to the x and / or y directions, i.e., parallel to the xy plane, and the term "perpendicular" means a direction parallel to the z direction.

[0027] The teachings in this specification are based on the following general considerations regarding the frequency behavior and resonant modes of MEMS sensors (such as audio MEMS microphones) and their consequent effects on the operating characteristics of MEMS microphones.

[0028] Figure 1a An exemplary illustration shows the displacement (deflection) process of the diaphragm structure and stator of a MEMS device (e.g., an audio MEMS microphone) in response to an acoustic input signal or acoustic excitation as a function of frequency. Figure 1b An exemplary illustration shows the process of the output voltage of a MEMS device responding to an acoustic input signal (acoustic excitation) as a function of frequency.

[0029] like Figure 1a As exemplified in the example, a MEMS microphone is a dynamic system that exhibits various resonances (MEMS resonance modes) due to the interaction of many different components. These components may include, for example, a membrane structure, a stator (counter-electrode or backplate), the microphone's sound port, and a back volume. Figure 1a This illustrates the displacement of the diaphragm and stator of a MEMS microphone in response to an acoustic input signal (e.g., sound or noise) as a function of frequency. Figure 1a It can be seen that MEMS microphones basically exhibit three different undesirable MEMS resonances.

[0030] At the primary resonance, which has the lowest frequency, the air mass at the sound port moves in phase with the membrane mass. The restoring force is generated by the membrane and the back volumetric compliance. More specifically, the air mass within the sound port and the membrane form a resonator, with a spring-like restoring force acting on the membrane. This resonant mode is typically the lowest frequency among the other resonant modes in the system. From a system design perspective, it is desirable to avoid the amplitude peaks associated with this resonance in the vocal tract, where this introduces a trade-off between the system noise level and acceptable peak behavior of the frequency response.

[0031] To provide master resonance control at the MEMS sensor (MEMS microphone), an appropriate shape selection of the input sound port and / or the acoustic mesh at the sound port can be provided. To reduce the quality factor of the master resonance, it is necessary to increase damping, this time primarily through viscous damping in the flow within the sound port. However, this increases noise and / or shifts the frequency of the master resonance into the acoustic band, both of which are undesirable.

[0032] When the membrane mass and the air mass at the sound port shift out of phase, the secondary resonance occurs at a second frequency (higher than the first resonant frequency of the primary resonance). The restoring force is provided by the compliance of the front cavity, membrane, and rear volume.

[0033] The third resonance (stator resonance) mode is caused by the stator mass and flexibility. Damping is provided by the viscous damping between the stator and the diaphragm.

[0034] One way to reduce or control stator oscillations (= third resonant mode) is to increase viscous (air) damping, particularly between the diaphragm and the stator. This lowers the quality factor Q of the unwanted (third) resonance. However, air damping between the stator and the diaphragm is a major contributor to microphone noise. So-called sealed dual-diaphragm (SDM) microphones reduce this noise by lowering the cavity pressure (between the diaphragm and the stator) to reduce the viscosity of the air cushion. In sealed dual-diaphragm (SDM) microphones, a high stator quality factor (~120) is necessary to achieve low noise. A trade-off must be made between noise and resonant performance.

[0035] Figure 2a A schematic cross-sectional view of a MEMS device 10 according to an embodiment is shown. Figure 2b A schematic diagram of the resulting spring-mass-damper system of the MEMS device 10 according to an embodiment is shown, wherein the TMD structure 16 is an integral part of the suspension electrode structure 12 / 13.

[0036] According to this embodiment, the MEMS device 10 includes suspended electrode structures 12 / 13 anchored to a substrate 14. The MEMS device 10 has a MEMS resonant mode at a resonant frequency, such as an undesirable MEMS resonant mode.

[0037] Regarding this point, please refer again. Figures 1a to 1bThe example illustrates different resonant modes of a MEMS device 10 in the form of an audio MEMS microphone. The MEMS device 10 also includes a TMD structure 16 (TMD = Tuned Mass Damping), wherein a portion 12-1 of the suspension electrode structure 12 (also referred to as the first suspension electrode) is arranged to form, for example, an integral TMD structure 16 having a TMD mass element 16-1 and a TMD spring element 16-2 for providing a TMD resonant mode at the TMD resonant frequency, canceling the MEMS resonant mode. The integral portion 12-1 of the suspension electrode structure 12 is arranged to at least partially or completely form the TMD mass element 16-1 and the TMD spring element 16-2 of the TMD structure 16. The flexibility (stiffness) of the TMD spring element 16-2 and the mass of the TMD mass element 16-1 can be set such that the resulting TMD resonant mode of the TMD structure 16 cancels the MEMS resonant mode. The resonant frequency of the TMD resonant mode of the TMD structure 16 can be set to or near the resonant frequency of the MEMS resonant mode.

[0038] like Figure 2b As exemplarily illustrated, the suspended electrode structure 12 can form a first mass-spring system, wherein the mass (movable mass) of the suspended electrode structure 12 forms an electrode mass 12-1, and the stiffness of the suspended electrode structure 12 forms an electrode spring 12-2, and a second mass-spring system having a TMD structure 16. The TMD structure 16 includes a TMD spring element 16-2 located between the electrode mass 12-1 of the suspended electrode structure 12 and the TMD mass element 16-1. The TMD resonant mode is defined by the compliance (stiffness or flexibility) of the TMD spring element 16-2 and the mass of the TMD mass element 16-1, wherein, for example, viscous (air) damping can act on the vibration of the TMD structure 16.

[0039] The mass of the TMD mass element 16-2, which serves as the secondary oscillator in the TMD structure 16, can be in the range of approximately 0.1% to 10% of the mass (main mass) of the suspension electrode structure 12, i.e., approximately 0.1% to 10% of the mass (main mass) of the movable portion of the suspension electrode structure 12, wherein the resonant frequency of the TMD structure 16 should be close to the resonant frequency (= main oscillator) of the suspension electrode structure 12. This arrangement of the MEMS device reduces the peak oscillation amplitude of undesirable MEMS resonant modes at the relevant resonant frequencies.

[0040] According to an embodiment of the MEMS device 10, the TMD spring element 16-2 includes an adjusted elastic modulus (spring constant) and an adjusted TMD mass 16-1 for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels (damps) a MEMS resonant mode having a MEMS resonant frequency. According to one embodiment, the TMD mass element 16-1 may include an additional mass element 16-1a for increasing the obtained TMD mass and for reducing (adapting) the obtained TMD resonant frequency. The additional mass element may include an insulating material (e.g., an oxide block) and / or a conductive material.

[0041] According to an embodiment of the MEMS device 10, the TMD structure 16 is an integral part of the first suspension electrode 12, wherein the separated (= mechanically decoupled from the second electrode) portion of the second suspension electrode can form an additional mass element of the TMD structure 16.

[0042] According to one embodiment, the MEMS device 10 operates as an audio microphone in a single-pair electrode (backplane) configuration, a dual-pair electrode configuration, or a hermetically sealed dual-film configuration.

[0043] Figure 3 A schematic cross-sectional view of a packaged MEMS microphone with a TMD structure according to an embodiment is shown.

[0044] According to one embodiment, the MEMS device 10 includes a suspension electrode structure 12 anchored to a substrate 14, the MEMS device having an (undesired) MEMS resonant mode, and a TMD (tuned mass damping) structure 16, wherein portions 12-1 / 13-1 of the suspension electrode structure 12 / 13 (portion 13-1 is also referred to as a stator mass element or through-hole) are arranged to (integrally) form a TMD structure 16 having a TMD spring element 16-2 and a TMD mass element 16-1 for providing a TMD resonant mode that cancels out the MEMS resonant mode.

[0045] According to one embodiment, the MEMS device 10 includes a first suspended electrode 12 and a second suspended electrode 13, which are spaced apart from each other and at least partially opposite each other, and both are anchored to a substrate 14. According to one embodiment, the first suspended electrode 12 and the second suspended electrode 13 operate as a sound transducer, a capacitive sensor, or an audio microphone.

[0046] According to one embodiment, the TMD structure 16 may be disposed at the central portion of the first suspension electrode 12 or the second suspension electrode 13. Optionally or additionally, the TMD structure 16 may be disposed at the peripheral portion (laterally offset to the central portion) of the first suspension electrode 12 or the second suspension electrode 13. According to one embodiment, the TMD structure 16 may be disposed adjacent to a ventilation hole in the first suspension electrode 12 or the second suspension electrode 13.

[0047] According to an embodiment of the MEMS device 10, for example in the form of an audio MEMS microphone, the first suspension electrode 12 is a deflectable (movable) membrane element, the second suspension electrode 13 is a static counter electrode (backplate or stator), and wherein the TMD structure 16 is an integral part of the first suspension electrode 12 and / or the TMD structure 16 is an integral part of the second suspension electrode 13.

[0048] According to another embodiment of the MEMS device 10, for example in the form of an audio MEMS microphone, the first suspension electrode 12 is a static counter electrode (backplate or stator), the second suspension electrode 13 is a deflectable (movable) membrane element, and wherein the TMD structure 16 is an integral part of the first suspension electrode 12 and / or the TMD structure 16 is an integral part of the second suspension electrode 13.

[0049] also, Figure 3 A schematic cross-sectional view of a MEMS device 10 and optional control circuitry 20 (ASIC) in a packaged (housing) configuration is shown. The MEMS device 10 can be arranged in a package with an internal volume V. 22 The housing 22 has an internal volume V to the MEMS device 10. 22 Access opening or audio port 24. The MEMS device 10 is arranged in a housing 22, for example, adjacent to the audio port 24. The housing 22 may then include, for example, a substrate 22-1 and an optional cover element 22-2, which may be at least partially or completely conductive. In an exemplary arrangement, the MEMS device 10 may have an internal volume V 22 Subdivided into front volume V F and the volume V B The front volume V F Located in the area between the audio port 24 and the MEMS device 10, and in which the rear volume V B The MEMS device 10 is located on the opposite side of the internal volume V22 of the housing 22.

[0050] Figure 4 A schematic diagram of a tuned mass-spring-damper system of a MEMS device 10 according to an embodiment is shown, wherein the TMD structure 16 is an integral part of the second suspension electrode 13.

[0051] According to one embodiment, the MEMS device 10 includes a first electrode and a second electrode that operate as an audio microphone, wherein the first suspended electrode 12 is a deflectable film element and the second suspended electrode 13 is a stator, such as a static counter electrode or a backplate. According to this embodiment, the TMD structure 16 is an integral part of the second suspended electrode 13 (static counter electrode).

[0052] When the DC bias voltage (V) MIC When the force exists between the first suspension electrode 12 and the second suspension electrode 13 (electrostatic force), the change in the distance between the first suspension electrode 12 and the second suspension electrode 13 causes the AC output voltage S to change. OUT .

[0053] like Figure 4 As shown, the first suspension electrode 12 is rotatably connected to the substrate 14. The rotatable portion of the first suspension electrode 12 forms a membrane mass element 12-1, wherein the flexibility (stiffness) of the first suspension electrode 12 forms a membrane spring element 12-2. The second suspension electrode 13 is anchored to the substrate 14, wherein the mass of the second suspension electrode 13 forms a stator mass element 13-1, and the stator stiffness forms a stator spring element 13-2. The TMD structure 16, including the TMD mass element 16-1 and the TMD spring element 16-2, is an integral part of the second suspension electrode 13. Changes in sound pressure from the environment cause deflection (displacement) of the first suspension electrode 12, wherein there is viscous (air) damping between the first suspension electrode 12 and the second suspension electrode 13, and between the first suspension electrode 12 and the TMD structure 16. Figure 4 As shown, these viscous damping values ​​can be different, where the damping value can be selected such that the TMD damping is higher than the main damping of the stator.

[0054] like Figures 1a to 1b As shown, the stator resonance is contributed by the mass and compliance of the second suspension electrode 13, where damping is provided by the viscous damping between the second suspension electrode 13 and the first suspension electrode 12. The mass of the TMD mass element 16-1 of the TMD structure 16, which serves as the secondary oscillator, can be in the range of approximately 0.1% to 10% of the mass (primary mass) 12-1 of the suspension electrode structure 12 (i.e., the movable portion of the suspension electrode structure 12).

[0055] Figure 5a A schematic plan view (top view) of the second suspended electrode 13 of a MEMS device 10 having a TMD structure 16 according to an embodiment is shown. Figure 5b An enlarged plan view of the TMD structure 16 in the second suspended electrode 13 of the MEMS device 10 according to an embodiment is shown.

[0056] like Figure 5a As shown, an exemplary implementation of the second suspension electrode 13 of the MEMS device 10 is illustrated, wherein the indicated rectangle 16' shows a possible location of the TMD structure 16 in the second suspension electrode 13. The second suspension electrode 13 is formed as a suspension electrode structure mechanically anchored (coupled) to the substrate 14.

[0057] The second suspension electrode 13 may include perforations 13-1 having a plurality of through holes or openings 13-2 through the stator material, wherein the through holes 13-2 may be substantially uniformly distributed on individual portions of the second suspension electrode 13 to allow sound pressure variations to be transmitted (e.g., to a membrane – not shown). The second suspension electrode 13 may also include so-called vents 13-3 for hydrostatic equalization (between opposite sides of the second suspension electrode 13), for example, in the central region of the second suspension electrode 13. In a sealed double-membrane (SDM) configuration (see, for example, [reference needed]). Figure 8c (and associated text channels), the vent 13-3 of the second suspension electrode 13 balances the pressure on either side of the first suspension electrode 12 and the third suspension electrode 12a. The vent 13-3 is implemented as a small "segment" between the first suspension electrode 12 and the third suspension electrode 12a. The hole 13-3 in the stator is used to bypass this "segment" and provide clearance.

[0058] The ventilation hole 13-3 may have a circular, rectangular, or other cross-section, for example. The diameter of the ventilation hole 13-3 is larger than the diameter of the through hole 13-2. The stator may also include a contact device 13-4 for electrically contacting the stator electrode 13. The second suspension electrode 13 may also include segments (segment lines) 13-5 for segmenting the second suspension electrode 13 into electrically insulated stator electrode portions (e.g., for suppressing parasitic capacitance).

[0059] Figure 5b An enlarged plan view of the TMD structure 16 in the second suspended electrode 13 of the MEMS device 10 according to an embodiment is shown. Figure 5b As shown, the TMD structure 16 is formed as two laterally opposing flaps at the center of the second suspension electrode 13, which are elastically coupled to the second suspension electrode 13, wherein the TMD structure 16 is formed by an integral part of the electrode material of the second suspension electrode 13.

[0060] like Figure 5b As shown, the second suspended electrode (counter electrode) 13 includes through holes 13-1 having a plurality of through holes 13-2, wherein at least part or all of the through holes 13-2' in the TMD structure 16, i.e., passing through the TMD structure 16 in the second suspended electrode 13, includes at least one of a reduced pore size and a reduced perforation density compared to the remainder of the second suspended electrode 13 (outside the TMD structure 16). Both of these arrangements—that is, a reduced pore size or a smaller number of through holes 13-2 compared to the remainder of the second suspended electrode 13 (lower perforation density), or a combination of both—provide increased viscous damping of the TMD structure 16 in the second suspended electrode 13.

[0061] like Figure 5bAs exemplarily shown, the vent 13-3 may include a diameter between 10 and 50 μm or 20 and 50 μm, wherein the through hole 13-2 may include an average diameter of 3 to 8 μm, and wherein the smaller through hole (=reduced diameter) 13-2' in the TMD structure 16 may include a diameter between 1 and 3 μm and approximately 1.9 μm. The implemented dimensions of the vent 13-3 and the smaller through holes 13-2, 13-2' of the MEMS device may be within a range of + / - 50% or + / - 30% of the indicated dimensions. Figure 5b In the area of ​​ventilation holes 13-3, a scale (10μm) is shown for calibration.

[0062] According to one embodiment, the TMD spring element 16-1 of the TMD structure (flap) 16 in the second suspension electrode 13 may include an adjusted elastic modulus (flexibility or spring constant) and an adjusted TMD mass 16-1 for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels the MEMS resonant mode having the MEMS resonant frequency. Therefore, the resonant frequency of the TMD resonant mode of the TMD structure 16 can be set to or close to the resonant frequency of the MEMS resonant mode.

[0063] According to one embodiment, the TMD mass element 16-1 may include an additional mass element 16-1a for increasing the obtained TMD mass and for reducing (or adjusting) the obtained TMD resonant frequency. The additional mass element may have an insulating material, such as an oxide block, or a conductive material mechanically coupled to the TMD mass element 16-1 of the TMD structure 16.

[0064] like Figure 5b As shown, by introducing different damping into the TMD structure 16 using different perforation densities in the second suspension electrode 13, the operating characteristics of the MEMS device 10 can be improved. The damping of the TMD structure 16 can be different (in terms of pressure per velocity) compared to the rest of the stator, which improves the performance of the TMD structure 16 with very little impact on the noise performance of the overall system.

[0065] Figures 6a to 6b An exemplary schematic diagram of the oscillation of the TMD structure (flap) 16 in the second suspended electrode 13 of the MEMS device 10 according to an embodiment is shown. Figure 6a This illustrates, for example, the maximum (or near-maximum) deflection of the TMD structure (flaps) 16, where Figure 6b The TMD structure 16 is shown in a zero-crossing position or a stationary state.

[0066] Figure 7A schematic diagram of a spring-mass-damper system of a MEMS device 10 according to an embodiment, having a TMD structure 16 as part of a first suspension electrode 12, is shown. According to the embodiment, the MEMS device 10 includes a first electrode and a second electrode operating as an audio MEMS microphone, wherein the first suspension electrode 12 is a deflectable film element and the second suspension electrode 13 is a stator. According to this embodiment, the TMD structure 16 is an integral part of the first suspension electrode 12.

[0067] like Figure 7 As shown, the first suspension electrode 12 is anchored to the substrate 14. The deflectable portion of the first suspension electrode 12 forms a membrane mass element 12-1, wherein the flexibility (stiffness) of the first suspension electrode 12 forms a membrane spring element 12-2. The stator is anchored (mechanically coupled) to the substrate 14, wherein the mass of the second suspension electrode 13 forms a stator mass element 13-1, and the stator stiffness forms a stator spring element 13-2. The TMD structure 16, including the TMD mass element 16-1 and the TMD spring element 16-2, is an integral part of the first suspension electrode 12.

[0068] Changes in sound pressure or pressure from the environment cause deflection of the first suspension electrode 12, wherein viscous (air) damping may exist between the first suspension electrode 12 and the second suspension electrode 13, and between the first suspension electrode 12 and the TMD structure 16, such as... Figure 7 As exemplarily shown, and / or viscous (air) damping may also exist between the second suspension electrode 13 and the TMD structure 16.

[0069] As already regarding Figures 1a to 1b As shown, at the main resonance, the sound port mass moves in phase with the diaphragm mass 12-1. The restoring force is generated by the first suspension electrode 12 and the rear volumetric compliance.

[0070] Figures 8a to 8c A schematic cross-sectional view is shown of different embodiments of the TMD structure 16, which is an integral part of the first suspended electrode 12 of the MEMS device 10, according to a further embodiment. The MEMS device 10 can operate as an audio microphone in different configurations, such as a single-diaphragm and single-backplane (single-stator) configuration, a dual-backplane (dual-stator) configuration, and (e.g., a hermetically sealed) dual-diaphragm configuration.

[0071] Figure 8a A schematic cross-sectional view of a MEMS device 10 with a single membrane and a single backplane configuration is shown. Figure 8aAs shown, the MEMS device 10 has a first suspension electrode 12 and a second suspension electrode (=stator) 13. The film element and the counter electrode may each comprise a semiconductive layer or a sequence or stack of multiple different layers, wherein at least one of the layers is conductive. The layer arrangement may be positioned on a carrier substrate 14, wherein the first suspension electrode 12 and the second suspension electrode 13 are separated and spaced apart from each other. The second suspension electrode 13, which is typically configured to be more rigid than the deflectable first suspension electrode 12, is spaced apart from the film element by a distance D, resulting in a capacitance C0 (=MEMS capacitance=capacitance of MEMS device 10) that can be formed between the second suspension electrode 13 and the first suspension electrode 12 and can be sensed by the readout circuit 20. The non-clamping region of the first suspension electrode 12 (relative to the counter electrode 13) is referred to as the deflectable (=displaceable) or movable (=active region) region of the first suspension electrode 12. The deflection Δx of the first suspended electrode 12 relative to the counter electrode structure 13 can then be detected and read out as a capacitance change ΔC by the readout circuit 20, in order to provide a corresponding (analog or digital-to-analog) output signal S of the MEMS device 10. out The deflection of the first suspended electrode 12 is (typically) caused by changes in acoustic pressure in the environment.

[0072] According to an embodiment of the MEMS device 10, the TMD structure 16 is an integral part of the first suspension electrode 12 of the MEMS device 10. The TMD spring element 16-2 includes an adjusted elastic modulus (spring constant) and an adjusted TMD mass 16-1 for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels (=damps) the MEMS resonant mode having the MEMS resonant frequency. The motion (oscillation) of the TMD structure 16 is partially coupled to, but independent of, the motion of the first suspension electrode 12.

[0073] like Figure 8a As shown, the TMD mass element 16-1 may include an additional mass element 16-1a for increasing the resulting TMD mass 16-1 and for reducing (adjusting) the resulting TMD resonant frequency. The additional mass element 16-1a may include an insulating material (e.g., an oxide block) and / or a conductive material. The TMD structure 16 is an integral part of the first suspension electrode 12, wherein a separate portion 13-1 of the second suspension electrode 13 (mechanically decoupled from the second electrode) may form another additional mass element 16-1b of the TMD structure 16. The additional mass element 16-1 may be mechanically connected between the other additional mass element 16-1b and a portion 12-1 of the first suspension electrode 12, which is an integral part of the TMD structure 16. Figure 8aAs shown, the tuned mass damper mass 16-1 may include additional mass elements 16-1a and / or 16-1b (attached to the first suspension electrode 12) for reducing the resonant frequency of the TMD structure 16, particularly for the main resonance. Changes in sound pressure or pressure from the environment cause deflection of the first suspension electrode 12, where viscous (air) damping may be present, which may exist between the second suspension electrode 13 and the TMD structure 16.

[0074] Figure 8b A schematic cross-sectional view of a MEMS device 10 in a dual (or dual) electrode pair configuration (dual backplane or dual stator configuration) is shown. The MEMS device 10 may include a second suspension electrode 13 anchored to a substrate 14 and another (second) electrode pair structure 13a anchored to the substrate 14, such that a first suspension electrode 12 anchored to the substrate 14 is disposed between the second suspension electrode 13 and the second electrode pair structure 13a. In the dual electrode pair configuration, the readout circuit 20 may be configured to detect the deflection or displacement Δx of the first suspension electrode 12 relative to the second suspension electrode 13 and / or relative to the other (second) electrode pair structure 13a, depending on a single-ended (common-mode) or differential readout configuration. The deflection of the first suspension electrode 12 is again caused by changes in acoustic pressure in the environment.

[0075] Also in Figure 8b In this embodiment, the TMD structure 16 is an integral part of the first suspension electrode 12 of the MEMS device 10. The TMD spring element 16-2 includes an adjusted elastic modulus (spring constant) and an adjusted TMD mass 16-1 for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels (=damps) the MEMS resonant mode having the MEMS resonant frequency. The motion (oscillation) of the TMD structure 16 is partially coupled to, but independent of, the motion of the first suspension electrode 12.

[0076] like Figure 8b As shown, the TMD mass element 16-1 may include at least one (or two) additional mass elements 16-1a for increasing the obtained TMD mass 16-1 and for reducing (adjusting) the obtained TMD resonant frequency. The additional mass element 16-1a may include insulating material (e.g., oxide block) and / or conductive material. The TMD structure 16 is an integral part of the first suspension electrode 12, wherein a separate portion 13-1 of the second suspension electrode 13 (mechanically decoupled from the second suspension electrode 13) may form at least one (or two) additional mass elements 16-1b of the TMD structure 16. The additional mass element 16-1a may be mechanically connected between the other additional mass element 16-1b and a portion 12-1 of the first suspension electrode 12, which is an integral part of the TMD structure 16. Figure 8bAs shown, the tuned mass damper mass 16-1 connected to the first suspension electrode 12 may include additional mass elements 16-1a and / or 16-1b (connected to the first suspension electrode 12) for reducing the resonant frequency of the TMD structure 16, particularly for the main resonance. Changes in sound pressure or pressure from the environment cause deflection of the first suspension electrode 12, where viscous (air) damping may be present, and may exist between the second suspension electrode 13 and the TMD structure 16.

[0077] Figure 8c A schematic cross-sectional view of a MEMS device in a dual (double)-film configuration is shown. The MEMS device 10 includes a third suspension electrode 12a anchored to a substrate 14, wherein a first suspension electrode 12 is a first film element, a second suspension electrode 13 is a counter electrode, and the third suspension electrode 12a is a second film element for an audio microphone. The second suspension electrode (stator) 13 is disposed between the first suspension electrode 12 and the third suspension electrode 12a, wherein a mechanical coupling structure 17 (having at least one or more mechanical connection elements) is mechanically coupled between the first and third suspension electrodes (first and second film elements) 12, 12a and mechanically decoupled from the second suspension electrode (counter electrode) 13.

[0078] In a sealed double-diaphragm (SDM) structure, the first suspension electrode 12 and the third suspension electrode 12a are arranged in a sealed configuration, and a cavity 15 may be formed between the first suspension electrode 12 and the third suspension electrode 12a, wherein, for example, when compared to ambient atmosphere, the second suspension electrode 13 is arranged in the cavity (volume under vacuum) 15. The cavity 15 may include a reduced atmospheric pressure, for example, an atmospheric pressure of approximately or below 100 Torr, 50 Torr, 5 Torr, or 1 Torr "vacuum". In the sealed double-diaphragm (SDM) configuration, a vent 13-3 of the second suspension electrode 13 equalizes the pressure on either side of the first suspension electrode 12 and the third suspension electrode 12a. The vent 13-3 is implemented as a small "segment" between the first suspension electrode 12 and the third suspension electrode 12a. A hole 13-3 in the stator is used to bypass this "segment" and provide clearance.

[0079] When the first suspension electrode 12 and the (mechanically coupled) third suspension electrode 12a deflect relative to the second suspension electrode 13, this deflection or displacement can then be capacitively read, for example, by the readout circuit 20, to provide an output signal S dependent on the deflection (gap change) relative to the second suspension electrode 13. OUT The deflection of the first suspension electrode 12 and the third suspension electrode 12a is caused by changes in acoustic pressure in the environment.

[0080] Also in Figure 8cIn this embodiment, the TMD structure 16 is an integral part of the first suspension electrode 12 and the third suspension electrode 12a of the MEMS device 10. The TMD spring element 16-2 includes an adjusted elastic modulus (spring constant) and an adjusted TMD mass 16-1 for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels (=damps) the MEMS resonant mode having the MEMS resonant frequency. The motion (oscillation) of the TMD structure 16 is partially coupled to, but independent of, the motion of the first suspension electrode 12.

[0081] like Figure 8c As shown, the TMD mass element 16-1 may include at least one (or two) additional mass elements 16-1a for increasing the obtained TMD mass 16-1 and for reducing (adjusting) the obtained TMD resonant frequency. The additional mass element 16-1a may include insulating material (e.g., oxide block) and / or conductive material. The TMD structure 16 is an integral portion 12-1 of the first suspension electrode 12 and the third suspension electrode 12a, wherein a separate portion 13-1 of the second suspension electrode 13 (mechanically decoupled from the second suspension electrode 13) may form another additional mass element 16-1b of the TMD structure 16. The additional additional mass element 16-1b may be mechanically connected between the additional mass element 16-1a and the portion 12-1 of the first suspension electrode 12 and the third suspension electrode 12a, which are integral portions of the TMD structure 16. Figure 8c As shown, the tuned mass damper mass 16-1 is attached to the first suspension electrode 12 and may include additional mass elements 16-1a and / or 16-1b for reducing the resonant frequency of the TMD structure 16, particularly for the main resonance. The stator material (e.g., polysilicon) may be used to form another additional mass element 16-1b of the TMD structure 16 to provide additional damping. Changes in sound pressure or pressure from the environment cause deflection of the first suspension electrode 12, wherein viscous (air) damping may exist between the first suspension electrode 12 and the second suspension electrode 13, and between the first suspension electrode 12 and the TMD structure 16 (see also...). Figure 7 ).

[0082] Figure 9aTypical dimensions of the relevant components of a MEMS device 10 having a TMD structure 16 are shown. The actual dimensions of the MEMS device can be within + / - 50% or + / - 30% of the indicated dimensions. D1 is approximately the gap between the TMD structure 16 and the adjacent first suspension electrode 12, third suspension electrode 12a, and second suspension electrode 13, and D1 can be approximately 16 μm or in the range of 12 to 20 μm. D2 is approximately the lateral extension of the added mass element 16-1b. D2 may be approximately 108 μm (= D1 + 92 μm) or in the range of 100 to 120 μm. D3 is approximately the lateral distance between the added mass element 16-1b and the cavity 15. D3 may be approximately 286 μm (= D1 + 270 μm) or in the range of 270 to 300 μm. D4 is approximately the radius of the first suspension electrode 12, the third suspension electrode 12a, and the second suspension electrode 13. D4 may be approximately 1275 μm or in the range of 1200 to 1350 μm. The area covered by / used by the TMD structure is approximately 5% of the total membrane area and approximately 8% of the effective (internal segmented) area of ​​the membrane element.

[0083] Figure 9b An exemplary schematic diagram of the oscillation of the TMD structure 16 in the first suspension electrode 12 and the third suspension electrode 12a of the MEMS device 10 according to an embodiment is shown. Figure 9b As shown, for example, the maximum (or near maximum) deflection of the TMD structure 16 compared to the zero-crossing position or the stationary state.

[0084] Below, we summarize some of the technical effects of the MEMS device 10 with the TMD structure described above, in which the concept of tuned mass damper allows control of two resonance modes of the microphone, namely master resonance and / or stator resonance.

[0085] Main resonance TMD;

[0086] For the master resonant tuned mass damper (TMD structure) 16, the tuned mass damper design can be matched to the acoustic port characteristics of the customer system.

[0087] The main mode implementation reduces the trade-offs required between low noise and acoustic frequency response flatness.

[0088] It can maintain the acoustic response flatness of MEMS device 10 while keeping the SNR trade-off to a low value (compared to what current solutions require).

[0089] Stator Resonance (Third Resonance) TMD:

[0090] Stator resonant TMD reduces the trade-offs required between low noise and high resonance performance, such as high suppression of unwanted resonances.

[0091] Unwanted oscillations and / or high total harmonic distortion (THD) values ​​can be reduced. Optionally, the signal-to-noise ratio (SNR) can be increased while maintaining high resonant performance.

[0092] Additional embodiments and aspects are described that can be used alone or in combination with the features and functions described herein.

[0093] According to one embodiment, the MEMS device includes a suspended electrode structure anchored to a substrate, the MEMS device having an (undesired) MEMS resonant mode, and a TMD (tuned mass damping) structure, wherein a portion of the suspended electrode structure is arranged to (integrally) form a TMD structure having a TMD spring element and a TMD mass element for providing a TMD resonant mode that cancels out the MEMS resonant mode.

[0094] According to one embodiment, the MEMS device includes a first suspended electrode and a second suspended electrode, the first suspended electrode and the second suspended electrode being spaced apart from each other and at least partially opposite each other, and both the first suspended electrode and the second suspended electrode being anchored to the substrate.

[0095] According to one embodiment, the TMD structure is arranged in the center portion of the first or second suspension electrode.

[0096] According to one embodiment, the TMD structure is arranged adjacent to the ventilation holes in the first or second suspended electrode.

[0097] According to one embodiment, the first electrode and the second electrode operate as sound transducers.

[0098] According to one embodiment, the first electrode and the second electrode operate as a capacitive sensor.

[0099] According to one embodiment, the first electrode and the second electrode operate as an audio microphone.

[0100] According to one embodiment, the first electrode is a (deflectable) membrane element, and the second electrode is a (static) counter electrode (backplate).

[0101] According to one embodiment, the TMD structure is an integral part of the (movable) membrane element.

[0102] According to one embodiment, the TMD structure is an integral part of the (static) counter electrode.

[0103] According to one embodiment, the counter electrode includes a perforation having a plurality of through holes, wherein at least a portion of the through holes in the counter electrode portion of the TMD element includes a reduced hole diameter and / or a reduced pore density compared to the remainder of the counter electrode.

[0104] According to one embodiment, the TMD spring element includes an adjusted elastic modulus (flexibility or spring constant) and an adjusted TMD mass for adjusting the TMD resonant frequency of the TMD resonant mode, which cancels (damps) the MEMS resonant mode having the MEMS resonant frequency.

[0105] According to one embodiment, the TMD mass element includes additional mass elements for increasing the obtained TMD mass and for reducing (adapting) the obtained TMD resonant frequency.

[0106] According to one embodiment, the TMD structure is an integral part of the first element suspension electrode, wherein the separated (= mechanically decoupled from the second electrode) portion of the second suspension electrode forms an additional mass element of the TMD structure.

[0107] According to one embodiment, the MEMS device operates as an audio microphone in a single counter electrode (backplane) configuration, a dual counter electrode configuration, or a hermetically sealed dual-film configuration.

[0108] According to one embodiment, the MEMS device is arranged in a dual (two) pair electrode configuration and includes a third suspended electrode anchored to the substrate, wherein the first electrode is a first pair of electrodes of an audio microphone, the second electrode is a diaphragm element of an audio microphone, and the third electrode is a second pair of electrodes of an audio microphone, wherein the diaphragm element is disposed between the first pair of electrodes and the second pair of electrodes.

[0109] According to one embodiment, the MEMS device is arranged in a dual (two)-membrane configuration and includes a third suspended electrode anchored to a substrate, wherein the first electrode is a first membrane element of an audio microphone, the second electrode is a counter electrode of the audio microphone, and the third electrode is a second membrane element of the audio microphone, wherein the counter electrode is disposed between the first membrane element and the second membrane element, and wherein a mechanical coupling structure is mechanically coupled between the first electrode and the third electrode (the first membrane element and the second membrane element) and mechanically decoupled from the second electrode (the counter electrode).

[0110] Additional embodiments and aspects are described that can be used alone or in combination with the features and functions described herein.

[0111] Although some aspects have been described as features within the context of the device, it is clear that this description can also be viewed as a description of the corresponding features of the method.

[0112] Depending on certain implementation requirements, embodiments of the control circuit can be implemented in hardware or software, or at least partially in hardware or at least partially in software. Typically, embodiments of the control circuit can be implemented as a computer program product having program code that, when run on a computer, performs one of the methods. The program code can, for example, be stored on a machine-readable medium.

[0113] As can be seen in the foregoing detailed description, various features are grouped together in the examples for the purpose of simplification of this disclosure. This approach should not be construed as reflecting an intention to reflect that the claimed examples require more features than expressly recited in each claim. Rather, as reflected in the appended claims, the subject matter may lie in fewer than all the features of a single disclosed example. Therefore, the appended claims are incorporated herein into the detailed description, wherein each claim may be considered a separate example. While each claim may be considered a separate example, it should be noted that although a dependent claim may refer in the claim to a specific combination of one or more other claims, other examples may also include combinations of dependent claims with the subject matter of each other dependent claim or combinations of each feature with other dependent or independent claims. Such combinations are presented herein unless it is stated that no particular combination is intended. Furthermore, it is intended to include features of any other independent claim, even if that claim does not directly depend on the independent claim.

[0114] Although specific embodiments have been illustrated and described herein, those skilled in the art will understand that various alternatives and / or equivalent implementations may be used instead of the specific embodiments shown and described without departing from the scope of these embodiments. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, the embodiments are intended to be limited only by the claims and their equivalents.

Claims

1. MEMS devices, including: A suspended electrode structure is anchored to a substrate; the MEMS device has a MEMS resonant mode, and A TMD tuned mass damping structure, wherein a portion of the suspended electrode structure is arranged to form the TMD tuned mass damping structure, the TMD tuned mass damping structure having a TMD spring element and a TMD mass element, the TMD tuned mass damping structure being used to provide a TMD resonant mode that cancels the MEMS resonant mode.

2. The MEMS device of claim 1, wherein the MEMS device includes a first suspended electrode and a second suspended electrode, the first suspended electrode and the second suspended electrode being spaced apart from each other and at least partially opposite each other, and the first suspended electrode and the second suspended electrode being anchored to the substrate.

3. The MEMS device according to claim 2, wherein the TMD tuned mass damping structure is arranged at the center portion of the first suspension electrode or the second suspension electrode.

4. The MEMS device according to claim 2 or 3, wherein the TMD tuned mass damping structure is arranged adjacent to the ventilation holes in the first suspension electrode or the second suspension electrode.

5. The MEMS device according to any one of claims 2 or 3, wherein the first suspended electrode and the second suspended electrode operate as sound transducers.

6. The MEMS device according to claim 2 or 3, wherein the first suspended electrode and the second suspended electrode operate as capacitive sensors.

7. The MEMS device according to claim 2 or 3, wherein the first suspended electrode and the second suspended electrode operate as an audio microphone.

8. The MEMS device according to claim 2 or 3, wherein the first suspended electrode is a film element and the second suspended electrode is a counter electrode.

9. The MEMS device according to claim 8, wherein the TMD tuned mass damping structure is an integral part of the membrane element.

10. The MEMS device of claim 8, wherein the TMD tuned mass damping structure is an integral part of the counter electrode.

11. The MEMS device of claim 10, wherein the counter electrode includes a perforation having a plurality of through holes, wherein at least a portion of the through holes in the counter electrode of the TMD tuned mass damping structure includes a reduced aperture and / or a reduced pore density compared to the remainder of the counter electrode.

12. The MEMS device according to any one of claims 1-3, 9-11, wherein the TMD spring element comprises an adjusted elastic modulus and an adjusted TMD mass for adjusting the TMD resonant frequency of the TMD resonant mode, the TMD resonant mode canceling the MEMS resonant mode having a MEMS resonant frequency.

13. The MEMS device according to any one of claims 1-3 and 9-11, wherein the TMD mass element includes an additional mass element for increasing the obtained TMD mass and reducing the obtained TMD resonant frequency.

14. The MEMS device according to any one of claims 2-3 and 9-11, wherein the TMD tuned mass damping structure is an integral part of the first suspension electrode, wherein the separate portion of the second suspension electrode forms an additional mass element of the TMD tuned mass damping structure.

15. The MEMS device according to any one of claims 1-3, 9-11, wherein the MEMS device operates as an audio microphone in a single-pair electrode configuration, a dual-pair electrode configuration, or a hermetically sealed dual-film configuration.

16. The MEMS device according to any one of claims 1-3, 9-11, wherein the MEMS device is arranged in a dual-pair electrode configuration and includes a third suspended electrode anchored to the substrate, wherein the first suspended electrode is a first pair of electrodes of an audio microphone, the second suspended electrode is a diaphragm element of the audio microphone, and the third suspended electrode is a second pair of electrodes of the audio microphone, wherein the diaphragm element is disposed between the first pair of electrodes and the second pair of electrodes.

17. The MEMS device according to any one of claims 1-3, 9-11, wherein the MEMS device is arranged in a dual-film configuration and includes a third suspended electrode anchored to the substrate, wherein the first suspended electrode is a first film element of an audio microphone, the second suspended electrode is a counter electrode of the audio microphone, and the third suspended electrode is a second film element of the audio microphone, wherein the counter electrode is arranged between the first film element and the second film element, and wherein a mechanical coupling structure is mechanically coupled between the first suspended electrode and the third suspended electrode and is mechanically decoupled from the second suspended electrode.

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