Acoustic transducer device with expanded rear volume

Abstract

An acoustic transducer device comprising: a substrate (102); and a cap (104) disposed on the substrate (102) and defining the acoustic chamber as a volume between the substrate (102) and the cap (102); an acoustic chamber comprising a support structure (106) disposed on the substrate (102); and a membrane (108) disposed on the support structure (106); a seal (110) between the cap (102) and the membrane (108) or the support structure (106); a front volume (112) defined by at least the membrane (108), the seal (110) and the cap (104); and a main back volume (114) defined by at least the membrane (108), the support structure (106) and the substrate (102); and a secondary rear volume (116); further included is a channel (118) in the substrate (102) or the support structure (106), where the channel (118) connects the primary back volume (114) and the secondary back volume (116).

Description

[0001] Related Applications

[0002] This application claims priority to German application 10 2022 113 720.1, filed on May 31, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to acoustic transducer devices and techniques for improving the signal-to-noise ratio (SNR) and / or its frequency response. Background Art

[0004] A microphone can use an electroacoustic transducer (e.g., an acoustic transducer) to convert acoustic vibrations into an electrical signal. Microphones are widely used in a variety of electronic devices, including but not limited to smartphones, smart watches, tablet computers, laptop computers, desktop computers, IoT devices, etc. Market forces may require the manufacture of acoustic transducers with a small form factor and the generation of high-quality audio signals.

[0005] The acoustic transducer can be implemented with various mechanisms to generate an electrical signal, such as relying on capacitive signal generation, optical signal generation, or other means. In this article, particular emphasis will be placed on acoustic transducers that generate electrical signals with optical sensors; however, nothing in this specification is intended to exclude any other method for signal generation. The acoustic transducer can include a membrane that is configured to bend or exhibit displacement in response to changes in sound pressure (e.g., in response to sound waves). The membrane can optionally include a reflective surface (e.g., a mirrored surface or a reflector), and the acoustic transducer can include a light source configured to direct light onto the membrane (and / or optionally onto a reflective surface) and detect changes in the reflected light to generate a corresponding electrical signal. The acoustic transducer can optionally be configured as a microelectromechanical system (MEMS) microphone.

[0006] As disclosed herein, an acoustic transducer can generally be understood to include a front volume and a rear volume, as demarcated by a membrane. The front volume can generally be understood as the volume between a housing having an acoustic port (e.g., a port for entering sound waves) and a membrane (e.g., between the housing and the membrane, and / or between the housing and the membrane (including both)). The rear volume can generally be understood as the volume on the opposite side of the membrane as the front volume, and it includes some or all of the sensor components (e.g., components of an optical sensor).

[0007] As a general concept, it may be desirable to design an acoustic transducer to have a high SNR. One technique for increasing the SNR is to reduce (e.g., minimize) the front volume while increasing (e.g., maximize) the rear volume. Various efforts to improve the SNR by reducing the front volume and increasing the rear volume have been disclosed at least below.

[0008] US2020 / 0245078 A1 of Lim et al. discloses hollowing out a substrate under a membrane. The hollowed-out area functionally expands the rear volume.

[0009] US2018 / 0302725 A1 by Ginnerup et al. discloses the use of a seal to define a front volume and sound path generated by creation of a gap between an integrated circuit and a substrate to amplify the rear volume.

[0010] SU 9,002,040 B2 to Yang discloses placing a membrane atop a wide structure and hollowing out the adjacent substrate to expand the rear volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the drawings, like reference characters generally refer to like parts throughout the different views. The drawings are not necessarily to scale, instead emphasis is generally placed on illustrating the present disclosure. The dimensions of the various features or elements may be arbitrarily expanded or reduced for clarity. In the following description, various aspects of the present disclosure are described with reference to the following drawings, in which:

[0012] Figure 1 An acoustic transducer device 100 according to a first aspect of the present disclosure is shown;

[0013] Figure 2 An acoustic transducer device according to a second aspect of the present disclosure is shown;

[0014] Figure 3 An acoustic transducer device according to a third aspect of the present disclosure is shown;

[0015] Figure 4 An acoustic transducer device according to a fourth aspect of the present disclosure is shown;

[0016] Figure 5 An acoustic transducer device with its photodiode in a cavity in a substrate is shown;

[0017] Figure 6 An acoustic transducer device using one or more through-silicon vias (TSVs) is shown;

[0018] Figure 7 shows a cross section of an acoustic transducer device;

[0019] Figure 8 An acoustic transducer device having a channel in a support structure is shown;

[0020] Fig. 9 An acoustic transducer device is shown wherein the secondary rear volume is built into the cap; and

[0021] Fig.10An acoustic transducer device is shown wherein the secondary rear volume is built into the cap. DETAILED DESCRIPTION

[0022] The following detailed description refers to the accompanying drawings that show, by way of illustration, exemplary details and embodiments in which aspects of the disclosure may be practiced.

[0023] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0024] Throughout the drawings, it should be noted that unless otherwise described, the same reference numbers are used to depict the same or similar elements, features, and structures.

[0025] The phrases "at least one" and "one or more" can be understood to include a numerical quantity greater than or equal to one (e.g., one, two, three, four, [...], etc.). The phrase "at least one" with respect to a group of elements can mean herein at least one element from the group consisting of the elements. For example, the phrase "at least one" with respect to a group of elements can mean herein a selection of: one of the listed elements, a plurality of one of the listed elements, a plurality of individually listed elements, or a plurality of a plurality of individually listed elements.

[0026] The words "plurality" and "multiple" in the specification and in the claims clearly refer to quantities greater than one. Thus, any phrase explicitly invoking the above words (e.g., "plurality [elements]," "multiple [elements]") that references a quantity of an element clearly refers to more than one of the element. For example, the phrase "plurality" can be understood to include a numerical quantity greater than or equal to two (e.g., two, three, four, five, [...], etc.).

[0027] The phrases "group", "a set", "set", "series", "sequence", "grouping", and the like in this specification and claims, if any, refer to a quantity equal to or greater than one, i.e., one or more. The terms "proper subset", "reduced subset", and "lesser subset" refer to a subset of a set that is not equal to the set, for example, a subset of a set that contains fewer elements than the set.

[0028] The present disclosure relates to an acoustic transducer device having low acoustic noise of the system, high membrane compliance (e.g., sensitivity), and a high resonant frequency (e.g., packaged with the membrane). The present disclosure seeks at least to provide a high signal-to-noise ratio (SNR) in an acoustic transducer device (e.g., such as a front port microphone) with an excellent frequency response, where existing concepts fail. As described above, other acoustic transducer devices may attempt to offset the low SNR by increasing the rear volume within the membrane tube core. The present disclosure instead reduces the front volume by acoustic sealing and expands the rear volume by including a channel between the primary rear volume and the secondary rear volume. In other words, the present disclosure reduces acoustic noise (e.g., as is common in top port microphones) by reducing the front volume and thereby establishing a high resonant frequency; increasing the rear volume to reduce acoustic noise dominated by thermal boundaries; and combining the compliance (e.g., sensitivity) of the membrane machinery with the acoustic front and rear volumes.

[0029] Figure 1 An acoustic transducer device 100 according to a first aspect of the present disclosure is shown. A cap 104 defines an acoustic chamber as a volume between a PCB / substrate 102 and the cap 104. The acoustic chamber comprises a membrane substrate (e.g., a support structure) 106 disposed on the PCB / substrate 102. The acoustic chamber comprises a membrane 108 disposed on the support structure 106. The membrane 108 is capable of displacement in response to changes in acoustic pressure. The acoustic chamber further comprises a seal 110 disposed between the cap 104 and the membrane 108 or between the cap 104 and the support structure 106. The acoustic chamber comprises a front volume 112 defined at least by the membrane 108, the seal 110, and the cap 104. Acoustic waves enter the front volume 112 from an area outside the device and cause displacement of the membrane 108. The acoustic chamber comprises a main rear volume 114, which is defined at least by the membrane 108, the support structure 106, and the PCB / substrate 102. The main rear volume 114 is separated from the front volume 112 by the membrane 108. The acoustic chamber further includes a secondary rear volume 116 that is different from the front volume 112 or the primary rear volume 114. The primary rear volume 114 and the secondary rear volume 116 are connected by a channel 118 in the PCB / substrate 102 or the support structure 106, wherein the channel 118 connects the primary rear volume 114 and the secondary rear volume 116. The acoustic chamber can define the acoustic compliance of the acoustic transducer.

[0030] The acoustic transducer device can further include an acoustic port 120, which can be configured as an opening within the cap 104. The acoustic port 120 can be positioned to create an opening between the space outside the acoustic device 100 and the front volume 112, for example, for sound waves to travel into the front volume 112. The acoustic port 120 can be created with any size to accommodate the needs of a given implementation of the acoustic transducer. The acoustic port 120 can be centered relative to the membrane 108. Alternatively, the acoustic port 120 can be off-center relative to the membrane 108. In some configurations, it may be desirable to place the acoustic port 120 off-center relative to the membrane, such as to improve eye safety (e.g., to avoid light source lasers emitted from the acoustic port, such as in a membrane failure). In one non-limiting example, the diameter of the acoustic port 120 can be less than 2 mm; in another non-limiting example, the diameter of the acoustic port 120 can be less than 1 mm; in a non-limiting example, the diameter of the acoustic port 120 can be less than 0.5 mm; in a non-limiting example, the diameter of the acoustic port 120 can be about 0.3 mm. Alternatively or additionally, the acoustic transducer device can include multiple smaller diameter sound ports. Such ports can be, for example, smaller 0.3 mm.

[0031] The acoustic transducer device includes a sensor configured to generate an electrical signal representing an acoustic wave in an acoustic chamber. Although various sensor types (e.g., capacitance, optics, etc.) can be used in the acoustic transducer disclosed herein, an acoustic transducer having a light source and an optical sensor (e.g., a photodiode) will be described below. As described above, the acoustic transducer can include a light source 122 that can be configured to generate light (e.g., electromagnetic wavelengths in the visible spectrum and / or the invisible spectrum, optionally including infrared wavelengths and / or ultraviolet wavelengths). An exemplary configuration of the light source 122 can be a vertical cavity surface emitting laser (VCSEL). The light source 122 (e.g., a VCSEL) can be configured to guide light into the membrane 108. Due to changes in sound pressure, changes in the bending of the membrane 108 (e.g., displacement of the membrane) will result in changes in the reflection of light on the membrane 108. The acoustic transducer device may include a photodiode / photodiode chip 124 that can be configured to detect light generated by the light source 122 and reflected from the membrane 108, and to generate an electrical signal based on the detected light. In an optional configuration, the membrane can include a reflector 128 or other reflective surface disposed on a second side of the membrane (e.g., a side surface within the main rear volume), which can increase the amount of light reflected from the surface of the membrane. Alternatively, the membrane can be configured without a reflector, in which case the light generated by the light source 122 can simply be reflected by the material of the membrane. Although the membrane itself can be less reflective than a reflector, the acoustic transducer can be operated without a reflector. If a reflector is used, the diameter of the reflector should generally be smaller than the membrane diameter. In an optional configuration, the diameter of the reflector can be between 10 μm and 120 μm; for example, a diameter of approximately 100 microns.

[0032] The sound transducer device can include a metallization layer 126 .

[0033] The acoustic transducer device may include an integrated circuit 130. The integrated circuit 130 can be attached to the PCB / substrate 102 optionally using a digital die attach 132 such as, for example, a flip chip connection or wire bonding.

[0034] The acoustic transducer device can include one or more surface mount devices 134. The one or more surface mount devices 134 can include one or more electrical components, including but not limited to ohmic resistors, inductors, capacitors, transistors or others. The one or more surface mount devices 134 can be configured to change the current or voltage of an electrical signal within the acoustic transducer.

[0035] Figure 2 An acoustic transducer according to the second aspect of the present disclosure is shown. In this configuration, Figure 2 Each element of the acoustic transducer is Figure 11 and 2, respectively, except that a solder ball array 136 can be present, wherein the solder ball array can conductively connect the photodiode / photodiode chip 124 to the metallization layer 126.

[0036] Figure 3 An acoustic transducer according to a third aspect of the present disclosure is shown. In this configuration, Figure 3 Each element of the acoustic transducer is Figure 1 1 and 2, with the exception that photodiode chip 124 can be configured with an integrated photodiode 138.

[0037] Figure 4 An acoustic transducer according to a fourth aspect of the present disclosure is shown. In this configuration, solder ball array 136 and integrated photodiode 124 are each present.

[0038] Figure 5 Shows Figures 1 to 4 The present invention relates to any acoustic transducer in which a cavity is formed in a PCB / substrate 102 and a photodiode / photodiode chip 124 is placed in the cavity. In this configuration, a light source 122 may be placed on the PCB / substrate 102, such as above the photodiode / photodiode chip 124.

[0039] Figure 6 Shows Figures 1 to 4 The subject matter of FIG. 1 is a schematic diagram of an embodiment of the present invention, wherein one or more through-silicon vias (TSVs) 140 are used to connect the metallization layer 126 at the top of the photodiode to the metallization layer (not labeled) at the bottom of the photodiode.

[0040] Figure 7 Shows Figures 1 to 6104 is a cross section of an acoustic transducer in any figure of FIG. In the figure, cap 104 is placed on substrate 102 and defines an acoustic chamber. Support structure 106 is arranged on substrate 102, and film 108 is arranged on support structure 106. Seal 110 is arranged between support structure and / or film 108 and cap 104, and therefore the volume between cap 104, film 108 and seal 110 is defined as front volume. On the other side of film 108, the main rear volume is defined by the volume between support structure 106, film 108 and substrate 102. The main rear volume includes light source 122 and photodiode / photodiode chip 124. In the main rear volume, substrate includes channel 118, which connects the main rear volume to the secondary rear volume. In the figure, channel 118 is depicted as spanning the same plane as the main length of substrate but perpendicular to the axis of the main length of substrate. In other words, support structure 106 includes four walls to form a closed structure (e.g., defined by four walls, substrate and film). Alternatively, the support structure 106 may include any number of walls with a closed structure provided between the walls of the support structure, the membrane, and the substrate. A channel can be created in the substrate below one or more walls of the support structure 106. Figure 7 In the figure, the wall below which forms the channel is not shown. Figure 7 is a cross section, and the wall forming the bottom of the channel lies in a plane outside the plane forming the basis of the cross section.

[0041] In an optional configuration, the height of the seal 110 (eg, the distance along the seal between the cap and the support structure) can be less than 0.5 mm, for example, less than 0.2 mm. In an optional aspect of the present disclosure, the height of the seal can be approximately 0.1 mm.

[0042] In an optional configuration, the height of the support structure 106 can be less than 1 mm, and for example, less than 0.8 mm. In an optional aspect of the present disclosure, the height of the support structure can be about 0.65 mm. The support structure 106 can optionally be made of multiple layers (e.g., multiple layers of the same material). The layering of such materials may be more cost-effective than etching a thicker substrate (e.g., a substrate thicker than 0.65 mm).

[0043] In an optional configuration, the outer dimension of the support structure 106 (e.g., the length or width from outer wall surface to outer wall surface) can be less than 2 mm, for example, less than 1.6 mm. According to optional aspects of the present disclosure, the outer dimension can be about 1.4 mm×1.4 mm. In these optional aspects, the inner dimension of the support structure 106 (e.g., from inner wall surface to inner wall surface) can be less than 1.5 mm, or, for example, less than 1.3 mm. In optional aspects, the inner dimension of the support structure can be about 1 mm, about 1.1 mm, or about 1.2 mm.

[0044] According to an optional aspect of the disclosure, the photodiode / photodiode chip 124 and light source 122 together can be less than 1.0 mm high, such as less than 0.7 mm. According to an optional aspect of the disclosure, the height of the photodiode / photodiode chip 124 and light source 122 together can be about 0.45 mm.

[0045] According to an optional aspect of the present disclosure, the channel 118 can be less than 2.0 mm wide, such as less than 1.0 mm wide, such as a maximum of 0.9 mm wide. According to an optional aspect of the present disclosure, the channel 118 can be a minimum of 0.05.

[0046] According to optional aspects of the present disclosure, the film can be greater than 0.5 mm wide, for example, at least 1.0 mm wide, for example, in the range from about 1.0 mm to about 1.2 mm wide.

[0047] Figure 8 An acoustic transducer is shown where the channels are created in the support structure 106 rather than in the substrate 102. In this manner, channels (e.g., openings) are created in the vertical walls of the support structure 106, which allow air communication between the primary rear volume 114 and the secondary rear volume 116. The air communication is represented by arrows along the channels 118. In optional aspects of the present disclosure, when the channels are created in the support structure 106, the substrate can remain intact (e.g., without the channels).

[0048] Fig. 9 An optional alternative configuration is shown, in which the secondary rear volume is built into the cap. In this configuration, the acoustic transducer device may include a substrate 102, including a recess 142 (corresponding to the primary rear volume 114); a chip 130, which is arranged above the recess and includes a first side facing the recess and a second side opposite the first side, and defines an acoustic chamber as a volume between the recess and the chip; and a cap 104, which is arranged on the substrate 102 and above the chip 130, wherein the acoustic chamber includes a support structure 106 disposed in the recess, which is located on the first side of the chip; and a membrane 108 disposed on the support structure 106; the primary rear volume 114, which is defined by at least the membrane, the support structure and the chip; and a secondary rear volume 116, which is defined by at least the cap, the substrate and the chip and is different from the primary rear volume 114; further including a channel in the substrate or the support structure, wherein the channel connects the primary rear volume 114 and the secondary rear volume 116. Fig.10Another optional alternative configuration is shown, in which the secondary rear volume is built into the cap. In this optional alternative configuration, the acoustic transducer device includes a substrate 1002, the substrate including a recess (e.g., an area of ​​the recess within 1002); a chip 1030, which is arranged above the recess and includes a first side facing the recess and a second side opposite the first side, and defines an acoustic chamber as a volume between the recess and the chip; and a cap 1004, which is arranged on the substrate 1002 and above the chip 1030, wherein the acoustic chamber includes a support structure 1006 disposed in the recess, which is located at the first side of the chip. side; and a membrane 1008, which is arranged on the supporting structure; a seal 1010, which is arranged in a recess of the membrane or the supporting structure; a front volume 1012, which is defined by at least the membrane, the seal and the recess; and a main rear volume 1014, which is defined by at least the membrane, the supporting structure and the chip; and a secondary rear volume 1016, which is defined by at least the cap, the substrate and the chip, and is different from the front volume or the main rear volume; further includes a channel in the substrate or the supporting structure, wherein the channel connects the main rear volume and the secondary rear volume.

[0049] As described above, the acoustic transducer includes a channel between the primary rear volume and the secondary rear volume. The channel allows air communication between the primary rear volume and the secondary rear volume and effectively makes the primary rear volume and the secondary rear volume appear as separate rear volumes that are larger than the primary rear volume. In this way, the opening increases the size of the volume, which produces a higher SNR and improves the frequency response.

[0050] Various configurations of the channel are possible. According to one aspect, the channel can be a groove in the PCB / substrate. For example, the channel can be arranged below the support structure. According to other aspects, the channel can be located within the support structure rather than in the PCB / substrate. Whether the channel is located in the PCB / substrate or in the support structure can be selected based on manufacturing requirements, materials used, or other needs.

[0051] The channel can be made in any of a variety of shapes. The channel can optionally be made so that the cross-section of the channel is rectangular, square, triangular or any combination thereof. Alternatively or additionally, the channel can optionally have a cross-section in the shape of an irregular polygon. The channel can be made at any height, although the channel can preferably be at least 50 μm high.

[0052] The acoustic impedance is at least partially determined by the opening of the channel (by the profile of the channel and the length of the channel). The channel height can greatly affect the acoustic impedance, and therefore a channel height of at least 50 μm can be provided. The channel width can be selected based on other factors (such as, for example, the film die size). In many cases, it may be desirable to design the channel width to be as large as possible.

[0053] The acoustic transducer device includes a cap covering the substrate and capable of defining an acoustic chamber including a front volume, a primary rear volume, and a secondary rear volume. In some configurations, the cap includes an opening configured to allow acoustic waves to pass from outside the acoustic chamber into the front volume.

[0054] The acoustic transducer comprises a membrane configured to displace (e.g., exhibit movement or bending) in response to acoustic waves in the front volume. The membrane can comprise a first side and a second side, wherein the first side faces the cap, and wherein the second side faces the substrate. The membrane can be arranged on a support structure. The membrane can divide the front volume from the main rear volume. The membrane can optionally have a diameter of 100 μm to 2000 μm.

[0055] The acoustic transducer device comprises a seal which, in combination with the membrane and the support structure, seals the front volume to prevent or limit the movement of air from the front volume into the primary rear volume or the secondary rear volume.

[0056] The acoustic transducer device can include a reflector arranged on the second side of the membrane. In an alternative configuration, the reflector can be manufactured between the first side and the second side of the membrane. The reflector can be or include any reflective material, which can, for example, include gold and / or aluminum. The reflector can be deposited on the second side of the membrane using any deposition process. The reflector can increase the reflectivity of the second side of the membrane so that a greater amount of light is reflected from the membrane to the photodiode / photodiode chip. According to aspects of the present disclosure, the diameter of the reflector (e.g., when a reflector is used) can be less than 120 μm, for example, less than 80 μm, for example, less than 50 μm. The diameter of the reflector can optionally be in the range of from about 10 μm to about 120 μm.

[0057] Alternatively, the acoustic transducer can omit the reflector on the second side of the membrane. When the acoustic transducer is implemented without the reflector, the light source is configured to direct light to the second surface of the membrane, and the photodiode / photodiode chip is configured to detect light reflected from the second surface of the membrane without the reflector. Although the non-mirrored surface of the membrane is expected to reflect less light than the mirrored surface, the surface of the membrane still exhibits a certain amount of reflectivity, and this amount is generally sufficient to detect the reflected light and generate a corresponding electrical signal.

[0058] The membrane can include one or more openings that can exist to allow static pressure equalization between the front volume and the rear volume. Such an opening or openings can allow at least limited transfer of air between the front volume and the main rear volume. Such openings can be, for example, 6 μm or less. In a further example, the openings can be 3 μm to 6 μm. In the absence of an opening, additional openings for pressure equalization can alternatively be created in the cap or substrate.

[0059] Various elements of the acoustic transducer can be located in the rear volume, preferably in the main rear volume. These can include a light source, which can be a VCSEL and a photodiode / photodiode chip.

[0060] The light source can be configured to direct light onto the second side of the film. The light source can preferably be a VCSEL, although other light sources can also be used. VCSELs are known, and therefore the details of VCSELs or their creation will not be described herein. When the VCSEL emits light perpendicular to the VCSEL, the VCSEL can be placed or formed substantially parallel to the PCB / substrate below the film so that the emission of light perpendicular to the PCB / substrate results in the emission of light directed to the film. In this way, the VCSEL can have a line of sight connection to the second side of the reflector or film.

[0061] The acoustic transducer device further includes an optical sensor configured to detect light reflected from the membrane (e.g., from the second surface of the membrane or from a reflector applied to the second surface) and generate an electrical signal corresponding to the detected light. A specific type of optical sensor can be selected for a given implementation, but is not limited to this. Feasibility of optical sensors include, but are not limited to, photoconductive devices, which can be configured to produce a change in impedance in response to incident light; photovoltaics, which can be configured to generate a voltage in response to incident light; photodiodes or phototransistors, which can be used to generate an output current in response to incident light. The terms "photodiode", "photodiode chip" and "integrated photodiode" are used herein as a non-limiting list of optical sensor types.

[0062] In some configurations, the acoustic transducer device can include a tertiary rear volume that can be different from the front volume, the primary rear volume, and the secondary rear volume. In this configuration, the channel as described above is the first channel, and the acoustic transducer device also includes a second channel configured to connect the primary rear volume and the tertiary rear volume. In this way, an additional rear volume is added to the primary rear volume.

[0063] In an optional configuration, the membrane can include one or more holes. These one or more holes can be called "vent holes" or "pressure balance holes" and can balance the pressure at low frequencies and improve robustness. By using these optional holes, the acoustic transducer device can be configured so that the high-pass cutoff frequency is less than 20 Hz. The number and diameter of the holes can be selected so that the equivalent acoustic resistance is as high as possible, i.e., greater than 1e15 N / m 3. These parameters can depend on the number, location and diameter of the pressure equalization holes. In various aspects of the present disclosure, two or more holes with a diameter of 3 μm can be used, and these can be located near the larger DRIE holes that form the main rear volume. The diameter of each of the optional one or more holes in the membrane can be at least 2 μm. In a non-limiting example, the diameter of each of the optional one or more holes in the membrane can not exceed 10 μm. In a non-limiting example, the diameter of each of the optional one or more holes can be about 3 μm. The material of the membrane can be selected for a given implementation without limitation; however, in a non-limiting example, the membrane can contain or include silicon nitride (SiN) and / or polysilicon (Poly Si). The membrane can optionally be generated by plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, silane-based coating application or physical vapor deposition (PVD) (such as sputtering).

[0064] As described above, although the acoustic transducer device disclosed herein can be configured as an optical microphone. Note that the optical microphone may lack a backplate, but instead has a line of sight between the laser (e.g., VCSEL) and the membrane (which can optionally include a reflector). The membrane can be flat or corrugated, and may include raised microstructures. In various aspects of the present disclosure, the membrane has a diameter between 500 μm and 1500 μm. The membrane should not be less than, for example, 100 microns and should not be greater than 2000 μm.

[0065] The material used for the seal can be selected for a given implementation without limitation; however, in non-limiting examples, the seal can contain or include silicone, UV-cured epoxy, heat-cured epoxy, or any of these. The material can be selected on the basis that it provides a good acoustic seal with low permeation toward the edges. Contamination of the membrane by the seal should be prevented, and thus degrading the performance of the membrane. The material used for the seal can ideally be able to harden quickly.

[0066] In a non-limiting example, the acoustic transducer device of any aspect of the present disclosure and / or any aspect disclosed herein can be configured as a micro-electromechanical microphone.

[0067] Additional aspects of the disclosure will be shown by way of example.

[0068] In Example 1, an acoustic transducer device includes: a substrate; and a cap, which is arranged on the substrate and defines an acoustic chamber as a volume between the substrate and the cap; wherein the acoustic chamber includes: a support structure, which is arranged on the substrate; and a membrane, which is arranged on the support structure; a seal, which is arranged between the cap and the membrane or the support structure; a front volume, which is defined by at least the membrane, the seal and the cap; and a main rear volume, which is defined by at least the membrane, the support structure and the substrate; and a secondary rear volume, which is different from the front volume or the main rear volume; further includes a channel in the substrate or the support structure, wherein the channel connects the main rear volume and the secondary rear volume.

[0069] In Example 1, the acoustic transducer device according to Example 1, wherein the channel is a groove, and the groove is in the substrate.

[0070] In Example 2, the acoustic transducer device according to Example 2, wherein the channel is a groove, and the groove is in the substrate, below the support structure.

[0071] In Example 3, the acoustic transducer device according to Example 1, wherein the channel is in the support structure.

[0072] In Example 4, the acoustic transducer device according to any one of Examples 1 to 4, wherein the channel is at least 50 μm high.

[0073] In Example 5, according to the sound transducer device of any one of Examples 1 to 5, the cross-section of the channel is rectangular, square, triangular, or any combination thereof.

[0074] In Example 6, according to any one of Examples 1 to 6, the acoustic transducer device, wherein the cap includes an opening configured to allow acoustic waves to pass from outside the acoustic chamber into the front volume; and wherein the membrane is configured to displace in response to the acoustic waves in the front volume. In an optional configuration, the cap may include a plurality of such openings, wherein each opening has a diameter of 50 μm to 300 μm.

[0075] In Example 7, the acoustic transducer device according to Example 7, wherein the main rear volume includes a transducer configured to generate an electrical signal based on a displacement of the membrane.

[0076] In Example 8, the acoustic transducer device according to Example 8, wherein the transducer comprises an optical sensor.

[0077] In Example 9, the acoustic transducer device according to any one of Examples 1 to 9, wherein the membrane includes a first side facing the cap and a second side facing the substrate.

[0078] In Example 10, the sound transducer device according to any one of Examples 1 to 10, wherein the electromechanical microphone further includes a reflector located on the second side of the membrane.

[0079] In Example 10a, the sound transducer device according to any one of Examples 1 to 10, wherein the electromechanical microphone further includes a reflector located between the first side of the membrane and the second side of the membrane.

[0080] In Example 11, the acoustic transducer device according to any one of Examples 9 to 11, wherein the transducer includes a laser.

[0081] In Example 12, the acoustic transducer device according to Example 12, wherein the laser has a line-of-sight connection to the reflector.

[0082] In Example 13, according to the acoustic transducer device of any one of Examples 11 to 13, the reflector comprises aluminum or gold.

[0083] In Example 14, the acoustic transducer device according to any one of Examples 11 to 14, wherein the diameter of the reflector is between 10 μm and 120 μm.

[0084] In Example 15, the acoustic transducer device according to any one of Examples 1 to 15, wherein the membrane has a diameter of 100 μm to 2000 μm.

[0085] In Example 16, the acoustic transducer device according to Example 16, wherein the membrane has a diameter of 500 μm to 1500 μm.

[0086] In Example 17, the acoustic transducer device according to any one of Examples 1 to 17, wherein the front volume is sealed to prevent air from moving from the front volume into the primary rear volume or the secondary rear volume.

[0087] In Example 18, an acoustic transducer device according to any one of Examples 1 to 18, wherein the acoustic chamber further includes a tertiary rear volume different from the front volume, the primary rear volume, and the secondary rear volume; wherein the channel is a first channel; and further includes a second channel configured to connect the primary rear volume and the tertiary rear volume.

[0088] In Example 19, the acoustic transducer device according to any one of Examples 1 to 19, wherein the membrane includes one or more holes.

[0089] In Example 20, the acoustic transducer device according to Example 20, wherein a diameter of each of the one or more holes is at least 2 μm and no more than 10 μm.

[0090] In Example 21, the acoustic transducer device according to Example 21, wherein a diameter of each of the one or more holes is approximately 3 μm.

[0091] In Example 22, according to the acoustic transducer device of any one of Examples 1 to 22, the sealant includes silicone, UV-curable epoxy, or thermally-curable epoxy.

[0092] In Example 23, the acoustic transducer device according to any one of Examples 1 to 23, wherein the membrane includes silicon nitride (SiN) or polysilicon (Poly Si).

[0093] In Example 24, the acoustic transducer device according to any one of Examples 1 to 24, wherein the film is generated by plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, silane-based coating application or physical vapor deposition (PVD) (such as sputtering).

[0094] In Example 25, the acoustic transducer apparatus according to any one of Examples 1 to 25, wherein the acoustic chamber defines an acoustic compliance of the acoustic transducer.

[0095] In Example 26, the sound transducer device according to any one of Examples 1 to 26, wherein the sound transducer is configured as a micro-electromechanical microphone.

[0096] In Example 27, the acoustic transducer device includes: a substrate including a recess; a chip arranged above the recess and including a first side facing the recess and a second side opposite to the first side, and defining an acoustic chamber as a volume between the recess and the chip; and a cap arranged on the substrate and located above the chip, wherein the acoustic chamber includes: a support structure arranged in the recess and located on the first side of the chip; and a membrane arranged on the support structure; a seal arranged in the recess on the membrane or the support structure; a front volume defined by at least the membrane, the seal and the recess; and a main rear volume defined by at least the membrane, the support structure and the chip; and a secondary rear volume defined by at least the cap, the substrate and the chip and different from the front volume or the main rear volume; further including a channel in the substrate or the support structure, wherein the channel connects the main rear volume and the secondary rear volume.

[0097] In Example 28, the acoustic transducer device according to Example 28, wherein the channel is a groove, and the groove is in the substrate.

[0098] In Example 29, the acoustic transducer device according to Example 28 or Example 29, wherein the channel is at least 50 μm high.

[0099] In Example 30, the sound transducer device according to any one of Examples 28 to 30, wherein the cross-section of the channel is rectangular, square, triangular, or any combination thereof.

[0100] In Example 31, an acoustic transducer device according to any one of Examples 28 to 31, wherein the recess includes an opening configured to allow sound waves to pass from outside the acoustic chamber into the front volume; and wherein the membrane is configured to displace in response to sound waves in the front volume.

[0101] In Example 32, the acoustic transducer device according to Example 32, wherein the main rear volume includes a transducer configured to generate an electrical signal based on a displacement of the membrane.

[0102] In Example 33, the acoustic transducer device according to Example 33, wherein the transducer comprises an optical sensor.

[0103] In Example 34, the acoustic transducer device according to any one of Examples 28 to 34, wherein the membrane includes a first side facing the cap and a second side facing the substrate.

[0104] In Example 35, the sound transducer device according to any one of Examples 24 to 31, wherein the electromechanical microphone further includes a reflector located on the second side of the membrane.

[0105] In Example 36, the acoustic transducer device according to any one of Examples 33 to 35, wherein the transducer comprises a laser.

[0106] In Example 37, the acoustic transducer device according to Example 36, wherein the laser has a line-of-sight connection to the reflector.

[0107] In Example 38, the acoustic transducer device according to any one of Examples 35 to 37, wherein the reflector comprises aluminum or gold.

[0108] In Example 39, the acoustic transducer device according to any one of Examples 35 to 38, wherein the diameter of the reflector is between 10 μm and 120 μm.

[0109] In Example 40, the acoustic transducer device according to any one of Examples 28 to 39, wherein the membrane has a diameter of 100 μm to 2000 μm.

[0110] In Example 41, the acoustic transducer device according to Example 40, wherein the membrane has a diameter of 500 μm to 1500 μm.

[0111] In Example 42, the acoustic transducer device according to any one of Examples 28 to 41, wherein the front volume is sealed to prevent air from moving from the front volume into the primary rear volume or the secondary rear volume.

[0112] In Example 43, an acoustic transducer device according to any one of Examples 28 to 42, wherein the acoustic chamber further includes a third rear volume different from the front volume, the primary rear volume, and the secondary rear volume; wherein the channel is a first channel; and further includes a second channel configured to connect the primary rear volume and the third rear volume.

[0113] In Example 44, the acoustic transducer device according to any one of Examples 28 to 43, wherein the membrane includes one or more holes.

[0114] In Example 45, the acoustic transducer device according to Example 44, wherein each of the one or more holes has a diameter of approximately 3 μm.

[0115] In Example 46, the acoustic transducer device according to any one of Examples 28 to 45, wherein the seal comprises silicone, UV-cured epoxy, or thermally cured epoxy.

[0116] In Example 47, the acoustic transducer device according to any one of Examples 28 to 46, wherein the membrane includes silicon nitride (SiN) or polysilicon (Poly Si).

[0117] In Example 48, the acoustic transducer device according to any one of Examples 28 to 47, wherein the membrane is generated by plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, silane-based coating application, or physical vapor deposition (PVD) (such as sputtering).

[0118] In Example 49, the acoustic transducer apparatus according to any one of Examples 28 to 48, wherein the acoustic chamber defines an acoustic compliance of the acoustic transducer.

[0119] In Example 50, the sound transducer device according to any one of Examples 28 to 49, wherein the sound transducer is configured as a micro-electromechanical microphone.

[0120] In Example 51, a method for manufacturing an acoustic transducer device includes: wherein an acoustic chamber includes: creating a channel in a substrate; setting a support structure on the substrate, wherein at least a portion of the support structure is set above the channel; setting a membrane on the support structure; setting a seal on the membrane or the support structure; setting a cap on the substrate, wherein the cap defines the acoustic chamber as a volume between the substrate and the cap; wherein a front volume is defined by at least the membrane, the seal and the cap; and a main rear volume is defined by at least the membrane, the support structure and the substrate; wherein the acoustic chamber further includes a secondary rear volume different from the front volume or the main rear volume; and wherein the channel connects the main rear volume to the secondary rear volume.

[0121] In Example 52, according to the method of manufacturing the acoustic transducer device of Example 51, the channel is a groove, and the groove is in the substrate.

[0122] In Example 53, according to the method of manufacturing the acoustic transducer device of Example 52, the channel is a groove, and the groove is in the substrate, below the support structure.

[0123] In Example 54, according to the method of manufacturing the acoustic transducer device of any one of Examples 51 to 53, the channel is at least 50 μm high.

[0124] In Example 55, according to the method of manufacturing the sound transducer device of any one of Examples 51 to 54, the cross-section of the channel is rectangular, square, triangular, or any combination thereof.

[0125] In Example 56, according to a method of manufacturing an acoustic transducer device of any one of Examples 51 to 55, the cap includes an opening configured to allow sound waves to pass from outside the acoustic chamber into the front volume; and wherein the membrane is configured to displace in response to sound waves in the front volume.

[0126] In Example 57, the method of manufacturing the acoustic transducer device of Example 56 further includes arranging a transducer in the main rear volume, wherein the transducer is configured to generate an electrical signal based on a displacement of the membrane.

[0127] In Example 58, according to the method of manufacturing the acoustic transducer of Example 57, the transducer includes an optical sensor.

[0128] In Example 59, according to the method of manufacturing the acoustic transducer device of any one of Examples 51 to 58, the membrane includes a first side facing the cap and a second side facing the substrate.

[0129] In Example 60, the method of manufacturing the sound transducer device according to any one of Examples 51 to 59 further includes arranging a reflector on the second side of the membrane.

[0130] In Example 61, according to the method of manufacturing the acoustic transducer device of any one of Examples 58 to 60, the transducer includes a laser.

[0131] In Example 62, according to the method of manufacturing the acoustic transducer device of Example 61, wherein the laser has a line-of-sight connection to the reflector.

[0132] In Example 63, according to the method of manufacturing the acoustic transducer device of any one of Examples 60 to 62, the reflective mirror comprises aluminum or gold.

[0133] In Example 64, according to the method of manufacturing the acoustic transducer device of any one of Examples 60 to 63, the diameter of the reflective mirror is between 10 μm and 120 μm.

[0134] In Example 65, according to the method of manufacturing the acoustic transducer device of any one of Examples 51 to 64, the membrane has a diameter of 100 μm to 2000 μm.

[0135] In Example 66, according to the method of manufacturing the acoustic transducer device of Example 65, wherein the membrane has a diameter of 500 μm to 1500 μm.

[0136] In Example 67, according to the method of manufacturing the acoustic transducer device of any one of Examples 51 to 66, the front volume is sealed to prevent air from moving from the front volume into the primary rear volume or the secondary rear volume.

[0137] In Example 68, a method for manufacturing an acoustic transducer device includes: forming a recess in a substrate; arranging a chip above the recess, and wherein the chip includes a first side facing the recess and a second side opposite to the first side, and defining an acoustic chamber as a volume between the recess and the chip; and arranging a support structure in the recess, which is located on the first side of the chip; arranging a membrane on the support structure; arranging a seal in the recess on the membrane or the support structure; arranging a cap on the substrate and above the chip, wherein the acoustic chamber includes: a front volume defined by at least the membrane, the seal and the recess; and a main rear volume defined by at least the membrane, the support structure and the chip; and a secondary rear volume, which is defined by at least the cap, the substrate and the chip and is different from the front volume or the main rear volume; further including forming a channel in the substrate or the support structure, wherein the channel connects the main rear volume and the secondary rear volume.

[0138] In Example 69, according to the method of manufacturing the acoustic transducer device of Example 68, the channel is a groove, and the groove is in the substrate.

[0139] In Example 70, according to the method of manufacturing the acoustic transducer device of Example 68 or Example 69, wherein the channel is at least 50 μm high.

[0140] In Example 71, according to the method of manufacturing the sound transducer device of any one of Examples 68 to 70, the cross-section of the channel is rectangular, square, triangular, or any combination thereof.

[0141] In Example 72, according to a method of manufacturing an acoustic transducer device of any one of Examples 68 to 71, the recess includes an opening configured to allow sound waves to pass from outside the acoustic chamber into the front volume; and wherein the membrane is configured to displace in response to sound waves in the front volume.

[0142] In Example 73, the method of manufacturing the acoustic transducer device of Example 72 further includes arranging a transducer in the main rear volume, wherein the transducer is configured to generate an electrical signal based on a displacement of the membrane.

[0143] In Example 74, according to the method of manufacturing the acoustic transducer device of Example 73, the transducer includes an optical sensor.

[0144] In Example 75, according to the method of manufacturing the acoustic transducer device of any one of Examples 68 to 74, the membrane includes a first side facing the cap and a second side facing the substrate.

[0145] In Example 76, according to the method of manufacturing the sound transducer device of any one of Examples 68 to 75, the electromechanical microphone further includes a reflector located on the second side of the membrane.

[0146] In Example 77, according to the method of manufacturing the acoustic transducer device of any one of Examples 73 to 75, the transducer includes a laser.

[0147] In Example 78, according to the method of manufacturing the acoustic transducer device of Example 76, wherein the laser has a line-of-sight connection to the reflector.

[0148] Reference Symbols List

[0149] 100 sound transducers

[0150] 102 Printed Circuit Board / Substrate

[0151] 104 cap / shell

[0152] 106 Support structure / membrane core

[0153] 108 Membrane

[0154] 110 Seals

[0155] 112 front volume

[0156] 114 Main rear volume

[0157] 116 Secondary rear volume

[0158] 118 Channel

[0159] 120 Acoustic Port

[0160] 122 Light Source

[0161] 124 Photodiode / Photodiode Chip

[0162] 126 metallization layer

[0163] 128 reflectors

[0164] 130 Integrated Circuits / Chips

[0165] 132 Digital die attach (e.g., flip chip or wire bonding)

[0166] 134 Surface Mount Devices

[0167] 136 ball array

[0168] 138 Integrated photodiode

[0169] 140Through Silicon Via (TSV)

[0170] 142 recess

[0171] 1002 substrate

[0172] 1030 Chip

[0173] 1004 Hat

[0174] 1006 Support structure

[0175] 1008 Membrane

[0176] 1010 Seals

[0177] 1012 front volume

[0178] 1014 Main rear volume

[0179] 1016 Secondary Post Volume.

Claims

1. An acoustic transducer device, comprising: substrate(102); and a cap (104) disposed on the substrate (102) and defining an acoustic chamber as a volume between the substrate (102) and the cap (104); Wherein, the acoustic chamber comprises: a support structure (106) disposed on the substrate (102); and a membrane (108) disposed on the support structure (106); a seal (110) disposed between the cap (102) and the membrane (108) or the support structure (106); a front volume (112) defined by at least the membrane (108), the seal (110) and the cap (104); and a main rear volume (114) defined by at least the membrane (108), the support structure (106), and the substrate (102); and a secondary rear volume (116), the secondary rear volume being different from the front volume (112) or the primary rear volume (114); The acoustic transducer device further comprises a channel (118) in the substrate (102) or the support structure (106), wherein the channel (118) connects the primary rear volume (114) and the secondary rear volume (116).

2. The acoustic transducer device according to claim 1, wherein: The channel (118) is a trench, and the trench is in the substrate (102).

3. The acoustic transducer device according to claim 2, wherein: The channel (118) is a trench, and the trench is in the substrate (102) below the support structure (106).

4. The acoustic transducer device according to claim 1, wherein: The channel (118) is in the support structure (106).

5. The acoustic transducer device according to any one of claims 1 to 4, wherein: The trench (118) is at least 50 μm high.

6. The acoustic transducer device according to any one of claims 1 to 5, wherein: The cap (104) includes an opening configured to allow sound waves to pass from outside the acoustic chamber into the front volume (112); and wherein the membrane (108) is configured to displace in response to the sound waves in the front volume (112).

7. The acoustic transducer device according to claim 6, wherein: The main rear volume (114) includes a transducer configured to generate an electrical signal based on the displacement of the membrane (108).

8. The acoustic transducer device according to claim 7, wherein: The transducer comprises an optical sensor.

9. The acoustic transducer device according to any one of claims 1 to 8, wherein: The membrane (108) includes a first side facing the cap and a second side facing the substrate (102).

10. The acoustic transducer device according to claim 9, wherein: The acoustic transducer device further comprises a reflector (128) located on the second side of the membrane (108).

11. The acoustic transducer device according to any one of claims 8 to 10, wherein: The transducer comprises a laser, and wherein the laser has a line-of-sight connection to the reflector (128).

12. The acoustic transducer device according to any one of claims 8 to 11, wherein: The diameter of the reflector (128) is between 10 μm and 120 μm.

13. The acoustic transducer device according to claim 12, wherein: The membrane (108) has a diameter of 500 μm to 1500 μm.

14. The acoustic transducer device according to any one of claims 1 to 13, wherein: The acoustic chamber further includes a tertiary rear volume, which is different from the front volume (112), the primary rear volume (114) and the secondary rear volume (116); wherein the channel (118) is a first channel; and further includes a second channel, which is configured to connect the primary rear volume and the tertiary rear volume.

15. The acoustic transducer device according to any one of claims 1 to 14, wherein: The sealing member (110) comprises silicone, ultraviolet curing epoxy resin or thermal curing epoxy resin.

16. The acoustic transducer device according to any one of claims 1 to 15, wherein: The acoustic transducer is configured as a micro-electromechanical microphone.

17. An acoustic transducer device, comprising: A base plate (1002) including a recess; a chip (1030), the chip being arranged above the recess and comprising a first side facing the recess and a second side opposite to the first side; an acoustic chamber as a volume defined by the first side and the recess; and a cap (1004) disposed on the substrate (1002) and above the chip (1030); Wherein, the acoustic chamber comprises: a support structure (1006), the support structure being disposed in the recess and on the first side of the chip; a membrane (1008), the membrane being disposed on the support structure; a seal (1010) disposed in the recess on the membrane or the support structure; a front volume (1012) defined at least by the membrane (1008), the seal (1010), and a portion of the recess; and a main rear volume (1014), the main rear volume being defined by at least the membrane (1008), the support structure (1006) and the chip (1030); wherein the acoustic transducer device further comprises a secondary rear volume (1016) defined by at least the cap (1004), the substrate (1002) and the chip (1030) and different from the front volume (1012) or the primary rear volume (1014); The acoustic transducer device further comprises a channel in the substrate or the support structure, wherein the channel connects the primary rear volume (1014) and the secondary rear volume (1016).

18. The acoustic transducer device of claim 17, wherein: The trench is at least 50 μm high.

19. The acoustic transducer device of claim 17, wherein: The main rear volume (1014) includes a transducer configured to generate an electrical signal based on the displacement of the membrane (1008).

20. The acoustic transducer device according to any one of claims 17 to 19, wherein The transducer comprises an optical sensor.

21. The acoustic transducer device of claim 20, wherein: The optical sensor includes a vertical cavity surface emitting laser (VCSEL) and a photodiode, and is configured to detect movement of the membrane.

22. The acoustic transducer device of claim 21, wherein: The optical sensor further includes an application specific integrated circuit configured to generate a digital output based on an output of the photodiode.

23. The acoustic transducer device of claim 20, wherein: The film comprises a reflector, and wherein the reflector is implemented as an aluminum plate or a gold plate.

24. An acoustic transducer device, comprising: a membrane (108) comprising a first side and a second side opposite the first side; a front volume (112) defined by at least the first side of the membrane (108); a main rear volume (114) defined by at least the second side of the membrane (108); and a secondary rear volume (116), the secondary rear volume being different from the front volume (112) or the primary rear volume (114); The acoustic transducer device further comprises a channel (118) connecting the primary rear volume (114) and the secondary rear volume (116).

25. The acoustic transducer device of claim 24, further comprising a cap (104) and a substrate (102), wherein: The cap is arranged on the substrate (102) and defines an acoustic chamber as a volume between the substrate (102) and the cap (102); Wherein, the acoustic chamber includes the front volume or the secondary rear volume.

26. The acoustic transducer device of claim 24, further comprising: A substrate (102) and a support structure (106) disposed on the substrate (102); Wherein, the channel is in the substrate or the supporting structure.

27. An acoustic transducer device according to any one of claims 24 to 26, wherein: The channel is configured as a trench.

28. An acoustic transducer device according to any one of claims 24 to 26, wherein: The channel (118) is at least 50 μm high.

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