Microphone Components and Manufacturing Method

Abstract

An optical microphone module (2) for mounting in a microphone assembly is described. The module (2) is manufactured by assembling a semiconductor chip (4), a spacer (6), and an interferometry assembly (8) into a stack, wherein the spacer (6) is disposed between the semiconductor chip (4) and the interferometry assembly (8). The interferometry assembly (8) includes a diaphragm (12) and a substrate (10) including optical elements (14) spaced apart from the diaphragm (12). The semiconductor chip (4) includes a photoelectric circuit (20) containing at least one photodetector (18) and has a light source (16) mounted thereon or integrated therein. The light source (16) is positioned to provide light to the interferometry arrangement (8) such that two light portions (26, 28) propagate via corresponding optical paths to produce an interference pattern at the photodetector (18) that depends on the position of the diaphragm (12). The stack includes an inner cavity (30) and at least one orifice (40) providing an air passage between the inner cavity (20) and the outer surface (34) of the stack, such that the inner cavity (30) is in fluid communication with the outer surface (34) of the stack. A first side of the diaphragm (12) is in fluid communication with the outer surface (34) of the stack, and a second side of the diaphragm (12) is in fluid communication with the inner cavity (30).

Description

[0001] The present invention generally relates to optical microphones, and more particularly to components for optical microphones and methods of manufacturing such components.

[0002] Microphones are typically used to convert sound waves into electrical signals by measuring the displacement of a movable part (such as a diaphragm) that vibrates in response to ambient acoustic vibrations. Several methods exist for measuring this displacement of the movable part, including capacitive readout (often referred to as a condenser microphone) and electrostatic or electromagnetic readout mechanisms (e.g., dynamic microphones).

[0003] An alternative method for reading out the position of the microphone diaphragm is optical interferometry readout. In a typical example of such a system, a diffraction grating is provided adjacent to the diaphragm, and electromagnetic radiation is directed onto the grating. A first portion of the light is reflected back from the grating. A second portion is transmitted through the grating, which diffracts the radiation. The diffracted radiation strikes the diaphragm, which reflects it back onto the grating. The radiation passes through the grating, and the two portions of the light interfere to form an interference pattern detectable by a detector. The interference pattern has a shape (i.e., spatial distribution) that matches the diffraction orders of the grating, but the intensity of the light directed into these diffraction orders depends on the relative phase of the two portions of the light, and therefore on the distance between the grating and the diaphragm. Thus, the position of the diaphragm (and therefore, movement) can be determined from the change in light intensity at the detector.

[0004] In such optical microphone arrangements, a diaphragm is typically mounted within a housing to form an optical microphone assembly, wherein the diaphragm is arranged such that one side of the diaphragm is in fluid communication with the outside of the microphone assembly, and the other side of the diaphragm is in fluid communication with a closed acoustic cavity (often referred to as a back cavity) within the microphone assembly. Incoming sound waves then exert force only on said side of the diaphragm in fluid communication with the outside, thereby generating a pressure differential that causes the diaphragm to vibrate.

[0005] Optical microphones offer high signal-to-noise ratios (SNR) and high sensitivity. However, due to the length scale of the physical processes involved in optical readout methods as discussed above, optical microphones typically comprise small components (e.g., micrometer-scale) that can pose significant manufacturing challenges.

[0006] This invention provides a method for manufacturing an optical microphone module for mounting in a housing to form an optical microphone assembly, wherein the optical microphone module comprises:

[0007] An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate;

[0008] A semiconductor chip, comprising an optoelectronic circuit, the optoelectronic circuit including at least one photodetector;

[0009] A light source, which is mounted on the semiconductor chip or integrated with the photoelectric circuit and the at least one photodetector in the semiconductor chip; and

[0010] Spacers;

[0011] The method includes:

[0012] The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component;

[0013] The light source and the at least one photodetector are positioned on the semiconductor chip such that, after the semiconductor chip, the spacer, and the interferometric assembly have been assembled into the stack, the light source is positioned to provide light to the interferometric arrangement, such that a first portion of the light propagates along a first optical path via the interferometric arrangement, and a second portion of the light propagates along a different second optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element; and the at least one photodetector is positioned to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference.

[0014] The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the outside of the stack, such that the inner cavity and the outside of the stack are in fluid communication; and

[0015] The first side of the diaphragm is in fluid communication with the outer side of the stack, and the second side of the diaphragm is in fluid communication with the inner cavity.

[0016] This invention extends to optical microphone modules manufactured using the methods of this invention as defined above.

[0017] From a second aspect, the present invention provides an optical microphone module for mounting in a housing to form an optical microphone assembly, wherein the optical microphone module comprises:

[0018] An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate;

[0019] A semiconductor chip, comprising an optoelectronic circuit, the optoelectronic circuit including at least one photodetector;

[0020] A light source, which is mounted on the semiconductor chip or integrated with the photoelectric circuit and the at least one photodetector in the semiconductor chip; and

[0021] Spacers;

[0022] The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component;

[0023] The light source is arranged to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement and a second portion of the light propagates along a different second optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element, and wherein the at least one photodetector is arranged to detect at least a portion of an interference pattern generated by the first and second portions of the light that depends on the optical path difference;

[0024] The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the outside of the stack, such that the inner cavity and the outside of the stack are in fluid communication; and

[0025] The first side of the diaphragm is in fluid communication with the outer side of the stack, and the second side of the diaphragm is in fluid communication with the inner cavity.

[0026] When a semiconductor chip is claimed to include optoelectronic circuitry containing at least one photodetector, this means that the optoelectronic circuitry containing at least one photodetector is integrated into the semiconductor chip, e.g., monolithically integrated. The light source can be monolithically integrated with the circuitry and photodetector within the chip. The semiconductor chip may include integrated circuits, such as application-specific integrated circuits (ASICs).

[0027] When two regions are said to be fluidly connected, this can be understood as meaning that air can flow between the regions, thereby achieving a basic instantaneous pressure equalization between them, such as when two regions are fluidly connected via one or more orifices. Fluid connection can be understood as meaning that air can flow through the orifices without significant acoustic resistance. Therefore, it should be understood that the term "fluidly connected" is not applicable to small gaps, such as vents that only allow for static pressure equalization between two regions over a longer timescale (e.g., to accommodate changes in ambient pressure at the location where an optical microphone assembly will be used). However, such vents can be additionally provided (e.g., in a diaphragm) to allow static pressure equalization between the acoustic cavity of the optical microphone assembly and the exterior of the optical microphone assembly.

[0028] It should be understood that the “outside” of the stack refers to areas not within the stack, but these areas may not necessarily be fluidly connected to each other, for example, when an optical microphone module is mounted within a housing to form an optical microphone assembly. For instance, the cavity is allegedly fluidly connected to the outside of the stack, and a first side of the diaphragm is also fluidly connected to the outside of the stack. This could also be expressed as the cavity being fluidly connected to a first region outside the stack, and the first side of the diaphragm being fluidly connected to a second region outside the stack. When the module is mounted within a housing, the first and second regions may correspond to the outside of the acoustic cavity and the optical microphone assembly, respectively.

[0029] As can be understood from the above disclosure, when the semiconductor chip, spacer, and interferometry component are allegedly arranged in a stack, this means that these components are arranged such that the spacer is positioned between two other components. Assembling in a stack can be understood as arranging the semiconductor chip, spacer, and interferometry component in a layered arrangement, one on top of the other (although it should be understood that a specific orientation of the assembled stack is not required). For example, the semiconductor chip, spacer, and interferometry component may each define a layer in the stack. Each of the semiconductor chip, spacer, and interferometry component may be substantially or entirely contained within its own layer, for example, such that the semiconductor chip is substantially or entirely on a first side of the spacer and the interferometry component is substantially or entirely on a second side of the spacer. The semiconductor chip and interferometry component may be positioned to define a volume therebetween, wherein the spacer is partially, substantially, or entirely contained within said volume. Although in some embodiments the lateral dimensions of the semiconductor chip, spacer, and interferometry component may be the same (or substantially the same), or occupy the same area or 'coverage area' in the stack, this is not necessary. One or more of the semiconductor chip, spacer, and interferometry assembly may have different lateral dimensions than the other components, such as different lengths and / or widths.

[0030] In one set of embodiments, at least one of the interferometric component and the spacer has a shape that defines an inner cavity in the stack. It should be understood that this means the spacer has a shape that defines an inner cavity in the stack, or the interferometric component has a shape that defines an inner cavity in the stack, or the spacer and the interferometric component each have a corresponding shape, wherein their corresponding shapes cooperate to define an inner cavity in the stack.

[0031] For example, the spacer may include, for instance, a hole or hollow body surrounded by a peripheral wall. For example, the spacer may include a hole extending from its first side to its second side, with a semiconductor chip mounted against the first side of the spacer and an interferometry assembly mounted against the second side of the spacer to surround the hole. As another example, the interferometry assembly may include, for instance, a hole or hollow body surrounded by a spacer portion or a peripheral wall. For example, the interferometry assembly may be shaped such that a hole or hollow body is positioned between the substrate and the spacer (when assembled in a stack). These examples may be provided in combination. For example, the spacer and the interferometry assembly may each include a corresponding hole or hollow body such that when the spacer and the interferometry assembly are stacked, their respective holes or hollow bodies engage together to form a single combined volume, which forms an inner cavity.

[0032] In one set of embodiments, at least one of the spacer and the interferometry component includes at least one aperture. For example, one or more apertures may be present in the spacer and / or one or more apertures may be present in the interferometry component.

[0033] It should be understood that the method of the present invention does not necessarily include the step of mounting the optical microphone module in the housing, although, as discussed below, the method may also include such mounting steps.

[0034] Each of the semiconductor chip, spacer, and interferometric assembly can be a microelectromechanical system (MEMS) assembly or a non-MEMS assembly. The meaning of the term MEMS is well understood by those skilled in the art, and therefore it should be understood that when an assembly is described as a "MEMS assembly," it means that the assembly includes, for example, miniaturized mechanical and / or electromechanical elements (i.e., devices and structures) that can be manufactured using microfabrication techniques, where miniaturization means that the physical size of the miniaturized element is on the scale of micrometers, for example, at most one millimeter or less. It should also be understood that a "non-MEMS" structure is a structure that does not meet the "MEMS" definition given above.

[0035] The method and optical microphone module of the present invention offer advantages in the production (especially mass production) of optical microphone modules and optical microphone assemblies. Due to the optical readout methods used in optical microphones, precise alignment of the light source, interferometry components, and photodetectors is typically required when manufacturing optical microphone assemblies. However, optical microphone assemblies may also require the inclusion of large housings, such as large shells containing a large acoustic cavity for forming a large acoustic cavity. A large acoustic cavity is desirable because it reduces the effects of air compression within the cavity when the diaphragm vibrates. The effects of air compression are equivalent to diaphragm hardening, especially under large deflections, which can negatively impact microphone performance. The step of assembling the semiconductor chip, spacer, and interferometry components into a stack preferably includes aligning the light source, photodetector, optical elements, and / or diaphragm.

[0036] Large housings for mounting interferometric components can make it difficult to precisely position the light source and photodetector relative to each other to achieve the necessary alignment. According to the invention, by providing the light source and photodetector on a semiconductor chip assembled into a stack with spacers and interferometric components (and including one or more apertures to provide fluid communication between the diaphragm and acoustic cavity via an internal cavity), it is possible to align the light source and photodetector in an initial alignment step during stack assembly before mounting the optical microphone module in the large housing using less precise techniques. For example, alignment during stack assembly can be performed using techniques that are easier and / or more precise than those required for mounting and aligning the interferometric components and individual light sources and photodetectors in a large housing (e.g., MEMS-based techniques, wafer-level packaging, fan-out techniques). Furthermore, since the mounting step can be performed less precisely, it can be done more quickly and easily. Therefore, the invention advantageously facilitates easier, faster, and / or cheaper production, including mass production.

[0037] The present invention also advantageously allows the optical microphone module to be supplied to customers (e.g., manufacturers of optical microphone host devices) as a single prefabricated integrated component, enabling customers to install the optical microphone module in their own host devices using relatively imprecise techniques, since the alignment of the interferometry components, light source, and photodetector has already been achieved during the manufacturing stacking.

[0038] Using a semiconductor chip that includes a light source, a photodetector, and an optoelectronic integrated circuit is advantageous because it facilitates the use of a stacked structure without the need to separately mount components, such as photodetectors, on separate application-specific integrated circuit (ASIC) chips, which would require separate alignment of these components.

[0039] The spacer can advantageously provide, or facilitate providing, sufficient distance between the semiconductor chip and the interferometry component, such that (e.g., in the spacer and / or the interferometry component) a sufficiently large air passage, i.e., one or more orifices, can be provided to allow fluid communication between the second side of the diaphragm and the acoustic cavity when the optical microphone module is mounted in the housing. The invention can therefore advantageously allow for the provision of a single integrated optical microphone module in which the light source, the interferometry component, and its photodetector are precisely aligned due to a stacked configuration, and said component is also suitable for use in optical microphone assemblies having a large acoustic cavity that does not form part of the stack.

[0040] Therefore, it will be understood from this disclosure that "module" can be understood as meaning a single unit including integrated components, such as pre-aligned components. "Module" can be understood as meaning a prefabricated unit, such as one that is easy to install. "Optical microphone module" can be described as standalone, which may mean, for example, that no external light source, detector, or optical components are required for operation.

[0041] In one set of embodiments, a first side of the diaphragm is open to the outside of the stack, and the substrate of the interferometry assembly includes one or more substrate apertures, through which a second side of the diaphragm is in fluid communication with the cavity. In such embodiments, the interferometry assembly may be arranged such that its substrate is positioned between the diaphragm and the cavity.

[0042] In another set of embodiments, the substrate of the interferometric measurement assembly includes a substrate aperture, a first side of the diaphragm is in fluid communication with the outside of the stack via the substrate aperture, and a second side of the diaphragm is open to the inner cavity. When it is claimed that one side of the diaphragm is open to the region, this can be understood to mean that there is no intermediate aperture between the diaphragm and the region, such as any aperture smaller than the diaphragm. The term "substrate aperture" means an aperture in the substrate and is used to distinguish it from the apertures mentioned above that provide fluid communication between the inner cavity and the outside of the stack.

[0043] The substrate may have any suitable thickness. In some embodiments, the substrate has a uniform thickness. In some embodiments, the substrate does not have a uniform thickness; for example, the substrate may include a thin (e.g., etched) region surrounded by a thicker support region.

[0044] The spacers can be attached to the semiconductor chip, for example, using bonding, adhesive, or any suitable fastening mechanism. The method may include attaching the spacers to the semiconductor chip.

[0045] The spacer can be integrally formed with the interferometric measurement assembly, for example, such that the spacer and the substrate of the interferometric measurement assembly are formed from a single sheet.

[0046] Alternatively, the spacers and interferometry components can be formed from separate pieces. Any suitable fastening device can be used to attach the spacers to the interferometry components. The method may include attaching the spacers to the interferometry components. The spacers may be formed from a single piece or from two or more pieces. For example, the spacers may include two or more pieces arranged in a layered or stacked configuration. The method may include assembling the spacers from two or more pieces, such as in a layered or stacked configuration. The step of assembling the semiconductor chip, spacers, and interferometry components into a stack may include assembling the spacers from two or more pieces, such as in a layered or stacked configuration.

[0047] When components of an optical microphone module (e.g., spacers, interferometry components, semiconductor chips, light sources) are described as being mounted or fixed on or between another component, this can be achieved by any suitable means or method. Some non-limiting examples include wafer-level assembly techniques, such as wafer bonding or fan-out methods; chip-level assembly, such as flip-chip bonding or component pick-and-place; and surface mount / soldering.

[0048] The method may include mounting an optical microphone module in a housing to form an optical microphone assembly.

[0049] The housing may include a housing base suitable for mounting an optical microphone module thereon. The method may include mounting the optical microphone module onto the housing base. The housing base may include an application-specific integrated circuit (ASIC) chip.

[0050] The housing may include a shell for mounting above a stack to form a acoustic cavity. The method may include mounting the housing above a stack to form a acoustic cavity.

[0051] The housing may be configured, for example shaped, to be adapted for attachment to a housing base or semiconductor chip, such that the housing covers the stack. The semiconductor chip may include mounting regions surrounding a stack on the semiconductor chip, wherein the mounting regions are adapted for mounting the housing thereon, for example by sealing the housing to the semiconductor chip. For example, the mounting regions may include a flat surface surrounding the stack, such as a surface free of components and integrated circuits. The method may include attaching the housing to a housing base or semiconductor chip, such that the housing covers the stack.

[0052] The housing may include an acoustic port, such as an aperture substantially the same size as the diaphragm of an optical microphone module to be mounted in the housing. The size, shape, and / or location of the acoustic port may be configured such that the housing can be sealed to the stack when mounted above it, wherein the acoustic port is aligned with the diaphragm, for example by sealing an interferometry component or another portion of the stack to the periphery of the acoustic port. The method may include, for example, sealing the housing to the stack by sealing an interferometry component or another portion of the stack to the periphery of the acoustic port, wherein the acoustic port is within the housing aligned with the diaphragm.

[0053] The housing may define an acoustic cavity such that when the optical microphone module is mounted in the housing to form an optical microphone assembly, a first side of the diaphragm (e.g., via an acoustic port) is in fluid communication with the exterior of the optical microphone assembly, and a second side of the diaphragm is in fluid communication with the acoustic cavity via stacked cavities.

[0054] The stack (e.g., an interferometry assembly) may include an attachment region surrounding a diaphragm, wherein the attachment region is adapted to be sealed to a housing. For example, the attachment region may be a flat surface portion surrounding the diaphragm. The attachment region may be a protruding portion, such as a wall surrounding the diaphragm. This can be advantageous because when the housing is sealed to a protruding attachment region, the diaphragm is moved back from the surface of the housing and thus less exposed, thereby reducing the risk of damage to the diaphragm during use of the optical microphone assembly. The method may include sealing the housing to the attachment region of the stack (e.g., an interferometry assembly), wherein the attachment region surrounds the diaphragm.

[0055] An optical microphone module (e.g., a semiconductor chip) may include an exposed surface (e.g., the side of the semiconductor chip facing away from the spacer and the interferometry assembly) suitable for mounting the optical microphone module within a housing (e.g., for securing the optical microphone module to a housing base). The method may include mounting the optical microphone module within the housing by securing the exposed surface to the housing (e.g., to a housing base).

[0056] An arrangement in which a semiconductor chip is mounted on a housing base and the housing has an acoustic port can be described as a "top port" configuration. The optical microphone module does not necessarily need to be mounted in such a "top port" configuration. The optical microphone module can be mounted in a "bottom port" configuration. In a "bottom port configuration," the acoustic port can be located within the housing base. The optical microphone module can be mounted in an inverted orientation, for example, where an interferometry component is attached to the housing base and a diaphragm is aligned with the acoustic port, such that the diaphragm is open to the outside of the housing via the acoustic port in the housing base.

[0057] When an element of an optical microphone assembly is described as being mounted on another element, this may include sealing, gluing, joining, or otherwise securing one element to the other.

[0058] An optical microphone assembly may be mounted in a host device (e.g., a smartphone), adapted to be mounted in said host device, or formed part of said host device. The optical microphone assembly may be formed separately from the host device, i.e., an optical microphone module may be mounted in a housing to form the optical microphone assembly, and then the optical microphone assembly may be mounted in the host device. Alternatively, the optical microphone assembly may be formed in the host device, for example, including (or comprising a portion of) the host device. For example, mounting an optical microphone module in a housing to form the optical microphone assembly may include (e.g., by attaching a semiconductor chip) directly mounting the optical microphone module on the surface of the host device and mounting the housing on top of a stack.

[0059] The present invention extends to optical microphone assemblies or host devices that include an optical microphone module as defined above mounted therein or on it.

[0060] The size of a semiconductor chip can be approximately 2 mm. 2 However, larger or smaller sizes are possible; for example, the size of a semiconductor chip can be as small as 0.01 mm. 2 (i.e., 100x100 μm) 2 ) to 8 mm 2 Within a range, for example, within 0.1 mm 2 up to 4 mm 2 Within a range, for example, within 1 mm 2 up to 2 mm 2 Within the scope. It should be understood that the size of a semiconductor chip refers to the area of ​​the semiconductor chip surface, which includes photoelectric circuitry with a photodetector incorporated therein and a light source mounted thereon or integrated therein.

[0061] Semiconductor chips may include semiconductor wafers, such as silicon wafers or GaAs or InGaAs wafers. For example, if the semiconductor chip includes an ASIC, then silicon can be used, and if the light source is integrated into the semiconductor chip, then GaAs or InGaAs can be used.

[0062] As described above, the semiconductor chip may include an ASIC (e.g., which may incorporate optoelectronic circuitry). However, this is not mandatory, and in some embodiments, a separate ASIC chip including the ASIC is provided. In some embodiments where the ASIC chip is separate from the semiconductor chip, the ASIC chip may be mounted separately in the optical microphone assembly (e.g., adjacent to the semiconductor chip), or the semiconductor chip may be mounted on top of the ASIC chip, such that the optical microphone module further includes the ASIC chip. The optoelectronic circuitry may be configured to allow the transmission of raw or processed signals to or outside the ASIC chip, such as to a separate ASIC chip provided herein. The ASIC may be configured to control a light source and / or a photodetector. The ASIC may be configured to process signals received from the photodetector; for example, the ASIC may include a microprocessor, a digital signal processor, or a field-programmable gate array. The ASIC may be configured to perform all the processing required to operate the optical microphone without requiring a separate processor; for example, the ASIC may include an output pin for outputting a signal, wherein the ASIC is configured to process the signal received from the photodetector to generate an output signal representing the amplitude of the incoming sound wave and output the output signal to the output pin.

[0063] As described above, the spacer provides the spacing between the semiconductor chip and the interferometric measurement assembly. Specifically, the spacer can provide the spacing between the light source and photodetector on the semiconductor chip and the optical elements and diaphragms of the interferometric measurement assembly. The interferometric measurement assembly can also provide the spacing between the light source / photodetector and the diaphragms / optical components. The interferometric measurement assembly may include a spacer portion, for example, where the spacer portion provides the spacing between the diaphragms or optical components of the interferometric measurement assembly and the spacer.

[0064] The interferometric measurement assembly may include a spacer portion shaped to define an interior cavity (e.g., by itself or in combination with a spacer). The spacer portion may be shaped to surround or partially surround the space between the diaphragm or optical component and the spacer, thereby defining an interior cavity or a portion thereof; for example, the spacer portion may be a peripheral wall. An aperture may be provided in the spacer portion, for example, only in the spacer portion or in the spacer portion and in the spacer.

[0065] Therefore, the spacer, the spacer portion, or both the spacer and the spacer portion together can provide sufficient space for one or more orifices in one or both of the spacer and the interferometric assembly (e.g., in the spacer portion) to provide fluid communication between the cavity and the acoustic cavity.

[0066] The spacer (or spacer together with spacer portion) may have a height that provides the spacing between the optical element and the semiconductor chip, said height being greater than 200 μm, for example greater than 300 μm, for example greater than 400 μm, for example greater than 500 μm, for example greater than 600 μm, for example greater than 700 μm, for example greater than 800 μm, for example greater than 900 μm, for example greater than 1 mm. The spacing between the optical element and the semiconductor chip may be more precisely defined as the vertical distance between the optical element and the surface of the semiconductor chip including the photodetector.

[0067] The height of the spacer or spacer together with the spacer portion can be selected based on the required light propagation distance between the interferometric assembly and the light source and photodetector on the semiconductor chip. For example, the first and second light portions can propagate at an angle to the surface of the diaphragm, such that the second light portion strikes a photodetector laterally displaced from the light source on the semiconductor chip. The propagation angle of the light portion can be determined by the nature of the interferometric assembly (e.g., the type of optical element) or, for example, by the angle of the detected diffraction order.

[0068] Therefore, the height of the spacer or the spacer together with the spacer portion can be selected to ensure that the spacing between the detector and the interferometric measurement assembly is sufficient to allow the second light portion to reach the photodetector for a specific propagation angle and the spacing between the light source and the photodetector. Providing the photodetector and the light source on the same semiconductor chip according to the invention advantageously allows for a smaller spacing between the semiconductor chip and the interferometric measurement assembly, because the light source and the photodetector can be positioned closer together than is possible, for example, when they are provided separately rather than integrated on the same chip as the light source.

[0069] The provision of spacers can advantageously allow one or more optical components, such as microlenses, to be disposed between the semiconductor chip and the interferometric measurement components. In one set of embodiments, one or more optical components (e.g., lenses or microlenses) are disposed in or on the spacers.

[0070] Positioning one or more optical components within or on spacers advantageously allows for alignment of the optical components during the assembly of stacked optical microphone modules. As mentioned above, the techniques for assembly and alignment used for stacking may be more precise and / or easier than those used for assembling larger portions of the optical microphone assembly (e.g., the base and housing). Therefore, according to embodiments of the invention, precise alignment of the optical components can be achieved more easily.

[0071] This is novel and inventive in itself, and therefore, when viewed from a third aspect, the present invention provides an optical microphone module for mounting in a housing to form an optical microphone assembly, the optical microphone module comprising:

[0072] An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate;

[0073] A semiconductor chip, comprising at least one photodetector and a light source, wherein the at least one photodetector and the light source are mounted on or integrated into the semiconductor chip;

[0074] Spacers; and

[0075] One or more optical components disposed in or on the spacer;

[0076] The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component;

[0077] The light source is arranged to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement and a second portion of the light propagates along a different second optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element, and wherein the at least one photodetector is arranged to detect at least a portion of an interference pattern generated by the first and second portions of the light that depends on the optical path difference;

[0078] The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the outside of the stack, such that the inner cavity and the outside of the stack are in fluid communication; and

[0079] The first side of the diaphragm is in fluid communication with the outer side of the stack, and the second side of the diaphragm is in fluid communication with the inner cavity.

[0080] Viewed from a fourth aspect, the present invention provides a method for manufacturing an optical microphone module for mounting in a housing to form an optical microphone assembly, wherein the optical microphone module comprises:

[0081] An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate;

[0082] A semiconductor chip, comprising at least one photodetector and a light source, wherein the at least one photodetector and the light source are mounted on or integrated into the semiconductor chip;

[0083] Spacers; and

[0084] One or more optical components disposed in or on the spacer;

[0085] The method includes:

[0086] The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component;

[0087] The light source and the at least one photodetector are positioned on the semiconductor chip such that, after the semiconductor chip, the spacer, and the interferometric assembly have been assembled into the stack, the light source is positioned to provide light to the interferometric arrangement, such that a first portion of the light propagates along a first optical path via the interferometric arrangement, and a second portion of the light propagates along a different second optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element; and the at least one photodetector is positioned to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference.

[0088] The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the outside of the stack, such that the inner cavity and the outside of the stack are in fluid communication; and

[0089] The first side of the diaphragm is in fluid communication with the outer side of the stack, and the second side of the diaphragm is in fluid communication with the inner cavity.

[0090] The present invention extends to optical microphone modules manufactured using the method of the fourth aspect of the invention as defined above.

[0091] Semiconductor chips may include optoelectronic circuitry integrated therein. Optoelectronic circuitry may include photodetectors. When it is claimed that at least one photodetector and a light source are mounted on or integrated into a semiconductor chip, this should be understood to include a combination of mounting and integration, such as a light source mounted on the semiconductor chip and a photodetector integrated therein, and vice versa.

[0092] In one set of embodiments, at least one of the spacer and the interferometry component has a shape defining an inner cavity in the stack. In another set of embodiments, at least one of the spacer and the interferometry component includes one or more apertures.

[0093] Where applicable, optional features of the first and second aspects of the invention may also be optional features of the third and fourth aspects of the invention.

[0094] Optical components may be integrated into or formed in the spacer, or mounted or manufactured on the spacer. The optical components may be positioned between the semiconductor chip and the diaphragm, for example, such that the first and / or second light portions partially or completely pass through the optical components. The optical components may thus allow the first and / or second light portions to be guided (e.g., focused) to facilitate the operation of the optical microphone module.

[0095] The optical components may include one or more refractive and / or diffractive optical components. One or more of the optical components may, for example, collimate the first and / or second light portions as light propagates from the light source to the diaphragm. One or more of the optical components may split the light emitted by the light source into two or more portions, for example, by splitting the light into first and second portions or by splitting the first and / or second portions into additional portions. As the first and / or second light portions propagate back from the interferometric assembly, one or more optical components may guide, deflect, or focus the first and / or second light portions such that they strike the photodetector.

[0096] The steps of assembling semiconductor chips, spacers, and interferometry components into a stack may include aligning optical components relative to a light source, photodetector, optical element, and / or diaphragm.

[0097] The spacer may include a support structure (e.g., a bridge structure) suspended in the region between the semiconductor chip and the interferometric measurement components. Optical components may be disposed in or on the support structure, such as integrated into or formed in the support structure, or mounted or manufactured on the support structure.

[0098] As described above, the spacer may have a shape that defines an inner cavity in the stack. When the spacer includes a support structure, the support structure may form a barrier within the spacer, such that the support structure defines the boundary of the inner cavity. Alternatively, the support structure may include one or more orifices that allow air to pass through, such that the support structure does not form a barrier within the spacer; in this case, the support structure may be described as being within the inner cavity of the stack.

[0099] The spacing between the light source and the photodetector can be chosen large enough that thermal effects (i.e., heat from the light source) do not significantly affect the performance of the photodetector. A low-power light source (e.g., less than 10 mW) can be used to reduce thermal effects. The spacing can be chosen small enough that the spacer (or spacer together with the spacer portion) can be conveniently compact in size (although, as discussed above, the spacing required to allow fluid communication via the orifice is acceptable). The spacing between the light source and the photodetector can be between 100 μm and 500 μm, for example, between 200 μm and 300 μm. If there is more than one photodetector, the distance between the light source and the photodetector can refer to the average distance between the light source and the photodetector, or the maximum distance between the light source and any one photodetector.

[0100] The height of the spacer or the spacer together with the spacer portion may be less than 3 mm, for example less than 2.5 mm, for example less than 2 mm, for example less than 1.5 mm, for example less than 1 mm, for example less than 500 μm.

[0101] As described above, the optical element can be a diffractive optical element. It should be understood that in embodiments where the surface of the diaphragm is in fluid communication with the stacked external or internal cavity via substrate apertures in the substrate of the interferometric assembly, these substrate apertures differ from, for example, apertures forming part of a diffraction grating (e.g., elongated apertures forming grating lines). Such grating line apertures are typically small and thin and do not provide sufficiently large air channels for fluid communication in the foregoing sense.

[0102] For example, the optical element may be a reflective surface, such that the reflective surface and the diaphragm together operate as a Fabry-Perot interferometer. In some embodiments, the optical element may be a reflective surface, and diffractive optical elements may be fabricated on the diaphragm. For example, this may be used in embodiments as described above, wherein the diaphragm of the interferometry assembly is positioned between the stacked cavity and the substrate of the interferometry assembly.

[0103] Some preferred embodiments will now be described with reference to the accompanying drawings, by way of example only, in which:

[0104] Figure 1 A cross-section of an optical microphone module according to a first embodiment of the present invention is shown;

[0105] Figure 2 Display and integration Figure 1 The cross-section of the optical microphone assembly of the optical microphone module;

[0106] Figure 3 exhibit Figure 2 A partially cut 3D representation of an embodiment;

[0107] Figure 4An optical microphone assembly incorporating an optical microphone module is shown according to a second embodiment of the present invention.

[0108] Figure 5 An optical microphone assembly incorporating an optical microphone module is shown according to a third embodiment of the present invention;

[0109] Figure 6 An optical microphone assembly incorporating an optical microphone module is shown according to a fourth embodiment of the present invention.

[0110] Figure 7 The demonstration includes components installed in the host device. Figure 1 Optical microphone module, optical microphone assembly;

[0111] Figure 8 An optical microphone assembly incorporating an optical microphone module is shown according to a fifth embodiment of the present invention;

[0112] Figure 9 An optical microphone assembly incorporating an optical microphone module is shown according to a sixth embodiment of the present invention;

[0113] Figure 10 An optical microphone assembly incorporating an optical microphone module is shown according to a seventh embodiment of the present invention; and

[0114] Figure 11 An optical microphone module according to an eighth embodiment of the present invention is shown.

[0115] Figure 1 A first embodiment of an optical microphone module 2 according to the present invention is shown. The optical microphone module 2 includes a semiconductor chip 4, a spacer 6, and an interferometry assembly 8 arranged in a stacked manner, wherein the spacer 6 is located between the semiconductor chip 4 and the interferometry assembly 8. The interferometry assembly 8 includes a substrate 10 and a diaphragm 12. A diffractive optical element 14 is disposed on the surface of the substrate 10 facing the diaphragm 12.

[0116] A vertical-cavity surface-emitting laser (VCSEL) 16 is mounted on a semiconductor chip 4. The semiconductor chip also includes a photodetector 18 and an application-specific integrated circuit (ASIC) 20 adjacent to the VCSEL 16. The ASIC 20 is connected to the VCSEL 16 via a wire connection 22 and includes a photoelectric circuitry 23 incorporating the photodetector 18. The operation of the VCSEL 16 and the photodetector 18 is thus controlled via the ASIC 20.

[0117] During operation in the optical microphone assembly, VCSEL 16 emits light 24 toward interferometric measurement assembly 8. The light passes through substrate 10 and strikes diffractive optical element 14. A first portion 26 of the light is reflected back from diffractive optical element 14 and propagates back through substrate 10 to strike photodetector 18. A second portion 28 of the light passes through and is diffracted by diffractive optical element, and is then reflected from diaphragm 12. The reflected light propagates back through substrate 10 and strikes detector 18, which is positioned to receive one of the diffraction orders from diffractive optical element 14. The first and second portions of the light interfere to produce an interference pattern at detector 18, where the intensity measured at photodetector 18 depends on the spacing between diffractive optical element 14 and diaphragm 12. Therefore, when the diaphragm vibrates in the presence of an acoustic wave, the displacement of the diaphragm corresponding to the amplitude of the incoming wave can be correlated with the intensity of the light detected at photodetector 18. The displacement of the diaphragm, and thus the time-varying amplitude of the incoming acoustic wave, can be determined by the signal recorded at photodetector 18.

[0118] Spacer 6 is shaped to define an inner cavity 30 between semiconductor chip 4 and interferometry assembly 8. A first side 32 of diaphragm 12 is open to the exterior 34 of optical microphone module 2. A second side of diaphragm 36 is in fluid communication with the inner cavity 30 via a large aperture 38 in substrate 10. The inner cavity 30 is in fluid communication with the exterior 34 of optical microphone module 2 via a large aperture 40 in spacer 6. Interferometry assembly 8 is provided with an upper attachment region 42 surrounding the diaphragm. The attachment region 42 is adapted to seal to the periphery of an acoustic port in a housing that can be positioned above optical microphone module 2 to create an acoustic cavity, as described below. Figures 2 to 5 Further discussion.

[0119] The optical microphone module 2 is manufactured by assembling the semiconductor chip 4, spacer 6, and interferometry component 8 into a stack, using a precise alignment technique to properly align the VCSEL 16, interferometry component 8, and photodetector 18. In this example, the components are assembled using wafer bonding, but alternatively, other techniques (e.g., other wafer-level assembly techniques such as fan-out; flip-chip / bump bonding; adhesives utilizing component pick-and-place; surface mounting; soldering) may be used in this embodiment and in other embodiments. The stack is assembled before mounting the optical microphone module 2 into an optical microphone assembly or host device. The semiconductor chip 4 has an exposed surface 44 on its bottom, which is adapted to mount the optical microphone module 2 onto the surface of the optical microphone assembly or host device.

[0120] Figure 2 and 3 Showing the installation in the optical microphone assembly 46 Figure 1The optical microphone module 2 is included. The optical microphone assembly 46 includes a base 48 on which the optical microphone module 2 is mounted via the surface 44 of a semiconductor chip 4. The semiconductor chip 4 is connected to the base 48 via a wire bond 50 such that the output of the ASIC 20 is deflected from the transmission of the semiconductor chip 4. The wire bond is not required and alternative methods can be used. A housing 52 is mounted above the optical microphone module 2. The housing 52 is mounted on the base 48. The housing includes an acoustic port 54. The peripheral region 56 of the housing 52 surrounding the acoustic port 54 is sealed to the attachment region 42 of the interferometry assembly 8 using stress-free adhesive 58. The housing 52 thereby forms a closed acoustic cavity 60 that is not in fluid communication with the exterior 62 of the optical microphone assembly 46. When the optical microphone module 2 is installed in the optical microphone assembly 46 in this manner, the first side 32 of the diaphragm 12 is in fluid communication with the exterior 62 of the optical microphone assembly 46 via the acoustic port 54, and the second side 36 of the diaphragm 12 is in fluid communication with the acoustic cavity 60 via the aperture 38 in the interferometric measurement component substrate 10, the aperture 40 in the stacked inner cavity 30 and the spacer 6.

[0121] When an incoming sound wave strikes the optical microphone assembly, it exerts pressure on the first side 32 of the diaphragm 12. Because the acoustic cavity 60 is isolated from the exterior 62 of the optical microphone assembly, the sound wave does not exert pressure on the second side 36 of the diaphragm 12. This creates a pressure difference that causes the diaphragm 12 to shift according to an amount proportional to the time-varying amplitude of the incoming sound wave. This shift is then measured using the interferometric readout method described above. Therefore, the signal at the detector can be used to determine the amplitude of the incoming sound wave.

[0122] As discussed above, the semiconductor chip, spacer, and interferometry assembly 8 are aligned using a precision alignment technique during assembly stacking. This means that when the optical microphone module 2 is mounted in the optical microphone assembly 46, this can be achieved using a relatively imprecise positioning technique, since the alignment of the VCSEL 16, interferometry assembly 8, and photodetector 18 has already been established by the precision alignment technique during assembly stacking.

[0123] from Figure 3 As can be seen, the interferometric measurement assembly comprises two parts fixed together. The first part 11 includes a substrate 10 of the interferometric measurement assembly, on which optical elements 14 and apertures 38 are formed. The second part is a diaphragm support 9 mounted on top of the substrate.

[0124] Figure 4An optical microphone assembly 64 according to a second embodiment of the present invention is shown, wherein an optical microphone module 66 is mounted. The optical microphone module 66 of this embodiment is identical to the optical microphone module 2 of the first embodiment (comprising a semiconductor chip 70, spacers 72, and an interferometry component 74), except that the spacers 72 and the interferometry component 74 are located more centrally on the semiconductor chip 70. The semiconductor chip 70 includes a VCSEL 76, a photodetector 78, and an application-specific integrated circuit 80, which also... Figures 1 to 3 The corresponding components in the embodiments are positioned more centrally compared to those in the previous embodiment. Therefore, the semiconductor chip 70 has a peripheral surface 82 surrounding the spacer 72 and the interferometry assembly 74, wherein the peripheral surface 82 is adapted to mount a housing. Figure 4 As can be seen, housing 84 is mounted on the semiconductor chip in peripheral region 82 and includes acoustic port 86. Stress-free adhesive 88 is used around acoustic port 86 on housing 84. Figure 2 The embodiment shown is sealed to the interferometric measurement assembly 74 in a similar manner to that described above. The housing 84 thus forms the acoustic cavity 90, and the optical microphone is therefore referenced above. Figure 1 and 2 Operate in the same manner as described.

[0125] An optical microphone module 66, with housing 84 mounted on it, is mounted on a base 92 of the optical microphone assembly 64. Having a cavity mounted on a semiconductor chip can be advantageous, for example, as it allows the optical microphone assembly, including the housing, to be manufactured (e.g., mass-produced) by first assembling the optical microphone module stack and then mounting the housing 84 in a separate step. The optical microphone assembly provided in this manner can then be supplied to, for example, a third-party manufacturer, so that it can be immediately installed in a host device, making the base 92 a surface of the host device.

[0126] Figure 5 A third embodiment of the optical module assembly 94 installed in the optical microphone assembly 96 is shown. The optical microphone module 94 is the same as the optical microphone module 2 of the first embodiment, except that the optical microphone module 94 includes an interferometry assembly 98 that is inverted compared to the interferometry assembly 8 of the first embodiment. That is, the interferometry assembly includes a partially transparent diaphragm 100 and a substrate 102, wherein the diaphragm faces the photodetector 106 on the VCSEL 104 and the semiconductor chip 108, and the substrate 102 is adjacent to the acoustic port 110 in the housing 112 of the optical microphone assembly 96.

[0127] Therefore, in this embodiment, the first side 114 of the diaphragm is in fluid communication with the exterior 116 of the optical microphone assembly 96 via the acoustic port 110 and an aperture 118 in the substrate 102. The second side 120 of the diaphragm 100 is in fluid communication with the acoustic cavity 122 formed by the housing 112 via an aperture 126 in the cavity 124 of the optical microphone module 94 and a spacer 128 of the optical microphone module. In this example, the surfaces 130 of the diaphragm 100 and the substrate 102 together act as a Fabry-Perot interferometer to generate an interference pattern at the detector 106. However, alternative interferometric arrangements are possible; for example, diffractive optical elements may be formed on the diaphragm 100.

[0128] Figure 6 exhibit Figure 2 Variations of the embodiments are provided, wherein corresponding features are identified by the same numbers. In this embodiment, an ASIC chip 130 is provided in addition to the semiconductor chip 132. Connectors 134 and 136 are provided between the semiconductor chip 132 and the ASIC chip 130 to allow control of the photodetector 18 and the light source 16 via the ASIC chip 130, and are provided between the ASIC chip 130 and the base 48 to allow connection to external components, such as a power supply. The ASIC 138 is provided on the ASIC chip (instead of on the semiconductor chip), and the photoelectric circuit 140 including the photodetector 18 is provided on the semiconductor chip 132. A separate ASIC chip may similarly be provided in other embodiments, such as variations of the other embodiments described above.

[0129] Figure 7 Display installed in the main unit 142 Figure 2 The embodiment of the optical microphone module 2. The main unit 142 includes a housing 144 having a recess 146 formed therein. The optical microphone module 2 is mounted in the recess 146, and the housing 148 is positioned to cover the recess 146 such that the housing 148 and the recess 146 together form a acoustic cavity 150 for the optical microphone module 2, thereby forming an optical microphone assembly. The housing is sealed to the optical microphone module using stress-free adhesive 152. The housing is also sealed to the periphery 154 of the recess 146. As can be seen in this example mounted in the main unit, the housing of the main unit (and the recess formed therein) provides a large volume, which can be advantageously used to provide a large acoustic cavity for the optical microphone assembly.

[0130] Figure 8Another embodiment of the optical microphone module 156 according to the present invention is shown. The optical microphone module 156 includes a semiconductor chip 158, a spacer 160, and an interferometry assembly 162 arranged in a stacked manner, wherein the spacer 160 is located between the semiconductor chip 158 and the interferometry assembly 162. The interferometry assembly 162 is similar to the interferometry assembly of other embodiments described above and includes corresponding components, including a diaphragm 164, and functions in a similar manner. The optical microphone module 156 is mounted on a base 166, wherein a housing 168 forms a sound cavity 170.

[0131] and Figure 6 Similar embodiments exist, with a separate ASIC chip 172 including an ASIC 174 provided near the semiconductor chip 158. The semiconductor chip includes optoelectronic circuitry 176. In this example, optoelectronic circuitry 176 includes a monolithically integrated VCSEL 178 and two monolithically integrated photodetectors 180. It should be understood that such monolithically integrated VCSELs and two photodetectors are not required in this embodiment (or are not limited to this embodiment), and variations are possible.

[0132] Semiconductor chip 158, spacer 160, and interferometry assembly 162 together define a stacked cavity 182. In this embodiment, spacer 160 includes a bridge structure 184 suspended within cavity 182. The spacer includes an air passage 186 in the body of spacer 160 and an air passage 188 in bridge structure 184, such that the bridge does not interrupt fluid communication between diaphragm 164 and acoustic cavity 170. The air passages may be positioned in different ways within the spacer (e.g., above bridge structure 184 in the body of spacer 160, in which case bridge structure 184 may be provided without an air passage passing through it (e.g., discussed below)). Figure 9 (As shown in the embodiments).

[0133] Bridge structure 184 includes a microlens 190 formed therein. In variations, other optical components may be formed in or mounted on the spacer, such as on the bridge structure. Microlenses or other optical components disposed in or on the spacer can advantageously manipulate light propagating between the light source and the diaphragm and / or the diaphragm and the photodetector, for example, focusing or guiding light to improve or optimize optical microphone performance.

[0134] Figure 9Another embodiment of the optical microphone module 192 according to the present invention is shown. The optical microphone module 192 includes a semiconductor chip 194, a spacer 196, and an interferometry assembly 198 arranged in a stacked manner, wherein the spacer 196 is located between the semiconductor chip 194 and the interferometry assembly 198. The interferometry assembly 198 is similar to the interferometry assembly of other embodiments described above and includes corresponding components, including a diaphragm 200, and functions in a similar manner. The optical microphone module 192 is mounted on a base 202, wherein a housing 204 forms a sound cavity 206.

[0135] and Figure 1 Similar to the embodiment, semiconductor chip 194 also includes a photodetector 208 and an application-specific integrated circuit (ASIC) 210 adjacent to VCSEL 212 mounted on semiconductor chip 194. ASIC 210 is connected to VCSEL 212 via wire connection 214 and includes a photoelectric circuit system 216 incorporating photodetector 208. The operation of VCSEL 212 and photodetector 208 is thus controlled via ASIC 210.

[0136] Similar to Figure 8 In one embodiment, the spacer 196 includes a bridge structure 218 suspended between the semiconductor chip 194 and the interferometry assembly 198. However, in this embodiment, the bridge structure 218 does not include vents and forms a barrier within the spacer. Therefore, the bridge structure 218, the interferometry assembly 198, and the upper portion 220 of the spacer together define an inner cavity 222 in the stack. An air channel is provided in the upper portion 220 of the spacer to allow fluid communication between the diaphragm 200 and the acoustic cavity 206.

[0137] Similar to Figure 8 In one embodiment, a microlens is formed in the bridge structure to guide light propagating between the VCSEL 212, the diaphragm 200, and the photodetector 208. One or more other optical components, alternative to or excluding the microlens, may be provided.

[0138] Figure 10 Another embodiment of the optical microphone module 224 according to the present invention is shown. The optical microphone module 224 includes a semiconductor chip 226, a spacer 228, and an interferometry assembly 230 arranged in a stacked manner, wherein the spacer 228 is between the semiconductor chip 226 and the interferometry assembly 230. The interferometry assembly 230 is similar to the interferometry assembly of other embodiments described above and includes corresponding components, including a diaphragm 232, and functions in a similar manner. The optical microphone module 224 is mounted on a base 234, wherein a housing 236 forms a sound cavity 238.

[0139] and Figure 1Similar to other embodiments, semiconductor chip 226 also includes a photodetector 240 and an application-specific integrated circuit (ASIC) 242 adjacent to VCSEL 244 mounted on semiconductor chip 226. ASIC 242 is connected to VCSEL 244 via wire connection 246 and includes a photoelectric circuit system 248 incorporating photodetector 240. The operation of VCSEL 244 and photodetector 240 is thus controlled via ASIC 242.

[0140] Compared to the embodiments shown in the foregoing figures, in this embodiment, the interferometric measurement assembly 230 includes a spacer portion 250 in the form of a peripheral wall 252 surrounding a hollow space 254 below a central portion 256 of a substrate 258, the central portion including an optical element 260.

[0141] Similar to Figure 9 In one embodiment, the spacer 228 includes a bridge structure 262 suspended between the semiconductor chip 226 and the interferometry assembly 230. Figure 9 Compared to the previous embodiment, the bridge structure 262 is formed across the top of the spacer 228 rather than within it. The bridge structure 262 does not include vents and thus forms a barrier across the top of the spacer 228. Therefore, the shape of the interferometry assembly 230 defines an inner cavity 264 in the stack, with the bridge structure 262 forming its lower boundary wall. An air channel 266 is disposed in the spacer portion 250 of the interferometry assembly to allow fluid communication between the diaphragm 232 and the acoustic cavity 238.

[0142] In variations of this and other embodiments, the spacer can be shaped differently such that the shape of the interferometry component and the spacer together define the cavity. For example, a bridging structure in the spacer may be located in the lower part of the spacer, or it may include one or more vents, or the spacer may be provided without a bridging structure.

[0143] and Figure 8 and 9 Similar to other embodiments, a microlens 268 is formed in the bridge structure 262 to guide light propagating between the VCSEL 244, the diaphragm 232, and the photodetector 240. One or more other optical components may be provided instead of the microlens 268.

[0144] Figure 11 Another embodiment of the optical microphone module 270 according to the present invention is shown. Figures 1 to 10 Similar to other embodiments, the optical microphone module 270 includes a semiconductor chip 272, a spacer 274, and an interferometry component 276 arranged in a stacked manner, wherein the spacer 274 is located between the semiconductor chip 272 and the interferometry component 276. The optical microphone module 270 includes and contains... Figures 1 to 10 The equivalent optical and electronic components (including VCSEL 278 and photodetector 280) in the embodiments are used and operate in an equivalent manner. This embodiment demonstrates several variations compared to the embodiments discussed above. These variations may also be provided individually or in combination in other embodiments.

[0145] In this embodiment, the acoustic port 282 is disposed within the base 284 of the optical microphone housing. The optical microphone module 270 is mounted in an inverted orientation, with the attachment region 286 of the interferometry component attached to the periphery of the acoustic port 282. This configuration may be referred to as a 'bottom port' configuration. Figures 1 to 10 The configuration shown can be referred to as the 'top port' configuration.

[0146] The interferometry assembly 276 includes a substrate 288 and a diaphragm 290. In this embodiment, the substrate 288 of the interferometry assembly 276 is larger than... Figures 1 to 10 The substrate in this embodiment is thin. The substrate 288 has a thicker peripheral support region 292.

[0147] A substrate 288 (particularly the thicker support region 292) is shaped to define an inner cavity 294, which is in fluid communication with a stacked outer cavity 296 via apertures 298 in a spacer. The stacked outer cavity 296 corresponds to the acoustic cavity (back cavity) of the housing. One side of a diaphragm 290 is in fluid communication with the inner cavity 294 via apertures 300 in the substrate. The other side of the diaphragm is open to the outer cavity 302 of the housing via an acoustic port 282.

[0148] In this embodiment, the width of the semiconductor chip 272 is smaller than that of the spacer 274, such that when the semiconductor chip 272, the spacer 274 and the interferometry component 276 are still arranged in a stacked manner, the spacer 274 is located between the semiconductor chip 272 and the interferometry component 276, and the semiconductor chip 272 only covers a relatively small portion of the surface of one side of the spacer 274.

[0149] It should be understood that only some possible embodiments of the invention have been described, and other embodiments and variations are possible within the scope of the invention as defined by the appended claims. The present invention relates to the domain of computational architectures, and more specifically, to hardware architectures for spiking neural networks and methods for operating such networks.

Claims

1. A method of manufacturing an optical microphone assembly, the optical microphone assembly comprising an optical microphone module, wherein the optical microphone module comprises: An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate; A semiconductor chip, comprising an optoelectronic circuit, the optoelectronic circuit including at least one photodetector; A light source, which is mounted on the semiconductor chip or integrated with the optoelectronic circuit and the at least one photodetector in the semiconductor chip; as well as Spacers; The method includes: The optical microphone module is formed by assembling the semiconductor chip, the spacer, and the interferometry component into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometry component; The light source and the at least one photodetector are positioned on the semiconductor chip such that, after the semiconductor chip, the spacer, and the interferometric assembly have been assembled into the stack, the light source is positioned to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement, and a second portion of the light propagates along a second optical path different from the first optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element, and the at least one photodetector is positioned to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference; The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the exterior of the stack to allow substantially instantaneous pressure equalization therebetween, such that the inner cavity and the exterior of the stack are in fluid communication; and The first side of the diaphragm is in fluid communication with the outer part of the stack, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization, and the second side of the diaphragm is in fluid communication with the inner cavity, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization. The method further includes mounting the formed optical microphone module in a housing to form the optical microphone assembly, wherein the housing includes a housing base and a housing, the housing base or the housing including an acoustic port, wherein mounting the optical microphone module includes sealing the housing or the housing base to the stack, wherein the acoustic port is aligned with the diaphragm.

2. The method of claim 1, wherein at least one of the interferometric measurement component and the spacer has a shape defining the cavity in the stack.

3. The method according to claim 1 or 2, wherein at least one of the spacer and the interferometric measurement assembly includes the at least one aperture.

4. The method of claim 1 or 2, wherein the step of assembling the semiconductor chip, the spacer, and the interferometry assembly into the stack includes aligning the light source, the photodetector, the optical element, and / or the diaphragm.

5. The method of claim 1 or 2, wherein the substrate of the interferometric measurement assembly includes one or more substrate apertures such that, after the semiconductor chip, the spacer and the interferometric measurement assembly have been assembled into the stack, the first side of the diaphragm is open to the outside of the stack, and the second side of the diaphragm is in fluid communication with the cavity via the substrate aperture.

6. The method of claim 1 or 2, wherein the substrate of the interferometric measurement assembly includes a substrate aperture such that, after the semiconductor chip, the spacer and the interferometric measurement assembly have been assembled into the stack, the first side of the diaphragm is in fluid communication with the outside of the stack via the substrate aperture, and the second side of the diaphragm is open to the cavity.

7. The method according to claim 1, wherein, Installing the optical microphone module includes mounting the optical microphone module on the housing base.

8. The method according to claim 1 or 7, wherein, Installing the optical microphone module includes mounting the housing on top of the stack to form a acoustic cavity.

9. The method of claim 1 or 2, wherein after the semiconductor chip, the spacer and the interferometry assembly have been assembled into the stack, the vertical distance between the optical element and the surface on the semiconductor chip including the photodetector is greater than 200 µm.

10. The method according to claim 1 or 2, wherein the at least one optical element comprises a diffractive optical element.

11. The method of claim 1, wherein one or more optical components are disposed in or on the spacer.

12. A method of manufacturing an optical microphone assembly, the optical microphone assembly comprising an optical microphone module, wherein the optical microphone module comprises: An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate; A semiconductor chip, comprising at least one photodetector and a light source, wherein the at least one photodetector and the light source are mounted on or integrated into the semiconductor chip; Spacers; as well as One or more optical components are integrated into or formed in the spacer, or mounted on or manufactured on the spacer; The method includes: The optical microphone module is formed by assembling the semiconductor chip, the spacer, and the interferometry component into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometry component; The light source and the at least one photodetector are positioned on the semiconductor chip such that, after the semiconductor chip, the spacer, and the interferometric assembly have been assembled into the stack, the light source is positioned to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement, and a second portion of the light propagates along a second optical path different from the first optical path via the interferometric arrangement, thereby generating an optical path difference between the first and second optical paths that depends on the distance between the diaphragm and the optical element, and the at least one photodetector is positioned to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference; The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the exterior of the stack to allow substantially instantaneous pressure equalization therebetween, such that the inner cavity and the exterior of the stack are in fluid communication; and The first side of the diaphragm is in fluid communication with the outer part of the stack, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization, and the second side of the diaphragm is in fluid communication with the inner cavity, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization. The method further includes mounting the formed optical microphone module in a housing to form the optical microphone assembly, wherein the housing includes a housing base and a housing, the housing base or the housing including an acoustic port, wherein mounting the optical microphone module includes sealing the housing or the housing base to the stack, wherein the acoustic port is aligned with the diaphragm.

13. The method of claim 11 or 12, wherein the spacer comprises a support structure suspended in a region between the semiconductor chip and the interferometric measurement assembly, wherein the optical assembly is disposed in or on the support structure.

14. An optical microphone module for mounting in a housing to form an optical microphone assembly, the optical microphone module comprising: An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate; A semiconductor chip, comprising an optoelectronic circuit, the optoelectronic circuit including at least one photodetector; A light source, which is mounted on the semiconductor chip or integrated with the photoelectric circuit and the at least one photodetector in the semiconductor chip; and Spacers; The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component; The light source is arranged to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement and a second portion of the light propagates along a second optical path different from the first optical path via the interferometric arrangement, thereby generating an optical path difference between the first optical path and the second optical path that depends on the distance between the diaphragm and the optical element, and wherein the at least one photodetector is arranged to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference; The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the exterior of the stack to allow substantially instantaneous pressure equalization therebetween, such that the inner cavity and the exterior of the stack are in fluid communication; and The first side of the diaphragm is in fluid communication with the outer part of the stack, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization, and the second side of the diaphragm is in fluid communication with the inner cavity, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization. The optical microphone module is a prefabricated unit that is easily installed in the housing to form the optical microphone assembly. The interferometry component includes an attachment area surrounding the diaphragm, wherein the attachment area is adapted to be sealed to the housing base or housing.

15. The optical microphone module of claim 14, wherein at least one of the interferometry component and the spacer has a shape defining the cavity in the stack.

16. The optical microphone module of claim 14 or 15, wherein at least one of the spacer and the interferometric measurement component includes the at least one aperture.

17. The optical microphone module of claim 14 or 15, wherein the first side of the diaphragm is open to the outside of the stack, and the substrate of the interferometry assembly includes one or more substrate apertures, and the second side of the diaphragm is in fluid communication with the cavity via the substrate apertures.

18. The optical microphone module of claim 14 or 15, wherein the substrate of the interferometric measurement component includes a substrate aperture, the first side of the diaphragm is in fluid communication with the stacked exterior via the substrate aperture, and the second side of the diaphragm is open to the cavity.

19. The optical microphone module of claim 14 or 15, wherein the vertical distance between the optical element and the surface on the semiconductor chip including the photodetector is greater than 200 μm.

20. The optical microphone module according to claim 14 or 15, wherein the at least one optical element comprises a diffractive optical element.

21. The optical microphone module of claim 14, wherein one or more optical components are disposed in or on the spacer.

22. An optical microphone module for mounting in a housing to form an optical microphone assembly, the optical microphone module comprising: An interferometric measurement assembly includes a substrate, a diaphragm, and at least one optical element spaced apart from the diaphragm, wherein the at least one optical element includes a surface of the substrate and / or is disposed on the surface of the substrate; A semiconductor chip, comprising at least one photodetector and a light source, wherein the at least one photodetector and the light source are mounted on or integrated into the semiconductor chip; Spacers; as well as One or more optical components are integrated into or formed in the spacer, or mounted on or manufactured on the spacer; The semiconductor chip, the spacer, and the interferometric measurement component are assembled into a stack, wherein the spacer is disposed between the semiconductor chip and the interferometric measurement component; The light source is arranged to provide light to the interferometric arrangement such that a first portion of the light propagates along a first optical path via the interferometric arrangement and a second portion of the light propagates along a second optical path different from the first optical path via the interferometric arrangement, thereby generating an optical path difference between the first optical path and the second optical path that depends on the distance between the diaphragm and the optical element, and wherein the at least one photodetector is arranged to detect at least a portion of the interference pattern generated by the first and second portions of the light that depends on the optical path difference; The stack includes an inner cavity and at least one orifice, the orifice providing an air passage between the inner cavity and the exterior of the stack to allow substantially instantaneous pressure equalization therebetween, such that the inner cavity and the exterior of the stack are in fluid communication; and The first side of the diaphragm is in fluid communication with the outer part of the stack, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization, and the second side of the diaphragm is in fluid communication with the inner cavity, allowing air to flow therebetween to allow for substantially instantaneous pressure equalization. The optical microphone module is a prefabricated unit that is easily installed in the housing to form the optical microphone assembly. The interferometry component includes an attachment area surrounding the diaphragm, wherein the attachment area is adapted to be sealed to the housing base or housing.

23. The optical microphone module of claim 21 or 22, wherein the spacer comprises a support structure suspended in a region between the semiconductor chip and the interferometric measurement component, wherein the optical component is disposed in or on the support structure.

24. An optical microphone module manufactured using the method according to claim 1 or 12.

25. An optical microphone assembly or host device comprising an optical microphone module as claimed in or on which it is mounted.

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