Light emitter devices, photoacoustic gas sensors and methods for forming light emitter devices

Abstract

A light emitter module (100, 210, 400, 500, 600, 700), comprising: an emitter component comprising a heater structure (110) arranged on a membrane structure (120), wherein the membrane structure (120) is arranged over a first cavity (130), the first cavity (130) being arranged between the membrane structure (120) and at least a section of a support substrate (140) of the emitter component, wherein the heater structure (110) is configured to emit light when a predefined current flows through the heater structure (110); a lid substrate (150) with a recess (160), wherein the lid substrate (150) is attached to the emitter component such that the recess (160) forms a second cavity (170) between the membrane structure (120) and the lid substrate (150), and wherein the pressure in the second cavity (170) is less than 100 mbar; and an optical filter structure (410) arranged vertically between the first cavity (130) and the support substrate (140) or between the second cavity (170) and the cover substrate (150), the second cavity (170) extends laterally outside the first cavity (130) closer to the supporting substrate (140) than the membrane structure (120).

Description

Technical field

[0001] Examples refer to concepts for generating light and related applications, and in particular to light emitter devices, photoacoustic gas sensors and methods for forming light emitter devices. background

[0002] Light emitter devices (e.g., light emitter devices of microelectromechanical systems) may need to be optimized with regard to cost. Nevertheless, it is desirable to design light emitter devices with reduced power consumption.

[0003] The publications WO 2006 / 031 125 A1, JP 2000 - 236 110 A, DE 10 2014 114 873 A1, JP 2015 - 088 481 A and EP 1 779 418 B1 describe known semiconductor devices. Summary

[0004] There may be a need to provide concepts for light emitter components with reduced power consumption.

[0005] Such a need can be met by the subject matter of the claims.

[0006] Some embodiments relate to a light-emitting device. The light-emitting device comprises an emitter component including a heater structure arranged on a membrane structure. The membrane structure is arranged over a first cavity. Additionally, the first cavity is located between the membrane structure and at least a section of a support substrate of the emitter component. Furthermore, the heater structure is configured to emit light when a predefined current flows through it. The light-emitting device also includes a cover substrate with a recess. The cover substrate is attached to the emitter component such that the recess forms a second cavity between the membrane structure and the cover substrate. The pressure in this second cavity is less than 100 mbar.

[0007] Some embodiments relate to a photoacoustic gas sensor. The photoacoustic gas sensor comprises a light emitter element.

[0008] Some embodiments relate to a method for forming a light-emitting device. The method comprises forming an emitter component including a heater structure arranged on a membrane structure. The membrane structure is arranged over a first cavity. Additionally, the first cavity is located between the membrane structure and at least a portion of a support substrate of the emitter component. Furthermore, the heater structure is configured to emit light when a predefined current flows through it. The method also includes attaching a cover substrate with a recess to the emitter component, such that the recess forms a second cavity between the membrane structure and the cover substrate. The pressure in the second cavity is less than 100 mbar. Brief description of the drawings

[0009] The following are some examples of devices and / or methods, described solely by way of example and with reference to the accompanying drawings, in which Fig. Figure 1 shows a schematic cross-section of part of a light emitter component; Fig. 2 shows a schematic representation of a photoacoustic gas sensor; Fig. 3 shows a flowchart of a process for forming a light emitter component; Fig. 4a-4i show process steps for forming a light emitter component; Fig. 5a-5h show process steps for forming another light emitter device; Fig. 6a-6h show process steps for forming another light emitter device; and Fig. 7a-7h show process steps for forming another light emitter device. Detailed description

[0010] Several embodiments are now described in more detail with reference to the accompanying drawings, in which some embodiments are illustrated. For clarity, the thickness of lines, layers, and / or regions in the figures may be exaggerated.

[0011] While other examples of various modifications and alternative forms are appropriate, some examples are shown in the figures and described in detail here. It is understood, however, that the intention is not to limit examples to the specific forms revealed. Further examples may encompass all modifications, correspondences, and alternatives falling within the scope of revelation. Throughout the description of the figures, identical reference signs refer to identical or similar elements, which may be implemented identically or in a modified form compared to one another, while providing the same or similar functionality.

[0012] It is understood that when an element is described as "connected" or "coupled" to another element, the elements may be directly connected or coupled, or via one or more intermediate elements. When two elements A and B are connected with an "or," this should be understood to reveal all possible combinations, i.e., only A, only B, and A and B. An alternative wording for the same combinations is "at least one of A and B." The same applies to combinations of more than two elements.

[0013] The terminology used herein is intended to describe specific examples and is not meant to be limiting to further examples. Whenever a singular form such as "a" or "the" is used, and the use of only one element is neither explicitly nor implicitly defined as mandatory, further examples may also include the plural forms to implement the same functionality. Similarly, if a functionality is subsequently described as being implemented using multiple elements, further examples may implement the same functionality using a single element or processing entity.It is further understood that the terms “include”, “comprehensive”, “exhibit” and / or “exhibiting” as used herein indicate the presence of specified features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0014] Unless otherwise defined, all terms used herein (including technical and scientific terms) are used in their usual sense, which includes the examples.

[0015] Fig. Figure 1 shows a schematic cross-section of part of a light-emitting device 100. The light-emitting device 100 comprises an emitter component including a heater structure 110, which is arranged on a membrane structure 120. The membrane structure 120 is arranged over a first cavity 130. Additionally, the first cavity 130 is arranged (vertically) between the membrane structure 120 and at least a section of a support substrate 140 of the emitter component. Furthermore, the heater structure 110 is configured to emit light when a predefined current flows through the heater structure 110. The light-emitting device 100 also includes a cover substrate 150 with a recess 160. The cover substrate 150 is attached to the emitter component such that the recess 160 forms a second cavity 170 between the membrane structure 120 and the cover substrate 150.Furthermore, the (gas) pressure in the second cavity 170 is less than 100 mbar (or less than 10 mbar, less than 1 mbar or less than 0.1 mbar).

[0016] Due to the low gas pressure in the second cavity 170 (e.g., compared to the average atmospheric pressure at sea level of 1013 mbar), heat conduction through the second cavity 170 can be reduced. This reduces the power loss of the light emitter element 100 due to heat conduction. Consequently, the power consumption of the light emitter element 100 can be reduced.

[0017] For example, a (quasi-)vacuum can be formed in the second cavity 170. For example, the gas pressure in the second cavity can be greater than 0.001 mbar or greater than 0.01 mbar. For example, the gas pressure in the first cavity 130 can be equal to the gas pressure in the second cavity 170. The first cavity 130 and / or the second cavity 170 can be filled with air or with a gas that has a lower thermal conductivity than, for example, air (e.g., radon, xenon, or argon).

[0018] For example, the flow of the predefined current can be generated by applying a voltage to the electrical contacts of the heater structure 110. For example, the predefined current can be less than 10 mA (or less than 1 mA, less than 0.1 mA, less than 0.01 mA, or less than 1 µA). The predefined current can be supplied by a power supply circuit implemented on the support substrate 140 or by an external power supply circuit.

[0019] The flow of the predefined current through the heater structure 110 can cause a Joule heating of the heater structure 110 and can thereby lead to the emission of thermal radiation by the heater structure, for example. For example, the heater structure 100 can be configured to emit infrared light (e.g., light with a wavelength in the range of 700 nm to 1 mm), visible light (e.g., light with a wavelength in the range of 400 nm to 700 nm), and / or a combination thereof. For example, the heater structure 110 can be configured to emit light with a spectrum that has maximum intensity at a wavelength greater than 700 nm and less than 1 mm. Radiation or emission of light in a vacuum can enable heat conduction through a large air interface with a small gap, for example.

[0020] For example, the light emitter element 100 can further comprise an optical filter structure arranged vertically between the first cavity 130 and the support substrate 140, or between the second cavity 170 and the cover substrate 150. In this way, a wavelength of the emitted light can be efficiently controlled. Additionally, a separate component containing the optical filter element can be omitted. This reduces the dimensions (e.g., size or height) of a system comprising the light emitter element 100 and the optical filter element. Furthermore, the manufacturing costs of the system can be reduced. For example, the optical filter structure can comprise a Bragg filter with different polysilicon layers and / or insulating layers (e.g., layers comprising silicon oxide or silicon nitride) on a substrate (e.g., a silicon substrate).For example, the optical filter structure can be arranged within the recess 160 (e.g., on a surface of the lid substrate 150) or on a front surface of the support substrate 140. The front surface of the support substrate 140 can be the surface of the support substrate 140 on which the membrane structure 120 is arranged, for example.

[0021] For example, the light-reflecting layer or a light-absorbing layer can be arranged vertically between the first cavity 130 and the support substrate 140 or between the second cavity 170 and the cover substrate 150. This allows for efficient control of the direction of light emission from the light-emitting element 100. The light-reflecting layer can reflect more than 50% (or more than 80%) of the incident light, for example. For example, the light-reflecting layer can have a metallic film. For example, the light-reflecting layer can absorb more than 50% (or more than 80%) of the incident light. The light-absorbing layer can, for example, have a black layer. For example, the light-reflecting layer or the light-absorbing layer can be located within the recess 160 (e.g.,be located on a surface of the lid substrate 150) or on the front surface of the support substrate 140.

[0022] For example, the support substrate 140 can have a support layer arranged on the front surface of a semiconductor substrate or a glass substrate of the support substrate 140. In this way, the membrane structure 120 can be efficiently implemented. The support layer can be formed by removing a section of the support substrate 140 to form the first cavity 130, for example. For example, the support layer can be formed as a continuous element surrounding the first cavity 130. Alternatively, the support layer can form at least one wall of the first cavity 130. For example, the membrane structure 120 can be attached, fixed, or anchored to the support layer.

[0023] For example, the first cavity 130 and the second cavity 170 can be connected by at least one opening through the membrane structure 120. In this way, the gas pressure in the first cavity 130 can be equalized with the gas pressure in the second cavity 170. For example, the gas pressure in the first cavity 130 can be equal to the gas pressure in the second cavity 170.

[0024] For example, the light emitter device 100 can further comprise a heater wiring structure for supplying the predefined current. The heater wiring structure can include a via (through hole) extending through the support substrate 140. This allows an electrical contact for supplying the predefined current or a voltage for generating it to be efficiently provided to the heater structure 110 in a gas-tight manner. For example, an electrically conductive material (e.g., copper or tungsten) can be deposited in a hole through the support substrate 140 to form the via. The via can be a through-silicon via (TSV). For example, the via can be electrically connected to the heater structure 110 and insulated from a semiconductor substrate of the support structure 140. The supply circuit can provide the predefined current or the voltage for generating it to the via, for example.

[0025] For example, the heater wiring structure can include redistribution wiring within a redistribution layer (RDL) located on a (backside) surface of the support substrate 140. This simplifies the provision of the predefined current or voltage to generate it. For example, the (backside) surface of the support substrate 140 can be the surface of the support substrate 140 opposite the frontside surface where the membrane structure 120 is implemented. The redistribution layer can include one or more redistribution wiring structures implemented by an electrically conductive material (e.g., copper or tungsten). For example, the redistribution wiring can be electrically connected to the via.

[0026] For example, the light emitter element 100 can further have a wiring structure for providing different voltages to a prestressing structure of the support substrate 140 or the lid substrate 150 and to the membrane structure 120 in order to move at least a section of the membrane structure 120 electrostatically in the direction of the support substrate 140 or the lid substrate 150. This allows the membrane structure 120, and consequently also the heater structure 110, to be efficiently cooled by contacting the support substrate 140 or the lid substrate 150. For example, the section of the membrane structure 120 can be moved away from the support substrate 140 or the lid substrate 150 during an emission or radiation operating mode of the light emitter element 100, and can be moved towards the support substrate 140 or the lid substrate 150 and thereby cooled during a non-emission or non-radiation operating mode of the light emitter element 100.For example, a movable membrane structure 120 can allow rapid switching between radiation and non-radiation operating modes.

[0027] For example, the prestressing structure of the support substrate 140 or the cover substrate 150 can have a grounding layer located between the first cavity 130 and the support substrate 140 or between the second cavity 170 and the cover substrate 150. The wiring structure can be electrically connected to the grounding layer. In this way, the support substrate 140 or the cover substrate 150 and the membrane structure 120 can be efficiently set to different potentials. For example, the grounding layer can be located within the first cavity 130 on the front surface of the support substrate 140 or within the recess 160 on a surface of the cover substrate 150. The grounding layer can be made of, for example, copper, tungsten, or polysilicon.For example, the light emitter component 100 can further comprise a supply circuit for providing different voltages to the ground connection layer and the membrane structure 120. This additional supply circuit can be implemented on the support substrate 140 or on an external supply circuit, for example.

[0028] For example, at least one section of the support substrate 140 can be a semiconductor substrate or a glass substrate. For example, at least one section of the lid substrate 150 can be a semiconductor substrate or a glass substrate. For example, the semiconductor substrate can be a silicon-based substrate, a silicon carbide (SiC)-based semiconductor substrate, a gallium arsenide (GaAs)-based semiconductor substrate, or a gallium nitride (GaN)-based semiconductor substrate. A semiconductor substrate can be a semiconductor wafer or a semiconductor chip, or part of a semiconductor wafer or a semiconductor chip, for example. For example, a glass substrate can be a silica (e.g., SiO2)-based glass substrate, a borolilicate-based glass substrate, an aluminosilicate-based glass substrate, or an oxide-based glass substrate.A glass substrate can be a glass wafer, a glass lid wafer or a glass lid, or part of a glass wafer, a glass lid wafer or a glass lid, for example.

[0029] For example, the membrane structure 120 can incorporate a heat spreader structure. A (first) insulating layer can be arranged between the heat spreader structure and the heater structure 110. This allows for smoother light emission. For example, the heat spreader structure can form a heat spreader layer. The heat spreader structure can incorporate a material with high optical emissivity at a wavelength of interest (e.g., black platinum, graphene, polysilicon, or silicon). For example, the (first) insulating layer can incorporate a nitride or an oxide (e.g., silicon dioxide or silicon nitride).

[0030] For example, the heater structure 110 can have a first layer containing a first metal and a second layer containing a second metal. The second layer can cover the first layer. For example, the first metal can be titanium and the second metal can be platinum. Alternatively, the heater structure can have a single metal layer. For example, the single metal layer can contain tungsten.

[0031] For example, the heater structure 110 can be covered by a second insulating layer. For example, the second insulating layer can consist of a nitride or an oxide (e.g., silicon oxide or silicon nitride).

[0032] For example, at least one section of the heater structure 110 can be a meander or ring shape. This allows the length of the heater structure 110 to be increased. This, in turn, increases the electrical resistance of the heater structure 110 and, consequently, the Joule heating of the heater structure 110 due to the flow of the predefined current. This, in turn, increases the intensity of light emission. For example, the recess 160 can have a rectangular (lateral) cross-section.

[0033] For example, the cover substrate 150 can be attached to the emitter component in a gas-tight manner. This eliminates the need for a gas-tight seal on the light emitter component 100. Alternatively, the cover substrate 150 can be anodically bonded to the emitter component. Finally, at an interface between the cover substrate 150 and the support substrate 140, a glass can be in contact with a semiconductor material.

[0034] For example, the light-emitting device 100 can be a component of a microelectromechanical system (MEMS). The MEMS component can have an anchor element arranged on a surface of the support substrate 140. Additionally, the MEMS component can have the heater structure 110 anchored to the support substrate 140 by the anchor element. The MEMS component can also have the cover substrate 150, with the recess 160 located on a surface of the cover substrate 150. The cover substrate 150 can be bonded to the support substrate 140 such that the recess 160 forms the second cavity 170 between the support substrate 140 and the cover substrate 150. Furthermore, the heater structure 110 can be arranged within the second cavity 170. In addition, the gas pressure in the second cavity can be less than 100 mbar. For example, the anchoring element can be made of an oxide (e.g.,from silicon dioxide) are formed by growing an oxide layer on the support substrate 140 and etching the grown oxide layer.

[0035] The light emitter component 100 can be an infrared (IR) emitter or a MEMS IR emitter, for example. It can be used, for instance, as part of a photoacoustic gas sensor, a photoacoustic spectroscopy system, a thermal flow sensor, or a mobile device (such as a smartphone or tablet computer). The light emitter component 100 can also be used to implement any other gas sensor principle where emitted optical radiation is used to trigger a sensor effect, such as NDIR sensor systems.

[0036] For example, the light emitter component 100 (e.g., an IR emitter chip) can be implemented as a MEMS chip with a thin heater membrane, a cavity in the silicon substrate, and optionally a vent hole. Additionally, the infrared filter structure (e.g., an IR filter chip) can be implemented as a Bragg reflector with different poly / oxide layers on a silicon substrate.

[0037] For example, a vertical direction can be measured orthogonally to the front surface of the support substrate 140 or the lid substrate 150, and a lateral direction can be measured parallel to the front surface of the support substrate 140 or the lid substrate 150. The front or front surface of the support substrate 140 or the lid substrate 150 may be the side used to implement more sophisticated and complex structures than the back side of the support substrate 140 or the lid substrate 150, since the process parameters (e.g., temperature) and handling may be limited for the back side if structures have already been formed on one side of the support substrate 140 or the lid substrate 150.

[0038] Fig. Figure 2 shows a schematic representation of a photoacoustic gas sensor 200. The photoacoustic gas sensor 200 comprises a light emitter element 210. The implementation of the light emitter element 210 can be similar to the implementation of the light emitter element that is used in conjunction with Fig. The photoacoustic gas sensor 200 is described in Figure 1. The light emitter element 210 is arranged within a volume 220, which is to be filled with the gas to be analyzed (e.g., air or a gas containing carbon dioxide (CO2) or carbon monoxide (CO)). The photoacoustic gas sensor 200 further comprises a pressure-sensitive module 230 (e.g., a microphone) arranged within a reference gas volume 240. The reference gas volume 240 is separated from the volume 220, which is to be filled with the gas to be analyzed. In addition, the light emitter element 210 is configured to emit a light pulse 250 to generate an acoustic wave 260 in the reference gas volume 240 by interacting with a reference gas (e.g., nitrogen) within the reference gas volume 240.The pressure-sensitive module 230 can be configured to detect the acoustic wave 260 and, based on the detected acoustic wave 260, generate a sensor signal that provides information about the acoustic wave 260. Since the emitted light pulse 250 passes through a section of the volume 220, which is to be filled with a gas to be analyzed, the generated sensor signal can further indicate information (e.g., a CO2 concentration or a CO concentration) about the gas to be analyzed in the volume. Furthermore, the photoacoustic gas sensor 200 can have an inlet and / or an outlet for filling the volume 220 with the gas to be analyzed.

[0039] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in section 2 may have one or more optional additional features corresponding to one or more aspects that are related to the proposed concept or one or more of the above (e.g. Fig. 1) or below (e.g. Fig. Examples of implementation described in sections 3 - 7h) are mentioned.

[0040] Fig. Figure 3 shows a flowchart of a process 300 for forming a light-emitting device. The process 300 comprises forming 310 an emitter component comprising a heater structure 110 arranged on a membrane structure 120. The membrane structure 120 is arranged (vertically) over a first cavity 130. Additionally, the first cavity 130 is located between the membrane structure 120 and at least one section of a support substrate 140 of the emitter component. Furthermore, the heater structure 110 is configured to emit light when a predefined current flows through the heater structure 110. The process also includes attaching 320 a cover substrate 150 with a recess 160 to the emitter component such that the recess 160 forms a second cavity 170 between the membrane structure 120 and the cover substrate 150. The (gas) pressure in the second cavity 170 is less than 100 mbar.

[0041] In this way, a light-emitting device with low power loss due to heat conduction can be efficiently created. This allows for the production of a light-emitting device with reduced power consumption.

[0042] For example, the membrane structure 120 can be formed by depositing a heat spreader structure (e.g., a polysilicon layer) onto a base substrate of the support structure 140. Additionally, the heat spreader structure can be covered by an insulating layer (e.g., a nitride layer). The heater structure 110 can be formed by depositing at least one metal layer (e.g., comprising tungsten or titanium / platinum) onto the insulating layer covering the heat spreader structure. The first cavity 130 can be formed by etching the support substrate 140 after the heater structure 110 has been formed, for example. Similarly, the recess 160 in the lid substrate 150 can be formed by an etching process. For example, the attachment of the lid substrate 320 to the emitter component 150 can be carried out in a (quasi-)vacuum or at an ambient gas pressure of less than 100 mbar (or less than 10 mbar, less than 1 mbar or less than 0.1 mbar).

[0043] For example, the attachment of the lid substrate 150 to the emitter component can involve anodic bonding of the lid substrate 150 to the emitter component. In this way, the lid substrate 150 can be efficiently fixed to the support substrate 140. Alternatively, the attachment of the lid substrate 150 to the emitter component can involve metal-to-metal bonding, wafer bonding, eutectic bonding, hermetically sealed bonding, or spin-on glass bonding.

[0044] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in section 3 may have one or more optional additional features corresponding to one or more aspects that are related to the proposed concept or one or more of the above (e.g. Fig. 1-2) or below (e.g. Fig. Examples of implementation described in sections 4a - 7h) are mentioned.

[0045] Fig. Figures 4a-4i show process steps for forming a light emitter component 400. The method for forming the light emitter component 400 can be similar to the method used in conjunction with Fig. 3 is described. Fig. Figure 4a shows a support substrate 140 on which an infrared (IR) filter structure 410, a first insulating layer 420, a second insulating layer 430, and a membrane structure 120 are formed. For example, the support substrate 140 can be a silicon-based substrate. The infrared filter structure 410 can have a stack of polysilicon layers and insulating layers (e.g., silicon oxide layers or silicon nitride layers). For example, the infrared filter structure 410 can be a Bragg reflector with different polysilicon / oxide layers. For example, the first insulating layer 420 can have an oxide (e.g., silicon oxide), and the second insulating layer 430 can have a nitride (e.g., silicon nitride). The membrane structure 120 can have a heat spreader structure (e.g., formed from polysilicon).

[0046] For example, the support substrate 140 (e.g., a Si substrate wafer) can be pre-processed with the infrared filter structure 410 (e.g., an IR filter layer), the first insulating layer 420 (e.g., an oxide layer), and the membrane structure 120 (e.g., a polysilicon heat spreader layer). The second insulating layer 430 (e.g., a nitride layer) can then be deposited on the same substrate, and a hard mask 421 for the formation of a through-silicon via (TSV) can be etched onto it.

[0047] As in Fig. As shown in Figure 4b, a trench is etched into the support substrate 140. Furthermore, an insulating layer 441 is formed within the trench 440. Additionally, an electrically conductive material 442 (e.g., copper (Cu) or tungsten) is deposited within the trench 440. The insulating layer 441 insulates the electrically conductive material from the support substrate 140. For example, the trench 440, the insulating layer 441, and the electrically conductive material 442 can form a TSV (e.g., a Cu-TSV). For example, a TSV can be formed with a trench etch, insulation, and typically a copper or tungsten filling. The predefined current can be supplied to the (not yet formed) heater structure 110 through the TSV or the electrically conductive material 442. For example, another TSV can be formed in the support substrate 140 to provide the predefined current to the heater structure 110.

[0048] A heater structure 110 is formed on the membrane layer 120, as shown in Fig. Figure 4c shows that the heater structure 110 comprises a first layer 451 comprising a first metal (e.g., titanium), a second layer 452 comprising a second metal (e.g., platinum) covering the first layer 451, and an insulating layer 453 (e.g., a nitride) covering the second layer. The second insulating layer 430 can be arranged between the heater structure 110 and the membrane structure 120.

[0049] For example, the heater structure 110 or a metal heater (e.g., Ti / Pt or W) can be formed and covered by the insulating layer 453 (e.g., a nitride layer), which is open within the spacing of the heat distribution layer of the membrane structure 120. For example, the heat distribution layer can be a material with high optical emissivity at the wavelength of interest, such as black platinum, graphene, or silicon. The infrared filter structure 410 (e.g., a filter layer) and / or the support substrate 140 can also be in contact with the metal of the heater structure 110 (e.g., to form a counter electrode for the heat distribution layer).

[0050] As in Fig. As shown in section 4d, a first cavity 130 is formed by etching the first insulating layer 420 between the membrane structure 120 and the infrared filter structure 410. For example, the first insulating layer 420 (e.g., an oxide) between the membrane structure 120 or a heat distribution structure (e.g., a heat distribution layer) and the infrared filter structure 410 (e.g., a filter layer) can be etched by wet chemical etching at regions 461, 462, where anodic bonding can subsequently be carried out. The etching of the first insulating layer 420 can include oxide release etching, for example.

[0051] A lid substrate 150 (e.g., a glass lid wafer) with a recess 160 is attached to the support substrate 140, as shown in Fig. Figure 4e shows that the recess 160 forms a second cavity 170 between the membrane structure 120 and the lid substrate 150. The membrane structure 120 comprises a plurality of openings 471 that connect the first cavity 130 to the second cavity 170. For example, the lid substrate 150 can be anodically bonded to the support substrate 140 in a vacuum. For example, the lid substrate 150 (e.g., a lid glass wafer) with the recess 160 (e.g., an etched cavity) in the region of the heater structure 110 can be bonded to the support substrate 140 (e.g., a substrate wafer) by anodic bonding under vacuum.

[0052] Fig. Figure 4f shows an optional process step in which a coating 481 is formed within the recess 160 of the lid substrate 150. The coating 481 can be a light-reflecting coating (e.g., a metal film) or a light-absorbing coating (e.g., a black film). For example, the formation of the coating 481 can involve the deposition of a metal film on the lid substrate 150 (e.g., on a glass wafer). During the formation of the coating 481, the lid substrate 150 can be attached to a lift-off resist element 482. For example, a reflective and / or absorbing coating of the lid substrate can optionally be applied.

[0053] As in Fig. As shown in Figure 4g, the support substrate 140 is thinned such that the trench 440 is opened and the electrically conductive material 442 can be electrically contacted on a rear surface 141 of the support substrate 140. For example, the support substrate 140 (e.g., a substrate wafer) can be thinned by wafer grinding and / or plasma etching. The TSV can be opened during this thinning process, for example.

[0054] An insulating layer 491 (e.g., an oxide) and a redistribution layer 492 with a contact surface 493 are formed on or at the back 141 of the support substrate 140, as shown in Fig. Figure 4h shows that the redistribution layer 492 electrically contacts the electrically conductive material 442. For example, a redistribution layer (RDL) 492 with contact surfaces 493 for nailhead bonding or protrusion can be formed on the back 141 of the support substrate 140. Any or any type of metallization and contact surface formation can be used in the RDL 492, for example.

[0055] As in Fig. As shown in Figure 4i, the lid substrate 150 (e.g., a lid wafer) is thinned to a target thickness, and wafer sawing of the support substrate 140 and the lid substrate 150 is performed, as indicated by arrows 494, to form the light-emitting device 400. A vertical dimension 495 of the lid substrate 150 can be selected depending on the gas pressure in the second cavity 170. For example, the vertical dimension 495 can be larger than 1 µm (e.g., larger than 10 µm, larger than 30 µm, larger than 50 µm, or larger than 100 µm). A vertical dimension 496 of the support layer 140 can be greater than 1 µm (e.g., greater than 10 µm, greater than 30 µm, greater than 50 µm, or greater than 100 µm). For example, a vertical distance 497 between the heater structure 110 and the lid substrate 150 can be in the range of 500 nm to 10 µm. A vertical distance 498 between the membrane structure 120 and the infrared filter structure 410 can be in the range of 500 nm to 5 µm. Fig. Figure 4i shows an example with an integrated IR emitter / filter using TSV.

[0056] For example, a cavity containing a heater membrane and a filter can be processed by an anodic bonding process of two wafers. Bonding can be performed in a low-pressure environment, thus placing the heater and filter under a (quasi-)vacuum. Since the heater can be implemented as a movable membrane, it can be electrostatically moved towards the substrate and cooled during a non-radiative operating mode, and moved away from the substrate during a radiative operating mode by applying a potential difference between the substrate and the heat spreader layer.

[0057] For example, due to the vacuum in the respective cavities 130 and 170, power dissipation can be reduced, since heat conduction is minimized in a vacuum and thermal radiation can now be the only dominant effect. Cooling by means of a movable membrane can be advantageous for rapid switching between radiative and non-radiative operating modes.

[0058] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in 4a-4i may have one or more optional additional features corresponding to one or more aspects that are related to the proposed concept or one or more of the above (e.g. Fig. 1-3) or below (e.g. Fig. Examples of implementation described in sections 5a - 7h are mentioned.

[0059] Fig. Figures 5a-5h show process steps for forming another light emitter component 500. The method for forming the light emitter component 500 can be similar to the method described in connection with Fig. 3 is described. Fig. Figure 5a shows a support substrate 140 on which a grounding layer 510, an insulating layer 520, and a membrane structure 120 are formed. For example, the support substrate 140 can be a glass-based substrate. The grounding layer 510 can, for example, be an electrically conductive material (e.g., copper, tungsten, or polysilicon). For example, the insulating layer 520 can be a nitride (e.g., silicon nitride). The membrane structure 120 can be a heat-distributing structure (e.g., formed from polysilicon). For example, in contrast to the process steps shown in Fig. 4a-4i, the support substrate 140 (e.g., a substrate wafer) may be made of glass. For example, in contrast to the process steps shown in Fig. 4a-4i instead of the infrared filter structure 410 in the support substrate 140 (e.g. a substrate wafer) an (electrical) ground connection layer 510 (e.g. a ground layer) is implemented to enable a connected counter electrode for the movable membrane structure 120 (e.g. a movable heating element).

[0060] As in Fig. As shown in Figure 5b, a trench 530 is etched into the support substrate 140. Additionally, an electrically conductive material 531 (e.g., copper (Cu) or tungsten) is deposited within the trench 530. For example, the trench 530 and the electrically conductive material 531 can form a TSV (e.g., a Cu-TSV). For example, in contrast to the process steps shown in Fig. 4a-4i The insulating layer 441 or an insulating layer in the TSV can be omitted, since glass is already an insulating layer. The predefined current can be supplied to the (not yet formed) heater structure 110 through the TSV or the electrically conductive material 531. For example, another TSV can be formed in the support substrate 140 to supply the predefined current to the heater structure 110.

[0061] A heater structure 110 is formed on the membrane structure 120, as shown in Fig. Figure 5c shows the heater structure 110 comprising a first layer 451 comprising a first metal (e.g., titanium), a second layer 452 comprising a second metal (e.g., platinum) covering the first layer 451, and an insulating layer 453 (e.g., a nitride) covering the second layer. The second insulating layer 430 is arranged between the heater structure 110 and the membrane structure 120.

[0062] As in Fig. In the 5d stage, a first cavity 130 is formed by etching the support substrate 140 between the membrane structure 120 and the mass bonding layer 510. The etching of the first support substrate 140 can be a glass release etch or an oxide release etch, for example.

[0063] A lid substrate 150 (e.g., a structured silicon or glass lid wafer) with a recess 160 is attached to the support substrate 140, as shown in Fig. Figure 5e shows that the recess 160 forms a second cavity 170 between the membrane structure 120 and the lid substrate 150. An infrared filter structure 410 (e.g., a filter layer) is arranged adjacent to the lid substrate 150. The membrane structure 120 comprises a plurality of openings 471 that connect the first cavity 130 to the second cavity 170. For example, the lid substrate 150 can be anodically bonded to the support substrate 140 in a vacuum. For example, the lid 150 (e.g., a lid wafer) can be made of silicon or glass, and the infrared filter structure 410 (e.g., a filter layer) can be deposited onto the lid substrate 150 (e.g., a structured lid wafer).

[0064] As in Fig. As shown in Figure 5f, the support substrate 140 is thinned in such a way that the trench 530 is opened and the electrically conductive material 531 can be electrically contacted on a rear side 141 of the support substrate 140.

[0065] A redistribution layer 492 with a connection surface 493 is formed on or at the back side 141 of the support substrate 140, as shown in Fig. 5g is shown. The redistribution layer 492 electrically contacts the electrically conductive material 531. For example, in contrast to the process steps shown in Fig. 4a-4i, the insulating layer 491 (e.g. an insulating layer) on the back side 141 (e.g. in the RDL 492) can be omitted or skipped, since glass is already an insulating layer.

[0066] As in Fig. As shown in Figure 5h, the lid substrate 150 is thinned to a target thickness and wafer sawing of the support substrate 140 and the lid substrate 150 is performed as indicated by arrows 494 to form the light emitter device 500. Fig. Figure 5h shows an example with a filter on a lid wafer and a glass substrate / Si or glass lid.

[0067] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in 5a-5h may have one or more optional additional features corresponding to one or more aspects related to the proposed concept or one or more of the above (e.g. Fig. 1-4i) or below (e.g. Fig. Examples of implementation described in 6a - 7h) are mentioned.

[0068] Fig. Figures 6a-6h show process steps for forming another light emitter component 600. The method for forming the light emitter component 600 can be similar to the method described in connection with Fig. 3 is described. Fig. Figure 6a shows a support substrate 140 on which an infrared filter structure 410, an insulating layer 520, and a membrane structure 120 are formed. For example, the support substrate 140 can be a glass-based substrate. The membrane structure 120 can have a heat-distributing structure (e.g., made of polysilicon). For example, in contrast to the process steps shown in Fig. 5a-5h, the infrared filter structure 410 (e.g. a filter layer) is implemented in the support substrate 150 (e.g. in a substrate layer).

[0069] As in Fig. As shown in Figure 6b, a trench 530 is etched into the support substrate 140. Additionally, an electrically conductive material 531 (e.g., copper (Cu) or tungsten) is deposited within the trench 530. For example, the trench 530 and the electrically conductive material 531 can form a TSV (e.g., a Cu-TSV). The predefined current can be supplied to the (not yet formed) heater structure 110 through the TSV or the electrically conductive material 531. For example, another TSV can be formed in the support substrate 140 to supply the predefined current to the heater structure 110.

[0070] A heater structure 110 is formed on the membrane structure 120, as shown in Fig. Figure 6c shows the heater structure 110 comprising a first layer 451 comprising a first metal (e.g., titanium), a second layer 452 comprising a second metal (e.g., platinum) covering the first layer 451, and an insulating layer 453 (e.g., a nitride) covering the second layer. The second insulating layer 430 can be arranged between the heater structure 110 and the membrane structure 120.

[0071] As in Fig. As shown in step 6d, a first cavity 130 is formed by etching the support substrate 140 between the membrane structure 120 and the infrared filter structure 410. The etching of the first support substrate 140 can be a glass-release etching or an oxide-release etching, for example.

[0072] A lid substrate 150 (e.g., a silicon lid wafer) with a recess 160 is attached to the support substrate 140, as shown in Fig. Figure 6e shows that the recess 160 forms a second cavity 170 between the membrane structure 120 and the lid substrate 150. The membrane structure 120 comprises a plurality of openings 471 that connect the first cavity 130 with the second cavity 170. For example, the lid substrate 150 can be anodically bonded to the support substrate 140 in a vacuum.

[0073] As in Fig. As shown in Figure 6f, the support substrate 140 is thinned in such a way that the trench 530 is opened and the electrically conductive material 531 can be electrically contacted on a rear side 141 of the support substrate 140.

[0074] A redistribution layer 492 with a connection surface 493 is formed on or at the back side 141 of the support substrate 140, as shown in Fig. Figure 6g shows the redistribution layer 492 electrically contacts the electrically conductive material 531.

[0075] As in Fig. As shown in Figure 6h, the lid substrate 150 is thinned to a target thickness and wafer sawing of the support substrate 140 and the lid substrate 150 is performed as indicated by arrows 494 to form the light emitter device 600. Fig. Figure 6h shows an example with a filter on a substrate wafer and a glass substrate / Si lid.

[0076] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in 6a-6h may have one or more optional additional features corresponding to one or more aspects that are related to the proposed concept or one or more of the above (e.g. Fig. 1-5h) or below (e.g. Fig. Examples of implementation described in sections 7a - 7h are mentioned.

[0077] Fig. Figures 7a-7h show process steps for forming another light emitter component 700. The method for forming the light emitter component 700 can be similar to the method described in connection with Fig. 3 is described. Fig. Figure 7a shows a support substrate 140 on which a first insulating layer 420, a second insulating layer 430, and a membrane structure 120 are formed. For example, the support substrate 140 can be a silicon-based substrate. The membrane structure 120 can have a heat-distributing structure (e.g., made of polysilicon).

[0078] As in Fig. As shown in Figure 7b, a trench 440 is etched into the support substrate 140. Furthermore, an insulating layer 441 is formed within the trench 440. Additionally, an electrically conductive material 442 (e.g., copper (Cu) or tungsten) is deposited within the trench 440. The insulating layer 441 insulates the electrically conductive material from the support substrate 140. For example, the trench 440, the insulating layer 441, and the electrically conductive material 442 can form a TSV (e.g., a Cu-TSV). The predefined current can be supplied to the (not yet formed) heater structure 110 through the TSV or the electrically conductive material 442. For example, another TSV can be formed in the support substrate 140 to supply the predefined current to the heater structure 110.

[0079] A heater structure 110 is formed on the membrane structure 120, as shown in Fig. Figure 7c shows that the heater structure 110 comprises a first layer 451 comprising a first metal (e.g., titanium), a second layer 452 comprising a second metal (e.g., platinum) covering the first layer 451, and an insulating layer 453 (e.g., a nitride) covering the second layer. The second insulating layer 430 is arranged between the heater structure 110 and the membrane structure 120.

[0080] As in Fig. 7d gezeit is, a first cavity 130 is formed by etching the first insulating layer 420 between the membrane structure 120 and a front face 142 of the support substrate 140.

[0081] A lid substrate 150 (e.g., a structured silicon or glass lid wafer) with a recess 160 is attached to the support substrate 140, as shown in Fig. Figure 7c shows an infrared filter structure 410 arranged within the recess 160. Additionally, the recess 160 forms a second cavity 170 between the membrane structure 120 and the lid substrate 150. The membrane structure 120 comprises a plurality of openings 471 connecting the first cavity 130 to the second cavity 170. For example, the lid substrate 150 can be anodically bonded to the support substrate 140 in a vacuum. For example, a structured filter layer can be formed on the lid substrate 150 (e.g., a lid glass wafer). For example, the support substrate 150 can be a silicon wafer.

[0082] As in Fig. As shown in Figure 7f, the support substrate 140 is thinned in such a way that the trench 440 is opened and the electrically conductive material 442 can be electrically contacted on a rear side 141 of the support substrate 140.

[0083] An insulating layer 491 (e.g., an oxide) and a redistribution layer 492 with a contact surface 493 are formed on or at the back 141 of the support substrate 140, as shown in Fig. Figure 7g is shown. The redistribution layer 492 electrically contacts the electrically conductive material 442.

[0084] As in Fig. As shown in Figure 7h, the lid substrate 150 is thinned to a target thickness and wafer sawing of the support substrate 140 and the lid substrate 150 is performed as indicated by arrows 494 to form the light emitter device 700. Fig. Figure 7h shows an example with a filter on a lid wafer and a Si substrate / glass lid.

[0085] Further details and aspects are mentioned in connection with the exemplary embodiments described above or below. The in Fig. The embodiment shown in 7a-7h may have one or more optional additional features corresponding to one or more aspects that are related to the proposed concept or one or more of the above (e.g. Fig. 1-6h) or the embodiments described below.

[0086] Some embodiments relate to a structure and method for integrated IR emitters and filters with minimized power consumption.

[0087] From one perspective, integrated circuits like MEMS can be optimized in terms of size, height, and power dissipation, especially when the chip is intended for implementation in mobile devices such as smartphones or tablets. Additionally, MEMS solutions can be optimized for low cost.

[0088] According to one aspect, an IR emitter and an IR filter can be implemented in a single package with additional other chips, with the smallest possible size / height and cost.

[0089] One aspect of this light-emitting component is the optimization of the entire IR emitter / filter system, thereby minimizing costs. Simultaneously, power dissipation during application can be minimized, and acoustic cross-coupling due to overpressure can be avoided in certain variants.

[0090] According to one aspect, in order to reduce size and height and also to reduce the cost of forming the light emitter device, this can be based on wafer-level processes and wafer-to-wafer bonding processes.

[0091] According to one aspect, integrating the filter and heater system at the wafer level can reduce costs and allow for compact systems.

[0092] According to one aspect, the light emitter component can be realized with lower costs, smaller height / size and lower power consumption.

[0093] According to one aspect, other materials as well as other production steps could be used in the process for forming the light emitter component or for assembling the same or a comparable system.

[0094] According to one aspect, the principle of attracting the heated membrane structure towards the “cold” system to provide rapid cooling may be optional for “frequency-noncritical” or stationary systems (such as NDIR or slow photoacoustic spectroscopy (PAS) systems).

[0095] The aspects and features mentioned and described in conjunction with one or more of the previously detailed examples and figures can further be combined with one or more of the other examples to replace a similar feature of the other example or to additionally introduce the feature into the other example.

[0096] Examples may also include a computer program with program code for performing any of the above procedures, or refer to the execution of the computer program on a computer or processor. Steps, operations, or processes of various procedures described above can be performed by programmed computers. Examples may also include program storage devices, such as digital data storage media, that are machine-, processor-, or computer-readable and encode machine-, processor-, or computer-executable programs of instructions. The instructions perform or cause some or all of the steps of the procedures described above. Program storage devices may include, for example, digital storage devices, magnetic storage media such as magnetic disks and magnetic tapes, hard disk drives, or optically readable digital data storage media.Further examples should also cover computers, processors or control units programmed to perform the steps of the procedures described above, or (field) programmable logic arrays ((F)PLA = (Field) Programmable Logic Arrays) or (field) programmable gate arrays ((F)PGA = (Field) Programmable Gate Arrays) programmed to perform the steps of the procedures described above.

[0097] The description and drawings represent only the principles of revelation. Furthermore, all examples listed here are expressly intended for teaching purposes only, to assist the reader in understanding the principles of revelation and the concepts contributed by the inventor(s) to the advancement of technology. All statements made here concerning principles, aspects, and examples of revelation, as well as specific embodiments thereof, are intended to encompass their equivalents.

[0098] A block diagram can, for example, represent a detailed circuit diagram that implements the principles of the disclosure. Similarly, a flowchart, process diagram, state transition diagram, pseudocode, and the like can represent various processes that are essentially represented in a computer-readable medium and can thus be executed by a computer or processor, irrespective of whether such a computer or processor is explicitly shown. Methods disclosed in the description or in the claims can be implemented by an apparatus that includes means for performing each of the corresponding steps of those methods.

[0099] Furthermore, it is understood that the disclosure of multiple steps, processes, operations, sequences, or functions revealed in the description or claims should not be interpreted as being in a specific order, unless explicitly or implicitly stated otherwise, e.g., for technical reasons. The disclosure of multiple steps or functions therefore does not restrict them to a specific order, unless these steps or functions are not interchangeable for technical reasons. Furthermore, in some examples, a single step, function, process, or sequence may include or be broken down into multiple sub-steps, functions, processes, or sequences. Such sub-steps may be included and form part of the disclosure of that single step unless they are expressly excluded.

[0100] Furthermore, the following claims are hereby included in the detailed description, where each claim can stand alone as a separate example. While each claim can stand alone as a separate example, it should be noted that—although a dependent claim may refer in the claims to a particular combination with one or more other claims—other embodiments may also include a combination of the dependent claim with the subject matter of any other dependent or independent claim. These combinations are suggested here unless it is stated that a particular combination is not intended. Furthermore, features of a claim are also intended to apply to any other independent claim, even if that claim is not directly dependent on the independent claim.

Claims

[1] A light emitter assembly (100, 210, 400, 500, 600, 700) comprising: an emitter component comprising a heater structure (110) arranged on a membrane structure (120), wherein the membrane structure (120) is arranged over a first cavity (130), the first cavity (130) being arranged between the membrane structure (120) and at least a section of a support substrate (140) of the emitter component, wherein the heater structure (110) is configured to emit light when a predefined current flows through the heater structure (110); a lid substrate (150) with a recess (160), wherein the lid substrate (150) is attached to the emitter component such that the recess (160) forms a second cavity (170) between the membrane structure (120) and the lid substrate (150), and wherein the pressure in the second cavity (170) is less than 100 mbar; and an optical filter structure (410) arranged vertically between the first cavity (130) and the support substrate (140) or between the second cavity (170) and the cover substrate (150), the second cavity (170) extends laterally outside the first cavity (130) closer to the supporting substrate (140) than the membrane structure (120). [2] The light emitter element (100, 210, 400, 500, 600, 700) according to claim 1, wherein a light-reflecting layer or a light-absorbing layer is arranged vertically between the first cavity (130) and the support substrate (140) or between the second cavity (170) and the cover substrate (150). [3] The light emitter element (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the first cavity (130) and the second cavity (170) are connected by at least one opening (471) through the membrane structure (120). [4] The light emitter element (100, 210, 400, 500, 600, 700) according to one of the preceding claims, further comprising a heater wiring structure for providing the predefined current, wherein the heater wiring structure has a via extending through the support substrate (120). [5] The light emitter component (100, 210, 400, 500, 600, 700) according to claim 4, wherein the heater wiring structure has a redistribution wiring within a redistribution layer (492) which is arranged adjacent to a surface (141) of the support substrate (140). [6] A light emitter assembly (100, 210, 400, 500, 600, 700) comprising: an emitter component comprising a heater structure (110) arranged on a membrane structure (120), wherein the membrane structure (120) is arranged over a first cavity (130), the first cavity (130) being arranged between the membrane structure (120) and at least a section of a support substrate (140) of the emitter component, wherein the heater structure (110) is configured to emit light when a predefined current flows through the heater structure (110); a lid substrate (150) with a recess (160), wherein the lid substrate (150) is attached to the emitter component such that the recess (160) forms a second cavity (170) between the membrane structure (120) and the lid substrate (150), and wherein the pressure in the second cavity (170) is less than 100 mbar; and a wiring structure for providing different voltages to a prestressing structure of the support substrate (140) or the cover substrate (150) and to the membrane structure (120) in order to move at least a section of the membrane structure (120) electrostatically in the direction of the support substrate (140) or the lid substrate (150). [7] The light emitter device (100, 210, 400, 500, 600, 700) according to claim 6, wherein the prestressing structure of the support substrate (140) or the cover substrate (150) has a ground connection layer (510) arranged between the first cavity (130) and the support substrate (140) or between the second cavity (170) and the cover substrate (150), and wherein the wiring structure is electrically connected to the ground connection layer (510). [8] The light emitter device (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein at least one section of the support substrate (140) is a semiconductor substrate or a glass substrate. [9] The light emitter device (100, 210, 400, 500, 600, 700) according to any of the preceding claims, wherein at least one section of the lid substrate (150) is a semiconductor substrate or a glass substrate. [10] The light emitter element (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the membrane structure (120) has a heat distribution structure, and wherein an insulating layer (430) is arranged between the heat distribution structure and the heater structure (110). [11] The light emitter element (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the heater structure (110) is covered by a second insulating layer (453). [12] The light emitter component (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein at least one section of the heater structure (110) has a meander shape or a ring shape. [13] The light emitter component (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the lid substrate (150) is attached to the emitter component in a gas-tight manner. [14] The light emitter component (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the lid substrate (150) is anodically bonded to the emitter component in a gas-tight manner. [15] The light emitter device (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein a glass is in contact with a semiconductor material at an interface of the cover substrate (150) and the support substrate (140). [16] The light emitter element (100, 210, 400, 500, 600, 700) according to one of the preceding claims, wherein the gas pressure in the second cavity (170) is less than 10 mbar. [17] The light emitter element (100, 210, 400, 500, 600, 700) according to any one of the preceding claims, wherein the heater structure (110) is configured to emit light with a spectrum having a maximum intensity at a wavelength greater than 700 nm and less than 1 mm. [18] A photoacoustic gas sensor (200) comprising a light emitter element (100, 210, 400, 500, 600, 700) according to any one of the preceding claims. [19] A method (300) for forming a light emitter device (100, 210, 400, 500, 600, 700), comprising: Forming (310) an emitter component comprising a heater structure (110) arranged on a membrane structure (120), wherein the membrane structure (120) is arranged over a first cavity (130), the first cavity (130) being arranged between the membrane structure (120) and at least a section of a support substrate (140) of the emitter component, wherein the heater structure (110) is configured to emit light when a predefined current flows through the heater structure (110); and Attaching (320) a lid substrate (150) with a recess (160) to the emitter component, such that the recess (160) forms a second cavity (170) between the membrane structure (120) and the lid substrate (150), and wherein a pressure in the second cavity (170) is less than 100 mbar, wherein an optical filter structure is arranged vertically between the first cavity (130) and the support substrate (140) or between the second cavity (170) and the cover substrate (150), wherein the first cavity (130) is formed by etching a first insulating layer (130) deposited on the support substrate (140).

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