Method for producing microelectromechanical device and microelectromechanical device

Abstract

The invention relates to a method for producing a microelectromechanical device (1) having a functional unit (2), at least one chamber (3) and a cover structure (4) delimiting the at least one chamber (3), the cover structure (4) having at least one chamber access channel (5), the at least one chamber (3) being arranged between the cover structure (4) and the functional unit (2), the cover structure (4) is produced by stepwise applying and optionally structuring material layers (A1, A2, A3, M1, M2, M3, O1) on a cover substrate (6), the functional unit (2) is attached to the cover structure (4), and the at least one chamber access channel (5) is introduced into the cover structure (4) by etching, an etch stop structure (7), which covers the outlet of the chamber access channel (5) and protrudes into the chamber (3), is produced, said etch stop structure having an etch stop element (8) and a first etch stop region (9) arranged in the etch stop element (8). The invention also relates to a microelectromechanical device (1).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a microelectromechanical device (MEMS) and a MEMS device. Background Technology

[0002] Microelectromechanical devices, also known as MEMS devices, and their manufacturing methods are known from existing technologies.

[0003] US 10 626 008 B2 discloses a microelectromechanical device and a method for manufacturing the same. The device is made of semiconductor material and has a sensor region with multiple chambers. A cover wafer with chamber inlets covers the sensor region.

[0004] US 10 508 029 B2 describes a MEMS pressure sensor and a method for manufacturing the same. A cover wafer is mounted on the pressure sensor using eutectic bonding, wherein at least one chamber is formed between the pressure sensor and the cover wafer.

[0005] US 10 023 461 B2 relates to a MEMS sensor having a sensing layer, a cover layer, and an isolation layer extending between edge regions of the sensing layer and the cover layer. Fluid pathways are formed by through-grooves in the central region of the sensing layer and through-openings in the cover layer via air gaps. Summary of the Invention

[0006] According to the features of independent claim 1, a method for manufacturing a microelectromechanical device (MEMS) is proposed, the MEMS having a functional unit, at least one chamber, and a cover structure defining the at least one chamber, the cover structure having at least one chamber access channel, wherein the at least one chamber is disposed between the cover structure and the functional unit, wherein the cover structure is manufactured by progressively applying and optionally structuring layers of material on a cover substrate, the functional unit being attached to the cover structure, and the at least one chamber access channel being introduced into the cover structure by etching, wherein, during the manufacture of the cover structure, an etch stop structure extending into the chamber and covering the outlet of the chamber access channel is generated, the etch stop structure having an etch stop element and a first etch stop region disposed in the etch stop element.

[0007] By fabricating an etch-stop structure attached to the chamber inlet channel outlet on the chamber side, covering the chamber inlet channel, the functional unit of the microelectromechanical device (MEMS) is protected from potentially undesirable etch corrosion when the chamber inlet channel is introduced into the cover substrate. Through a first etch-stop region, the etch depth during the fabrication of the chamber inlet channel is reliably limited, and the chamber inlet channel is introduced into the cover structure only up to the first etch-stop region in the etch-stop structure, without a straight passage through the chamber, allowing for the fabrication of a chamber channel inlet that protects the functional unit from etch corrosion. Through the etch-stop structure covering the outlet of the chamber inlet channel, extending into the chamber, and thus allowing the gas volume within the chamber to flow around at least partially from all sides, the etch-stop region is provided only locally in the region of the chamber inlet channel, such that the chamber volume and the flow path between the chamber inlet channel and the chamber are almost unaffected by the etch-stop structure. Therefore, the fabricated etch-stop structure provides etch protection for the functional unit and enables lower flow resistance and a smaller pressure drop over the inlet channel for the gas volume flowing through the device. Furthermore, as will be explained later, the etching stop structure can form a defined inlet (Zugang) between the chamber inlet channel and the chamber, thereby enabling additional protection of the chamber from environmental influences, liquids and / or solids from a specific defined particle size during device operation.

[0008] The etching stop element may optionally be implemented at a distance from the cover substrate and may be mechanically and / or electrically attached directly to the transverse chamber boundary of the chamber and / or attached to the cover substrate via at least one fixing element.

[0009] Microelectromechanical devices (MEMS) can be devices with microstructures, particularly those manufactured using semiconductor technology. These devices may have mechanical, optical, physical, and / or chemical components and / or functions, and can be used, for example, as miniature sensors or actuators. Such MEMS devices can be, for example, ambient environment sensors, such as pressure sensors. MEMS devices configured as pressure sensors can be based on different pressure measurement principles, such as piezoresistive, piezoelectric, or capacitive pressure sensors. However, the devices and methods described in this application are also applicable in principle to other MEMS devices, such as those configured as actuator devices.

[0010] Functional units of a microelectromechanical device (MEMS) can form functional parts of a device and, for example, are implemented as sensing units with sensing regions. The functional unit may have one or more movable microstructures in the sensing region, the microstructures being configured to perform the sensor function of the functional unit. The movable microstructures may, for example, be constructed as diaphragms. The functional unit may also be or have electronic circuitry, or be connected to circuitry units. The circuitry and / or circuitry units may, for example, be constructed as an ASIC (Application-Specific Integrated Circuit).

[0011] The chamber of a microelectromechanical device (MEMS) can be a cavity constructed between a housing structure and a functional unit, extending into the housing structure, and enabling, for example, the movement of the microstructure within the sensing region. The chamber can be a cavity defined on one side by a housing substrate or a layer of material on the housing substrate. The cavity can be defined on its lateral sides by lateral chamber boundaries of the housing structure, which extend substantially orthogonally to the surface of the housing substrate. After the housing substrate is connected to the functional unit, the chamber can be additionally defined by the surface of the functional unit. Interaction between the microstructure and the surrounding environment of the MEMS can be achieved via the chamber and chamber access channels, for example, to detect ambient pressure. The MEMS may optionally have other chambers, such as hermetically sealed chambers with a predefined reference pressure, to enable measurements based on a reference-based measurement principle.

[0012] The cover structure of a microelectromechanical device (MEMS) can form a protective overlay layer for the functional unit, generated by microstructuring. This protective overlay layer, for example, protects the sensing area of ​​the functional unit from mechanical forces or undesirable environmental influences, and enables controlled and bounded interaction between the sensing area and its surrounding environment via a defined chamber access channel. The cover structure is progressively created by applying material layers to a flat cover substrate, wherein the material layers can substantially have a layer plane with a planar extension dimension parallel to the surface of the cover substrate that is larger than the extension dimension in layer height. The material layers can be structured in separate manufacturing steps to create specific functional cover regions and / or prepare for additional manufacturing steps. For example, bounded areas or segments of the material layer can be locally removed, for example, by applying a mask to one or more material layers and then immediately etching.

[0013] The chamber inlet channel introduced into the cover structure can be formed, for example, substantially orthogonal to the surface of the cover substrate. The chamber inlet channel can be configured to penetrate the cover substrate completely. The chamber inlet channel has an outlet facing the chamber and an inlet facing away from the chamber. An etch-stop structure can be configured to cover the outlet of the chamber inlet channel. The etch-stop structure can be configured to adjoin the outlet of the chamber inlet channel. "Adjoining" in this context means that the structure or component of the etch-stop structure is directly connected to the cover substrate or configured to be spaced apart from the cover substrate in the region of the chamber inlet channel, particularly in the region of the chamber inlet channel facing the chamber outlet. The fluid path configuration between the chamber inlet channel and the chamber can be achieved, for example, by providing at least one etch-stop element, at least one fixing element, and / or at least one connecting channel in the region of the etch-stop structure and / or the cover substrate. It is also conceivable that the etch-stop structure cavity adjoins the region adjacent to the chamber inlet channel on the chamber side; in other words, the etch-stop structure is attached to the cover substrate such that the central axis of the etch-stop structure is implemented to be offset relative to the central axis of the chamber inlet channel. Such misalignment can be, for example, smaller than the minimum lateral dimension of the etch-stop structure, and also smaller than the minimum lateral dimension of the fixing element of the etch-stop structure. The chamber entry channel can be arranged above the sensing area of ​​the functional unit within the housing structure for area optimization of the MEMS device, such as a sensor device and / or an actuator device. The chamber entry channel can, for example, be introduced substantially centrally or at least in the region near the center of the sensing area onto the surface of the housing structure. Therefore, subsequent molding methods for the microelectromechanical device, such as thin-film assisted molding (FAM), can be implemented, in which the device is provided with a housing made of a robust encapsulation material for better protection outside at least one chamber entry channel. In this case, a seal of the chamber entry channel is required technically on the side of the housing substrate opposite to the chamber, and for this purpose, sufficient covering surface surrounding the chamber entry channel is required to secure the protective film, making it advantageous to arrange the chamber entry channel near the center relative to the sensing area. In principle, multiple chamber entry channels and / or at least one chamber entry channel can also be provided outside the sensing area near the center, for example, in the region of the lateral chamber boundary.

[0014] An etch-stop structure for a cover structure can be formed by applying a material layer to a component of the cover structure, such as a cover substrate, and structuring it. The etch-stop structure has an etch-stop element that forms a support structure for a first etch-stop region and protects the first etch-stop region from etch erosion during the sacrificial layer etching process. The etch-stop element can be made of, for example, silicon, such as polysilicon. The etch-stop structure is manufactured such that it extends into a cavity disposed between the cover structure and subsequently attached functional units. The etch-stop structure can therefore be at least sectionally surrounded in its circumferential direction by a cavity cavity and / or a gas volume contained therein. Furthermore, the etch-stop structure can also be connected to and / or integrated therein at least on one side and at least partially with a lateral cavity boundary.

[0015] The first etch stop region can be a material layer or a structured region of a material layer, which preferably has higher etch selectivity or etch resistance relative to the etch process forming the chamber entry channel and the etch medium used therein than the material layer at least directly adjacent to the first etch stop region, and can prevent the etch process or etch progression in the material layer protected by the etch stop region. For example, the material layer of the first etch stop region may be chemically and / or physically more resistant than at least the directly adjacent layer and / or have a significantly lower etch rate relative to at least the directly adjacent layer. The etch stop region is advantageously coordinated with the etch method and etch medium used for manufacturing the cover structure and / or the chamber entry channel.

[0016] The application of a material layer can be performed, for example, by deposition methods known in semiconductor technology, particularly semiconductor-based material layers, such as single-crystal or polycrystalline silicon layers, or dielectric layers composed of silicon compounds, such as silicon dioxide (SiO2) or silicon nitride (Si3N4). The material layer is applied onto a substrate, also known as a mask wafer, which may be, for example, a silicon substrate. The material layer can be applied continuously or partially onto the substrate and / or the already applied material layer. For example, structuring and / or the introduction of cavities and / or recesses can be achieved by an etching process, where the layer material can be locally removed, for example, by a mask. The etching process can advantageously be performed using dry etching methods, such as plasma etching. However, wet chemical etching methods can also be used in principle. Furthermore, the device can be processed by additional processing methods in other optional manufacturing steps, and here it is thinned and / or chemically mechanically polished (CMP process), for example, by a grinding process.

[0017] The attachment of functional units to the cover structure can be performed, for example, in the bonding region by means of a bonding frame structure and, for example, using wafer bonding methods known in semiconductor technology. The bonding frame structure enables the cover structure to be mechanically and / or at least regionally electrically and / or at least regionally non-electrically connected to the functional units. The bonding frame structure can be made, for example, of a hot-pressing material, such as containing gold, or of a eutectic material, such as containing aluminum, silicon, germanium, copper and / or gold, or of a material containing tin and / or copper, or of a polymer-based material or glass paste. At least one dielectric layer may be disposed between the bonding frame structure and the cover structure. This dielectric layer may contain, for example, silicon (Si), aluminum (Al), titanium (Ti), tantalum (Ta), oxygen (O), and / or nitrogen (N), and / or at least one adhesion reinforcement layer may be disposed, for example, containing tantalum (Ta), titanium (Ti), tungsten (W), nickel (Ni), nitrogen (N), and / or platinum (Pt), or a combination of layers composed of the aforementioned materials may be disposed. These layers or combinations of layers may also optionally be used to fabricate electrical conductor rails and electrical contact structures. The aforementioned chemical elements may also exist in the layers as chemical compounds, for example, as silicon dioxide (SiO2), silicon nitride (Si3N4), silicon oxynitride (SiON), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), and / or aluminum oxide (Al2O3) in the dielectric layer, or as, for example, tantalum nitride (TaN), titanium nitride (TiN), and / or titanium-tungsten alloy (TiW) in the adhesion reinforcement layer.

[0018] Functional units can be provided, for example, on a separate functional wafer and connected to a cover structure provided on another wafer, here on a cover substrate, using wafer bonding methods. Thus, a microelectromechanical device (MEMS) can, for example, have a cover wafer and a functional wafer connected thereto. In the lateral direction, i.e., viewed, for example, parallel to the substrate surface, the MEMS can, for example, have a bonding region configured for mechanically and / or electrically connecting the functional units and the cover structure, a sensing region on which the functional units are attached, wherein the device is configured to perform sensor functions by means of at least one microstructure, and a bonding pad region in which the sensing region can make electrical contact with, for example, analytical evaluation circuitry via conductive rails and by means of wire bonding.

[0019] According to one embodiment, a first etch stop region can be surrounded within an etch stop element such that the first etch stop region is completely surrounded by the etch stop element. This allows the first etch stop region to be protected from etch erosion during the etch process steps that occur temporally before the chamber enters the channel. The first etch stop region can form a buried hard mask. This enclosure can be achieved, for example, by applying and structuring an etch stop layer on a first material layer of the etch stop element and by covering the etch stop layer with a second material layer of the etch stop element, wherein the second material layer can cover the first etch stop region such that the first etch stop region is also laterally surrounded by the second material layer. The first and second material layers of the etch stop element can be made of silicon, for example, polysilicon.

[0020] According to one embodiment, at least one connecting channel connecting the chamber to the chamber inlet channel is formed between the etch stop element and the cover substrate and / or in the etch stop element and / or in the cover substrate. This allows a fluid path to be constructed between the chamber inlet channel and the chamber, and the configuration can be tailored to the specific requirements of the cover structure or device. For example, the connecting channel between the etch stop element and the cover substrate can be manufactured by applying and subsequently removing a sacrificial material layer. In this case, the height of the sacrificial material layer can define the height of the connecting channel. The height of the connecting channel, along with its additional lateral dimensions, can determine the blocking effect on particles or liquids ranging from a specific particle size. Manufacturing at least one connecting channel in the cover substrate can be done, for example, by etching a blind-hole-like recess in the substrate surface. Therefore, the connecting channel can be easily manufactured by processing the cover substrate before applying an additional material layer. The connecting channel manufactured in the cover substrate can advantageously also form an etch channel through which the etching medium can be introduced into the cover structure, thereby simplifying or accelerating the etching process. Connecting channels can form transverse channels that extend substantially orthogonal to the perpendicular line of the chamber inlet channel and lead into the chamber inlet channel and the chamber. Multiple connecting channels can form transverse channels that extend substantially orthogonal to the perpendicular line of the chamber inlet channel and lead into the chamber inlet channel and the chamber. An etch-stop structure can at least partially cover one or more transverse channels fabricated in the cover substrate. If the etch-stop structure does not completely cover one or more transverse channels fabricated in the cover substrate, fluid can enter or exit one or more transverse channels in uncovered areas. If the etch-stop structure completely covers one or more transverse channels fabricated in the cover substrate, at least one outlet channel can be introduced into the etch-stop structure to create a fluid path between the chamber and the transverse channels. The outlet channel in the etch-stop structure can extend laterally offset relative to the chamber inlet channel. The outlet channel can extend substantially orthogonal to the connecting transverse channels.

[0021] In principle, it is conceivable to fabricate at least one connecting channel in the etch-stop structure, and additionally, at least one connecting channel in the cover substrate. Furthermore, it is advantageous to fluidically connect the connecting channels to each other to further reduce flow resistance. The geometry and / or shape of the chamber inlet channel, the lateral connecting channel, and / or the outlet channel extending substantially perpendicular to the lateral connecting channel can be selected such that only gaseous media can flow through the chamber inlet, while liquid or solid particles from a certain particle size are blocked upon entering the chamber. This is further facilitated by diversion from the chamber inlet channel into the connecting channel and, if necessary, further diversion into the outlet channel.

[0022] According to one embodiment, a first etch-stop region can be configured to be spaced apart from the outlet of the chamber inlet channel by means of an etch-stop element and / or by means of a fixing element fixed to a cover substrate and / or fixed to a transverse chamber boundary. In this case, the first etch-stop region can particularly cover the outlet of the chamber inlet channel. Therefore, the etch-stop structure can be manufactured, for example, by applying a material layer such that the etch-stop element having the first etch-stop region disposed therein does not directly adjoin the chamber inlet channel, especially not directly adjoin the outlet of the chamber inlet channel, or in other words, at least another material layer is introduced between the chamber inlet channel and the etch-stop element surrounding the etch-stop region. The other material layer can be, for example, a sacrificial material layer. The other material layer can correspond to the material layer of the etch-stop region. By spaced apart from the chamber inlet channel by the etch-stop element having the first etch-stop region disposed therein, for example, it is possible to realize the manufacture of the connecting channel between the chamber and the chamber inlet channel and / or better control the introduction of the chamber inlet channel. Furthermore, the first etch stop region can be protected from etch erosion by setting surrounding etch stop elements during the etch process steps that occur in time before the chamber enters the channel, such as when removing another layer of material.

[0023] According to one embodiment, the first material layer or first etch-stop region of the etch-stop element may be directly adjacent to the outlet of at least one chamber inlet channel. This allows for a compact etch-stop structure. The etch-stop element and / or etch-stop region may, in particular, completely cover the outlet of the chamber inlet channel.

[0024] According to one embodiment, at least one bonding pad region leading to the bonding pad structure and / or an access port leading to the bonding pad structure can be introduced into the cover structure. This achieves good accessibility to the bonding pad region and / or the bonding pad structure.

[0025] According to one embodiment, an etching stop element can be attached to a cover structure and / or a transverse chamber boundary by means of at least one fixing element. For example, the etching stop element can be attached to a cover substrate by means of a fixing element. The fixing element can be constructed outside the chamber inlet channel so that it can be held in place on a structure surrounding the chamber inlet channel. The fixing element can be an integral part of the etching stop element. The fixing element can be made of the same material as the etching stop element, such as a silicon material having silicon or a silicon compound. The fixing element can be entirely constructed between the etching stop element and the cover substrate, or form a substantially point-like or segmental coupling of the etching stop element on the cover substrate and / or on the transverse chamber boundary, and can achieve a spacing between the etching stop element and the cover substrate. The fixing element can be constructed, for example, substantially cuboid or cubic, strip-shaped, annular, segmental, or other suitable geometry. The etching stop element can be attached to the cover substrate by means of multiple fixing elements. For example, multiple cuboid or strip-shaped fixing elements can form a grid structure through which the etching stop element is attached to the cover substrate. An etch-stopping element, implemented with a spacing relative to the substrate, can form at least one fluid path between the chamber and the chamber inlet channel. In other words, at least one connecting channel can be formed in the etch-stopping structure within the plane of the fixing element. Such a connecting channel can be created, for example, by a sacrificial material layer that is applied and subsequently removed, wherein the thickness of the sacrificial material layer can define the spacing of the etch-stopping element relative to the substrate, the height of the fixing element, and the height of the connecting channel. The geometry of the length and cross-section of the at least one connecting channel and / or the shape of the at least one connecting channel can be selected such that only gaseous media can flow into the chamber, while liquid or solid particles from a certain particle size are prevented from entering the chamber.

[0026] According to one embodiment, a sacrificial material layer can be applied and then partially removed to fabricate a fixing element, wherein at least one region in which the sacrificial material has been removed is at least partially filled by a material layer applied on top of the sacrificial material layer. Thus, the fixing element can be fabricated in a simple manner. The filled region or multiple filled regions can each form a fixing element connecting an etch stop element to a cover substrate. The additional material layer can be, in particular, the material layer of the etch stop element, and is made of, for example, silicon, such as polysilicon. The sacrificial material layer can be, for example, a silicon dioxide layer. The sacrificial material layer can be, for example, applied and structured on the cover substrate so that the fixing element can be formed on the cover substrate. The sacrificial material layer can optionally also be formed from multiple sacrificial material monolayers. The sacrificial material layer can optionally also be obtained and / or structured outside the etch stop element to prepare for further process steps and / or to become part of a layer system surrounding the chamber.

[0027] The first etch stop region can be formed, for example, from silicon dioxide. This results in an etch stop region that is easy to manufacture and highly effective. The first etch stop region made of silicon dioxide can, for example, have high chemical etch resistance during plasma etching, allowing the introduction of the chamber entry channel to be carried out in a controlled manner, and the introduction depth can be reliably controlled or limited by the first etch stop region.

[0028] According to one embodiment, a substrate recess can be fabricated before, during, and / or after the formation of the chamber inlet channel. By providing the substrate recess, the entrance to the chamber inlet channel on the side of the substrate opposite to the chamber can be spaced apart from the surface of the cover structure, thereby preventing mechanical damage and / or buildup of the protective film material in the inlet region of the chamber inlet channel during thin-film assisted molding (FAM) in subsequent processes. Before forming the chamber inlet channel, the back side of the substrate can be thinned to a desired target thickness, for example by grinding and / or polishing. To prepare for the fabrication of the chamber inlet channel and the substrate recess, the region of the substrate on the side opposite to the etch stop structure, hereinafter also referred to as the back side of the substrate, can be masked by a third etch stop region or by a third etch stop layer, and then a photoresist mask is applied to the cover structure such that no photoresist is present at least in the region of the chamber inlet channel. The chamber inlet channel can then be etched, wherein the etching process advantageously stops at the first etch stop region of the etch stop structure. During or after the etching chamber entry channel, the photoresist mask can be removed, and a recessed portion of the mask substrate is introduced into the area of ​​the mask substrate not covered by the third etch stop region or the third etch stop layer mask. Subsequently, the third etch stop region or the third etch stop layer can optionally be removed, or left on the mask structure as a mechanical protection and mechanical contact area for further process steps or for the operation of the device.

[0029] For some microelectromechanical devices (MEMS), it may be desirable to fabricate the largest possible chamber volume. In principle, it is conceivable to choose the thickness of the material layer forming the etch-stop element and the lateral chamber boundary as large as possible to enable the fabrication of a large chamber.

[0030] According to one embodiment, a second etch stop region can be created on the etch stop structure, and the lateral chamber boundary of the cover structure is increased such that the height of the lateral chamber boundary of the cover structure relative to the cover substrate is greater than the height of the etch stop structure relative to the cover substrate. This increases the spacing between the etch stop structure and the subsequently attached functional unit, reliably eliminating potential effects, for example, on the movable microstructures of the functional unit caused by the etch stop structure, and increasing the degrees of freedom of movement of the movable microstructures of the functional unit, making, for example, more pronounced deflection of the microstructures possible. Furthermore, for example, in a microelectromechanical device configured as a sensor, the increased chamber volume here can reduce time-related effects such as pressure increases within the chamber caused by diffusion of gaseous elements through the layer system surrounding the chamber, thereby extending the lifespan of the sensor device. The height of the lateral chamber boundary relative to the cover substrate can be understood as the extension scale of the lateral chamber boundary orthogonal to the substrate surface or main extension plane of the cover substrate. The height of the etch stop structure relative to the cover substrate can be understood as the extension scale of the etch stop structure orthogonal to the substrate surface or main extension plane of the cover substrate. The second etch stop region can be considered as a hard mask, for example, made of silicon dioxide, that defines the lateral dimensions of the etch stop structure. During the aforementioned process of increasing the lateral chamber boundary by applying and selectively removing at least one of the material layers, the etch stop structure is reliably protected by the second etch stop region, such that the function of the first etch stop region contained within the etch stop structure for introducing the chamber entry channel can be reliably maintained.

[0031] According to one embodiment, a cavity recess can be introduced into the cover substrate of the cover structure during and / or after the formation of the etch stop structure. This allows the cavity to expand inwards into the cover substrate. For this purpose, the etch stop structure and the lateral cavity boundaries of the cover structure can be masked, for example, by a photoresist mask, and etching can be performed until it penetrates into the cover substrate. If a sacrificial material layer has been applied to the cover substrate in previous process steps, this sacrificial material layer is first removed in a region of the cover substrate where the cavity recess should be formed during the preparation step for introducing the cavity recess. For example, removal of residual sacrificial material layer in the region between the etch stop element and the cover substrate can be performed immediately after the introduction of the cavity recess or at a later time. The cavity recess can achieve an expansion of the cavity cavity formed between the cover structure and the functional unit, i.e., an increase in the volume of the enclosed cavity. By using a larger chamber, for example for a microelectromechanical device configured as a sensor, the time-dependent effect of the increase in intramural pressure per unit time caused by the diffusion of gaseous elements through the layered system surrounding the chamber can be reduced, thereby extending the lifespan of the sensor device.

[0032] It is also conceivable that, during the fabrication of the cover structure, recesses and / or through openings in the bond pad region are introduced into the cover structure. Providing recesses in the bond pad region can be advantageously used, for example, to avoid removing the entire thickness of the cover structure during or after the creation of the chamber access channel, thus enabling the creation of free access ports to the bond pad structure and / or the bond pad region. Openings that completely penetrate the cover structure can be provided in the bond pad region.

[0033] After the chamber inlet channel is introduced into the cover structure, the chamber inlet channel may optionally be closed again, for example by means of a laser-melted layer and / or a substrate material and / or deposition of at least one conductive and / or non-conductive sealing layer. This may be desirable, for example, for sensors, such as inertial sensors, in microelectromechanical devices that operate in a closed chamber and with defined, enclosed internal pressure.

[0034] In principle, it is conceivable that the applied silicon layer and / or the substrate can be doped to improve its conductivity and, for example, can be additionally used as an EMV shield.

[0035] According to the features of independent claim 12, a microelectromechanical device (MEMS) is proposed, the MEMS having a functional unit, at least one chamber, and a cover structure defining the at least one chamber, the cover structure having at least one chamber access channel, wherein the at least one chamber is disposed between the cover structure and the functional unit, wherein the cover structure has a cover substrate and at least one material layer applied to the cover substrate and optionally structured, and wherein the cover structure has an outlet covering the chamber access channel, an etch stop structure extending into the chamber, the etch stop structure having an etch stop element and a first etch stop region disposed in the etch stop element.

[0036] This provides a simple and reliable manufacturable device whose functional units are protected from process influences during manufacturing and from environmental influences during operation by an etch-stop structure.

[0037] According to one embodiment, the first etch stop region can be completely surrounded by the etch stop element. This provides a simple and reliable manufacturable device because the first etch stop region is protected from etch erosion during the etch process steps that occur temporally before the chamber enters the channel.

[0038] According to one embodiment, the shield structure may have at least one connecting channel between the etch stop element and the shield substrate and / or within the shield substrate, connecting the chamber and the chamber inlet channel. This allows a fluid path to be constructed between the chamber inlet channel and the chamber, and can be configured according to specific requirements for the shield structure or device.

[0039] Furthermore, the device may have other features in conjunction with the methods described above, such as... - The first etch stop area at the exit of the covered chamber inlet channel can be set; - The first etch stop region may be set at a distance from the outlet of the chamber inlet channel by means of an etch stop element and / or a fixing element; - The etching stop element can be attached to the cover structure and / or the transverse chamber boundary by means of at least one fixing element; - The first material layer and / or the first etch stop region of the etch stop element may be directly adjacent to the outlet of the chamber inlet channel; - The cover structure can have a recessed portion in the cover base; -The transverse chamber boundary of the cover structure has a greater height relative to the cover substrate than the etch stop structure; - The cover structure can have a recessed chamber; and / or - The cover structure may have an access port leading to the bond disk structure and / or the bond disk region.

[0040] The aforementioned apparatus and method can be applied, for example, in MEMS sensor technology. In principle, the method can be used to fabricate any microelectromechanical device in which a chamber is provided or requires a chamber access channel. The proposed method avoids etching on the sensing area of ​​the device, and in principle, also on other components of the device, such as circuit elements.

[0041] In a completely general sense, in the context of this application, the word “a / one” should not be understood as a quantifier unless otherwise stated, but rather as an indefinite article with the meaning of “at least one”. Attached Figure Description

[0042] This invention allows for different implementations, and will be further explained below with reference to the accompanying drawings and embodiments. In the drawings: Figure 1-6 :- A schematic side sectional view illustrates the method steps for manufacturing a microelectromechanical device according to the first embodiment; Figure 7-8 :- The schematic side sectional view illustrates the method steps for manufacturing the microelectromechanical device according to the second embodiment; Figures 9a-9b :- The method steps for manufacturing a microelectromechanical device according to the third embodiment are shown in the schematic side sectional view; Figure 10 :-The schematic cross-sectional view illustrates the method steps for manufacturing the microelectromechanical device according to the fourth embodiment; Figures 11a-11c According to three variations of the fourth embodiment Figure 10 A magnified view of a portion of the image. Detailed Implementation

[0043] First refer to Figure 6 The first embodiment of the microelectromechanical device 1 is explained below, which can be manufactured by a method that will be further described below.

[0044] Figure 6 A microelectromechanical device 1 according to a first embodiment is shown. The device 1 shown has a functional unit 2, at least one chamber 3, and a cover structure 4 of the boundary chamber 3. The cover structure has at least one chamber entry channel 5, wherein the at least one chamber 3 is disposed between the cover structure 4 and the functional layer 2. The cover structure 4 has an outlet covering the at least one chamber entry channel 5 and an etch stop structure 7 extending into the chamber 3. The etch stop structure has an etch stop element 8 and a first etch stop region 9 arranged in the etch stop element 8.

[0045] By fabricating an etching stop structure 7 covering the outlet of the chamber inlet channel 5, the functional unit 2 of the microelectromechanical device 1 is protected from unwanted etching during the introduction of the chamber inlet channel 5. The etching depth during the fabrication of the chamber inlet channel 5 is reliably limited by the first etching stop region 9. The etching stop region 9 is provided only locally in the region of the chamber inlet channel 5 by the etching stop structure 7, which covers the outlet of the chamber inlet channel 5, extends into the chamber 3, and is therefore at least partially bypassed by the gas volume in the chamber, such that the chamber volume and the flow path 10 between the chamber inlet channel 5 and the chamber 3 are almost unaffected by the etching stop structure 7. In principle, the material of the etching stop region 9 can also be present in the layer system surrounding the chamber 3. Furthermore, the etching stop structure 7 can form a defined inlet between the chamber inlet channel 5 and the chamber 3, thereby enabling, during operation of the device 1, the chamber 3 to be additionally protected from environmental influences, liquids, and / or solids from a specific particle size.

[0046] exist Figure 6 In the diagram, the etched chamber inlet channel 5 is shown as a free surface. In relation to the method steps for manufacturing the apparatus 1 described below, the chamber inlet channel 5 is indicated by dashed lines in the process steps prior to this etching, so as to illustrate its position within the cover structure 6.

[0047] exist Figure 6The functional unit 2 of the device 1 shown can be, for example, a sensing unit. The region of the chamber 3 can be considered the sensing region 16, while the laterally adjacent region having the bonding frame structure 17 and a bonding pad (not shown) can be referred to as the bonding pad region 15 and is used for the electrical contact of the device 1. The bonding pad region 15 has a bonding pad region recess 21. The cover base 6 of the cover structure 4 has an optional cover base recess 12 and an optional third etch stop region 18. The chamber 3 has a lateral chamber boundary 20. The etch stop structure 7 has an etch stop element 8, a first etch stop region 9 completely surrounded therein, at least one fixing element 11, and at least one connection channel 10 constructed between the etch stop element 8 and the cover base 6 for connecting the chamber inlet channel 5 to the chamber 3. The above components and features will be further explained according to the method steps for manufacturing the device 1.

[0048] The following will be based on Figures 1 to 6 An embodiment of the method for manufacturing the microelectromechanical device 1 according to the first embodiment is explained, wherein, Figures 1 to 3 Basically, the fabrication of the cover structure 4 is shown and Figures 4 to 6 This basically shows further manufacturing of device 1. Figure 1 As can be seen, a sacrificial material layer O1, for example made of silicon dioxide, is first deposited on the substrate 6. The sacrificial material layer O1 is structured such that the sacrificial material is removed in the bonding frame region shown above the bonding frame structure 17 in the figures. It is also conceivable that the sacrificial material of the sacrificial material layer O1 is also disposed outside the chamber region such that it is not removed during the sacrificial layer etching process used to remove the sacrificial material of the sacrificial material layer O1 in the chamber region and can be retained at least regionally, for example, in the region of the bonding frame structure 17. Furthermore, the sacrificial material is removed in the region adjacent to the chamber inlet channel 5 so that the fixing element 11 of the etch stop structure 7 can be constructed in subsequent steps. Figure 1 It can be further seen that the first material layer M1 is deposited after the structured sacrificial material layer O1 such that the area where the sacrificial material layer O1 is removed is at least partially filled with the material of the material layer M1. Thus, the fixing element 11 of the etch stop structure 7 is fabricated using the first material layer M1, which may be made of, for example, polysilicon. Furthermore, the first material layer M1 constitutes part of the etch stop element 8 of the etch stop structure 7. If as in Figure 1As shown, at multiple locations adjacent to the chamber entry channel 5, the sacrificial material layer O1 has been removed and multiple retaining elements 11 have been formed by filling. These retaining elements can, for example, form a grid structure surrounding the chamber entry channel 5, which can then prevent particles from entering the chamber 3. The height of the retaining elements 11 depends on the thickness of the sacrificial material layer O1, such that the spacing between the retaining elements 11 and / or the selection of the thickness of the sacrificial material layer O1 can limit the size of particles that can be prevented from entering the chamber 3. Because the sacrificial material layer O1, for example, made of silicon dioxide, can be manufactured very thin, effective protection can be achieved even for the intrusion of very small particles.

[0049] Following deposition, the first material layer M1 can optionally be planarized to produce a flat surface. (As shown by...) Figure 1 Furthermore, in another step, a first etch stop layer A1 is applied and structured to enable the construction of at least one first etch stop region 9 within the etch stop structure 7. In principle, the material of the etch stop region 9 can also be present in the layer system surrounding the chamber 3. The first etch stop region 9 can, for example, be made of silicon dioxide. The first etch stop region 9 then serves as an etch stop surface to limit the introduction depth of the chamber entry channel 5, as will be further explained later. Figure 1 Furthermore, in another step, a second material layer M2, which may be made of polysilicon, is deposited such that the first etch stop region 9 is covered by the material layer M2, particularly surrounding its sides. Subsequently, the second material layer M2 may optionally be planarized. (As shown by...) Figure 1 Furthermore, in another step, a bonding framework structure 17 is formed on the second material layer M2. The bonding framework structure 17 may have at least one element for creating a eutectic bonding connection, a thermoforming bonding connection, or a brazing connection between the cover substrate 6 and the functional unit 2, and may contain, for example, elements such as gold, tin, nickel, aluminum, titanium, tantalum, tungsten, copper, germanium, silicon, oxygen, or nitrogen. The bonding framework structure 17 may also optionally be composed, for example, of a glass paste, a sealing glass material, or a glass solder.

[0050] In principle, it can also be conceivable that the etch stop element 8 is made of the material of the second material layer M2 and / or the third material layer M3, if a suitable gap has been created in the previously applied material layer before the deposition of the material layer or these material layers.

[0051] exist Figure 2As can be seen, after fabricating the bonding frame structure 17, a first photoresist mask F1 is applied, which covers at least one region of the etch stop structure 7, the bonding frame structure 17, and the region of the cover structure 4 configured to construct the lateral chamber boundary 20 and / or the bonding pad region recess 21. Specifically, the first photoresist mask F1 is positioned in the region of the etch stop structure 7 such that the first etch stop region 9 is completely and at least partially located within the region masked by the photoresist mask F1. To avoid unwanted etching of the first etch stop region 9 during subsequent etching steps to remove the sacrificial material layer O1, the position of the first etch stop region 9 within the region masked by the photoresist mask F1 is preferably chosen such that the spacing between the etch stop region 9 and the surrounding contour of the masked region is not less than a defined minimum spacing.

[0052] As by Figure 2 Further, an etching process, such as a silicon etching process, is then performed. This etching process removes the first material layer M1 and the second material layer M2 in the area not masked by the photoresist mask F1, and stops on the sacrificial material layer O1 made of silicon dioxide. Through this etching process, a chamber 3 with a lateral chamber boundary 20 and an etching stop structure 7 are constructed. Alternatively, a bonding pad region recess 21 can be constructed by the same etching process. With the first photoresist mask F1 applied over a correspondingly large area, the etching stop structure 7 can be constructed such that the first etching stop region 9 is set at a distance from the surrounding contour of the etching stop element 8 formed by the first material layer M1 and the second material layer M2.

[0053] exist Figure 3 As can be seen, the sacrificial material layer O1 is completely removed in another step to expose at least one fixing element 11 and to create a connection channel 10 between the etch stop element 8 and the cover substrate 6 in the region of the etch stop structure 7, through which a fluid path can be constructed between the chamber inlet channel 5 and the chamber 3. In other words, the connection channel 10 is created by removing the sacrificial material layer O1 between the cover substrate 6 and another etch stop element 8 of the etch stop structure 7, in which a cross-section of the connection channel 10 can be created that is defined by one or more spacings between the fixing elements 11 and / or the thickness of the sacrificial material layer O1. After the removal of the first photoresist mask F1, there is a prepared cover structure 4, which is based on the... Figure 4 The schematic diagram shown can be attached to functional unit 2.

[0054] exist Figure 4As can be seen, in another step, the prepared cover structure 4 can be attached to the functional unit 2 via the bonding frame structure 17. The functional unit 2 can be, for example, a functional wafer with MEMS components and / or ASIC components. The etching stop structure 7 subsequently prevents etching on the surface of the functional unit 2 during the fabrication of the chamber entry channel 5. Following the attachment of the functional unit 2, optionally, the cover substrate 6 and / or the functional unit 2 can be thinned to the desired target thickness by grinding and / or polishing in the back-side thinning step.

[0055] exist Figure 5 As can be seen, in another step, a third etch stop region 18 can be formed on the back side of the back-side thinned cover substrate 6, which is made, for example, by an applied and structured third etch stop layer A3. The third etch stop layer A3 can, for example, be a silicon dioxide layer. Briefly, the second etch stop region 13 is still combined below according to... Figure 7 The second embodiment is explained. The third etch stop region 18 can be used in subsequent steps to create the cover substrate recess 12 and / or to create a channel leading to the bonding pad region 15, and optionally to subsequently form the mechanical protection or mechanical contact region of the device 1. Figure 5 Furthermore, it can be seen that the second photoresist mask F2 can be applied to the third etch stop region 18 and the back surface of the mask substrate 6, wherein a notch is created in the region of the chamber entry channel 5 during masking. Figure 5 Furthermore, the chamber entry channel 5 is etched through the cover substrate 6 by an etching process, particularly a plasma etching process. This plasma etching process not only removes the cover substrate material but also at least partially removes the first material layer M1 in the etching stop structure 7. After at least partially removing the first material layer M1, the plasma etching process stops at the first etching stop region 9, thus preventing etching erosion on the functional unit 2. If optionally, the material in the third etching stop region 18 is located in the region of the chamber entry channel 5, then that material must be removed along with the material as it is introduced into the chamber entry channel 5 through the cover substrate 6. Alternatively, the material in the third etching stop region 18 can also be removed before being introduced into the chamber entry channel 5 by performing a separate etching process.

[0056] For example, by Figure 6 As can be seen, after the inlet channel 5 passes through the cover substrate 6, the second photoresist mask F2 is removed in another step, creating a cover substrate recess 12. The third etch stop region 18, acting as a mask, can at least partially pre-define the lateral boundaries of the cover substrate recess 12. Subsequently, the third etch stop region 18 can optionally be removed or retained on the device 1 as a mechanical contact area.

[0057] The following is for reference. Figure 7and Figure 8 The microelectromechanical device 1 according to the second embodiment and the method for manufacturing it will be explained, wherein two individual intermediate states of the method are selected and other steps can be performed similarly to the method according to the first embodiment. For some microelectromechanical devices 1, it may be desirable to manufacture a chamber volume as large as possible. In principle, it is conceivable that the thicknesses of the material layers M1 and M2 forming the etch stop element 8 and the lateral chamber boundary 20 are chosen to be as large as possible to create a large chamber 3. However, it is also possible, for example, as in... Figure 7 As shown, a second etch stop region 13 is created on the etch stop structure 7 by applying and structuring a second etch stop layer A2, followed by the application of at least one additional material layer M3. Subsequently, the area of ​​the cover structure 4 can be masked by a photoresist mask F1 to pre-define the lateral boundaries of the lateral chamber boundary 20 and / or the bonding pad region recess 21, and then the chamber 3 and / or the bonding pad region recess 21 are etched in the cover structure 4, wherein the etching process stops on the sacrificial material layer O1. Through the second etch stop region 13 previously applied to the etch stop structure 7, the etch stop structure 7 is reliably protected from etching within the chamber 3, thus maintaining its function. The third material layer M3 increases the chamber size of the chamber 3 and further increases the spacing between the etch stop structure 7 and the functional unit 2, as described by... Figure 8 As can be seen, after manufacturing chamber 3, the second etch stop region 13 may optionally be removed together with the sacrificial material layer O1. Figure 8 The diagram shows the state of device 1 after the cover structure 4 is attached to the functional unit 2 and after the cover base recess 12 and the chamber entry channel 5 are introduced. Figure 8 As can be further seen, the transverse chamber boundary portion 20 has a greater height h1 relative to the cover substrate 6 than the etch stop structure 7 with a height h2, due to the raised portion 20' formed by the third material layer M3. The spacing of the etch stop structure 7 relative to the functional unit 2 can be determined by the height of the other material layer M3.

[0058] The following is for reference. Figure 9a and 9b The microelectromechanical device 1 according to the third embodiment and the method of manufacturing the same are explained, wherein two individual intermediate states of the method are selected and other steps can be performed similarly to the method according to the first and / or second embodiments.

[0059] exist Figure 9aAs shown, after fabricating the etch stop structure 7, a chamber recess 14 is introduced into the cover substrate 6 of the cover structure 4. For this purpose, in the region of the already formed cover recess 14, the sacrificial layer material of the sacrificial material layer O1 applied to the cover substrate 6 is removed such that the remaining sacrificial material of the sacrificial material layer O1 is used at least regionally as an etch mask during the fabrication of the cover recess 14. In this case, it is preferable to retain material of the sacrificial layer O1 between the etch stop element 8 and the cover substrate 6 in the region of the etch stop structure 7 to create at least one connecting channel 10 between the chamber inlet channel 5 and the cover recess 14 and / or the chamber 3. On the structured sacrificial material layer O1, a first material layer M1, a first etch stop region 9, and a second material layer M2 are subsequently formed, and optionally a second etch stop region 13 and a third material layer M3 are formed to fabricate the etch stop structure 7. Immediately afterwards, the region of the etch stop structure 7 and the region of the cover structure 4 are masked by a photoresist mask F1 and etched until they penetrate into the cover substrate 6. The recessed portion 14 allows the chamber volume of chamber 3 to be increased towards the cover base 6, thus providing a more compact device 1 with a larger chamber volume. Figure 9b As can be seen, the remaining sacrificial material layer O1 between the etch stop element 8 of the etch stop structure 7 and the cover substrate 6 is then removed, and the cover structure 4 is prepared for attachment to the functional unit 2. In this embodiment, the sacrificial material layer O1, which additionally serves as an etch mask, is disposed in the region of the etch stop structure 7 such that the outline of the sacrificial material layer O1 surrounds the etch stop structure 7 and at least partially protrudes beyond the outline of the etch stop structure 7.

[0060] Below Figure 10 The method for manufacturing the microelectromechanical device 1 according to the fourth embodiment is explained based on an intermediate state. Figure 11a , 11b And 11c shows in Figure 10 Different variations of the detailed portion marked in the figure relate to the transition between the etch stop structure 7 and the adjacent chamber inlet channel 5. As shown, an etch channel 19 can be introduced into the cover substrate 6 in or adjacent to the chamber inlet channel 5, via which rapid removal of the sacrificial material layer O1 in the region of the etch stop structure 7 can be achieved. The etch channel 19 can be introduced into the cover substrate 6, particularly as a narrow tunnel structure, which can be well closed on the surface. Furthermore, at least one etch channel can extend beyond the width of the etch stop structure 7, such that, as in Figure 11bAs shown, a connecting channel 10 is formed between the chamber inlet channel 5 and the chamber 3 in the cover substrate 6, thus providing a fluid path into the chamber 3. In this case, the etching stop element 8 of the etching stop structure 7 does not need to be attached to the cover substrate 6 via a fixing element 11 with a notch in the middle to create a chamber inlet; instead, the etching stop element 8 can be directly and fully attached to the cover substrate 6. According to Figure 11c At least one etching channel 19 may also be entirely disposed within a transverse region defined by the surrounding contour of the etching stop structure 7 within the cover substrate 6, and at least one outlet channel 22 is introduced into the etching stop structure 7, which creates a fluid path between the etching channel 19, which serves as a connecting channel 10 leading to the chamber inlet channel 5, and the chamber 3. In this embodiment variant, the etching channel 19 may be at least partially and / or at least surface-levelly closed by the material of the first etching stop region 9 immediately after being introduced into the cover substrate. Figure 11b and / or Figure 11c In one of the variations shown, the etch stop element 8 and / or the first etch stop region 9 may be configured to directly adjoin at least one chamber inlet channel 5, and the material applied to the cover substrate 6, for example, the first etch stop region 9, is used to at least surface-close the chamber inlet channel 5. Thus, the etch stop structure 7 can be constructed relatively flat and have a large spacing relative to the attached functional unit 2. Furthermore, the application of the second material layer M2 and the sacrificial material layer O1 can be omitted, thereby simplifying the manufacturing process.

[0061] It should be noted, as a precaution, that the method steps and variations described according to the first to fourth embodiments can be combined with each other in any way.

[0062] With the methods and apparatus described, it is possible to manufacture microelectromechanical devices in a simple and reliable manner, as well as to operate them safely and for a long period of time.

Claims

1. A method for manufacturing a microelectromechanical device (1), the microelectromechanical device having a functional unit (2), at least one chamber (3) and a cover structure (4) defining the at least one chamber (3), the cover structure (4) having at least one chamber access channel (5). in, The at least one chamber (3) is disposed between the cover structure (4) and the functional unit (2). The cover structure (4) is fabricated on a cover substrate (6) by progressively applying and optionally structuring material layers (A1, A2, A3, M1, M2, M3, O1), the functional unit (2) is attached to the cover structure (4), and the at least one chamber inlet channel (5) is introduced into the cover structure (4) by etching. In the process of manufacturing the cover structure (4), an etch stop structure (7) extending into the cavity (3) and covering the outlet of the cavity inlet channel (5) is generated. The etch stop structure has an etch stop element (8) and a first etch stop region (9) arranged in the etch stop element (8).

2. The method according to claim 1, wherein, The first etch stop region (9) is thus surrounded in the etch stop element (8) such that the first etch stop region is completely surrounded by the etch stop element (8).

3. The method according to claim 1 or 2, wherein, At least one connection channel (10) is created between the etching stop element (8) and the cover substrate (6) and / or in the etching stop element (8) and / or in the cover substrate (6) to connect the chamber (3) to the at least one chamber entry channel (5).

4. The method according to any one of the preceding claims, wherein, The first etching stop region (9) is set apart from the chamber entry channel (5) by means of the etching stop element (8) and / or by means of the fixing element (11) by fixing it to the cover base (6) and / or fixing it to the transverse chamber boundary (20, 20').

5. The method according to any one of claims 1 to 3, wherein, The first material layer (M1) or the first etching stop region (9) of the etching stop element (8) is directly adjacent to the outlet of the at least one chamber inlet channel (5).

6. The method according to any one of the preceding claims, wherein, Introduce at least one access point to the bonding disk region (15) and / or the bonding disk structure into the cover structure (4).

7. The method according to any one of the preceding claims, wherein, The etching stop element (8) is attached to the cover structure (4) and / or the transverse chamber boundary (20, 20') by means of at least one fixing element (11).

8. The method according to claim 7, wherein, In order to manufacture the fixing element (11), a sacrificial material layer (O1) is applied and then partially removed, wherein at least one area in which the sacrificial material is removed is at least partially filled by a material layer (M1) applied on the sacrificial material layer (O1).

9. The method according to any one of the preceding claims, wherein, Before and / or during and / or after the chamber entry channel (5) is created, a cover base recess (12) is made.

10. The method according to any one of the preceding claims, wherein, A second etch stop region (13) is created on the etch stop structure (7), and the lateral chamber boundaries (20, 20') of the cover structure (4) are increased such that the height (h1) of the lateral chamber boundaries (20, 20') of the cover structure (4) (h1) relative to the cover substrate (6) is greater than the height (h2) of the etch stop structure (7) relative to the cover substrate (6).

11. The method according to any one of the preceding claims, wherein, During and / or after the creation of the etch stop structure (7), the chamber recess (14) is introduced into the cover substrate (6) of the cover structure (4).

12. A microelectromechanical device (1) having a functional unit (2), at least one chamber (3), and a cover structure (4) defining the at least one chamber (3), the cover structure having at least one chamber access channel (5), wherein, The at least one chamber (3) is disposed between the cover structure (4) and the functional unit (2), wherein the cover structure (4) has a cover base (6) and at least one material layer (A1, A2, A3, M1, M2, M3, O1) applied to the cover base and optionally structured, wherein the cover structure (4) has an outlet covering the chamber entry channel (5) and an etch stop structure (7) extending into the chamber (3), the etch stop structure having an etch stop element (8) and a first etch stop region (9) arranged in the etch stop element (8).

13. The microelectromechanical device (1) according to claim 12, wherein, The first etch stop region (9) is completely surrounded by the etch stop element (8).

14. The microelectromechanical device (1) according to claim 12 or 13, wherein, The cover structure (4) has at least one connection channel (10) between the etching stop element (8) and the cover substrate (6) and / or in the cover substrate (6) to connect the chamber (3) to the at least one chamber access channel (5).

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