Method for manufacturing a microelectromechanical component structure, microelectromechanical component structure, microelectromechanical device and microelectromechanical loudspeaker

Abstract

The invention relates to a method (100) for producing a microelectromechanical component structure (200) with a first substrate (20) having a substrate surface (21) and with at least one vertical functional area (F) extending substantially perpendicular to the substrate surface (21), wherein the at least one vertical functional area (F) is delimited from an adjacent sacrificial area (O) by creating and passivating at least one vertical trench (70) and is exposed by removing the sacrificial area (O), wherein a bonding surface (23) is produced on the substrate surface (21) of the first substrate (20) by applying at least one layer (22), and wherein a second substrate (30) is applied to the bonding surface (23), in which at least one vertical trench (70) is created up to the bonding surface (23) of the first substrate (20).The invention also relates to a microelectromechanical component structure (200), a microelectromechanical device (300) and a microelectromechanical loudspeaker (400).

Description

[0001] The invention relates to a method for manufacturing a microelectromechanical component structure, a microelectromechanical component structure, a microelectromechanical device and a microelectromechanical loudspeaker. State of the art

[0002] Microelectromechanical structures, also known as MEMS structures, as well as methods for their production are known from the state of the art.

[0003] DE 10 2015 206 996 A1 discloses a method for manufacturing microelectromechanical structures in a layer sequence and a corresponding electronic component with a microelectromechanical structure.The process comprises providing a support substrate with a first surface, applying an insulating layer to the first surface, epitaxially growing a first silicon layer onto the insulating layer, structuring the first silicon layer to form trenches in the first silicon layer, passivating the first silicon layer, wherein the trenches are filled and a passivation layer forms on a side facing away from the first surface, structuring the passivation layer, wherein sacrificial areas and functional areas are formed in the first silicon layer and the sacrificial areas are at least partially free of the passivation layer on a side facing away from the support substrate, and finally removing the sacrificial areas.

[0004] EP 3 912 953 A1 describes a method for manufacturing a MEMS device in which a first and a second structural layer are produced and provided with trenches and masking layers.

[0005] US 2015 / 0 274 ​​512 A1 describes MEMS devices and manufacturing processes in which a first dielectric layer with integrated circuits is formed on a first substrate, a second dielectric layer with an accelerometer is created on top of this, and a second substrate is applied to the second dielectric layer.

[0006] US Patent 8 043 931 B1 relates to a process for manufacturing a multilayer silicon structure by producing structured individual layers and aligning and joining the individual layers. Disclosure of the invention

[0007] According to the features of independent claim 1, a method is proposed for producing a microelectromechanical component structure with a first substrate having a substrate surface and with at least one vertical functional region which extends substantially perpendicular to the substrate surface, wherein the at least one vertical functional region is delimited from an adjacent sacrificial region by creating and passivating at least one vertical trench and is exposed by removing the sacrificial region, wherein a bonding surface is created on the substrate surface of the first substrate by applying at least one layer, and wherein a second substrate is applied to the bonding surface, in which at least one vertical trench is created.

[0008] In other words, the proposal aims to produce microelectromechanical component structures with a layered architecture comprising more than one substrate. The use of substrates allows for greater layer thicknesses than, for example, epitaxial growth or deposition processes. Therefore, the proposed method enables the simplified production of microelectromechanical component structures and functional areas with large vertical dimensions, such as those exceeding 100 µm. Furthermore, the presented method allows for the fabrication of laterally narrow structures, for example, with a width of less than 20 µm, which can also be achieved with tight tolerances, such as less than 10 µm, less than 5 µm, or less than 2 µm. A narrow structure can, for example, increase the mobility of the functional area and reduce its stiffness.The manufacturing process, which utilizes passivated vertical grooves and optional horizontal etch stop zones (described later), allows for a high degree of design freedom with virtually any vertical and horizontal structure. These zones can separate sacrificial and functional areas, enabling the removal of the sacrificial zones or, alternatively, the separation of functional areas with different potentials. The functional areas can, for example, form mechanical or electrical connections and extend across the entire vertical dimension of the component structure or a substrate (such as a MEMS chip), or only across a portion thereof, and can be individually configured locally.This allows, for example, the creation of movable structures or the free definition and design of electrical connections and insulation; for instance, vertical and / or horizontal electrical potential guidance or separation is possible. Furthermore, horizontal electrical potential guidance can be used for mechanical stability purposes or for the horizontal connection of vertically offset structures. Moreover, the trenches in the second substrate, or in other substrates described later, can be created easily and with high accuracy compared to trench construction using layered material sequences with individually applied material layers of comparable vertical extent.Furthermore, the microelectromechanical structure can be manufactured economically and efficiently using the presented method, as a single substrate can achieve a large layer height cost-effectively compared to material layers of comparable vertical extent produced by epitaxial growth or deposition processes. Furthermore, the presented method is suitable for CMOS and high-temperature applications. Attaching a second or additional substrate, for example, using a direct wafer bonding process, is also thermally and energetically more advantageous than, for example, epitaxial growth processes with a comparable structure height. For example, epitaxial growth processes can require a process temperature of over 1,000 °C, while wafer bonding processes can take place at temperatures below 100 °C. Furthermore, a smaller wafer bow can be expected with the presented method.By creating a stable, solid layer structure with substrates, no moving structures are present during the process. The resulting structures are fixed during the process flow via vertical and horizontal passivation and etch stop structures, thus ensuring high process reliability. The deep structuring of the component is achieved by contouring the functional and sacrificial areas, eliminating the need for large-volume etching in the trench process and allowing for more precise definition of the structural elements, resulting in a reduced trench angle and less tilting.

[0009] The first substrate, also known as a wafer, can be, for example, a silicon substrate, particularly a monocrystalline one. The first substrate can form a planar support structure for the microelectromechanical component structure, having a base area and a substrate surface opposite the base area, on which the further component structure can be built up as a layer sequence. The base area and the substrate surface can comprise the largest surface area of ​​the first substrate and each have a length and width that are greater than the depth of the first substrate. The extension directions of the substrate surface can define a horizontal plane of the microelectromechanical component structure. The component structure can, for example, have a rectangular cross-sectional profile.

[0010] The vertical functional region produced using the method presented can have a vertical extension perpendicular to the substrate surface that is greater than a horizontal extension of the functional region parallel to the substrate surface. The vertical functional region can, in particular, be embodied as a narrow structure, for example, have a width of less than 20 µm or have an extension in the vertical direction that is several times, for example, at least five times or at least ten times greater than in the horizontal width and / or depth direction. As a narrow structure, the vertical functional region can advantageously fulfill certain functions of the microelectromechanical component structure, for example, form a movable structure and thereby a sensing element, or assume a mechanical function such as a support function between spaced-apart component elements.

[0011] Creating a vertical trench can be achieved, for example, using a trenching process to produce a narrow trench with high accuracy. At least one trench created in the second substrate can advantageously extend to the bonding surface of the first substrate. The position of the trench, or multiple trenches, can be predetermined for trench creation, for example, by a structured etch stop layer acting as a masking layer. Passivation of the created vertical trench can be achieved by surface passivation of the trench surface or, for example, by filling it with a passivation material that acts as an etch barrier, thus stopping the etching process at the passivated trench. For example, a horizontal etch stop layer can be applied to the second substrate containing the vertical trench. Due to capillary action, this layer penetrates the vertical trench and passivates it.

[0012] The application of at least one layer can refer to the application of a material layer made of, in particular, a semiconductor-based material. Such a material layer can, for example, be a monocrystalline, polycrystalline, or amorphous silicon layer or a dielectric layer with a silicon compound such as silicon dioxide (SiO2) or silicon nitride (Si3N4). The application of at least one layer can further refer to the application of an auxiliary layer such as an etch stop layer or sacrificial layer, which can be optionally removed again during the process or subsequently, for example by means of an HF gas-phase etching process. Etch stop layers or sacrificial layers can, for example, comprise a silicon compound such as silicon dioxide (SiO2) or silicon nitride (Si3N4).An etch-stop layer can be used, for example, to define horizontal boundaries within the component structure and protect adjacent structural areas from etching. In particular, it is conceivable to include etch-stop areas in sections of the component structure where a subsequently added vertical trench is intended to end. The application of at least one layer can also refer to the application of a layer sequence, which may, for example, consist of one or more material layers and / or one or more auxiliary layers. An applied layer can also optionally be structured, for example, by etching, to create spaced-apart layer regions.

[0013] The second substrate, as well as any further substrates discussed later, can be similar to or identical to the first substrate in terms of material and dimensions. For example, the second or further substrate can advantageously be a silicon substrate, particularly a monocrystalline one. According to one embodiment, the first substrate and the second or further substrate can have essentially the same substrate height. Alternatively, it is conceivable that the second or further substrate has a greater or lesser substrate height in order to define individual layer heights of the microelectromechanical component structure. The substrate height can also be influenced, for example, by thinning the second or further substrate. The application of the second or further substrate can be carried out, for example, by a wafer direct bonding process.

[0014] The bonding surface can be a surface of the layer structure facing away from the first substrate, comprising the first substrate and at least one layer, wherein the bonding surface can run parallel to the substrate surface of the first substrate. The bonding surface is provided for connecting the second substrate to the existing layer structure and forms an interface between at least one layer applied to the first substrate and the second substrate. In this case, it can be advantageous to create a continuous bonding surface so that the second substrate can lie flat on the bonding surface. In particular, a structured layer with layer sections spaced apart from one another by the structuring can be filled with a material in such a way that a continuous bonding surface is created.

[0015] After the introduction and passivation of at least one vertical trench, or in a final step of the process, the functional area can be exposed by removing an adjacent sacrificial layer. The functional area may also be bordered by several sacrificial layers, for example, two or more, which are removed to expose the functional area. This removal can be achieved by an etching process, which can stop vertically at the passivated trench and horizontally at an auxiliary layer such as an etch stop layer. The etching process can be suitable, for example, for removing silicon material. The etching process can be, for example, an isotropic plasma etching process using sulfur hexafluoride (SF6) or a gas-phase etching process using xenon difluoride (XeF2).The removal of sacrificial areas can be performed starting from the surface of a recently applied substrate and / or from the back side of the first substrate, opposite the substrate surface of the first substrate. Optionally, following the removal of the sacrificial area, passivation and etch stop material can also be removed from the component structure to ensure complete exposure of the functional area.

[0016] According to one embodiment, the bonding surface of the first substrate can be created by applying and structuring a first etch stop layer to form spaced-apart etch stop regions and by filling gaps between the etch stop regions with a material layer. This allows a bonding surface to be specifically created that can provide etch stop regions as an etch barrier, for example, to limit the depth of vertical trenches. Furthermore, the etch stop regions can form a horizontal boundary, for example, between a sacrificial region and a functional region of the component structure, so that an etching process for removing a sacrificial region stops on the etch stop region and an adjacent region is protected from etching attack. The etch stop layer can be, for example, a silicon dioxide layer or a silicon nitride layer.The etch stop layer can be applied, for example, by thermal oxidation and / or chemical vapor deposition. Horizontally oriented etch stop areas and vertically oriented passivated grooves allow for a high degree of design freedom in the geometric configuration of the functional and sacrificial areas. Furthermore, overlapping or interlocking structural elements or areas can be realized. The material layer can be, for example, a semiconductor material, particularly silicon.

[0017] According to one embodiment, the spaces between the substrates can be filled with a monocrystalline silicon material as a layer. This allows, for example, a continuous monocrystalline vertical structure to be created across the entire layered structure, such as with a monocrystalline first substrate and a monocrystalline second substrate. A continuous monocrystalline vertical structure can exhibit particularly favorable mechanical and electrical properties. For example, the structure can have increased fracture toughness or improved thermal conductivity. The material layer can be applied, for example, by epitaxial growth or by deposition, such as chemical vapor deposition (CVD). According to other embodiments, it is also conceivable to use, for example, a polycrystalline or amorphous silicon material for the material layer.

[0018] According to one embodiment, the bonding surface of the first substrate can be prepared for the application of the second substrate by chemical and / or mechanical processing. This ensures a reliable and flat bond between the second substrate and the bonding surface. For example, the bonding surface can be planarized. This processing can be carried out, for instance, by polishing, such as chemical-mechanical polishing (CMP). Furthermore, it is conceivable, for example, to thin the second substrate to a predefined structural height after its application to the bonding surface by grinding and / or polishing. The second substrate can have a thickness of, for example, over 100 µm, over 200 µm, or over 400 µm before or after an optional thinning process.

[0019] According to one embodiment, a further bonding surface can be created on the substrate surface of the second substrate facing away from the first substrate, and a further substrate can be applied to the bonding surface of the second substrate, in which at least one further vertical groove is created. This allows the vertical extent of the component structure, as well as a functional area of ​​the component structure, to be efficiently and easily increased. The at least one further vertical groove can, in particular, extend to the bonding surface of the second substrate.The creation of the additional bonding surface can be carried out analogously to the creation of the bonding surface on the first substrate, for example by applying and structuring an etch stop layer to form spaced-apart etch stop areas and by filling the spaces between the etch stop areas with a material layer. This material layer could be, for example, a silicon material, particularly a monocrystalline silicon material, and could be applied, for example, by epitaxial growth or by deposition. The application of the additional substrate can be carried out analogously to the application of the second substrate, for example, by means of a wafer direct bonding process. Furthermore, it is conceivable, for example, to thin the additional substrate to a predefined structural height of the substrate surface of the additional substrate after its application to the bonding surface by grinding and / or polishing.The additional substrate can have a thickness of, for example, over 100 µm, over 200 µm, or over 400 µm before or after an optional thinning process. Creating further vertical trenches can be done analogously to creating trenches in the second substrate, for example, using a trenching process.

[0020] According to one configuration of the above-described embodiment, applying at least one layer to a substrate surface of a substrate, creating a bonding surface, applying a further substrate, and creating and passivating at least one vertical trench in the further substrate can be repeated cyclically until a predefined target height of the vertical functional region is reached. This allows the vertical extension of the component structure and of a functional region of the component structure to be further increased efficiently and easily. After reaching the predefined target height, which can optionally be precisely adjusted by thinning the last applied substrate, the functional region can be exposed by removing the sacrificial region.

[0021] According to one embodiment, the method can have a start process, a cycle process and a finish process, wherein the start process comprises the following steps: - Providing the first substrate; - Applying a first etch stop layer to the first substrate; and - Creating spaced-apart etch stop areas by structuring the first etch stop layer.

[0022] Accordingly, the process can be divided into different process phases, with an initial phase referred to as the start process and a final phase as the closing process. The cycle process can comprise a sequence of process steps that can be repeated cyclically as often as desired between the start and closing processes. This allows for a highly versatile yet simple process that, for example, can be varied in its number of cycles and individually adapted to predefined requirements for the component structure to be produced. The individual layer levels can be structured and designed independently of one another, so that in each cycle a section of the overall component structure layout with individual geometric structures can be produced. The initial start process enables entry into the cycle process.During the start-up process, an initial substrate is prepared as a support structure, and an initial etch stop layer is applied and structured onto it. Further process steps can then be carried out directly afterwards, for example, as part of the cycle process.

[0023] According to one embodiment, the cycle process may comprise the following steps: - Filling gaps between the spaced etch stop areas with a layer of material to form a bonding surface; - Bonding a second or further substrate to the formed bonding surface; - Applying a second etch stop layer to the further substrate; - Creating spaced-apart etch stop regions by structuring the second etch stop layer; - Creating at least one vertical trench between the etch stop areas of the second etch stop layer, in particular up to an etch stop area of ​​the first etch stop layer; - Application of a third etch stop layer and passivation of at least one trench; and - Creating spaced-apart etch stop areas by structuring the third etch stop layer.

[0024] The aforementioned steps can be repeated cyclically in the described sequence, for example, until the component structure or a functional area of ​​the component structure has reached a predefined vertical target height. Optionally, after filling the gaps between the spaced etch stop regions with a material layer to form a bonding surface, the bonding surface can be planarized to provide an optimized flat surface for connecting the second or further substrate. The etch stop regions of the second etch stop layer can form a mask, wherein the regions between the etch stop regions can define the positions of the trenches to be created.Optionally, the etch stop regions of the second etch stop layer can be removed again after the creation of the at least one vertical trench, for example by etching and / or mechanical processing, in order to enable a uniform application of a third etch stop layer. The third etch stop layer can be created, for example, by deposition or growth on the substrate surface of the second substrate facing away from the first substrate, wherein the application of the third etch stop layer also forms a passivation layer on the surface of the at least one vertical trench and closes a trench structure opening of the trench on the substrate surface. The second and third etch stop layers can be, for example, a silicon dioxide layer or a silicon nitride layer.The last described step of creating spaced-apart etch stop regions by structuring the third etch stop layer provides spaced-apart etch stop regions that can be filled with a material layer upon a new cycle entry according to the first step of the cycle process in order to form another bonding surface and enable the bonding of another substrate to the bonding surface. Thus, the cycle process of the method can be carried out and repeated with a closed circuit. It should be noted that during a second cycle pass, the created vertical trench is no longer introduced, in particular, up to an etch stop region of the first etch stop layer, but rather ends, in particular, on an etch stop region of the third etch stop layer in the sense of the etch stop layer last applied in the previous cycle pass.If no further cycle entry is planned, the spaced-apart etch stop regions of the third etch stop layer can form horizontal boundaries of functional regions in order to protect them from an etch attack during a subsequent exposure of the functional regions.

[0025] According to one embodiment, the closing process may include the following step: - Isolating the functional area by removing the victim area.

[0026] This allows the microelectromechanical component structure to be provided with exposed functional areas. Optionally, the final process can include a further step following the exposure, in which the etch stop and passivation material is at least partially removed from the component structure. The described steps can, for example, follow directly after a completed cycle of the process. The sacrificial area can be removed, for instance, using an etching process suitable for silicon material removal. The etching process can be, for example, an isotropic plasma etching process using sulfur hexafluoride (SF6) or a gas-phase etching process using xenon difluoride (XeF2).The distance to the sacrificial area is horizontally limited by the surface passivation of the trench structures, while the vertical limitation of the etching process is achieved by the etch stop zones of the respective substrate surfaces. Material connections between two substrate layers, which are realized via the material layer, particularly one containing silicon, can form a vertical etch channel for the sacrificial areas across the substrate layers.

[0027] The invention also relates to a microelectromechanical component structure with a first substrate having a substrate surface and with at least one vertical functional region which extends substantially perpendicular to the substrate surface, wherein the vertical functional region extends over a material layer arranged on the substrate surface and over a second substrate arranged on the material layer. The component structure is characterized by particularly simple and efficient production. The construction of the component structure, which is based on a layered structure with at least two substrates arranged in the layered structure, makes it possible to provide functional regions with a high vertical extent, high stability and optionally with very narrow structures, e.g. with a width of less than 20 µm, and tight tolerances, for example less than 10 µm, less than 5 µm or less than 2 µm.For example, the functional area can have a vertical extent greater than 100 µm. The component structure can be manufactured using the method described above. The component structure can, for example, have a rectangular cross-sectional profile.

[0028] According to one embodiment, the material layer can comprise a monocrystalline silicon material. This allows, for example, a consistently monocrystalline vertical structure to be provided across the layer structure in the case of a monocrystalline first substrate and a monocrystalline second substrate.

[0029] According to one embodiment, the vertical functional area can extend over at least one further material layer and over at least one further substrate arranged on the further material layer. This allows for a component structure with a very high vertical extent of the component structure or of a functional area of ​​the component structure.

[0030] The invention also relates to a microelectromechanical device with a microelectromechanical component structure according to one of the features described above, wherein the microelectromechanical component structure forms, at least partially, a displacement structure for generating fluid pressure. The displacement structure can, for example, be formed by at least one functional area of ​​the component structure. Here, for example, at least one functional area of ​​the component structure can form a movable element of the displacement structure, wherein excitation of the functional area can cause a change in volume within the component structure, thereby generating fluid pressure. With the presented component structure, it is possible to provide functional areas with a high vertical extent and a narrow design, which exhibit low stiffness and are therefore easily excitable.Such functional areas enable highly efficient fluid pressure generation with low energy consumption. According to one embodiment, the device can be designed, for example, as a pump or a valve for microfluidic applications. According to another embodiment, the device can be designed as an acoustic sound generator.

[0031] The invention also relates to a microelectromechanical loudspeaker comprising a previously described microelectromechanical device, wherein the displacer structure is configured to generate sound pressure as fluid pressure, and wherein the loudspeaker further comprises a signal processing unit for applying and processing signals from the microelectromechanical device. The displacer structure can, for example, be formed by at least one functional area of ​​the component structure. With the presented component structure, it is possible to provide functional areas with a high vertical extent and a narrow design. Due to the narrow, elongated design, the functional areas exhibit low stiffness and are easily driven. The functional areas can advantageously form vertically oriented lamellae of the loudspeaker, enabling sound pressure generation with high sound quality and low energy consumption.The microelectromechanical loudspeaker can, for example, be implemented as a system-on-chip (SoC).

[0032] In general, in the context of this application, the words “a / an”, unless expressly defined otherwise, are not to be understood as a number, but as an indefinite article with the literal meaning of “at least one”.

[0033] The invention permits various embodiments and is explained in more detail below using exemplary embodiments and the accompanying drawings. They show schematically: Fig. 1 - a method for manufacturing a microelectromechanical component structure according to an embodiment; Fig. 2a-2k - a method for manufacturing a microelectromechanical component structure according to a further embodiment; Fig. 3a-3b - one according to the procedure Fig. 2a-2k manufactured microelectromechanical component structure before and after a final process of the process; Fig. 4 - a schematic diagram of a microelectromechanical loudspeaker with a microelectromechanical device.

[0034] Fig. 1 shows schematically a method 100 for producing a, for example, in the Fig. 3a and Fig. Figure 3b shows a microelectromechanical component structure 200 according to an exemplary embodiment. The method 100 comprises a start process 110, a cycle process 120, and a finish process 130. The component structure 200 has a first substrate 20 with a substrate surface 21. As shown in Fig. As shown in Figure 3a, vertical functional areas F extend essentially perpendicular to the substrate surface 21. The vertical functional areas F are delimited from adjacent sacrificial areas O by created and passivated trenches 70 and in Fig. 3b is exempted by removing the victim areas O. As shown below with reference to the Fig. 1, a bonding surface 23 is produced on the substrate surface 21 of the first substrate 20 by applying at least one layer 22. A second substrate 30 is applied to the bonding surface 23, in which vertical trenches 70 are created. With the proposed method, microelectromechanical component structures 200 and functional regions F with large vertical dimensions and a narrow design can be manufactured in a simplified process. Furthermore, the presented method allows a high degree of design freedom in the creation of functional regions F in component structures 200.

[0035] The following describes procedure 100 based on the one in Fig. 1 are explained in more detail. The start process 110 begins in a first step 1 with the provision of the first substrate 20 having a substrate surface 21. In a second step 2, a first etch stop layer 22a is applied as layer 22 to the substrate surface 21 of the first substrate 20. In a third step 3, spaced-apart etch stop regions 24a are created by structuring the first etch stop layer 22a. The method 100 then enters the cycle process 120. In a fourth step 4, gaps 25a between the spaced-apart etch stop regions 24a are filled with a material layer 22b to form a bonding surface 23. In an optional fifth step 5, a CMP process is used to planarize the bonding surface 23. In a sixth step 6, a second substrate 30 is bonded to the bonded surface 23 formed.The second substrate 30 has a substrate surface 31 facing away from the first substrate 20. In a seventh step 7, the second substrate 30 is optionally thinned by grinding and polishing. In an eighth step 8, a second etch stop layer 26 is applied to the substrate surface 31 of the second substrate 30. In a ninth step 9, the second etch stop layer 26 is structured such that spaced-apart etch stop regions 24b are formed. In a tenth step 10, vertical trenches 70 are introduced between the etch stop regions 24b of the second etch stop layer 26. According to the exemplary embodiment shown, the vertical trenches 70 end on the etch stop regions 24a of the first etch stop layer 22a. In an eleventh step 11, a third etching stop layer 27 is applied, which simultaneously passivates the trenches 70 with passivating material 71.In a twelfth step 12, the third etch stop layer 27 is structured to create spaced-apart etch stop regions 24c. Subsequently, the cycle process 120 can optionally be repeated with the inclusion of further substrates, for example with a third substrate 40, a fourth substrate 50 and a fifth substrate 60, as shown below. Fig. 2a to 2k will be explained in more detail. Alternatively, after each cycle iteration, it is conceivable to enter the final process 130, in which the functional areas F are released by removing the sacrificial areas O. The final process 130 can be started, for example, when the functional areas F of the component structure 200 have reached a predefined target height.

[0036] Based on the Fig. Sections 2a to 2k explain how a component structure 200 with individually designed functional areas F can be manufactured using the presented method 100 by going through several cycle processes 120.

[0037] In Fig. Figure 2a shows that a first substrate 20 with a substrate surface 21 was provided and that a first etch stop layer 22a was applied and structured as layer 22 on the substrate surface 21. The structuring created etch stop areas 24a spaced apart from each other, with gaps 25a between them.

[0038] The Fig. 2b shows that the gaps 25a have been filled with a material layer 22b, and a bonding surface 23 has been formed. The material layer 22b can be applied, for example, by deposition or growth of a particularly monocrystalline silicon layer. The growth process can create a polycrystalline layer 80 on the etch stop regions 24a of the first etch stop layer 22a. Optionally, following the application of the material layer 22b, the produced bonding surface 23 was chemically mechanically polished to create a topography balance and a smooth bonding surface 23. Subsequently, a second substrate 30, particularly a silicon substrate, with a substrate surface 31, was bonded to the bonding surface 23 using the wafer bonding process.Subsequently, optional back-grinding of the second substrate 30 and chemical-mechanical polishing of the second substrate surface 31 were performed to bring the second substrate 30 to a target layer thickness. In addition, the second substrate 30 was structured by creating grooves 70 in it, exposing the side surfaces of the functional areas F and terminating at the etch-stop areas 24a of the first etch-stop layer 22a.

[0039] In Fig. Figure 2c shows that a third etch-stop layer 27 was applied to the substrate surface 31 of the second substrate 30, thereby passivating the surfaces of the trenches 70 with a passivating material 71. Furthermore, the third etch-stop layer 27 seals the trenches 70 on the substrate surface 31 of the second substrate 30. Additionally, the third etch-stop layer 27 was structured to form spaced-apart etch-stop areas 24c.

[0040] The Fig. 2d shows that, analogous to the one to Fig. In the procedure described in 2b, a further bonding surface 23 was created by applying another material layer 22b and a third substrate 40 was attached. Trenches 70 were created in the third substrate 40, terminating at the etch stop areas 24c of the third etch stop layer 27. The trenches 70 in the second substrate 30 and the trenches 70 in the third substrate 40 are predominantly arranged such that they merge into each other as vertically continuous trenches 70. Additionally, in Fig. However, it is also evident in Figure 2d that an etch stop region 24c' was formed as a horizontal boundary of a functional region F, such that a vertical trench 70 of the second substrate 30 is arranged at this etch stop region 24c', offset from a vertical trench 70 of the third substrate 40. This shows that with etch stop layers and passivated vertical trenches, almost any geometry of the functional regions F can be designed. Furthermore, in Fig. Figure 2d shows that with vertical trenches and horizontal etch stop areas 24c', adjacent functional areas F can also be structurally separated from one another. This allows, for example, electrically isolated functional areas F to be produced for separate potential guidance in the component structure 200.

[0041] In Fig. Figure 2e shows that a fourth etch-stop layer 28 was applied to the third substrate 40, thereby passivating the surfaces of the trenches 70 with a passivating material 71. The fourth etch-stop layer 28 was structured to form further etch-stop areas and also to create another horizontal etch-stop area 24c'.

[0042] In Fig. 2f shows that, in an analogous manner to the steps described above, a fourth substrate 50 was attached and structured by vertical trenches 70.

[0043] In Fig. 2g shows the passivation of the trenches 70 in the fourth substrate 50 by a fifth etch stop layer 29 and the formation of horizontal etch stop regions 24c' by structuring the fifth etch stop layer 29. Furthermore, analogously to the previous steps, a fifth substrate 60 was bonded to a bonding surface 23 formed on the fourth substrate 50.

[0044] In Fig. In 2h, the further structuring of the fifth substrate 60 can be seen through vertical grooves 70 passivated with passivating material 71 and further horizontal etch stop areas 24c' of a sixth etch stop layer 29-2. In addition, a seventh etch stop layer 29-3 was applied to the back 21-2 of the first substrate 20, which is opposite the substrate surface 21, structured, and vertical grooves 70 were created and passivated in the first substrate 20, the grooves 70 in the first substrate 20 forming connections to vertical grooves 70 of the second substrate 30. This allows the structuring of the component structure 200 into sacrificial areas O and functional areas F to also be carried out in the area of ​​the first substrate 20 and the contouring of the sacrificial areas O and functional areas F to be created over the entire component structure 200. Fig. After 2 hours, the desired target level of the functional areas F is reached and the procedure 100 can enter a closing process 130.

[0045] In Fig. 2i The sacrificial areas O of the second substrate 30, the third substrate 40, the fourth substrate 50 and the fifth substrate 60 accessible from the surface of the fifth substrate 60 were removed contiguously by isotropic sacrificial layer etching.

[0046] In Fig. In 2j, the sacrificial areas O of the second substrate 30, the third substrate 40, the fourth substrate 50, and the fifth substrate 60, accessible from the back side 21-2 of the first substrate 20, were removed contiguously by isotropic sacrificial layer etching. The removal of the sacrificial areas O exposed the functional areas F.

[0047] In Fig. In 2k, the accessible passivation and etch stop layers of the component structure 200 were removed by HF gas phase etching to complete the exposure of the functional areas F.

[0048] In the Fig. 3a and Fig. 3b is a procedure according to Fig. The microelectromechanical component structure 200 produced by 2a-2k is shown before and after a finishing process 130 of the method 100. Fig. Figure 3a shows the layout of the component structure 200 based on the arrangement of vertical trenches 70 and horizontal etch stop areas 24c', which divide the component structure 200 into sacrificial areas O and functional areas F. The vertical trenches 70 and horizontal etch stop areas 24c' can be individually created in each layer of the component structure 200 and connected to trenches 70 and etch stop areas 24c' of other layer levels. This allows for a high degree of design freedom for the three-dimensional structures of the component structure 200.

[0049] In Fig. Figure 3b shows examples of structural elements of component structure 200, which are shown in Fig. 3a shown functional areas F can be produced. A first structural element 91 can, for example, be a movable three-dimensional structural element clamped in the viewing direction. A second structural element 92 can, for example, be a segmented, movable three-dimensional structural element clamped on both sides. A third structural element 93 can, for example, be a segmented, three-dimensional structural element clamped in the viewing direction and movable independently of one another in the segments. A fourth structural element 94 can, for example, be an immovable three-dimensional support structure clamped on both sides. A fifth structural element 95 can, for example, be a movable three-dimensional structural element suspended on one side. A sixth structural element 96 can, for example, be a horizontal connection of vertically offset structures of the same potential.A seventh structural element 97 can, for example, form horizontal electrical insulation. An eighth structural element 98 can, for example, form vertical electrical insulation. This demonstrates the high degree of design freedom with which the component structure 200 can be manufactured using the presented method 100.

[0050] Fig.Figure 4 schematically shows a microelectromechanical loudspeaker 400 with a device 300, which has a component structure 200 forming a displacement structure at least partially, according to the features described above, and with a signal processing unit 410, which is connected to the device 300 by a signal connection 420 and is configured for applying and processing signals from the microelectromechanical device 300. The displacement structure of the component structure 200 of the device 300 is configured to generate sound pressure as fluid pressure and is acoustically efficient with low power consumption. The microelectromechanical loudspeaker 400 can be implemented as a system-on-chip. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 206 996 A1

[0003] EP 3 912 953 A1

[0004] US 2015 / 0 274 ​​512 A1

[0005] US 8 043 931 B1

[0006]

Claims

[1] Method (100) for producing a microelectromechanical component structure (200) with a first substrate (20) having a substrate surface (21) and with at least one vertical functional region (F) which extends substantially perpendicular to the substrate surface (21), wherein the at least one vertical functional region (F) is delimited from an adjacent sacrificial region (O) by producing and passivating at least one vertical trench (70) and is exposed by removing the sacrificial region (O), wherein a bonding surface (23) is produced on the substrate surface (21) of the first substrate (20) by applying at least one layer (22), and wherein a second substrate (30) is applied to the bonding surface (23), in which at least one vertical trench (70) is produced. [2] Method (100) according to claim 1, wherein the bonding surface (23) of the first substrate (20) is produced by applying and structuring a first etch stop layer (22a) to form spaced-apart etch stop regions (24a) and by filling gaps (25a) between the etch stop regions (24a) with a material layer (22b). [3] Method (100) according to claim 2, wherein the gaps (25a) are filled with a monocrystalline silicon material as a material layer (22b). [4] Method (100) according to one of the preceding claims, wherein the bonding surface (23) of the first substrate (20) is prepared by chemical and / or mechanical processing for the application of the second substrate (30). [5] Method (100) according to one of the preceding claims, wherein a further bonding surface (23) is produced on the substrate surface (31) of the second substrate (30) facing away from the first substrate (20), and a further substrate (40) is applied to the bonding surface (23) of the second substrate (30), in which at least one further vertical trench (70) is produced. [6] Method (100) according to claim 5, wherein applying at least one layer (22) to a substrate surface (21, 31) of a substrate (20, 30, 40, 50, 60), creating a bonding surface (23), applying a further substrate (30, 40, 50, 60) and creating and passivating at least one vertical trench (70) in the further substrate (30, 40, 50, 60) are repeated cyclically until a predefined target height of the vertical functional region (F) is reached. [7] Method (100) according to one of the preceding claims, wherein the method (100) comprises a start process (110), a cycle process (120) and a termination process (130), and wherein the start process (110) comprises the following steps: - providing the first substrate (20) (1); - applying a first etch stop layer (22a) to the first substrate (20) (2); and - producing spaced-apart etch stop regions (24a) by structuring the first etch stop layer (22a) (3). [8] The method (100) of claim 7, wherein the cycle process (120) comprises the following steps: - filling gaps (25a) between the spaced etch stop regions (24a) with a material layer (22b) to form a bonding surface (23) (4); - bonding a second or further substrate (30, 40, 50, 60) to the formed bonding surface (23) (6); - applying a second etch stop layer (26) to the second or further substrate (30, 40, 50, 60) (8); - producing spaced-apart etch stop regions (24b) by structuring the second etch stop layer (26) (9); - producing at least one vertical trench (70) between the etch stop regions (24b) of the second etch stop layer (26), in particular up to an etch stop region (24a) of the first etch stop layer (22a) (10); - applying a third etch stop layer (27) and passivating the at least one trench (70) (11); and - producing spaced-apart etch stop regions (24c) by structuring the third etch stop layer (27) (12). [9] Method (100) according to claim 7 and 8, wherein the final process (130) comprises the following step: - Isolating the functional area (F) by removing the sacrificial area (O). [10] Microelectromechanical component structure (200) with a first substrate (20) having a substrate surface (21) and with at least one vertical functional region (F) which extends substantially perpendicular to the substrate surface (21), wherein the vertical functional region (F) extends over a material layer (22b) arranged on the substrate surface (21) and over a second substrate (30) arranged on the material layer (22b). [11] The microelectromechanical device structure (200) of claim 10, wherein the material layer (22b) comprises a monocrystalline silicon material. [12] Microelectromechanical component structure (200) according to claim 10 or 11, wherein the vertical functional region (F) extends over at least one further material layer (22b) and over at least one further substrate (40, 50, 60) arranged on the further material layer (22b). [13] Microelectromechanical device (300) with a microelectromechanical component structure (200) according to one of claims 10 to 12, wherein the microelectromechanical component structure (200) forms at least in sections a displacement structure for generating a fluid pressure. [14] Microelectromechanical loudspeaker (400) comprising a microelectromechanical device (300) according to claim 13, wherein the displacer structure is configured to generate sound pressure as fluid pressure, and a signal processing unit (410) for applying and processing signals of the microelectromechanical device (300).

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