Microelectromechanical pressure sensor and method for producing microelectromechanical pressure sensor

Abstract

The invention relates to a microelectromechanical pressure sensor (1), comprising: a substrate (2) having a layer system (3) arranged thereon; a sensor structure (5) which is fastened to the layer system (3) in a cantilevered manner by means of at least one suspension structure (4), having a first membrane structure (6) and a second membrane structure (7), between which a cavity region (8) is formed, a first measuring electrode arranged in the hole region is fastened to the first film structure and a second measuring electrode arranged in the hole region is fastened to the second film structure, the first and second measuring electrodes forming a measuring capacitance in the hole region; a cap structure (11) which delimits a pressure measuring chamber (12) in which the sensor structure (5) is arranged in a cantilevered manner; and at least one pressure inlet channel (13) to the pressure measurement chamber, the at least one pressure inlet channel extending through the substrate. A method for manufacturing such a microelectromechanical pressure sensor.

Description

Technical Field

[0001] The invention relates to a micro-electro-mechanical pressure sensor and a method for producing a micro-electro-mechanical pressure sensor. Background Art

[0002] Micro-electromechanical devices, also called MEMS devices, and methods for their production are known in the prior art.

[0003] JP 2013-22 4937A describes a MEMS pressure sensor having a carrier substrate and a membrane substrate, wherein the carrier substrate has a membrane carrier section and a base section, and the membrane substrate has a base region and a membrane. The base section and the base region are used, for example, to decouple the membrane stress from packaging and assembly loads. The pressure sensor can be provided with a cap structure. In addition, a method for manufacturing a pressure sensor is described.

[0004] EP 2 871 455 A1 discloses a pressure sensor having a substrate, a cap structure, a cavity and a membrane. The membrane is mechanically decoupled from the substrate to reduce stresses. Furthermore, a method for producing the pressure sensor is described.

[0005] US Pat. No. 11,402,288 B2 discloses a microelectromechanical sensor having a membrane layer, a cavity and a cap layer, wherein a spacer is arranged between the cap layer and the membrane layer, wherein a cap electrode is arranged in the cap layer above the cavity. Furthermore, a method for producing the sensor is described.

[0006] US 2003 / 0 102 552 A1 relates to a microelectromechanical device having a cap structure which is firmly connected to a substrate of the device and having conductor connections which extend through the substrate. Furthermore, a method for producing the device is described. Summary of the invention

[0007] According to the present invention, a micro-electromechanical pressure sensor is provided, which has:

[0008] a substrate having a layer system arranged thereon;

[0009] a sensor structure fastened in cantilevered fashion to the layer system by means of at least one suspension structure, the sensor structure comprising a first membrane structure and a second membrane structure, between which a cavity region is formed, wherein a first measuring electrode arranged in the cavity region is fastened to the first membrane structure and a second measuring electrode arranged in the cavity region is fastened to the second membrane structure, wherein the first measuring electrode and the second measuring electrode form a measuring capacitance in the cavity region;

[0010] a cap structure which delimits a pressure measurement chamber in which the sensor structure is arranged cantilevered; and

[0011] - At least one pressure access channel to the pressure measuring chamber, wherein the at least one pressure access channel extends through the substrate.

[0012] In other words, a micro-electromechanical pressure sensor is proposed, in which at least one pressure inlet channel leading to a pressure measuring chamber extends through a carrier structure of the pressure sensor formed by a substrate, instead of, for example, through a cap structure of the pressure sensor. On the one hand, an improved mechanical protection of the sensor structure can be achieved by a continuous cap structure, while on the other hand, for example, the cap structure can be provided with an electrical connection structure, for example, with a conductor track and / or a bonding pad structure. Advantages can be brought about in particular during the manufacture of the pressure sensor, since the pressure sensor can be connected to a circuit carrier such as an ASIC or a circuit board, for example, by means of a cap structure provided with an electrical connection structure, in a simple and efficient manner, for example, by means of a flip-chip assembly technique. Since at least one pressure inlet channel extends through the substrate instead of, for example, through the cap structure, the accessibility of the sensor structure and the pressure measuring chamber is not impaired when the cap structure is used to contact and assemble the pressure sensor. In addition, the manufacture and operation of the pressure sensor can be realized safely and gently for sensitive sensor structures. In addition, the pressure sensor can be packaged or encapsulated in a simple and material-saving manner, as will be explained in more detail below.

[0013] The micro-electromechanical pressure sensor can be a sensor produced in semiconductor technology, in particular, for measuring relative or absolute pressure values ​​by means of a movable microstructure. Here, the proposed pressure sensor is constructed as a membrane sensor having a first membrane structure and a second membrane structure that can move relative to each other. By fastening the measuring electrodes to the membrane structure, a measuring capacitor, which can also be called a sensing capacitor, is formed to obtain the capacitance value or capacitance change between the measuring electrodes, and the deflection state of the membrane structure representing the pressure value to be measured can be derived from the capacitance value or capacitance change. Compared with a single membrane structure, high measurement sensitivity can be achieved in a small area by using multiple membrane structures and by measuring electrodes arranged on the membrane structure and located in the cavity area. In a sensor structure with only one movable membrane, a larger and / or thinner membrane is required to achieve the same measurement sensitivity, or at least two membrane structures arranged side by side and having a comparable membrane area must be electrically interconnected with each other in a Wheatstone half-bridge configuration, whereas the same measurement sensitivity can be achieved in a significantly smaller area in a cantilevered double membrane structure. The advantage of this is that, for a limited pressure range and the same measurement sensitivity, the membrane structure can be thicker and / or smaller, and thus more stably implemented and the chip area required is significantly smaller than two membrane structures electrically interconnected in a Wheatstone half-bridge configuration. In addition, a plurality of capacitive pressure sensors with high measurement sensitivity for different pressure ranges can be arranged on a chip area comparable to a known capacitive pressure sensor, and therefore a large pressure range can be detected with high measurement sensitivity in measurement technology. In addition, a linear pressure measurement signal can be obtained by fastening a separate measuring electrode to the membrane structure. Compared with using a single measuring electrode and a static paired electrode arranged opposite to each other with the single measuring electrode (in the case of a conventional capacitive pressure sensor), the measuring electrodes fastened to the deflectable membrane structure will experience a greater distance change relative to each other when pressure is applied or pressure changes, thereby achieving an increase in measurement sensitivity when the basic capacitance is comparable. The micro-electromechanical pressure sensor can be implemented as a system on chip (SoC).

[0014] The cavity region formed between the first and second membrane structures can be a cavity bounded by the membrane structures and by side walls extending from the first membrane structure to the second membrane structure. Furthermore, the lateral perimeter of the cavity region can be bounded by the layer system, so that a circumferentially closed cavity is obtained. In particular, a pressure that is reduced compared to the environment of the pressure sensor can be set in the cavity region, so that, for example, thermal influences on the generated sensor signal due to the pressure enclosed in the cavity region can be minimized. By arranging the measuring electrode in the cavity region, it is arranged in a protected manner and can provide a precise linear measuring signal as a function of the deflection of the membrane structure.

[0015] By configuring the sensor structure as a cantilevered suspended sensor structure, stress decoupling of the membrane structure relative to the surrounding layer system and substrate is achieved. It is thereby achieved that mechanical bending of the sensor structure, for example due to bending of the substrate when the pressure sensor is installed in the housing and / or bending due to thermal expansion, does not influence the generated sensor signal. At least one suspension structure of the sensor structure can form a support arm of the sensor structure so as to hold the sensor structure in a cantilevered manner in the pressure measuring chamber. At least one suspension structure of the sensor structure can, for example, be configured as an elastically deformable spring structure, via which the sensor structure is suspended at the layer system. The elastically deformable spring structure can absorb mechanical stresses of the substrate and the layer system, and thus cause stress decoupling on the sensor structure. The region in the sensor structure that is kept cantilevered and in which the deflection of the membrane structure is achieved can be referred to as a sensing region. The membrane structure can have a movable part (also referred to as a membrane) and a clamping part, respectively, which is fixed to the sensor structure by means of a clamping structure. According to the embodiment, the first membrane structure and the second membrane structure may be identical or different in their geometry and dimensions, for example have movable membrane areas of the same size or of different sizes, or for example have identical or different membrane thicknesses.

[0016] The layer system can be formed by semiconductor material layers that are sequentially applied to the substrate surface of the substrate and optionally structured. The semiconductor material layers can have, for example, silicon material. The sensor structure and the optional cap structure can be formed as the layer system is manufactured, and thus form an integrated layer structure of the pressure sensor. The first membrane structure can be arranged closer to the substrate than the second membrane structure. In other words, if the side of the sensor structure facing the substrate is called the lower side and the side of the sensor structure facing the cap structure is called the upper side, the first membrane structure can form the lower membrane structure of the sensor structure, and the second membrane structure can form the upper membrane structure.

[0017] The cap structure of the pressure sensor can form a microstructurally generated protective cover of the pressure sensor, which protects the sensing area from mechanical influences or undesirable environmental influences, such as from the intrusion of particles. In addition, the cap structure can provide a connection area for electrically connecting the measuring structure of the pressure sensor to an evaluation circuit. The cap structure delimits a pressure measuring chamber, in which the sensor structure is arranged in a cantilevered manner. In other words, the cap structure spans the pressure measuring chamber or forms a cover of the pressure measuring chamber. The cap structure, for example, together with the substrate and with the lateral boundaries of the layer system passing through the pressure sensor, delimits the pressure measuring chamber, in which a protected detection of the ambient pressure of the pressure sensor can be performed. The pressure measuring chamber of the pressure sensor can be regarded as a cavity, in which the first membrane structure and the second membrane structure are movably arranged. The pressure sensor can optionally have a further cavity, for example also a cavity hermetically closed with a predefined reference pressure, so as to enable measurement using a reference-based measurement principle.

[0018] A fluid connection between the pressure measuring chamber and the environment of the pressure sensor is achieved by at least one pressure access channel extending through the substrate, which fluid connection connects the pressure measuring chamber to the sensor ambient atmosphere and thus enables the pressure measuring chamber to interact with the sensor environment, so that the ambient pressure can be detected by deflection of the first membrane structure and the second membrane structure.

[0019] According to one embodiment, the electrical connection structure and / or the circuit carrier can be arranged in the cap structure and / or on the surface of the cap structure facing away from the sensor structure. Thus, the cap structure can be used for electrical contacting of the sensor structure. The electrical connection structure can be, for example, a conductor line or a bonding pad structure. The circuit carrier can be, for example, a substrate or a carrier board with a circuit (which has a plurality of conductor lines), such as an ASIC wafer or a circuit board. Thus, an evaluation circuit, such as a signal processing unit for applying and processing the signal of the sensor structure, can be coupled to the cap structure, and an extended functional unit of the pressure sensor can be provided. The circuit carrier can be connected to the cap structure via a suitable bonding structure constructed between the cap structure and the circuit carrier, wherein the bonding structure can be formed, for example, by means of a flip chip assembly process, eutectic bonding, soldering, bonding, thermocompression bonding or glass frit bonding.

[0020] According to one embodiment, the cap structure can be formed by at least one cap structure layer of the layer system and / or by a circuit carrier. In other words, in the proposed pressure sensor, according to one configuration, a cap structure integrated into the layer system can be provided, by which a protected pressure measuring chamber for the sensor structure can be constructed. A compact and robust pressure sensor with high measurement sensitivity can be provided by a cap structure constructed integrally with the layer system. By constructing the cap structure as a component of the layer system, the pressure sensor can be produced cost-effectively and with high manufacturing accuracy, for example, it is not necessary to apply an additional separate cap substrate or to consider lateral tolerance areas or reserved areas on the pressure sensor for subsequent capping with a separate cap structure. Therefore, a pressure sensor with a particularly small chip size can be realized. If the cap structure constructed integrally with the layer system is provided with an electrical connection structure and / or a circuit carrier applied to the cap structure, the mechanical protection effect of the cap structure can be advantageously combined with a compact connection scheme for the sensor. According to another configuration, the cap structure can be formed directly by the circuit carrier, the carrier structure of the circuit carrier assuming the mechanical protection function of the cap structure. This makes it possible to combine the mechanical cap function and the electrical evaluation circuit in one component and to provide an even more compact pressure sensor.

[0021] According to one embodiment, the pressure entry channel can be configured as a pressure entry channel system, which has at least one input channel leading to the environment of the pressure sensor and at least one output channel leading to the pressure measuring chamber, wherein the at least one output channel has smaller geometric dimensions and / or a smaller channel cross section than the at least one input channel in at least one direction in a plane parallel to the back side of the substrate. By means of such a pressure entry channel system with different channel cross sections, the pressure measuring chamber can be advantageously protected from environmental influences, for example from the intrusion of particles exceeding a certain size. Here, a pressure entry channel system can be formed, in which at least one output channel connecting the input channel and the subsequent pressure measuring chamber is provided with a narrower and / or smaller channel cross section than the input channel. In addition, a sunken pressure entry area can be provided in the substrate. Thus, improved protection of the pressure entry channel or the pressure entry channel system from mechanical and environmental influences can be achieved. The narrowed channel cross section of the output channel can have at least one smaller geometric dimension (compared with the geometric dimensions of the input channel) parallel to the surface of the substrate. A smaller channel cross section can refer to a smaller cross-sectional area of ​​the output channel compared to the cross-sectional area of ​​the input channel. The output channel can, for example, have a smaller channel dimension than the input channel, such as a smaller channel height, channel width and / or channel length and / or a smaller channel cross-sectional area. The channel dimensions (e.g., channel height and channel width) can be channel dimensions transverse to the main flow direction of the fluid flowing through the channel. The channel length can be a channel dimension parallel to the main flow direction of the fluid flowing through the channel. The channel cross-sectional area can be an expansion area of ​​the channel transverse to the main flow direction of the fluid flowing through the channel. According to an advantageous improvement, the pressure inlet channel system can have an input channel, which transitions to a plurality of output channels with narrowed and / or smaller channel cross-sections in the bottom region of the input channel, so as to enable a full interaction of the pressure measuring chamber with the environment of the pressure sensor, and at the same time prevent particles from entering as much as possible.

[0022] According to an improved scheme of the above-mentioned embodiment, the pressure entry channel system may have at least one transverse channel connecting at least one input channel and at least one output channel. At least one input channel and at least one output channel may be configured to be orthogonal to the layer plane of the layer system, for example, and at least one transverse channel may be configured to extend parallel to the layer plane, or extend parallel to the substrate surface relative to the substrate. At least one transverse channel connects at least one input channel and at least one output channel to each other so that a fluid connection between the environment of the pressure sensor and the pressure measuring chamber can be realized through the substrate. Due to the direction of the input channel, the transverse channel and the output channel, the pressure entry channel system has a deflection portion at least at the transition of the corresponding channel section, and the direction of the fluid flow passing through the pressure entry channel system is changed at the deflection portion. The channel section of the pressure entry channel system may, for example, have a Z-shaped and / or Y-shaped direction passing through at least one cap structure layer. The geometric dimensions and / or shape of the input channel, the transverse channel and / or the output channel may be selected so that only gaseous medium can flow through the pressure entry channel system, while preventing liquid or solid particles exceeding a certain particle size from entering the pressure measuring chamber. This can be additionally promoted by multiple deflections of the pressure entry channel system. In principle, measured perpendicular to the substrate surface, at least one lateral channel can at least partially have a smaller channel height and / or a smaller channel cross section than the input channel and / or the output channel. The channel shape and / or channel cross section of the pressure entry channel system, the number of input channels, the number of output channels and the number of lateral channels can be individually adapted to the requirements of the pressure sensor, for example, by implementing narrow and groove-shaped channels and / or small channel cross sections, providing a high level of protection for the pressure measuring chamber from particles and liquids, or by using large channel cross sections and / or increasing the number of input channels, output channels and / or lateral channels to give priority to low flow resistance. The channel cross section should be understood in particular as the extension of the channel transverse to the main flow direction of the fluid flowing through the at least one pressure entry channel. The terms "input channel" and "output channel" are only used to facilitate the understanding of the pressure entry channel system. The pressure entry channel system can also allow bidirectional fluid movement between the environment and the pressure measurement chamber, so that the fluid can also enter the output channel from the pressure measurement chamber and the fluid can be discharged from the input channel to the environment on the surface of the cap structure.

[0023] According to one embodiment, the pressure sensor can have an encapsulation at least in the region of at least one pressure inlet channel, which has at least one encapsulation-free region on the back side of the substrate facing away from the sensor structure. On the one hand, good accessibility to the at least one pressure inlet channel can thereby be ensured, and on the other hand, a pressure sensor with a small installation height can be provided. The pressure sensor can be encapsulated together with a circuit carrier arranged thereon. The encapsulation-free region can, for example, be provided on the at least one pressure inlet channel, extend over a portion of the back side of the substrate or extend over the entire back side of the substrate. The encapsulation can be produced using a film-assisted molding encapsulation process.

[0024] According to one embodiment, the substrate may have at least one insulating trench. The insulating trench may be, for example, a trench extending orthogonally to the substrate surface of the substrate and forming an electrically insulating structure. By means of the insulating trench, for example, a connection structure such as a contact, a conductor line or a bonding pad structure may be provided in the substrate which is electrically insulated from the surrounding substrate.

[0025] According to one embodiment, at least one reference capacitor with a stationary reference electrode can be arranged in the cavity region between the first membrane structure and the second membrane structure, spaced apart from the first membrane structure and the second membrane structure. This can form an unchangeable reference capacitance, which can additionally be used to evaluate the capacitive signal of the measuring electrode of the membrane structure. The reference capacitor can be made of the same material as the measuring electrode of the membrane structure. The stationary reference electrodes can be, for example, two reference electrodes arranged opposite each other, wherein each of the stationary reference electrodes is arranged between the respective other stationary reference electrode and one of the membrane structures. The special design of the sensor structure makes it possible to provide an integrated reference capacitor, which can advantageously be arranged in a space-saving manner in the cavity region between the membrane structures.

[0026] According to one embodiment, the pressure sensor may have at least one cavity etching passage extending through a portion of the sensor structure, through the cap structure and / or through the substrate. With such a cavity etching passage, a cavity region between the first membrane structure and the second membrane structure can be produced in a simple and safe manner, thereby simplifying the manufacture of the pressure sensor. According to one configuration, the pressure sensor may have at least one measuring chamber etching passage extending through the cap structure and / or through the substrate. With such a measuring chamber etching passage, a pressure measuring chamber surrounding the sensor structure can be produced in a simple and safe manner, thereby simplifying the manufacture of the pressure sensor. At least one cavity etching passage and / or at least one measuring chamber etching passage can be closed with a closure, or in particular completely surrounded and / or closed by means of a bonding frame arranged on the cap structure. According to one embodiment, it is conceivable that in the region of the cavity etching passage and / or the measuring chamber etching passage, a corresponding deepening portion is optionally provided in a cap structure having the cavity etching passage and / or the measuring chamber etching passage and / or in a substrate having the cavity etching passage and / or the measuring chamber etching passage, wherein the cavity etching passage and / or the measuring chamber etching passage can be provided in the bottom region of the deepening portion. As a result, the cavity etching passage and / or the measuring chamber etching passage can be arranged in a deepening manner relative to the surface of the cap structure facing the environment and / or relative to the surface of the substrate facing the environment. Mechanical protection of the corresponding etching passage and / or sealing of the corresponding etching passage is achieved by the arrangement of the deepening of the cavity etching passage and / or the measuring chamber etching passage.

[0027] According to one embodiment, at least one mechanical stop structure can be fastened to the first and / or second membrane structure in the cavity region, which mechanical stop structure defines the smallest possible distance between the first and second membrane structure. Alternatively or additionally, at least one stop structure can be fastened to at least one of the measuring electrodes to define the smallest possible distance between the measuring electrodes. The stop structure can preferably consist of a non-conductive material, for example SiRiN, which advantageously also has a high etching resistance with respect to etching media, with which the sacrificial layer is removed from the cavity region.

[0028] The present invention also relates to a method for manufacturing the above-mentioned micro-electromechanical pressure sensor, wherein

[0029] - providing a substrate;

[0030] - producing a layer system on a substrate by applying and structuring a material layer;

[0031] - generating a cantilevered sensor structure with the material layers of the layer system, the cantilevered sensor structure having a first membrane structure, a second membrane structure, a first measuring electrode, a second measuring electrode and at least one suspension structure of the sensor structure;

[0032] the cap structure is arranged on the layer system or is produced by means of at least one cap structure layer of the layer system, wherein the cap structure delimits a pressure measuring chamber in which the sensor structure is arranged in a cantilevered manner; and

[0033] - Producing at least one pressure channel through the substrate to a pressure measuring chamber.

[0034] By means of the proposed method, a pressure sensor can be manufactured in a simple and efficient manner using conventional semiconductor technology process steps. According to an improved solution, the electrical connection structure and / or the circuit carrier can be arranged on the surface of the cap structure facing away from the sensor structure. This makes it possible to simplify the further processing of the pressure sensor, for example, processing it into a pressure sensor chip. For example, the pressure sensor manufactured using the proposed method can be rotated by means of flip-chip assembly technology and placed, for example, on a circuit board, a ceramic substrate or an ASIC substrate. For example, a wire bonding process can be replaced by, for example, a flip-chip process or a wafer bonding process, which represents a continuous process for establishing electrical contact between the pressure sensor and an electronic circuit such as an ASIC, and the flip-chip process or the wafer bonding process enables the establishment of electrical contact between the electrical connection structure of the pressure sensor and the electronic circuit at the same time.

[0035] Since at least one pressure access channel is produced in the substrate and not, for example, in a cap structure, during the production and further processing of the pressure sensor, the accessibility of the sensor structure and the pressure measuring chamber is not affected when the cap structure is used to contact and assemble the pressure sensor. In addition, the production and operation of the pressure sensor can be realized safely and gently for sensitive sensor structures. In addition, the pressure sensor can be packaged or encapsulated in a simple and material-saving manner. In addition, the pressure sensor chip that can be obtained with the proposed pressure sensor can be thinned to the desired extent without endangering the sensor structure during the thinning process. The at least one pressure access channel that passes through the substrate to the pressure measuring chamber can be produced, for example, by means of a substrate etching process.

[0036] The cantilevered sensor structure (with the first membrane structure, the second membrane structure, the first measuring electrode, the second measuring electrode and at least one suspension structure of the sensor structure) can be produced in particular such that the first measuring electrode is arranged in the cavity region on the first membrane structure and the second measuring electrode is arranged in the cavity region on the second membrane structure, wherein the first measuring electrode and the second measuring electrode form a measuring capacitance in the cavity region. This produces a pressure sensor with high measuring sensitivity.

[0037] According to one embodiment, the material layers of the layer system can be formed by a structural material layer and a sacrificial material layer, wherein, after the layer system is generated via at least one etching path, the sacrificial material layer is removed by means of a sacrificial layer etching process. It is thus possible to safely manufacture the structure of the pressure sensor (e.g., the sensor structure) in a simple manner, and then a defined cavity (e.g., a cavity region and a pressure measurement chamber) can be constructed. The structural material layer can be, for example, a single crystal or polycrystalline silicon layer or a dielectric layer, which is, for example, made of a silicon compound such as silicon-rich nitride (SiRiN). The sacrificial material layer can, for example, be a layer made of a silicon compound such as silicon dioxide (SiO2). The material layers of the layer system can be deposited on each other in a predetermined order, for example, by means of a deposition process known in semiconductor technology. The material layer is applied to a substrate, which can be, for example, a silicon substrate in the form of a wafer. The structuring of the material layer and / or the introduction of the cavity and / or the deep part are achieved, for example, by means of an etching process, wherein, for example, the locally limited removal of the layer material is achieved by means of a mask. The lateral and / or vertical etching stop structure can be produced by the following material layer, which has a high etching resistance relative to the etching process used to remove the sacrificial layer material. Suitable etching stop materials can be composed of, for example, silicon and / or SiRiN or comparable etch-resistant materials. In addition, auxiliary structures can be specifically arranged in the layer system used, with the aid of which cavities and / or etching channels can be generated, along which the etching medium for etching the sacrificial layer material can be quickly distributed over a large area. In this way, fast and effective sacrificial layer etching can be achieved in the pressure measuring chamber and / or the cavity region, even if the etching path is arranged outside the sensing region. The etching process can advantageously be carried out using a dry etching process such as plasma etching. However, in principle, a wet chemical etching process can also be used. For example, a medium containing HF in gaseous or liquid form can be used as an etching medium for etching the SiO2 sacrificial layer material. In addition, the pressure sensor can be processed using other processing methods in another optional manufacturing step, and thinning and / or chemical mechanical polishing (CMP process) can be performed here, for example, by means of a grinding process.

[0038] According to one embodiment, at least one pressure access channel can be produced through the substrate by means of a substrate etching process before the sacrificial layer etching process, wherein a sacrificial material layer of the layer system is provided adjacent to the substrate, at which the substrate etching process is stopped. As a result, etching attacks on the sensor structure can be reliably avoided during the substrate etching process.

[0039] According to one embodiment, at least one pressure inlet channel into the pressure measuring chamber can be produced stepwise by introducing an input channel (through the substrate) and by introducing an output channel (through a structural material layer of the layer system adjacent to the substrate). In this way, the input channel and the output channel can be configured individually, for example, produced with different channel cross sections. For example, by producing an output channel (which has a smaller channel cross section than the input channel), a pressure inlet channel with improved protection against particle ingress can be produced.

[0040] According to a refinement of the above-described embodiment, the introduction depth of the input channel can be limited by means of an etching stop structure. This makes it possible or facilitates the arrangement of the input channel in a precisely defined manner and the gradual generation of the input channel and the output channel. In addition, etching attacks on the sensor structure can be reliably avoided during the manufacture of the pressure channel system.

[0041] According to one embodiment, the cavity region can be constructed by removing a sacrificial material layer between the first membrane structure and the second membrane structure, wherein the sacrificial material layer is removed via at least one cavity etching path provided in the sensor structure, the cap structure and / or the substrate. Thus, the cavity region can be constructed between the first membrane structure and the second membrane structure simply by first constructing the cavity region of the sensor structure with the aid of a sacrificial layer material and constructing it as a cavity by subsequent etching. At least one cavity etching path can be advantageously manufactured, for example, by extending through a cap structure or a substrate. When the at least one cavity etching path is generated by a cap structure or by a substrate, the at least one cavity etching path can be connected to the cavity region, for example, by means of an etching channel extending through a suspension structure, so that an etching connection to the cavity region can be established. Alternatively or in addition, at least one cavity etching path can be generated in the sensor structure, for example, through a membrane structure. If a cavity etching path is provided in the sensor structure, the cavity etching path can be generated, for example, by a second membrane structure. The closure of the hole etching path guided through a part of the sensor structure (for example, through the membrane structure) can be designed so that the closure has a high etching resistance to the etching medium, which is used to remove the sacrificial material layer of the subsequent pressure measurement chamber. It is also conceivable that the at least one hole etching path is generated in the sensor structure outside the sensing area of ​​the sensor structure. Any damage to the membrane structure caused by the hole etching path and its closure in the membrane area can be reduced. According to one configuration, at least one anchoring structure can be generated in the sensor structure between the area of ​​the hole etching path in the sensor structure and the middle vertical line of the first membrane structure and the second membrane structure. The sensor structure can be stabilized thereby, and it can be achieved that the hole etching path and its closure are not located in the membrane area, so that the hole etching path and its closure have no effect or little effect on the performance of the sensor structure. In particular, a plurality of anchoring structures can define the geometry of the deflectable membrane area of ​​the membrane structure, and thus enable the personalized configuration of the deflectable area to be performed independently of the basic structure of the membrane structure.

[0042] According to one embodiment, the pressure measuring chamber can be formed by removing a sacrificial material layer surrounding the sensor structure, wherein the sacrificial material layer is removed via at least one measuring chamber etching passage provided in the cap structure and / or the substrate. It is thus possible to construct the pressure measuring chamber surrounding the sensor structure simply by first constructing the pressure measuring chamber of the pressure sensor with the aid of a sacrificial layer material and constructing it as a cavity by subsequent etching. According to the embodiment, at least one measuring chamber etching passage can be produced by extending through the cap structure or through the substrate, or at least one corresponding measuring chamber etching passage is provided through the cap structure and the substrate. It is also conceivable that at least one pressure entry channel is used as a measuring chamber etching passage, because the measuring chamber etching passage forms a through-channel through the substrate, and thus there is already an etching-technically usable connection to the sacrificial material layer of the pressure measuring chamber. Alternatively or additionally, a separate measuring chamber etching passage spaced apart from the at least one pressure entry channel can be provided through the substrate and / or the cap structure.

[0043] According to one embodiment, at least one cavity etching path and / or at least one measuring chamber etching path can be closed with a closure. In this way, after performing an etching process to remove the sacrificial layer material in the cavity area or the pressure measuring chamber, the cavity or etching path can be closed again. This closure can be obtained, for example, by means of a laser resealing process, in which the layer material is locally melted. Alternatively or in addition, the closure can be produced by depositing at least one closure material layer. According to the specific configuration, the closure material layer can be optionally constructed as, for example, conductive or electrically insulating, or have a layer structure, which is a combination of at least one conductive closure material layer and at least one electrically insulating closure material layer. According to an extension of the above-mentioned embodiment, the cavity etching path or the measuring chamber etching path produced by the cap structure can be closed with the help of a closure and covered by at least one cap structure layer. The closure can thus be protected from mechanical influences. The cap structure layer covering the closure can, for example, be additionally deposited on the layer system after manufacturing the closure.

[0044] Alternatively or additionally, at least one bonding frame can be arranged between the cap structure and the layer system of the pressure sensor, so that the cavity etched path and / or the measuring chamber etched path is in particular completely surrounded and / or closed and / or the closure is at least partially covered by the material of the bonding frame. By cleverly placing the bonding frame, the cavity etched path or the measuring chamber etched path extending through the cap structure can be reliably covered or circumferentially closed with the bonding frame, so that, depending on the configuration, additional process steps and / or additional closure material layers for producing the closure of the cavity etched path or the measuring chamber etched path can be omitted, or an existing closure can be at least partially covered by the material of the bonding frame.

[0045] According to one embodiment, an electrical connection structure can be applied to the cap structure, and the pressure sensor can be electrically and / or mechanically connected to the circuit carrier by a wafer bonding process or a flip chip process. By a wafer bonding process or a flip chip process, it is possible to achieve the electrical contact between the electrical connection structure of the pressure sensor and the electronic circuit at the same time. The process time can thus be significantly shortened relative to the wire bonding process. For example, after the electrical connection structure is applied to the cap structure, the pressure sensor can be rotated and placed, for example, on a circuit board, a ceramic substrate or an ASIC substrate. For example, the wafer bonding process can use eutectic bonding of aluminum and germanium, gold thermocompression bonding or glass frit bonding. Here, for example, a conductive chip-to-chip connection between the pressure sensor on the MEMS wafer and the evaluation circuit on the ASIC wafer can be constructed for all chips on the wafer at the same time. Here, after bonding the wafers, both the ASIC wafer and the MEMS wafer can be thinned to a predetermined thickness, so that a thin pressure sensor-ASIC-arrangement can be manufactured.

[0046] According to another embodiment, at least one cap structure layer and / or a circuit carrier can be arranged on the layer system to produce the cap structure. In other words, according to one configuration, the cap structure can be integrated into the layer system as a cap structure layer. Due to the integrated cap structure, a compact and robust pressure sensor with high measurement sensitivity can be produced. According to another configuration, the cap structure can be formed directly by the circuit carrier arranged on the layer system, so that its carrier structure assumes the mechanical protection function of the cap structure. It is thereby possible to combine the mechanical protection function and the electrical connection function in one structural component, and an even more compact pressure sensor can be provided.

[0047] According to another embodiment, the pressure inlet channel can be produced as a pressure inlet channel system (which has at least one input channel leading to the environment of the pressure sensor and at least one output channel leading to the pressure measuring chamber), wherein the output channel produced has a smaller channel cross section than the input channel. By means of such a pressure inlet channel system with different channel cross sections, the pressure measuring chamber can be advantageously protected from environmental influences, for example from the entry of particles exceeding a certain size. In addition, a transverse channel connecting the input channel to the output channel can be produced, for example, by means of an embedded cavity structure.

[0048] According to another embodiment, the pressure sensor can be provided with a package, wherein at least one non-packaged area is generated on the back side of the substrate facing away from the sensor structure. Such a package is advantageous in particular after the circuit carrier is arranged on the pressure sensor to form a pressure sensor system, and improves the protection of the pressure sensor system from environmental influences and mechanical influences. For example, the package can be performed using a film-assisted molding package process (FAM package process). Here, the FAM package process can be performed so that at least one pressure entry channel guided through the substrate remains freely accessible. Because according to some embodiments, no electrical connection structure is provided or required on the substrate side of the pressure sensor having at least one pressure entry channel, it is possible not to package the substrate side of the pressure sensor having at least one pressure entry channel, so that the substrate side, which can also be referred to as the back side of the pressure sensor, can form a flat plane (which has a packaging material surrounding the adjacent pressure sensor side). Therefore, a pressure sensor and a pressure sensor system with a low structural height and reduced space requirements can be provided.

[0049] According to a further embodiment, at least one insulation trench may be produced in the substrate. By means of the insulation trench, for example, connection structures such as contact structures, conductor track structures or bonding pad structures may be produced in the substrate which are electrically insulated from the surrounding substrate.

[0050] According to another embodiment, at least one reference capacitor with a stationary reference electrode can be arranged in the region of the cavity between the first and second membrane structures, spaced apart from the first and second membrane structures. This can form a non-variable reference capacitance, which can additionally be used to evaluate the capacitive signal of the measuring electrode of the membrane structure.

[0051] Generally speaking, in the context of the present application, unless explicitly defined otherwise, the terms “a” and “an” should not be understood as a numeral, but as an indefinite article having the literal meaning of “at least one”. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The present invention allows various embodiments, and the present invention will be explained in more detail below based on the embodiments in conjunction with the accompanying drawings. Fig.10 ) and block diagram ( Fig.11 ) schematically shows:

[0053] Figure 1a-1b - a micro-electromechanical pressure sensor according to the first embodiment and intermediate states of the pressure sensor during its manufacture;

[0054] Figure 2 - a micro-electro-mechanical pressure sensor according to the second embodiment;

[0055] Figure 3- a microelectromechanical pressure sensor with a connected circuit carrier according to the second embodiment;

[0056] Figure 4a-4c - a micro-electro-mechanical pressure sensor according to a third embodiment and intermediate states of the pressure sensor during its manufacture;

[0057] Figure 5a-5b - a micro-electromechanical pressure sensor according to a fourth embodiment and intermediate states of the pressure sensor during its manufacture;

[0058] Figure 6 - a micro-electro-mechanical pressure sensor according to a fifth embodiment;

[0059] Figure 7a-7b - a micro-electro-mechanical pressure sensor according to a sixth embodiment and intermediate states of the pressure sensor during its manufacture;

[0060] Figure 8a-8c - a micro-electromechanical pressure sensor according to a seventh embodiment and intermediate states of the pressure sensor during its manufacture;

[0061] Fig. 9 - a micro-electro-mechanical pressure sensor according to an eighth embodiment;

[0062] Fig.10 - a micro-electro-mechanical pressure sensor according to the ninth embodiment; and

[0063] Fig.11 - Simplified flow chart of a method for manufacturing a micro-electro-mechanical pressure sensor. DETAILED DESCRIPTION

[0064] Figure 1a and Figure 1b A microelectromechanical pressure sensor 1 according to a first embodiment is shown simplified and schematically in a sectional side view. Figure 1a shows an intermediate state of the pressure sensor 1 during its manufacture, while Figure 1b The pressure sensor 1 is shown after an etching process has been carried out to form a cavity in the pressure sensor 1 .

[0065] The pressure sensor 1 has a substrate 2 on which a layer system 3 is arranged. By means of at least one suspension structure 4, a sensor structure 5 is fastened to the layer system 3 in a cantilevered manner, thereby achieving stress decoupling of the sensor structure 5 relative to the surrounding layer system 3 and substrate 2. The region of the sensor structure 5 that remains cantilevered is referred to as a sensing region 16. The sensor structure 5 has a first membrane structure 6 and a second membrane structure 7, wherein the first membrane structure 6 is arranged between the second membrane structure 7 and the substrate 2. In the figure, the first membrane structure 6 is shown as a lower membrane facing the substrate 2, while the second membrane structure 7 is shown as an upper membrane opposite to the first membrane structure 6. A cavity region 8 is formed between the first membrane structure 6 and the second membrane structure 7, which is bounded by a side wall 15 between the first membrane structure 6 and the second membrane structure 7, wherein the side wall 15 is arranged in the form of a surrounding contour in the edge region of the sensor structure 5, wherein the side wall 15 can be formed at least by a material component for producing the layer system 3 and for realizing the sensor function. A first measuring electrode 9 located in the cavity region 8 is fastened to the first membrane structure 6. The second measuring electrode 10 located in the cavity region 8 is fastened to the second membrane structure 7. The first and second measuring electrodes 9, 10 form a measuring capacitance in the cavity region 8, with which capacitance values ​​and capacitance changes can be detected, from which the deflection state of the membrane structures 6, 7 and thus the pressure applied to the membrane structures 6, 7 can be inferred. With the measuring electrodes 9, 10 fastened to the membrane structures 6, 7 in the cavity region 8, a high measurement accuracy can be achieved with a pressure measurement signal that is as linear as possible, while the membrane structures 6, 7 themselves can be designed to be stable and robust. In the cavity region 8, a reduced pressure can be set compared to the environment 14 of the pressure sensor 1, so as to achieve a lower thermal dependency of the pressure measurement signal.

[0066] The pressure sensor 1 has a cap structure 11 which delimits a pressure measuring chamber 12 in which a sensor structure 5 is arranged. According to the embodiment shown, the cap structure 11 is constructed as a cap structure layer 11a of the layer system 3. Thus, a pressure sensor 1 having a cap structure 11 integrated into the layer system 3 is provided, which covers the pressure measuring chamber 12 for the sensor structure 5 and protects it from undesirable or excessive environmental influences and mechanical influences. The pressure measuring chamber 12 is a cavity which receives the sensor structure 5 in a cantilevered manner and enables the mobility of the membrane structures 6, 7 in space. A compact and robust ambient pressure sensor with high measuring sensitivity can be provided by means of a pressure sensor 1 with an integrated cap structure 11. The cap structure 11 protects the sensing area 16 from particles and mechanical influences, for example. Since the cap structure 11 is constructed as an integrated cap structure 11, it is not necessary to provide a lateral tolerance area or a reserved area on the pressure sensor 1 for a subsequent possible capping or a subsequent capping process using a separate cap substrate, so that a pressure sensor 1 with a small chip size can be realized. By combining integrated cap structure 11 with sensor structure 5 , which is extremely sensitive due to the provision of membrane structures 6 , 7 and having two measuring electrodes 9 , 10 arranged in cavity region 8 , a pressure sensor 1 with high measuring sensitivity and a long service life can be provided.

[0067] At least one pressure inlet channel 13 extends through the substrate 2 to the pressure measuring chamber 12, by means of which an atmospheric connection is achieved between the pressure measuring chamber 12 and the environment 14 of the pressure sensor 1. The membrane structures 6, 7 can thus interact with the ambient pressure of the pressure sensor 1 and can achieve pressure measurement by deflection of the membrane structures 6, 7. Due to the at least one pressure inlet channel 13 extending through the substrate 2, on the one hand, an improved mechanical protection of the sensor structure 5 can be achieved by a continuous cap structure 11, and on the other hand, for example, electrical connection structures, such as conductor tracks and / or bonding pad structures, can be provided for the cap structure 11. Since the at least one pressure inlet channel 13 extends through the substrate 2 and not, for example, through the cap structure 11, when the cap structure 11 is used for contacting and mounting the pressure sensor 1, neither the sensor structure 5 nor the accessibility of the pressure measuring chamber 12 is impaired. In addition, the production and operation of the pressure sensor 1 can be achieved safely and gently for the sensitive sensor structure 5. The pressure sensor 1 can also be packaged or encapsulated in a simple and material-saving manner.

[0068] according to Figure 1a and Figure 1b In the embodiment shown, the at least one pressure inlet channel 13 is designed as a straight, direct through-channel to the pressure measuring chamber 12 .

[0069] A reference capacitor 17 with stationary reference electrodes 17a, 17b can optionally be arranged in the cavity region 8 between the membrane structures 6, 7 and at a certain distance. In this way, a constant reference capacitance can be formed, which can be supplemented for the measurement and / or signal evaluation of the measurement capacitance formed by the measuring electrodes 9, 10. In this case, the reference electrodes 17a, 17b can be made of the same material as the measuring electrodes 9, 10. In addition, a mechanical stop structure 18 is provided in the cavity region 8, which is fastened to the first and / or second membrane structure 6, 7 and defines the smallest possible distance between the membrane structures 6, 7. Alternatively or additionally, the stop structure 18 can be fastened to at least one of the measuring electrodes 9, 10 in order to define the smallest possible distance between the measuring electrodes 9, 10. The stop structure 18 preferably consists of a non-conductive material, for example SiRiN, which advantageously also has a high etching resistance to etching media, with which the sacrificial layer is removed from the cavity region 8.

[0070] In a plane spaced apart from the cross section shown, local separating structures 26 can be provided, which at least in sections separate the cantilevered arrangement of the sensor structure 5 from the surrounding layer system 3. The separating structures 26 can also be used as etching channels in etching process steps used during the production of the pressure sensor 1. The separating structures 26 can also be used to produce at least one elastic or flexible suspension structure 4 of the sensor structure.

[0071] exist Figure 1a In the intermediate state of the production method shown, the layer system 3 has been produced on the substrate 2 and the sensor structure 5 is formed by means of the material layers of the layer system 3, which has a first membrane structure 6, a second membrane structure 7, measuring electrodes 9, 10 and at least one suspension structure 4 of the sensor structure 5. Figure 1a The layer system 3 in the state shown, the first SiO2 layer SO1, the first SiRiN layer SN1, the first polysilicon layer SP1, the second SiO2 layer SO2, the second SiRiN layer SN2, the second polysilicon layer SP2, the third SiO2 layer SO3, the third SiRiN layer SN3, the third polysilicon layer SP3, the fourth SiO2 layer SO4, the fourth SiRiN layer SN4, the fourth polysilicon layer SP4, the fifth SiO2 layer SO5, the fifth SiRiN layer SN5, the fifth polysilicon layer SP5 and the sixth SiRiN layer SN6 are deposited on the substrate 2 and are structured respectively, so as to construct elements or structures with the help of polysilicon and SiRiN structural material layers, and predefine the cavity area 8 to be subsequently constructed as a cavity and the first section of the pressure measurement chamber 12 by the SiO2 sacrificial material layer, the elements or structures forming the sensor structure 5, the cap structure 11 and at least one suspension structure 4 of the sensor structure 5. As shown in FIG. Figure 1aAs can be seen in FIG. 1 , the first SiO2 layer SO1 is supplementarily used as an etching stop region for at least one pressure inlet channel 13, which is produced through the substrate 2 by means of a substrate etching process, wherein the substrate etching process stops at the first SiO2 layer SO1. Figure 1a In the embodiment shown, at least one pressure access channel 13 is produced before the sacrificial layer etching process. In addition, a cavity etching passage 20a is produced through the cap structure 11 by a material layer etching process, wherein the material layer etching process stops on the fifth SiO2 layer SO5. Etching passages to the second, third and fourth SiO2 layers SO2, SO3, SO4 are produced via the cavity etching passage 20a so that they can be removed by means of a sacrificial layer etching process (e.g., an HF vapor phase etching process) and the cavity region 8 can be produced as a cavity. At least one pressure access channel 13 forms a measuring chamber etching passage 20b to the first and fifth SiO2 layers SO1, SO5 so that they can be removed by means of a sacrificial layer etching process and the pressure measuring chamber 12 can be constructed as a cavity. The SiRiN layer serves as a dielectric layer that is etch-resistant to the subsequent SiO2 sacrificial layer etching process and, as explained later, can serve as an electrical insulation structure and / or lateral etching stop structure 22 within the layer system 3, as exemplarily shown in Figure 1a For the sake of clarity, only Figure 1a The above-mentioned layers are provided with reference numerals in the figure. Even if the exemplary embodiments are described with reference to materials containing silicon, other semiconductor materials and / or conductive and / or non-conductive materials can in principle also be used to construct the layer system 3. In principle, it is also conceivable to arrange at least one electrical wiring plane and / or bonding pad structure on the cap structure 11 before the production of the hole etching path 20a and before the sacrificial layer etching process is performed. In this case, if a dielectric material layer is used, it is designed so that it has a high etching resistance with respect to the etching medium used for the sacrificial layer etching process.

[0072] Like from Figure 1b It can be seen that after the sacrificial layer etching process is performed, the hole etching passage 20a is closed by the sealing member 21. Figure 1b In the embodiment shown, Figure 2 For this purpose, the sealing material layer 21 shown in more detail in FIG is deposited on the cap structure 11 provided with the cavity etching passage 20a and is structured such that the sealing part 21 is formed in the region of the cavity etching passage 20a. Alternatively, it is conceivable to produce the sealing part 21 by locally melting the layer material, for example by means of a laser resealing process.

[0073] Figure 2 A microelectromechanical pressure sensor 1 according to a second embodiment is shown in a simplified and schematic side sectional view. Figure 2, at least one electrical connection structure 23 is arranged on a surface 11b of the cap structure 11 facing away from the sensor structure 5. The electrical connection structure 23 can, for example, have a conductor line 23a, or alternatively or additionally have at least one electrical contact structure 23b for establishing at least one electrical connection to at least one electrical component or at least one electrical member of the pressure sensor 1, and / or have a bonding frame structure, wherein the conductor line 23a, the contact structure 23b and / or the bonding frame structure can, for example, have at least one of the elements Al, Cu, Si, Au, Ge, Sn, Ni, Cr, Pt, Pd, W, Ti, Ta, N, O, F, B, P or As. Figure 2 As shown, the electrical contact of the sensor structure 5 can be achieved by means of the electrical connection structure 23 via, for example, the cap structure 11. Figure 2 As can be seen in FIG. 1 , in order to construct the closure 21 for the hole etching passage 20a, a closure material layer 21a is used and according to the embodiment only in the region of the closure 21 (see FIG. 1 ). Figure 1b ) or on the entire surface of the cap structure 11 (see Figure 2 ) leaving the closure material layer. In addition, an optional insulating layer 24 (for example made of SiO2) can be applied to the closure material layer 21a in order to be able to provide electrical insulation of the conductor line 23a and / or the bonding frame structure relative to the cap structure 11. Optionally, further dielectric and conductive material layers and / or bonding pad structures can be produced on the layer system 3 in order to, for example, be able to provide additional electrical wiring planes.

[0074] Figure 3 After the circuit carrier 25 is connected, Figure 2The pressure sensor 1 shown in FIG. The circuit carrier 25 can be, for example, an ASIC wafer or a circuit board, which can be electrically connected to the pressure sensor 1 via the electrical connection structure 23. In order to establish the connection, according to the embodiment shown, a bonding connection 27 is provided, which can be manufactured, for example, by a flip chip process, eutectic bonding, soldering, bonding, thermocompression bonding or glass frit bonding. For example, when using a flip chip process, the prepared pressure sensor 1 can be fastened to a silicon wafer after separation, for example, after the silicon wafer is sawed into individual pressure sensor chips, it is fastened to an ASIC chip, a circuit board or a ceramic substrate. Here, the bonding pad structure on the pressure sensor chip and the corresponding bonding pad structure on the ASIC chip can be electrically and mechanically connected to each other, for example, by means of so-called solder bumps or solder balls. The intermediate gap between the pressure sensor chip and the ASIC chip can be filled with an underfill. Here, the cap structure 11 can prevent the underfill from entering the pressure measurement chamber 12 and damaging the pressure sensor 1. When using a flip chip process, multiple chip-to-chip electrical connections can be constructed simultaneously between the pressure sensor chip and the ASIC chip. For example, the structural height of the pressure sensor system having the pressure sensor 1 and the ASIC chip can be reduced in comparison with a wire bonding process.

[0075] Figures 4a to 4c A microelectromechanical pressure sensor 1 according to a third embodiment and intermediate states of the pressure sensor 1 during its production are shown in simplified and schematic side sectional views. According to the third embodiment, the pressure inlet channel 13 is produced stepwise and configured as a pressure inlet channel system 13a, which has at least one input channel 13b leading to the environment 41 and (as shown in the figure) at least one of a plurality of output channels 13c leading to the pressure measuring chamber 12. Figures 4a to 4cIt can be seen that the output channels 13c each have a smaller channel cross section than the input channels 13b. This advantageously protects the pressure measuring chamber 12 from environmental influences, for example from the ingress of particles exceeding a certain size. The input channel 13b can also be regarded as a substrate deepening in the direction of the cap structure 11, wherein the channel cross section of the input channel 13b narrows towards the output channel 13c at the bottom region of the input channel 13b facing the pressure measuring chamber 12. By providing a plurality of output channels 13c, particle protection of the pressure inlet channel system 13a is achieved by utilizing a sufficient interaction of the pressure measuring chamber 12 with the environment 14 of the pressure sensor 1. In addition, when producing the pressure inlet channel 13 starting from the back side 2a of the substrate 2, it should be taken into account that larger channel cross sections can be produced more simply and safely, because, for example, a plasma-based trench process is used at a greater structural depth, which is however associated with a reduction in etching rate as the hole cross section becomes smaller due to the ARDE effect (aspectratio dependent etching). Thus, a small hole cross section, such as in the output channel 13 c shown, requires extremely long etching times or a limited insertion depth, but is nevertheless desirable in order to prevent particles or liquids from entering the pressure measuring chamber 12. Against this background, a combination of at least one input channel 13 b with a large channel cross section and at least one output channel 13 c with a correspondingly small channel cross section may also make sense, at least in terms of process technology.

[0076] To create a pressure inlet channel system 13a, such as Figures 4a to 4cAs shown in the intermediate state of the manufacturing method according to the pressure sensor 1, an additional first SiO2 layer SOW1 can be deposited on the substrate 2 and structured before the material layer of the original layer system 3 is deposited. For example, by growth in a silicon epitaxial reactor and / or by deposition in, for example, an LPCVD device, an additional first substrate layer SI1 made of silicon is applied to the additional first SiO2 layer SOW1. The additional first substrate layer SI1 can be constructed in a polycrystalline and / or single-crystalline manner in areas where the additional first SiO2 layer SOW1 has been removed and deposited in a polycrystalline manner in areas where the additional first SiO2 layer SOW1 is present. Subsequently, a CMP process can optionally be performed to flatten the surface and complete the further construction of the layer system 3 of the pressure sensor 1. If the input channel 13b is subsequently introduced starting from the back side 2a of the substrate 2, the further first SiO2 layer SOW1 can be used as a stop layer and / or as a hard mask for structuring the further first substrate layer SI1 and for producing the output channel 13c as a hole structure having geometric dimensions that are selected to be small at least in a direction parallel to the substrate surface and / or having a small cross-sectional area. Advantageously, starting from the back side 2a of the substrate 2 in the region of the input channel 13b, first a part of the pressure inlet system 13a with a large cross-sectional area and a correspondingly high etching rate can be produced, and starting from reaching the further first SiO2 layer SOW1, an output channel 13c with significantly smaller geometric dimensions and / or a smaller cross-sectional area can be produced through the further first substrate layer SI1 with the aid of the SiO2-free region in the further first SiO2 layer SOW1. In this way, a pressure entry channel system 13a having at least one input channel 13b (which has a relatively large cross-sectional area) can be realized, at the bottom of which particles exceeding a certain size can be prevented from entering the pressure measuring chamber 12 due to the fact that the output channel 13c introduced there into the further first substrate layer SI1 has a relatively small cross-sectional area. Figures 4a to 4c Also shown are two variants of removing sacrificial layer material from the cavity region 8 via a cavity etch path 20a and removing sacrificial layer material from the pressure measuring chamber 12 via a measuring chamber etch path 20b, which is formed through the pressure inlet channel system 13a according to the illustrated embodiment. Figure 4a , the pressure sensor 1 is shown in a state in which sacrificial layer material for forming the cavity is still present. Figure 4b In the process, the sacrificial layer material is removed from the cavity region 8 and the pressure measurement chamber 12 at the same time, and the cavity etching passage 20a is closed with the closing member 21. Figure 4cIn the embodiment of the present invention, initially only the sacrificial layer material is removed from the cavity region 8 and the cavity etching path 20a is closed with the closure 21. The sacrificial layer material can then be removed from the pressure measuring chamber 12 in a further process step at a later point in time in the manufacturing process (not shown in greater detail). In principle, it is also conceivable to first remove the sacrificial layer material from the pressure measuring chamber 12 and then remove the sacrificial layer material from the cavity region 8.

[0077] Figure 5a and Figure 5b A micro-electromechanical pressure sensor 1 according to a fourth embodiment and an intermediate state of the pressure sensor 1 during its manufacture are simplified and schematically shown in a side sectional view. According to the fourth embodiment, in addition to an input channel 13b and at least one output channel 13c, the pressure entry channel system 13a also has a channel system with at least one transverse channel 13d, which connects the input channel 13b and the at least one output channel 13c. In addition, at least one additional connecting channel 13e extending orthogonally to the at least one transverse channel 13d is provided. Therefore, the channel section of the pressure entry channel system 13a has a Z-shaped and / or Y-shaped direction through the substrate 2 and the other substrate layers SI1, SI2. Thus, a complex pressure inlet channel system 13a can be provided, which has multiple deflections of the fluid passing through the pressure inlet channel system 13a, wherein narrow and slot-shaped channels and / or individual channel sections can be provided with correspondingly selected small channel dimensions, such as a small channel height, channel width and / or channel length and / or a small channel cross-sectional area, which can provide a favorable interaction of the pressure measuring chamber 12 with the environment 1 of the pressure sensor 1 and suitable protection of the pressure measuring chamber 12 from the ingress of particles and liquids. The selection of a small channel dimension or the selection of a small channel cross-sectional area can be understood to mean that at least one geometric dimension or cross-sectional area of ​​the channel is designed to be small enough to technically achieve protection of the pressure measuring chamber against liquids and / or particles starting from a certain particle size. For example, depending on the configuration, particle sizes greater than 100 nm can be prevented from entering the pressure measuring chamber.

[0078] According to the fourth embodiment, in order to manufacture the pressure inlet channel system 13a, as in Figure 5aAs shown, after applying and structuring the additional first SiO2 layer SOW1, the additional first substrate layer SI1 can be applied and optionally flattened. Then, the additional second SiO2 layer SOW2 is applied and, after application, is structured in at least the following manner, so that in the area of ​​the later pressure entry channel system 13a, there is a structure made of the material of the additional second SiO2 layer SOW2 on the additional first substrate layer SI1, which at least partially covers the additional first SiO2 layer SOW1, and the connecting channel 13e passes through the additional first substrate layer SI1 and ends at the additional second SiO2 layer SOW2. Then, the additional second substrate layer SI2 can be applied, for example, epitaxially grown and / or applied by an LPCVD process. In the area where the additional second SiO2 layer SOW2 has been removed, the additional second substrate layer SI2 can be constructed polycrystalline and / or monocrystalline, and in the area where the additional second SiO2 layer SOW2 is present, it can be constructed polycrystalline. Before structuring the further second substrate layer SI2, a CMP process can optionally be carried out for planarization of the surface, and after structuring the further second substrate layer SI2, the further construction of the layer system starting with the first SiO2 layer SO1 is carried out. When producing the pressure entry channel system 13a, the etching process starting from the back side 2a of the substrate 2 on the further first SiO2 layer SOW1 is stopped. The etching process is continued only in the area in which the further first SiO2 layer SOW1 has been removed, so that the further first substrate layer SI1 is removed here and the etching process on the further second SiO2 layer SOW2 is stopped. If the hole structures provided in the first additional SiO2 layer SOW1 and the second additional SiO2 layer SOW2 are arranged offset relative to one another, then after removal of the first and second additional SiO2 layers SOW1, SOW2 and the SiO2 sacrificial layers SO1, SO2, SO3, SO4, SO5, at least one pressure inlet channel system 13a with a z-shaped and / or y-shaped channel section orientation is produced in the pressure measuring chamber 12, which is introduced into the pressure measuring chamber 12 via at least one inlet channel 13b, at least one connecting channel 13e, at least one transverse channel 13d and at least one outlet channel 13c. If the hole structures in the first additional SiO2 layer SOW1 and the second additional substrate layer SI2 are arranged sufficiently far apart from one another, at least one transverse channel 13d can be constructed with the aid of the second additional SiO2 layer SOW2, the minimum geometrical dimensions of which can be defined via the layer thickness of the second additional SiO2 layer SOW2. In this way, a pressure inlet channel system 13 a can be produced, via which it is possible to define, independently of the photoresist process, which particle sizes can still reach the pressure measuring chamber 12 and which can also reliably prevent the intrusion of liquids into the pressure measuring chamber 12 .According to the embodiment, the removal of the sacrificial material layers SO2, SO3, SO4, SO5 to construct the cavity region 8 can be performed simultaneously with the removal of the sacrificial material layers SO1, SO2, SO3, SO4, SO5 in the pressure measurement chamber 12 and with the removal of the additional first and second SiO2 layers SOW1, SOW2 in the pressure access channel system 13a, or this process step can be performed before or after the removal of the sacrificial material layers SO1, SO2, SO3, SO4, SO5 from the pressure measurement chamber 12 and the removal of the additional first and second SiO2 layers SOW1, SOW2 in the pressure access channel system 13a. Subsequently, the cavity etching passage 20a can be closed by means of the closing member 21 as described above.

[0079] Figure 6A microelectromechanical pressure sensor 1 according to a fifth embodiment is shown in a simplified and schematic manner. The fifth embodiment is essentially based on the fourth embodiment, but has a geometrically modified pressure inlet channel system 13a, which has a z-shaped and / or y-shaped channel section orientation, wherein at least one input channel 13b is produced in the substrate 2, and at least one lateral channel 13d connected to the at least one input channel and at least one output channel 13c connected thereto are produced in a further first substrate layer SI1 on the substrate 2. In this variant, the etching process for producing the pressure inlet channel system 13a stops over the entire surface of the structure formed by the further first SiO2 layer SOW1. The lateral dimensions of the further first SiO2 layer SOW1 extend beyond the lateral dimensions of the input channel 13b. If at least one output channel 13c is provided via the further first substrate layer SI1, which at least one output channel touches the further first SiO2 layer SOW1 and is located outside the input channel 13b when viewed laterally, a transverse channel 13d can be constructed based on the spacing of the output channel 13c from the input channel 13b, the minimum geometrical dimensions of which can be defined by the layer thickness of the further first SiO2 layer SOW1. In this way, a pressure inlet channel system 13a can be produced, via which it can be defined independently of the photoresist process which particle sizes can still reach the pressure measuring chamber 12 and which can also reliably prevent liquid from penetrating into the pressure measuring chamber 12. According to another embodiment option, which is not shown in greater detail, it is conceivable that the further first SiO2 layer SOW1 is implemented thicker in the region of the input channel 13b and laterally thinner at least in sections outside the region of the input channel 13b. As a result, a reliable etching stop can be achieved and unintentional etching through of the further first substrate layer SI1 can be reliably avoided, independently of the selected layer thickness of the further first SiO2 layer SOW1 (for the minimum geometrical dimension for producing the lateral channel 13d), for example the channel height measured perpendicularly to the surface of the substrate 2. Due to the possibility of producing the lateral channel 13d with the aid of the further first SiO2 layer SOW1 and / or optionally with the further second SiO2 layer SOW2, the output channel 13c can also be placed outside the sensing region 16 and thus a pressure access to the pressure measuring chamber 12 offset from the sensing region 16 can be achieved.

[0080] Figure 7a and Figure 7b A microelectromechanical pressure sensor 1 according to a sixth embodiment and intermediate states of the pressure sensor 1 during its production are shown simplified and schematically in a side sectional view. Figure 7a and 7bSchematically, it can be seen that the pressure sensor 1 is connected to a circuit carrier 25, such as an ASIC wafer. The connection can be established, for example, by a flip chip process or by a wafer bonding technique, such as eutectic bonding, thermocompression bonding or glass frit bonding. When using wafer bonding technology, the wafers or substrates connected to each other can be thinned back after the bonding process and further processed in further semiconductor technology process steps. Here, an electrical contact structure can be manufactured afterwards by at least one of the thinned wafers or substrates, and additional wiring planes and / or bonding pad structures can be provided on the surface of the wafer or substrate. After being separated into stacked individual chips, the bonding pad structure can be connected to an ASIC substrate, a ceramic substrate or a circuit board by means of wire bonding technology or flip chip assembly technology. Wafer bonding technology also enables the production of a hermetically sealed bonding frame structure, by means of which a hermetically sealed closed area can be produced, and the chip-to-chip contact structure can be located in this area. In this way, it can be avoided that liquid media and / or gaseous media will enter between the contact structures. Furthermore, it is also possible to omit the cap structure layer 11a at least in the sensing region 16 and use, for example, the circuit carrier 25 as the cap structure 11, as described below in conjunction with Figures 8a to 8c Explained.

[0081] If the pressure inlet channel 13 is produced on the back side 2a of the substrate 2 of the pressure sensor 1 only after optional back thinning of the pressure sensor 1 connected to the circuit carrier 25, it is advantageous if all sacrificial material layers SO1, SO2, SO3, SO4, SO5 in the cavity region 8 and preferably also in the pressure measuring chamber 12 are removed before producing at least one pressure inlet channel 13 or a pressure inlet channel system 13a.

[0082] Figure 7aA pressure sensor 1 is shown by way of example, which has been connected to a circuit carrier 25 configured as an ASIC wafer by a wafer bonding process. In the variant shown, a further first SiO2 layer SOW1 and a further second SiO2 layer SOW2 as well as a further first substrate layer SI1 and a further second substrate layer SI2 are used to produce at least one structure made of the material of the further second SiO2 layer SOW2 and completely surrounded by silicon material, which structure can then be used as an etching stop structure 29 in the production of the pressure inlet channel system 13a. With the help of the further first SiO2 layer SOW1 and the correspondingly arranged output channels 13c passing through the further first substrate layer SI1 and the further second substrate layer SI2 and terminating on the further first SiO2 layer SOW1, a z-shaped or y-shaped course of the channel section of the pressure inlet channel system 13a can be produced. The height of the lateral channel 13d can be defined by the thickness of the further first SiO2 layer SOW1. According to the embodiment shown, the first additional SiO2 layer SOW1 between the etching stop structure 29 and the substrate 2 is at least partially removed together with the SiO2 sacrificial material layers SO1, SO2, SO3, SO4, SO5 in the pressure measuring chamber 12 through at least one output channel 13c. The input channel 13b introduced from the back side 2a of the substrate 2 can realize a pressure passage to the pressure measuring chamber 12 via the removed first additional SiO2 layer SOW1 and the at least one output channel 13c. When removing the SiO2 sacrificial material layers SO1, SO2, SO3, SO4, SO5 from the pressure measuring chamber 12, the etching stop structure 29 arranged in the second additional SiO2 layer SOW2 and completely surrounded by silicon material is not involved in terms of etching technology. By providing an etching stop structure 29 of sufficient size, it is possible to avoid that when producing the input channel 13b, the second additional substrate layer SI2 is etched through and the sensor structure 5 (for example, the first membrane structure 6) is etched. Optionally, after manufacturing the input channel 13b, the etch stop structure 29 may be at least partially removed selectively to the surrounding silicon material.

[0083] exist Figure 7a and Figure 7b As can be seen, the cavity etching passage 20a and the measuring chamber etching passage 20b extend through the cap structure 11 of the pressure sensor 1 and can be closed in the aforementioned manner using the closure member 21 respectively after the corresponding etching process for removing the sacrificial material layers SO1, SO2, SO3, SO4 and SO5.

[0084] exist Figure 7bIt can also be seen that an insulating trench 28 is introduced into the substrate 2. For example, a contact structure 31 electrically insulated from the surrounding substrate 2, such as a conductor track and / or a bonding pad structure, can be provided in and / or on the substrate 2 by means of the insulating trench 28, which allows electrical contacting of the pressure sensor 1 and / or the circuit carrier 25.

[0085] Figures 8a to 8c A micro-electromechanical pressure sensor 1 according to a seventh embodiment and an intermediate state of the pressure sensor 1 during its manufacture are shown in a simplified and schematic side sectional view. According to the seventh embodiment, the cap structure 11 of the pressure sensor 1 is formed by a circuit carrier 25, which is configured as an ASIC wafer, for example, so that a particularly compact pressure sensor system (which has a pressure sensor 1 and a circuit carrier 25) can be provided, which circuit carrier has, for example, an evaluation circuit. In this case, the circuit carrier 25 assumes the mechanical protection function of the cap structure 11 and simultaneously assumes the electrical evaluation and / or control function of the pressure sensor 1. By the thickness of the fifth polysilicon layer SP5 arranged outside the sensing area 16 and / or the thickness of the bonding frame structure 30 used and / or the thickness of the fifth SiO2 sacrificial layer SO5 and / or the thickness of the fifth SiRiN layer SN5, a defined spacing can be established between the second membrane structure 7 facing the circuit carrier 25 and the circuit carrier 25.

[0086] In addition, from Figure 8b and Figure 8c As can be seen in FIG. 8 , when at least one bonding frame 30 is placed so that the hole etching passage 20a is enclosed by the at least one bonding frame (i.e., fully covered, see 8c) or the bonding frame structure 30 or at least a portion of the bonding frame structure 30 fully surrounds the hole etching passage 20a ( Figure 8b ) arrangement, the closure 21 of the hole etching passage 20a formed by the deposition of the closure material layer 21 can be optionally omitted. As a result, the process step of vodka for the closure 21 and / or the additional closure material layer can be omitted. The bonding frame 30 can especially completely surround the sensing area 16 and can preferably be arranged in an airtight manner. In this embodiment, the closed internal pressure set in the cavity area 8 can be set in the wafer bonding process. In addition, in this embodiment, the fifth polysilicon layer SP5 and / or the fifth SiO2 sacrificial layer SO5 and / or the fifth SiRiN layer SN5 for manufacturing the cap structure 11a can be eliminated, and the bonding frame or bonding frame structure 30, the fifth SiO2-sacrificial layer SO5 and / or the fifth SiRiN layer SN5 and / or the fifth polysilicon layer SP5 are arranged in a contact manner between the fifth SiO2 layer SO5 and / or the fifth SiRiN layer SN5 and / or the fifth polysilicon layer SP5 and the circuit carrier 25.

[0087] In a not shown embodiment variant, the hole etching passage 20a can be closed by depositing a closure material layer 21a and subsequently structured, wherein the closure structure 21 produced in the process in the region of the hole etching passage 20a can be at least partially covered by the material of the bonding frame 30. Furthermore, it is also possible to bring the bonding frame or the bonding frame structure 30 into direct contact with the closure material layer 21a at least partially.

[0088] Fig. 9 A pressure sensor 1 according to an eighth embodiment is shown, in which, starting from the back side 2a of the substrate 2, together with the input channel 13b of the pressure inlet channel system 13a, a measuring chamber etched passage 20a leading through the substrate 2 is also produced and, after the sacrificial material layers SOW1, SOW2, SO1, SO2, SO3, SO4, SO5 have been removed from the cavity region 8 and / or from the pressure measuring chamber 12, is closed with a closure 21. In an embodiment not shown, it is also possible to first produce the measuring chamber etched passage 20a and, before producing the input channel 13b through the pressure inlet channel system 13a of the substrate 2, remove the sacrificial material layers SOW1, SOW2, SO1, SO2, SO3, SO4, and close the measuring chamber etched passage 20a with a closure 21, and the sacrificial layers SOW1, SOW2 and the sacrificial layers SO1, SO2, SO3, SO4, SO5 are removed from the pressure measuring chamber 12.

[0089] Fig.10 A pressure sensor 1 according to a ninth embodiment is shown, wherein at least one hole etching passage 20a, for example in the form of an annular ring, is provided in the sensor structure 5 through the second membrane structure 7. The closure 21 of the at least one hole etching passage 20a is designed so that it has a high etching resistance with respect to an etching medium, which is used for removing sacrificial material layers SO1, SO2, SO3, SO4, SO5 (which form the subsequent pressure measuring chamber 12) and optionally for removing a further first SiO2 layer SOW1 and / or a further second SiO2 layer SOW2. It can also be seen that in the sensor structure 5, an anchoring structure 19 is produced between the region of the hole etching passage 20a in the sensor structure 5 and the middle vertical line M of the first and second membrane structures 6, 7. This makes it possible to stabilize the sensor structure 5 and achieve that the hole etching passage 20a and its closure 21 are not located in a movable membrane region, whereby the hole etching passage 20a and its closure 21 have no influence or very little influence on the performance of the sensor structure 5.

[0090] The SiRiN layers SN1, SN2, SN3, SN4, SN5, SN6, the polysilicon layers SP1, SP2, SP3, SP4, SP5 and the further substrate layers SI1, SI2 can be regarded as structural material layers of the layer system 3. The SiO2 layers SO1, SO2, SO3, SO4, SO5 and the further SiO2 layers SOW1, SOW2 can be regarded as sacrificial material layers of the layer system 3.

[0091] According to, for example, Figure 2 , Figure 4a and Fig. 9 The configuration possibilities shown can envisage that, selectively in the region of the cavity etching passage 20a and / or the measuring chamber etching passage 20b, a corresponding recess 32 is provided in the cap structure 11 (which has the cavity etching passage 20a and / or the measuring chamber etching passage 20b) and / or in the substrate 2 (which has the cavity etching passage 20a and / or the measuring chamber etching passage 20b), wherein the cavity etching passage 20a and / or the measuring chamber etching passage 20b are provided on the bottom region of the recess 32. As a result, the cavity etching passage 20a and / or the measuring chamber etching passage 20b can be arranged recessed relative to the surface 11b of the cap structure 11 facing the environment 14 and / or relative to the surface of the substrate 2 facing the environment 14. Due to the recessed arrangement of the cavity etching passage 20a and / or the measuring chamber etching passage 20b, mechanical protection of the corresponding etching passage and / or the closure 21 of the corresponding etching passage is achieved.

[0092] Fig.11 A simplified flow chart of a method 100 for producing a microelectromechanical pressure sensor 1 is shown. In this case, a substrate 2 is provided in a first step 110. Subsequently, according to a second step 120, a layer system 3 is produced on the substrate 2 by applying and structuring material layers. In this case, according to a third step 130, a cantilevered sensor structure 5 is produced with the material layers of the layer system 3, which has a first membrane structure 6, a second membrane structure 7, a first measuring electrode 9, a second measuring electrode 10 and a suspension structure 4 of the sensor structure 5. According to a fourth step 140, a cap structure 11 is arranged on the layer system 3 or produced with the aid of at least one cap structure layer 11a, wherein the cap structure 11 delimits a pressure measuring chamber 12 in which the sensor structure 5 is arranged in a cantilevered manner. By a fifth step 150, at least one pressure inlet channel 13 is produced through the substrate 2 of the pressure sensor 1 to the pressure measuring chamber 12.

[0093] With the aid of the above-described method steps for producing a microelectromechanical pressure sensor 1 and by means of the proposed design of the pressure sensor 1 , a compact and robust pressure sensor 1 with a high measuring sensitivity can be provided and produced in a simple and efficient manner.

Claims

1. A micro-electromechanical pressure sensor (1), comprising: - a substrate (2) having a layer system (3) arranged thereon; a sensor structure (5) fastened in cantilevered fashion to the layer system (3) by means of at least one suspension structure (4), the sensor structure comprising a first membrane structure (6) and a second membrane structure (7), between which a cavity region (8) is formed, wherein: A first measuring electrode (9) arranged in the cavity region (8) is fastened to the first membrane structure (6), and a second measuring electrode (10) arranged in the cavity region (8) is fastened to the second membrane structure (7), wherein the first measuring electrode (9) and the second measuring electrode (10) form a measuring capacitance in the cavity region (8); - a cap structure (11), which delimits a pressure measurement chamber (12), in which the sensor structure (5) is arranged in cantilevered fashion; and - at least one pressure inlet channel (13) to the pressure measuring chamber (12), wherein the at least one pressure inlet channel (13) extends through the substrate (2).

2. The pressure sensor (1) according to claim 1, wherein: An electrical connection structure (23) and / or a circuit carrier (25) are arranged in the cap structure and / or on a surface (11b) of the cap structure (11) facing away from the sensor structure (5).

3. The pressure sensor (1) according to claim 1 or 2, wherein: The cap structure (11) is formed by at least one cap structure layer (11a) of the layer system (3) and / or by a circuit carrier (25).

4. The pressure sensor (1) according to any one of the preceding claims, wherein: The at least one pressure inlet channel (13) is constructed as a pressure inlet channel system (13a), which has at least one input channel (13b) leading to the environment (14) of the pressure sensor (1) and at least one output channel (13c) leading to the pressure measuring chamber (12), wherein the at least one output channel (13c) has smaller geometric dimensions and / or a smaller channel cross section than the at least one input channel (13b) in at least one direction in a plane parallel to the back side (2a) of the substrate (2).

5. The pressure sensor (1) according to claim 4, wherein: The pressure inlet channel system (13a) has at least one transverse channel (13d) connecting the at least one input channel (13b) with the at least one output channel (13c).

6. The pressure sensor (1) according to any one of the preceding claims, wherein: The pressure sensor (1) comprises, at least in the region of the at least one pressure inlet channel (13), an encapsulation which comprises at least one encapsulation-free region on a back side (2a) of the substrate (2) facing away from the sensor structure (5).

7. The pressure sensor (1) according to any one of the preceding claims, wherein: The substrate (2) has at least one insulation trench (28).

8. The pressure sensor (1) according to any one of the preceding claims, wherein: At least one reference capacitor (17) having a stationary reference electrode (17a, 17b) is arranged in the cavity region (8) between the first membrane structure (6) and the second membrane structure (7), spaced apart from the first membrane structure (6) and the second membrane structure (7).

9. A method for producing a microelectromechanical pressure sensor (1) configured according to any one of claims 1 to 8, wherein - providing a substrate (2) (110); - producing a layer system (3) (120) on the substrate (2) by applying and structuring a material layer; - generating a cantilevered sensor structure (5) with the aid of the material layers of the layer system (3), the sensor structure having a first membrane structure (6), a second membrane structure (7), a first measuring electrode (9), a second measuring electrode (10) and at least one suspension structure (4) (130) of the sensor structure (5), wherein: A cavity region (8) is constructed between the first membrane structure (6) and the second membrane structure (7); a cap structure (11) being arranged on the layer system (3) or being produced (140) by means of at least one cap structure layer (11a) of the layer system (3), wherein the cap structure (11) delimits a pressure measuring chamber (12) in which the sensor structure (5) is arranged in a cantilevered manner; and - producing at least one pressure channel (13) (150) through the substrate (2) to the pressure measuring chamber (12).

10. The method (100) according to claim 9, wherein: The material layers of the layer system (3) are formed by structural material layers (SI1, SI2, SN1, SN2, SN3, SN4, SN5, SN6, SP1, SP2, SP3, SP4, SP5) and sacrificial material layers (SO1, SO2, SO3, SO4, SO5, SOW1, SOW2), wherein the sacrificial material layers (SO1, SO2, SO3, SO4, SO5, SOW1, SOW2) are removed via at least one etching path (20a, 20b) after the layer system (3) is generated by a sacrificial layer etching process.

11. The method (100) according to claim 10, wherein: Prior to the sacrificial layer etching process, the pressure inlet channel (13) is produced through the substrate (2) by means of a substrate etching process, wherein a sacrificial material layer (SO1) of the layer system (3) is provided adjacent to the substrate (2) and the substrate etching process is stopped on the sacrificial material layer.

12. The method (100) according to any one of claims 9 to 11, wherein: The at least one pressure inlet channel (13) into the pressure measuring chamber (12) is gradually produced by introducing an input channel (13b) through the substrate (2) and by introducing an output channel (13c), which passes through a structural material layer (SI1) of the layer system (3) adjacent to the substrate (2).

13. The method (100) according to claim 12, wherein the introduction depth of the supply channel (13b) is limited by means of an etch stop structure (29).

14. The method (100) according to any one of claims 10 to 13, wherein: The cavity region (8) is constructed by removing a sacrificial material layer (SO2, SO3, SO4) between the first membrane structure (6) and the second membrane structure (7), wherein the sacrificial material layer (SO2, SO3, SO4) is removed via at least one cavity etching path (20a) provided in the sensor structure (5), the cap structure (11) and / or the substrate (2).

15. The method (100) according to any one of claims 10 to 14, wherein: The pressure measuring chamber (12) is constructed by removing a sacrificial material layer (SO1, SO2, SO3, SO4, SO5) surrounding the sensor structure (5), wherein the sacrificial material layer (SO1, SO2, SO3, SO4, SO5) is removed via at least one measuring chamber etching passage (20b) provided in the cap structure (11) and / or the substrate (2).

16. The method (100) according to claim 14 or 15, wherein: The at least one cavity etching passage (20a) and / or the at least one measuring chamber etching passage (20b) are closed by means of a closure element (21).

17. The method (100) according to any one of claims 14 to 16, wherein: At least one bonding frame (30) is arranged between the cap structure (11) and the layer system (3) of the pressure sensor (1), so that the at least one cavity etching passage (20a) and / or the at least one measuring chamber etching passage (20b) are in particular completely surrounded and / or closed and / or the closing piece (21) is at least partially covered by the material of the bonding frame (30).

18. The method (100) according to any one of claims 9 to 17, wherein: An electrical connection structure (23) is applied to the cap structure (11) and electrically and / or mechanically connects the pressure sensor (1) to the circuit carrier (25) by a wafer bonding process or a flip chip process.

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