Inertial sensor and manufacturing process for producing an inertial sensor

Abstract

Inertial sensor (100) with the following features: an electrode layer (102) having an electrode (108); a counter electrode layer (106) comprising a first counter electrode (110) and a second counter electrode (112); and a sensor core layer (104) made of a monocrystalline material, comprising a first movably mounted sensor core (114) and a second movably mounted sensor core (116), wherein the sensor core layer (104) is arranged between the electrode layer (102) and the counter electrode layer (106), characterized by an insulation trench (214) which extends from the main side (218) of the counter electrode layer (106) facing away from the sensor core layer (104) through the counter electrode layer (106) to the sensor core layer (104) for electrical insulation of the first counter electrode (110) from the second counter electrode (112), wherein the insulation trench (214) is at least partially filled with an insulating material (224).

Description

State of the art

[0001] The present invention relates to an inertial sensor and a manufacturing method for manufacturing an inertial sensor.

[0002] The market for inertial sensors has undergone significant changes over the past two decades due to the introduction of sensors manufactured using microsystems technology. This has made it possible to offer inertial sensors in large quantities at low cost. Today's advancements require these MEMS sensors to become even more affordable and perform better. This pressure is leading to ever smaller sensors to save wafer space, and thus costs. To achieve ever more powerful sensors, the design, process, and structure of the sensors must be continuously improved. Another option for reducing costs is to manufacture both inertial sensors—angular rate and acceleration—in a single monolithic approach, the so-called 6DoF.

[0003] Currently, the sensors are built on a silicon substrate. The necessary layers for vertical electrodes and leads, electrical insulation, mechanical decoupling, and the sensor core are deposited one after the other.

[0004] DE 603 ​​195 28 T2 discloses a monolithic silicon accelerometer comprising four silicon acceleration sensor cells, each of which has a movable silicon inertial mass. For example, a cover structure with a metallic layer is shown, which is insulated from the silicon support structure and attached to it on both sides.

[0005] DE 198 10 534 A1 discloses a multi-axis acceleration sensor and a corresponding manufacturing method in which a movable electrode structure is formed in a single sensor element, wherein this movable electrode structure can be displaced along two axes within a plane and one axis outside the plane. A corresponding fixed detection electrode is provided.

[0006] From DE 41 32 232 a method for producing capacitive sensors, in particular for acceleration measurement, is known, in which the sensors are produced from a superficially conductive single-crystal wafer which is connected to at least one plate which is at least superficially conductive, wherein the wafer and the plate are insulated from each other.

[0007] From US 5,115,291 A a solid-state accelerometer is known in which two conductive silicon plates are placed on a frame surrounding a flywheel.

[0008] DE 10 2011 085 723 A1 discloses a component comprising a substrate with a first and a second cavity, wherein a first micromechanical structure is arranged in the first cavity and a second micromechanical structure is arranged in the second cavity. Different gas pressures are set in the two cavities. This allows, for example, the formation of an acceleration sensor. Disclosure of the invention

[0009] Against this background, the approach presented here is an inertial sensor and a manufacturing process for producing an

[0010] Inertial sensors according to the main claims are presented. Advantageous embodiments emerge from the respective subclaims and the following description.

[0011] An inertial sensor in which sensor cores made of a monocrystalline material are arranged movably, particularly between an electrode and a counter electrode, can be structured, designed and manufactured in a particularly small size.

[0012] By using the monocrystalline material, layer thickness tolerances for the sensor functional layer can be kept lower than those of a grown polycrystalline component layer of an inertial sensor. In addition to the possibility of using thicker sensor cores cost-effectively—the maximum manufacturable layer thickness of the monocrystalline material is unlimited—the use of the monocrystalline material also allows for the use of improved structuring processes that are based on the crystal orientation of the material, e.g., monocrystalline silicon.

[0013] Integrating the counter electrode via a cap layer of the inertial sensor can help increase the sensor's sensitivity to out-of-plane motion. Other quadrature compensation concepts are also feasible. In general, this aspect of the proposed inertial sensor concept also enables a further reduction in the sensor's installation space.

[0014] With the manufacturing process presented here, a small-sized, mechanically stable and high-temperature stable inertial sensor can be produced in which different pressures, which are suitable for example for yaw rate sensors and acceleration sensors, can be enclosed.

[0015] An inertial sensor with the following features is presented: an electrode layer having an electrode; a counterelectrode layer having a first counterelectrode and a second counterelectrode; and a sensor core layer made of a monocrystalline material, comprising a first movably mounted sensor core and a second movably mounted sensor core, wherein the sensor core layer is arranged between the electrode layer and the counter electrode layer.

[0016] The inertial sensor can be used to measure acceleration and / or angular rates, for example, in a vehicle. The counter electrodes can be designed to interact with the electrode and the sensor cores located between the electrode and the counter electrodes. The monocrystalline material can be monocrystalline silicon.

[0017] According to one embodiment of the inertial sensor presented herein, a first section of the electrode, the first sensor core, and the first counter electrode can form a rotation rate sensor element of the inertial sensor, and a second section of the electrode, the second sensor core, and the second counter electrode can form an acceleration sensor element of the inertial sensor. Thus, a rotation rate sensor and an acceleration sensor can be advantageously combined monolithically in a common sensor housing, thus saving space and costs.

[0018] According to a further embodiment, the inertial sensor can have a contacting trench for electrically contacting the electrode. The contacting trench can extend from a main side of the counterelectrode layer facing away from the sensor core layer, through the counterelectrode layer and the sensor core layer to the electrode. An inner wall of the contacting trench can have a conductive coating. With this embodiment, the electrode can be easily and reliably electrically contacted without the presence of vias. This is particularly possible in an exemplary sensor structure in which the electrode is present as an electrode buried in a substrate. In further embodiments, the inertial sensor can have a second contacting trench for electrically contacting the counterelectrode and / or a third contacting trench for electrically contacting the sensor core layer.

[0019] The inertial sensor can have a substrate that can be arranged adjacent to a main side of the electrode layer facing away from the sensor core layer. The substrate can be configured to support the layer stack comprising the electrode layer, sensor core layer, and counterelectrode layer and simultaneously provide contacts for electrically connecting individual or all layers. The contact trench can extend to a main side of the substrate facing away from the sensor core layer. This allows the electrode layer and / or the sensor core layer and / or the counterelectrode layer to be advantageously electrically contacted from two outer sides of the inertial sensor.

[0020] According to a further embodiment, the inertial sensor can have a shielding trench for electrically shielding the contacting trench. The shielding trench can be arranged such that it surrounds the contacting trench in a jacket-like manner. This allows capacitive losses of the inertial sensor to be avoided in a simple manner and without additional elements.

[0021] According to the invention, the inertial sensor can have an insulation trench for electrically insulating the first counterelectrode from the second counterelectrode. The insulation trench can extend from the main side of the counterelectrode layer facing away from the sensor core layer through the counterelectrode layer to the sensor core layer and can be at least partially filled with an insulation material. The insulation trench can be created using the same method as the contact trench described above. This allows the electrical separation of the two counterelectrodes to be achieved with little effort and using existing tools.By at least partially filling the insulation trench with the insulation material in a subsequent work step, the insulation trench can be closed in a simple manner and thus an undesired short circuit with electrical lines running on an outer side of the inertial sensor can be advantageously prevented.

[0022] The inertial sensor can have at least one further isolation trench, which can extend from the main side of the counterelectrode layer facing away from the sensor core layer through the counterelectrode layer to the sensor core layer to divide the first counterelectrode into a first counterelectrode section and a second counterelectrode section. The further isolation trench can also be at least partially filled with the insulation material. The further isolation trench can also be easily created and proves advantageous for the rapid and uniform introduction of, for example, an etchant into the layer structure for structuring the interior of the inertial sensor.

[0023] According to a further embodiment, the inertial sensor can have a first sensor cavity in which a first pressure prevails, and a second sensor cavity in which a second pressure different from the first pressure prevails. The first sensor core can be movably mounted in the first sensor cavity, and the second sensor core can be movably mounted in the second sensor cavity. For example, the first pressure can be a low pressure and the second pressure a high pressure. Thus, the functionality of the yaw-rate sensor element, which requires the low pressure, and the functionality of the acceleration sensor element, which requires the high pressure, can be optimally supported within the same sensor housing.

[0024] The first sensor cavity and / or the second sensor cavity can be sealed gas-tight from the surroundings of the inertial sensor by the conductive coating, also referred to as a metallization coating, of the contact trench and / or by the insulating material of the insulation trench and / or the further insulation trench. With this embodiment, the required pressures can advantageously be enclosed in the sensor cavities using elements already present in the inertial sensor.

[0025] According to a further embodiment, the inertial sensor can have at least one circuit element. The circuit element can be arranged on the main side of the counter electrode layer facing away from the sensor core layer. This allows for further functionalities, such as additional pressure measurement, to be easily incorporated into the inertial sensor.

[0026] In particular, the first counterelectrode and / or the second counterelectrode can be formed from a monocrystalline material. This embodiment allows a layer thickness and / or a structuring of the counterelectrode layer to be precisely determined and implemented. This allows for savings in manufacturing costs and installation space.

[0027] Furthermore, the sensor core layer and / or the counter electrode layer can comprise at least one functional element of a pressure sensor and / or a Hall sensor. With this embodiment, the inertial sensor can advantageously be expanded with additional functionalities.

[0028] According to a further embodiment, the first sensor core and / or the second sensor core can have spring elements for movable mounting. This allows the sensor cores to be attached to the housing of the inertial sensor without restricting their mobility. An extension direction of the spring elements can correspond to a crystal orientation of the monocrystalline material of the first sensor core and the second sensor core. This advantageously allows the stiffness of the spring elements to be easily adjusted.

[0029] A manufacturing method for producing an inertial sensor is also presented, the manufacturing method comprising the following steps: Providing a layer structure comprising an electrode layer having an electrode, a sensor core layer made of a monocrystalline material having a first movably mounted sensor core and a second movably mounted sensor core, and a counterelectrode layer having a first counterelectrode and a second counterelectrode; Etching a trench from the main side of the counter electrode layer facing away from the sensor core layer through the counter electrode layer to the sensor core layer to create an isolation trench between the first counter electrode and the second counter electrode; at least partially introducing an insulating material into the insulation trench to electrically insulate the first counter electrode from the second counter electrode; Etching a groove from a main side of the counter electrode layer facing away from the sensor core layer through the counter electrode layer and the sensor core layer to the electrode to create a contact trench for the electrode; and Applying an electrically conductive coating to an inner wall of the contact trench to electrically contact the electrode.

[0030] The manufacturing method can be used within an automated production line for the efficient production of a large number of the inertial sensors described above. This embodiment of the invention in the form of a manufacturing method also allows the problem underlying the invention to be solved quickly and efficiently.

[0031] According to one embodiment, the manufacturing method may include a step of sputtering a final metallization onto the main side of the counter electrode layer facing away from the sensor core layer. Thus, after completion, the inertial sensor can be easily connected to an external power source or expanded with additional electronic components.

[0032] The approach presented here further provides a device designed to carry out or implement the steps of a variant of the manufacturing method presented here in corresponding devices. This embodiment of the invention in the form of a device also allows the problem underlying the invention to be solved quickly and efficiently.

[0033] In this case, a device can be understood as an electrical device that processes sensor signals and outputs control and / or data signals depending on them. The device can have an interface, which can be implemented in hardware and / or software. In a hardware implementation, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the device. However, it is also possible for the interfaces to be separate integrated circuits or to consist at least partially of discrete components. In a software implementation, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

[0034] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular when the program product or program is executed on a computer or a device.

[0035] The approach presented here is explained in more detail below using the attached drawings. They show: Fig. 1 is a schematic diagram of an inertial sensor according to an embodiment of the present invention; Fig. 2 is a sectional view of an inertial sensor according to another embodiment of the present invention; Fig. 3 a sectional view of an inertial sensor with circuit elements arranged on the counter electrode, according to an embodiment of the present invention; Fig. 4 is a sectional view of an inertial sensor with bonded ASIC, according to an embodiment of the present invention; Fig. 5 is a sectional view of an inertial sensor with an unperforated counter electrode, according to an embodiment of the present invention; Fig. 6 is a sectional view of an exemplary layer structure for producing an inertial sensor according to an embodiment of the present invention; Fig. 7 is a sectional view of an inertial sensor with applied isolation trenches, according to an embodiment of the present invention; Fig. 8 is a sectional view of an inertial sensor with isolated isolation trenches, according to an embodiment of the present invention; Fig. 9 is a sectional view of a detail of an inertial sensor with silicon deposited on the insulation material, according to an embodiment of the present invention; Fig. 10 is a sectional view of an inertial sensor with contact trenches formed, according to an embodiment of the present invention; Fig. 11 is a sectional view of a detail of an inertial sensor with silicon deposited in the contact trenches, according to an embodiment of the present invention; Fig. 12 is a sectional view of a detail of an inertial sensor with metallization applied on the top side, according to an embodiment of the present invention; Fig. 13 to 15 electron microscope images illustrating an etching process for creating trenches and subsequent deposition of an electrically conductive polycrystalline silicon layer for electrical contacting; Fig. 16 is a sectional view of a coaxial structure of an inertial sensor according to an embodiment of the present invention; Fig. 17 a top view of the coaxial structure of an inertial sensor from Fig. 16, according to an embodiment of the present invention; Fig. 18 is a sectional view of a coaxial structure of a through-hole inertial sensor according to an embodiment of the present invention; Fig. 19 is a sectional view of an inertial sensor with trapped sputter pressure, according to an embodiment of the present invention; and Fig. 20 is a flowchart of a manufacturing method for manufacturing an inertial sensor according to an embodiment of the present invention.

[0036] In the following description of advantageous embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0037] Fig. Figure 1 shows a schematic diagram of an inertial sensor 100 according to an embodiment of the present invention. The inertial sensor 100 is designed in a layered structure and comprises an electrode layer 102, a sensor core layer 104 arranged parallel to the electrode layer 102, and a counterelectrode layer 106 arranged parallel to the sensor core layer 104. The sensor core layer 104 is arranged between the electrode layer 102 and the counterelectrode layer 106.

[0038] In the Fig. In the embodiment shown in Figure 1, the electrode layer 102 forms a base and the counterelectrode layer 106 forms a cover or cap of the sensor layer structure 100. Furthermore, the electrode layer 102 has an electrode 108. The counterelectrode layer 106 has a first counterelectrode 110 and a second counterelectrode 112, which are arranged adjacent to one another in a plane without contact. The sensor core layer 104 is a mechanically functional layer made of a monocrystalline material, e.g., silicon. As shown in Fig. 1, the sensor core layer 104 is composed of a first sensor core 114 and a second sensor core 116. The first sensor core 114 and the second sensor core 116 are arranged side by side in a plane, also without contact. Fig. 1, the first sensor core 114 and the second sensor core 116 each form a single crystal.

[0039] The first sensor core 114 is movably mounted in a first sensor cavity 124 formed by a first section 120 of the electrode 108 and the first counter electrode 110 via spring elements 118, and the second sensor core 116 is movably mounted in a second sensor cavity 126 formed by a second section 122 of the electrode 108 and the second counter electrode 112. An extension direction of the spring elements 118 corresponds to a crystal orientation of the monocrystalline material of the first sensor core 114 and the second sensor core 116. Fig. In the embodiment of the inertial sensor 100 shown in Figure 1, the first counter electrode 110 and the second counter electrode 112 are also formed from a monocrystalline material. The first counter electrode 110 is configured to provide a first electrical potential to the first sensor core 114, and the second counter electrode 112 is configured to provide a second electrical potential to the second sensor core 116 that differs from the first electrical potential.

[0040] In the Fig. 1, the first section 120 of the electrode 108, the first sensor core 114 and the first counter electrode 110 form a rotation rate sensor element 128 of the inertial sensor 100 and the second section 122 of the electrode 108, the second sensor core 116 and the second counter electrode 112 form an acceleration sensor element 130 of the inertial sensor 100.

[0041] Fig. 2 shows a cross section through an exemplary structure of the inertial sensor 100 presented here. In the Fig. In the embodiment shown in Figure 2, the inertial sensor 100 further comprises a substrate 200 and a first insulation layer 202, a second insulation layer 204, and a third insulation layer 206. The substrate 200 is arranged facing a main side 208 of the electrode layer 102, facing away from the sensor core layer 106, and is designed to support the layer structure 102, 104, 106. The term "main side" used herein, as shown in the illustration, refers to a side of an element with the largest dimensions compared to other sides of the same element.

[0042] The first insulation layer 202 is arranged between the substrate 200 and the electrode layer 102 forming a first functional layer, the second insulation layer 204 is arranged between the electrode layer 102 forming the first functional layer and the sensor core layer 104 forming a second functional layer, and the third insulation layer 206 is arranged between the sensor core layer 104 forming the second functional layer and the counterelectrode layer 106 forming a third functional layer. The insulation layers 202, 204, and 206 ensure at least partial electrical insulation between the substrate 200 and the electrode layer 102, as well as between the electrode layer 102 and the sensor core layer 104, and between the sensor core layer 104 and the counterelectrode layer 106. As the illustration shows, the insulation layers 202, 204, and 206 have a small thickness compared to the other layers of the sensor stack 100.The counterelectrode layer 106 is characterized by a significantly greater thickness than the electrode layer 102. The electrode 108 forming the electrode layer 102 is structured in the illustrated embodiment. It has a material separation into the first section 120 and the second section 122. Furthermore, the electrode 108 in the illustrated embodiment has a third section 210 and a fourth section 212, which are also separate.

[0043] As can be seen from the illustration in Fig. As can be seen in Figure 2, the first sensor cavity 124 and the second sensor cavity 126 are formed by removing sections of the insulation layers 202, 204, and 206. The first sensor core 114 and the second sensor core 116 are each movably arranged in the sensor cavities 124, 126 by means of spring elements (not shown here), so that they can oscillate freely in the cavities 124, 126, for example, to detect measured variables.

[0044] The Fig. The embodiment of the inertial sensor 100 shown in Figure 2 further comprises a plurality of isolation trenches 214, which extend transversely to a main extension direction 216 of the sensor layer stack 100, indicated by a double arrow in the illustration, from a main side 218 of the counter electrode layer 106 facing away from the sensor core layer 104 through the counter electrode layer 106 to the sensor core layer 104. In particular, in the embodiment shown in Fig. 2, one of the isolation trenches 214 electrically separates the first counter electrode 110 from the second counter electrode 112. Another isolation trench 214 electrically separates the first counter electrode 110 into a first counter electrode section 220 and a second counter electrode section 222. As shown in Fig. 2 shows, the insulation trenches 214 are spaced apart from one another at different distances and are each filled with an insulation material 224 starting at the main side 218 of the counter electrode layer 106 up to a predefined depth. Fig. 2, the further isolation trench 214 perforating the upper counter electrode 110 provides access for an RF sacrificial oxide etching process for the mechanical exposure of the underlying sensor core 114.

[0045] The Fig. The exemplary inertial sensor 100 shown in Figure 2 further comprises a plurality of contacting trenches 226 extending from the main side 218 of the counterelectrode layer 106 facing away from the sensor core layer 104 through the counterelectrode layer 106 to varying depths into the interior of the inertial sensor 100. A first contacting trench 226 extends from the main side 218 of the counterelectrode layer 106 facing away from the sensor core layer 104 through the counterelectrode layer 106, the third insulation layer 206, the sensor core layer 104, and the second insulation layer 204 to the electrode 108 to provide an electrical contacting option for the electrode 108.A second contacting trench 226 extends from the main side 218 of the counterelectrode layer 106 facing away from the sensor core layer 104, through the counterelectrode layer 106 and the third insulation layer 206 to the sensor core layer 104 to provide an electrical contacting option for the sensor core layer 104. A third contacting trench 226 extends from the main side 218 of the counterelectrode layer 106 facing away from the sensor core layer 106, through the counterelectrode layer 106, the third insulation layer 206, the sensor core layer 104, the second insulation layer 204, the electrode 108, and the first insulation layer 202 to the substrate 200 to provide an electrical contacting option for the substrate 200. Each of the contacting trenches 226 of the exemplary inertial sensor 100 in FIG. Fig. 2 has an electrically conductive coating 232 to ensure the electrical conductivity of the contact trenches 226. As shown, the electrically conductive coating 232 is completely applied to the inner walls 234 of the contact trenches 226.

[0046] The representation in Fig. 2 further shows that the first sensor cavity 124 is sealed gas-tight from the surroundings of the inertial sensor 100 by the insulation material 224 of the surrounding insulation trenches 214 and remaining sections of the insulation layers 202, 204, 206, and that the second sensor cavity 126 is sealed gas-tight from the surroundings of the inertial sensor 100 by remaining sections of the insulation layers 204 and 206 and the electrically conductive coating 232 of the first contact trench 226. Predefined, equal, or different pressures can be installed in the sensor cavity 124, 126 via the "walls" of the sensor cavity 124, 126.According to the functionality of the first sensor core 114 used in the first sensor cavern 124 for rotation rate detection, a first, low pressure prevails in the first sensor cavern 124 and a second, high pressure prevails in the second sensor cavern 126 according to the functionality of the second sensor core 116 used in the second sensor cavern 126 for acceleration detection.

[0047] The Fig. 2, the novel inertial sensor 100 proposed as an example based on the simplified cross section is constructed from bottom to top from the substrate 200, the first insulation layer 202, the first functional layer 102, the second insulation layer 204, the monocrystalline sensor core 104, the third insulation layer 206, the third functional layer 106 and the insulation or sealing layer made of the insulation material 224.

[0048] According to one embodiment, the substrate 200 is formed from silicon. The first insulation layer 202 electrically separates the first functional layer 102 from the substrate 200. The first insulation layer 202 can be structured if desired. If necessary, the first insulation layer 202 can consist of several insulating materials, such as SiO2 and / or SiN. The first functional layer 102 represents the lower electrode 108 and supply lines. It is either firmly connected to the substrate 200 via the first insulation layer 202 or arranged free-standing or floating above the substrate 200. According to one embodiment of the inertial sensor 100, the first functional layer 102 serves as the lower wiring level of the sensor 100. Depending on the application of the inertial sensor 100, the layer thickness of the first functional layer 102 can range from a few micrometers to several tens of µm.The first functional layer 102 can be made of polycrystalline silicon or, if more advantageous, can be used directly as SOI (silicon on insulator) together with the underlying first insulation layer 202 and the substrate 200. However, the first functional layer or electrode layer 102 is not limited to the use of silicon; other electrically conductive materials can also be used.

[0049] The second insulation layer 204 lying above the first functional layer 102 is in the Fig. The embodiment of the inertial sensor 100 shown in Figure 2 is structured and serves, on the one hand, as electrical insulation and a spacer between the lower electrode 108 and the actual inertial sensor core 104. The second insulation layer 204 can be made of SiO2, which advantageously results from thermal oxidation of silicon. This allows very precise layer thicknesses to be produced without significant variations. In the area below the sensor core 104, the second insulation layer 204 is at least partially removed as a sacrificial layer.

[0050] Above the second insulation layer 204 lies the sensor core or sensor core layer 104, which advantageously consists of crystalline silicon. As already mentioned, the use of crystalline silicon for the sensor cores 114, 116 has significant advantages. For example, the sensor core layer 104 has no grains and thus well-defined mechanical properties. By utilizing the anisotropic Young's modulus of crystalline silicon, Fig. 1 for supporting the cores 114, 116, different stiffnesses can be achieved by selecting the orientation to the crystal for the same cross-section. Crystal-oriented etching processes with better manufacturing tolerances can be used to manufacture the sensor cores 114, 116. Monocrystalline silicon surfaces also have a better surface quality than polycrystalline surfaces. This is reflected in improved photolithography and a lower roughness of the sensor core layer 104. Monocrystalline surfaces tend to smooth during the process rather than roughen, as is the case with polycrystalline silicon. According to embodiments of the inertial sensor 100, the second functional layer 104 can be used in conjunction with the third functional layer 106 as an SOI. As a result, the second functional layer 104 can be represented by the device layer of the SOI.The thickness variance of the device layer, consisting of the second functional layer 104 and the third functional layer 106, can be adjusted to up to ± 0.25 µm in current SOI processes, relatively independent of the layer thickness. These values ​​are difficult to achieve using polycrystalline layers. Finally, since SOI wafers are manufactured by bonding and grinding back the device layer, thicker layers can be used cost-effectively for the second functional layer or sensor core layer 104.

[0051] The requirements for the third insulation layer 206 located above the second functional layer 104 are the same as for the second insulation layer 204.

[0052] It is important that the third insulation layer 206 has as exactly the same layer thickness as the second insulation layer 204, which can be achieved very well by thermal oxidation.

[0053] The third functional layer 106 serves as the counter electrode or upper electrode in the inertial sensor 100. The upper electrode layer 106 and the lower electrode layer 102 allow the capacity for out-of-plane detection to be doubled. Furthermore, new concepts for quadrature compensation can be implemented, since the sensor cores 114, 116 can also be electrostatically attracted from above. This allows the sensor area 104 and the required voltages to be reduced, resulting in a cost advantage in the ASIC. Finally, the active upper electrode layer 106 can define and, if necessary, compensate for stray electrical fields.

[0054] In the inertial sensor 100 presented here, the counter electrodes 110, 112 represent a capping of the inertial sensor 100 and thus hermetically enclose a negative pressure inside the sensor 100. External influences, such as pressure changes, mechanical stress, etc., are shielded by the cap layer 106. As a consequence, this layer 106 is sufficiently thick, from a few tens of microns to a few hundred thousand microns. As in the case of the second functional layer 104, it is advisable to use an SOI wafer for the third functional layer 106. In such a case, the handle wafer simultaneously represents the third functional layer 106. In the manufacturing process of the inertial sensor 100 proposed here, the third functional layer 106 can be ground back to the desired thickness after being connected to the substrate 200. This is clearly more cost-effective than a deposition process given the required layer thicknesses.

[0055] In contrast to the lateral conductive paths found in CMOS devices, the thick monocrystalline third functional layer or counter electrode layer 106 can also be used for current flows in the vertical direction. This is clearly advantageous, for example, for the integration of horizontally measuring magnetic field sensors based on the Hall effect.

[0056] With the concept presented here, horizontally measuring magnetic field sensors can be realized with minimal effort, low cost, and low electrical power. Furthermore, a monocrystalline cover layer 106 allows the integration of piezoresistors, which can additionally measure, among other things, pressure or strain on the sensor 100, thus compensating for unwanted external influences.

[0057] The insulation or sealing layer 224 has several functions. Firstly, it electrically separates the various regions of the third functional layer 106, e.g., into the first counter electrode 110 and the second counter electrode 112, as well as the second counter electrode 112 into the first section 220 and the second section 222. Secondly, the insulation layer 224 represents a seal for enclosing a negative pressure, e.g., the first pressure in the first sensor cavity 124 for the exposed sensor core 114. The first pressure is set during the manufacture of the inertial sensor 100 by a deposition process in which the seal is closed. This can advantageously be done in an LPCVD process or chemical vapor deposition at low pressure at high temperatures. This seals in a pressure in the microbar range.This low pressure is suitable for achieving high oscillation quality and is thus advantageous for the functionality of the yaw rate sensor element 128 of the inertial sensor 100, which comprises the first section 120 of the electrode 108, the first sensor core 114, and the first counter electrode 110. The insulation or sealing layer 224 can consist of, among other materials, SiO2, SiN, or a combination of several layers, including, among other materials, electrically conductive layers, including polysilicon. The desired pressure in the cavity and thus the necessary process determine the choice of the sealing layer.

[0058] The final metallization 232 represents a further wiring level of the inertial sensor 100, which, in contrast to doped polysilicon tracks, has a lower electrical resistance. According to embodiments, the electrically conductive coating 232 can be separated from the third functional layer 106 by the insulating material 224.

[0059] According to embodiments of the inertial sensor 100 presented herein, the sensor core layer 104 and / or the counter electrode layer 106 may comprise at least one functional element of a pressure sensor and / or a Hall sensor.

[0060] Fig. 3 shows, again using a simplified cross-section, an exemplary integration of simple logical functions or passive electrical components such as, among others, capacities in the exemplary inertial sensor 100 from Fig. 2. As the illustration shows, the inertial sensor 100 is supplemented by two circuit elements 300. The circuit elements 300 are arranged on the main side 218 of the counter electrode layer 106 facing away from the sensor core layer 104, below the insulation material 224 or the metallization 232. Since in the Fig. 3, the counter electrode layer 106 forming the cover layer of the sensor 100 consists of monocrystalline silicon, logical functions can be integrated into the inertial sensor 100 by means of the switching elements 300, similar to a CMOS process.

[0061] Fig. 4 shows a sectional view of an addition to the inertial sensor 100 from Fig. 2 is an ASIC 400 according to an embodiment of the present invention. As the illustration shows, in the illustrated embodiment, the ASIC 400 forms a final cap for the inertial sensor 100, which is designed to reduce disruptive external influences on the sensor 100. The ASIC 400 was bonded to the counter electrode layer 106 during the manufacturing process of the sensor 100. In the inertial sensor concept presented here, the metallization 232 is located at the highest point of the sensor structure 100, thereby allowing a cost-effective electrical connection of the sensor 100 to the ASIC 400 by means of flip-chip bonding. In this way, disruptive external influences, such as pressure fluctuations, on the sensitive MEMS part of the inertial sensor 100 can be effectively reduced.

[0062] Furthermore, the metallization process can also be used to adjust the second pressure range in the second sensor cavity 126. If the metallization 232 is deposited using a sputtering process, a pressure in the millibar range can be achieved in the second sensor cavity 126. This is considered advantageous for the functionality of the acceleration sensor element 130 of the inertial sensor 100, which comprises the second section 122 of the electrode 108, the second sensor core 116, and the second counter electrode 112. In this way, both the rotation rate detection and the acceleration detection can be cost-effectively integrated into the sensor structure 100. Aluminum, among other materials, can be used for the metallization 232.

[0063] Fig. 5 shows, based on a further simplified cross-section, a section of another embodiment of the inertial sensor 100 proposed here. The sensor structure 100 shown in detail corresponds to the one shown in Fig. 2, with the difference that the first counter electrode 110 is formed in one piece, i.e. it is not divided into two sections by an insulation trench. Fig. In the embodiment of the inertial sensor 100 with a non-perforated upper electrode 110 shown in Figure 5, the sacrificial oxide layer or second insulation layer 204 between the lower electrode 108 and the sensor core 114 is removed before the sensor 100 is capped. Then, the previously structured cap wafer, which represents, among other things, the upper electrode or first counter electrode 110, is bonded in an aligned manner to the core 114.

[0064] With the proposed introduction of the upper surface electrode 110 located above the sensor core 114, electrostatic forces for positive feedback or electrostatic spring softening, quadrature compensation, and feedback control of Coriolis movements (in closed-loop operation) for out-of-plane movements of the yaw rate sensor element 128 of the inertial sensor 100 can now be applied in two directions. This pre-deviates the sensor core 114 in both directions: downward toward the substrate 200 and upward toward the cap, which positively influences the properties of the sensor 100. With quadrature compensation for out-of-plane modes, nonlinear forces that could significantly contribute to the excitation of spurious modes at higher frequencies or negatively impact the vibration robustness of the yaw rate sensor 128 can be eliminated.

[0065] This includes Fig. The concept proposed here, implemented in Figure 5, eliminates the limitation of the available sensor area of ​​the inertial sensor 100 due to the size of the capacitances of the sensor core 114 compared to the surface electrodes 108, 110 for motion detection and force coupling. The distance between the core 114 and the cap 110 is no longer subject to large process fluctuations and is generally no larger than a base distance between the core 114 and the lower electrode 108. Since the concept presented here eliminates the need for seal glass bonding and eutectic bonding processes for connecting the cap 110, the electrical potential of the cap 110 can be precisely defined. Electromagnetic conduction charges on the sensor core 114 can thus be avoided.

[0066] The so-called levitation effect in comb drive structures, which is based on an asymmetric termination of the stray electric fields at the top and bottom and which excites the yaw rate sensor 128 to in-plane oscillations, does not occur here. This means that the drive structure is also excited to out-of-plane oscillations at the frequency of the in-plane useful movement. The capacitances and electric fields between core 114 and upper electrode 110 are symmetrical to the capacitances and fields between core 114 and lower electrode 108. Excitation of spurious modes, which could negatively impact the performance of the yaw rate sensor element 128, can thus be advantageously avoided. Modulations in the capacitance between upper electrode 110 and lower electrode 108 caused by parallel in-plane movements of a perforated core mass in the drive mode can also be avoided by using the surface electrode 110.Increased noise from sensor 100 and excitation of parasitic modes are no longer to be expected.

[0067] The Fig. The concept of the imperforate upper surface electrode 110 shown in Figure 5 thus improves the performance in particular of the rotation rate sensor element 128 of the inertial sensor 100 in many ways. In addition, the invention allows a reduction in the area of ​​certain embodiments of the inertial sensor 100, since double the capacities of the electrodes 108, 110 for movement detection and force coupling for out-of-plane movements can be realized per sensor surface.

[0068] In addition, due to the lack of perforation, there is no / less undesirable electrical field line distortion between the movable, moving sensor core 114 and the upper unperforated surface electrode 110.

[0069] According to the Fig. In the embodiments of the inertial sensor 100 shown in Figures 1 to 5, a structure is proposed that is characterized by the buried contact level 102 as wiring and the lower electrode 108, and whose functional cap layer, represented by the counter electrode layer 106, is formed from monocrystalline material. The different potentials in the cap layer 106 are separated from one another by the filled isolation trenches 214. Silicon-rich nitride, for example, is used as the filling material 224. The electrically conductive coating 232 at the level of the cap 106 enables a simplified connection to the ASIC 400 without TSVs or through-contacts, for example, via flip-chip bonding. Circuit elements 300, such as piezoresistors, can be incorporated into the monocrystalline cap material 106.In particular, it is possible to monolithically integrate both inertial sensors, the acceleration sensor 130 and the yaw rate sensor 128, as well as other sensors such as pressure and Hall sensors, into one process or sensor 100. A two-stage closure of the gyro cavity 124 with a high-temperature LPCVD process and the acceleration sensor cavity 126 with a low-temperature sputter metallization process enables both compatibility with a non-stick coating and the inclusion of different pressures in the gyro cavity 124 and the acceleration sensor cavity 126, respectively.

[0070] The following refers to the production of the Fig. 1 to 5 presented inertial sensor 100.

[0071] The electrical contacting of layers that lie deep in the substrate or even electrical contacting through a silicon wafer is a technological challenge. In the current state of the art, electrical contact is made, for example, via the back side to the active layer using a thick silicon stamp that is electrically separated from the rest of the substrate by an oxide grid. The challenge here is to produce a mechanically stable oxide grid that can support the relatively large stamp. To do this, for example, a conical opening is trenched into the substrate and then an electrically insulating layer is deposited. This layer is opened at the bottom, in the trench, to enable electrical contact to the buried layer. A metallization is then deposited via sputtering, which creates the electrical contact between the surface and the buried layer.It is always challenging to create a contact that is as compact as possible, electrically conductive, and with low capacitance to the substrate. The general difficulty lies in integrating the contact in a conformal manner into a process flow.

[0072] Fig. 6 shows a sectional view of an exemplary layer structure for the production of the inertial sensor 100 proposed herein according to an embodiment of the present invention. The layer structure already shown in FIGS. Fig. 2 to 5 show a known functional layer structure prior to electrical contacting to establish the functionality of the inertial sensor 100. The layer structure comprises, from bottom to top, the substrate 200, the first insulation layer 202, the electrode layer 102 forming the first functional layer, the second insulation layer 204, the sensor core layer 104 forming the second functional layer, the third insulation layer 206, and the third functional layer 106 of the inertial sensor 100.

[0073] It should be noted that this invention is not limited to the Fig. 6, but can be used for electrically contacting levels in various structures. The structure used here consists of the three functional layers 102, 104, 106 and the substrate 200. Each of the functional layers 102, 104, 106 is separated from one another by one of the electrically insulating layers 202, 204, 206. The movable mass, for example, can be formed in the second functional layer 104. The first functional layer 102 can serve, for example, as the lower electrode, and the third functional layer 106 can form the counter electrode as well as a closure or capping of the sensor 100. The layer thicknesses are in the range between 150 µm and 200 µm for the substrate 200 and the third functional layer 106. The layer thicknesses of the functional layers 102 and 104 are in the range of 1 µm to 50 µm, and the insulating layers 202, 204, 206 have a thickness of 0.1 µm to 3 µm.During the process, the functional layers 104 and 106 are structured, and cavities may be created. As shown in . Fig. 6 shows, the isolation trenches 214 for electrically separating the functional layers 102 and 104 into different sections are already partially formed in the provided layer stack.

[0074] Fig. 7 shows in another sectional view the layer stack of Fig. 6 after a further process step for producing the inertial sensor 100. Here, after the structuring of the third functional layer 106, the isolation trenches or isolation trenches 214 are completely created, i.e., they extend from the main side 218 of the counterelectrode layer 106, facing away from the sensor core layer 104, to different depths into the interior of the stack. The isolation trench 214 created on the right in the illustration extends from the main side 218 through the counterelectrode layer 106 and the sensor core layer 104 to the second isolation layer 204; the remaining three isolation trenches 214 extend from the main side 218 through the counterelectrode layer 106, the sensor core layer 104, and the electrode layer 102 to the first isolation layer 202. This also separates the counterelectrode layer 106 into sections—here of equal size. The isolation trenches 214 can be created, for example, using an etching process.The isolation trenches 214 are dimensioned as narrow as possible, on the order of 1 µm to 5 µm. This corresponds to a high aspect ratio of approximately 1:50 to 1:100. Unlike the illustration in . Fig. 7, isolation trenches 214 can also be created in the substrate 200.

[0075] Fig. Figure 8 shows, in a further sectional view, the result of a subsequent process step in the manufacture of the inertial sensor 100. Here, the insulation trenches 214 are sealed with the insulation material 224. As the illustration shows, the insulation material 224 partially penetrates the insulation trenches 214 and lies partially on the main side 218 of the counter electrode layer 106 facing away from the sensor core layer 104. The insulation material 224 forms a gas-tight seal of the insulation trench 214. Sealing the insulation trenches 214 with the insulation material 224 creates electrical insulation. The insulation material 224 can be, for example, SiO2 or SiN. To apply the insulation, the insulation material 224 can be deposited using low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD) processes.Another option is deposition using a thermal oxidation process. Alternatively, the insulation can also be provided using a stack of different layers.

[0076] Fig. Figure 9 shows a sectional view of the result of a further process step for the production of the inertial sensor 100. Shown is a section of the layer structure of Fig. 8 with one of the insulation trenches 214 in the material of the counter electrode layer 106. As the illustration shows, a layer 900 of a conductive material was subsequently deposited on the insulation material 224, which extends into the insulation trench 214. In the Fig. In the embodiment shown in Figure 9, silicon was used. The additional closure with layer 900 is advantageous when using the isolation trenches 214 to enclose a negative pressure in the microbar range in the inertial sensor 100, which can be achieved, for example, using a high-temperature EpiPolySi process. In this case, the high temperatures are beneficial for achieving the most nonconformal closure possible, i.e., a closure with a low penetration depth into the trenches 214. The insulating layer 900 is patterned with a desired design.

[0077] Fig. 10 again shows in a cross-section the result of an exemplary creation of the contacting trenches 226 of the inertial sensor 100. As the illustration in Fig. 10 shows, in a further structuring of at least the third functional layer 106, the contacting trenches or contacting trenches 226 are etched from the main side 218 of the counter electrode layer 106 facing away from the sensor core layer 104 to different depths into the interior of the stack, namely in the case of Fig. 10, a contacting trench 226 is formed between two insulation trenches 214. The first contacting trench 226 on the left in the illustration penetrates the counter electrode layer 106, the third insulation layer 206, the sensor core layer 104, the second insulation layer 204, the electrode layer 102, and the first insulation layer 202 and reaches the substrate 200. The second contacting trench 226 in the middle of the illustration stops on the electrode layer 102, and the third contacting trench 226 on the right in the illustration stops on the sensor core layer 104.

[0078] In order to achieve the advantageously small dimensions, the separated structures 226 are in the order of 3 µm to 10 µm. This advantageously achieves high aspect ratios of 1:15 to 1:50. The insulation layers 202, 204, 206 are removed in sections, thus creating access to the respective layer 102, 104, 200 to be contacted. Deeper levels are achieved by etching additional insulation layers and underlying cavities. In this step of manufacturing the inertial sensor 100, undercuts inevitably occur, on the one hand due to isotropic removal or overetching of the insulation layers 202, 204, 206 and, on the other hand, due to unavoidable alignment offsets. These undercuts are compensated for by the contacting. The undercuts will be discussed in more detail below. Fig. 13 to 15 received.

[0079] Fig. Figure 11 again shows, in cross section, the result of a subsequent process step in the manufacture of the inertial sensor 100, according to an embodiment of the present invention. As previously with the isolation trenches, an electrically conductive layer 900 is also deposited on the inner walls 234 of the contacting trenches 226. In the Fig. In the embodiment of the inertial sensor 100 shown in Figure 11, a highly doped polysilicon or amorphous silicon layer was deposited in an LPCVD process to form the contact layer 900. The deposition temperature was clearly reaction-limited, so that the deposition rate is not determined by diffusion, so that the deposition 900 is uniform deep into the narrow trenches 226.

[0080] Fig. 12 shows a sectional view of an exemplary result of a final process step of the metallization of the inertial sensor 100. In the Fig. In the embodiment shown in Figure 12, a final metallization 1200 was applied to the top side of the inertial sensor 100 in a sputtering process. As shown in Fig. 12 shows, the final metallization 1200 is applied to the inertial sensor 100 using the sputtering process with only a small penetration depth into the contact trenches 226.

[0081] Fig. 13 to 15 illustrate, using electron microscope images, the formation of undercuts during an etching process for creating the isolation trenches and / or contact trenches.

[0082] Fig. Figure 13 shows a plurality of trenches created in a wafer using deep reactive ion etching (DRIE). The trenches were etched into the wafer with a width of three micrometers and a depth of 100 micrometers at an aspect ratio of 1:50.

[0083] Fig. 14 shows an enlarged detail of the image from Fig. 13 an undercut 1400 created in the etching process, which was filled into the trenches as a result of a conformal deposition of polysilicon.

[0084] Fig. Figure 15 shows the wafer at a depth of 100 µm after doped polysilicon was deposited in an LPCVD process at 620 °C. The layer thickness at the bottom of the trenches is only approximately 10% less than at the surface of the wafer.

[0085] Fig. 16 again shows, in a sectional view, an exemplary coaxial structure of the inertial sensor 100 as a result of an exemplary variant of the method for producing the inertial sensor 100 discussed above. The structure of the embodiment of the inertial sensor 100 shown in the illustration corresponds to that of the inertial sensor 100 shown in Fig. 12, with the difference that all contacting trenches 226 stop on the electrode layer 102 and the left insulation trench 214 in the illustration, like the right insulation trench 214 in the illustration, stops at the second insulation layer 204.

[0086] In the Fig. In the embodiment of the inertial sensor 100 shown in section in Figure 16, a shielding trench 1600 surrounds the centrally arranged contacting trench 226 in a jacket-like manner in order to electrically shield the contacting trench 226 in the sense of a shield. An electrical resistance of the Fig. The contact shown in Figure 16 is defined by the silicon layer 900 deposited here in a thickness of 1 mΩcm and by the conductivity of the individual functional layers 102, 104, 106. The representation in Fig. Figure 16 shows how contacts 226 and 1600 are constructed like a coaxial conductor to minimize capacitive losses. The contact trench 1600, which is arranged like a jacket around the contact trench 226, can be set to a defined potential.

[0087] Fig. 17 shows a top view of the coaxial structure of the inertial sensor 100 from Fig. 16 along a section line AA'. Here, it is clearly visible how the shielding trench 1600 surrounds the contact or contacting trench 226 as a closed silicon shield or silicon ring. The contact 226 is led outward via the insulation 224 via suitable rewiring or access to bond pads 1700 or the like.

[0088] Fig. 18 shows a sectional view of an embodiment of the inertial sensor 100 as a result of a further exemplary variant of the method for producing the inertial sensor 100 discussed above. Fig. 18 shows the inertial sensor 100 in a coaxial design with shield and through-hole plating. Fig. The embodiment of the inertial sensor 100 shown in Figure 18 corresponds to the Fig. 16, with the difference that both the isolation trenches 214 and the contacting trench 226 and the jacket-shaped shielding trench 1600 are passed from the main side 218 of the counter electrode layer 106 facing away from the sensor core layer 104 through the entire layer structure to a main side 1800 of the substrate 200 facing away from the sensor core layer 104.

[0089] According to the Fig. In the embodiment of the inertial sensor 100 shown in Figure 18, contacting of the first functional layer or electrode layer 102 is thus also possible from a counter-side to the counter-electrode layer 106. This variant of the inertial sensor 100 thus offers a decisive advantage for the integration of several of the sensors 100 into a multi-axis sensor, since electrical signals can be routed through the chip from the front to the back. To achieve this, the process steps that were performed on the third functional layer 106 in the embodiments shown above must also be carried out on the substrate 200. This creates a through-hole connection as in Fig. 18 shown.

[0090] Fig. 19 shows, in a further cross-section, a detailed section of an embodiment of the inertial sensor 100 as a result of a further exemplary variant of the method for manufacturing the inertial sensor 100 discussed above. One possibility for establishing the second, higher internal pressure in the second sensor cavity 126 required for the functionality of the acceleration sensor element of the inertial sensor 100 results from the inclusion of the sputter pressure during the manufacturing process of the inertial sensor 100. This is made possible by creating an extended, larger cavity 1900 in the first functional layer 102 or the second functional layer 104. This shifts the deposition conditions of the conductive layer 900 in the cavity 1900 toward the diffusion-limited region, and the cavity 1900 is thus not closed.In the final sputtering step, access to the adjacent contact trench 226 is then closed, and the sputtering pressure—including any partial pressures due to outgassing—is enclosed in the second sensor cavity 126. This allows a pressure of > 10 mbar to be enclosed.

[0091] Fig. 20 shows a summary of the Fig. 6 to 19 show a flow diagram of a basic embodiment of a manufacturing method 2000 for manufacturing an inertial sensor. The manufacturing method 2000 is an established manufacturing method from microsystem technology for manufacturing the inertial sensor, as described in the Fig. 1 to 5 is presented.

[0092] In a step 2002, a wafer layer structure is provided, which consists of an electrode layer having an electrode, a sensor core layer made of a monocrystalline material and having two movably mounted sensor cores, and a counterelectrode layer having two counterelectrodes. In a first step 2004, a plurality of shafts are etched from a main side of the counterelectrode layer facing away from the sensor core layer through the counterelectrode layer to the sensor core layer in order to provide isolation trenches in the layer structure. In a step 2006, an insulation material is introduced into the insulation trenches to electrically isolate the insulation trenches.In a step 2008, a further plurality of grooves is created from the main side of the counterelectrode layer facing away from the sensor core layer through the counterelectrode layer and / or the sensor core layer and / or the electrode layer to electrically contact individual elements of the inertial sensor. In a step 2010, an electrically conductive coating is applied to the inner walls of the contact trenches to establish the electrical contact. In a step 2012, a final metallization is sputtered onto the main side of the counterelectrode layer facing away from the sensor core layer.

[0093] According to one embodiment, in the manufacturing method 2000 for MEMS inertial sensors, a negative pressure is enclosed in the sensor cavity(ies). The optimal cavity pressure varies depending on the sensor. Angular rate sensors require a lower negative pressure than acceleration sensors. With the concept presented here, the required pressure can be enclosed in or between functional layers of the inertial sensor during the manufacturing process 2000. This eliminates the need for a cap consisting of a wafer that is subsequently bonded over the structure.

[0094] In summary, the 2000 manufacturing process consists of two processes. The first process creates the electrical insulation, and the second process creates the electrical contact.

[0095] Using manufacturing method 2000, an inertial sensor can be manufactured that, with electrical contact between the buried, electrically active layers, is compact, with an exemplary diameter of only 50 micrometers, exhibits an electrical resistance of less than 50 ohms, and is characterized by low capacitance to the surrounding layer. Due to the design, contact is achieved through different layers, such as silicon or SiO2, possibly with undercuts. Electrical contact between different levels is implemented at variable depths. Furthermore, an inertial sensor manufactured according to manufacturing method 2000 is high-temperature stable and mechanically stable, excluding the final metallization. Suitable pressures of less than one millibar for angular rate sensors and over 10 millibar for acceleration sensors are readily possible.

[0096] The exemplary embodiments described and shown in the figures are selected only as examples. Different exemplary embodiments can be combined with each other in their entirety or with regard to individual features. Furthermore, one exemplary embodiment can be supplemented by features of another exemplary embodiment.

[0097] Furthermore, the process steps presented here can be repeated and carried out in a different order than that described.

[0098] If an embodiment comprises an “and / or” link between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature and according to another embodiment has either only the first feature or only the second feature.

Claims

[1] Inertial sensor (100) with the following features: an electrode layer (102) having an electrode (108); a counterelectrode layer (106) having a first counterelectrode (110) and a second counterelectrode (112); and a sensor core layer (104) made of a monocrystalline material, comprising a first movably mounted sensor core (114) and a second movably mounted sensor core (116), wherein the sensor core layer (104) is arranged between the electrode layer (102) and the counter electrode layer (106), characterized byan isolation trench (214) which extends from the main side (218) of the counterelectrode layer (106) facing away from the sensor core layer (104) through the counterelectrode layer (106) to the sensor core layer (104) for electrically isolating the first counterelectrode (110) from the second counterelectrode (112), wherein the isolation trench (214) is at least partially filled with an isolation material (224). [2] Inertial sensor (100) according to claim 1, wherein a first portion (120) of the electrode (108), the first sensor core (114) and the first counter electrode (110) form a rotation rate sensor element (128) of the inertial sensor (100) and a second portion (122) of the electrode (108), the second sensor core (116) and the second counter electrode (112) form an acceleration sensor element (130) of the inertial sensor (100). [3] Inertial sensor (100) according to one of the preceding claims, with a contacting trench (226) for electrically contacting the electrode (108), wherein the contacting trench (226) extends from a main side (218) of the counterelectrode layer (106) facing away from the sensor core layer (104) through the counterelectrode layer (106) and the sensor core layer (104) to the electrode (108), and wherein an inner wall (234) of the contacting trench (226) has an electrically conductive coating (900). [4] Inertial sensor (100) according to claim 3, comprising a substrate (200) arranged adjacent to a main side (208) of the electrode layer (102) facing away from the sensor core layer (104), wherein the contacting trench (226) extends to a main side (1800) of the substrate (200) facing away from the sensor core layer (104). [5] Inertial sensor (100) according to claim 3 or 4, with a shielding trench (1600) for electrically shielding the contacting trench (226), wherein the shielding trench (1600) is arranged in a jacket-like manner surrounding the contacting trench (226). [6] Inertial sensor (100) according to one of the preceding claims, with a further insulation trench (214) which extends from the main side (218) of the counterelectrode layer (106) facing away from the sensor core layer (104) through the counterelectrode layer (106) to the sensor core layer (104) in order to divide the first counterelectrode (110) into a first counterelectrode section (220) and a second counterelectrode section (222), wherein the further insulation trench (214) is at least partially filled with the insulation material (224). [7] Inertial sensor (100) according to one of the preceding claims, which has a first sensor cavity (124) in which a first pressure prevails, and a second sensor cavity (126) in which a second pressure different from the first pressure prevails, wherein the first sensor core (114) is arranged in a movably mounted manner in the first sensor cavity (124) and the second sensor core (116) is arranged in a movably mounted manner in the second sensor cavity (126). [8] Inertial sensor (100) according to claim 7, wherein the first sensor cavity (124) and / or the second sensor cavity (126) is sealed in a gas-tight manner from an environment of the inertial sensor (100) by the electrically conductive coating (900) of the contacting trench (226) and / or by the insulation material (224) of the insulation trench (214) and / or of the further insulation trench (214). [9] Inertial sensor (100) according to one of the preceding claims, with at least one circuit element (300) which is arranged on the main side (218) of the counter electrode layer (106) facing away from the sensor core layer (104). [10] Inertial sensor (100) according to one of the preceding claims, wherein the first counter electrode (110) and / or the second counter electrode (112) is formed from a monocrystalline material. [11] Inertial sensor (100) according to one of the preceding claims, wherein the sensor core layer (104) and / or counter electrode layer (106) comprises at least one functional element of a pressure sensor and / or a Hall sensor. [12] Inertial sensor (100) according to one of the preceding claims, wherein the first sensor core (114) and / or the second sensor core (116) have spring elements (118) for movable mounting, wherein an extension direction of the spring elements (118) corresponds to a crystal orientation of the monocrystalline material of the first sensor core (114) and second sensor core (116). [13] Manufacturing method (2000) for manufacturing an inertial sensor (100), the manufacturing method (2000) comprising the following steps: Providing (2002) a layer structure comprising an electrode layer (102) having an electrode (108), a sensor core layer (104) made of a monocrystalline material and having a first movably mounted sensor core (114) and a second movably mounted sensor core (116), and a counterelectrode layer (106) having a first counterelectrode (110) and a second counterelectrode (112), wherein the sensor core layer (104) is arranged between the electrode layer (102) and the counterelectrode layer (106); Etching (2004) a shaft from a main side (218) of the counter electrode layer (106) facing away from the sensor core layer (104) through the counter electrode layer (106) to the sensor core layer (104) in order to create an isolation trench (214) between the first counter electrode (110) and the second counter electrode (112); at least partially introducing (2006) an insulating material (224) into the insulating trench (214) in order to electrically insulate the first counter electrode (110) from the second counter electrode (112); Etching (2008) a shaft from the main side (218) of the counter electrode layer (106) facing away from the sensor core layer (104) through the counter electrode layer (106) and the sensor core layer (104) to the electrode (108) in order to create a contacting trench (226) for the electrode (108); and Applying (2010) an electrically conductive coating (900) to an inner wall (234) of the contacting trench (226) in order to electrically contact the electrode (108). [14] Manufacturing method (2000) according to claim 13, comprising a step of sputtering (2012) a final metallization (1200) onto the main side (218) of the counter electrode layer (106) facing away from the sensor core layer (104).

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