Sensor element and method for manufacturing a sensor element

Abstract

The invention relates to a sensor element (100) for measuring a temperature, the sensor element comprising: - a carrier (2) having an upper side (11) and a lower side (12), the upper side (11) being electrically insulating, - at least one functional layer (7) comprising a material having a temperature-dependent electrical resistance, - a plurality of first and second electrodes (4a, 4b) for electrically contacting the functional layer (7), and - at least three contact pads (10a to 10f) for electrically contacting the sensor element (100), wherein the sensor element (100) has a variable nominal resistance, and wherein the at least one functional layer (7) comprises a plurality of regions (70) which are contacted separately such that the nominal resistance of the sensor element (100) depends on the contacted regions (70) of the functional layer (7). The invention also relates to a method for manufacturing a sensor element (100) and to a use of the sensor element (100).

Description

[0001] P2024, 0930 WO N September 8, 2025

[0002] 1

[0003] DESCRIPTION

[0004] SENSOR ELEMENT AND METHOD FOR MANUFACTURING A SENSOR ELEMENT

[0005] The present invention relates to a sensor element, in particular a temperature sensor. The present invention further relates to a method for manufacturing a sensor element, in particular a temperature sensor, and to the use of a sensor element.

[0006] To integrate passive components, such as sensors, capacitors, protective components or heaters, into electrical systems, the dimensions must be adapted for modern packaging designs, which are in the micrometer and even nanometer scale range.

[0007] To achieve this level of miniaturization, for example, ceramic thermistors (NTCs) are deposited as thin films onto substrates, usually silicon wafers, with electrical connections. These novel components can be integrated into MEMS (Micro Electromechanical Systems) or SESUB (Semiconductor Embedded in Substrate) structures.

[0008] To implement NTC sensors with different nominal resistances, current technology requires the integration of various components with such nominal resistances into a single circuit. The resistances are fixed by the manufacturer, e.g., 100 kΩ, and cannot be further adapted to specific applications. P2024, 0930 WO N 8, September 2025

[0009] 2

[0010] Changes in nominal resistance can also be achieved using trim electrodes. However, this requires additional trimming steps and can damage the sensors. Furthermore, trimming typically only produces small changes in resistance.

[0011] The German patent application DE 10 2020 122 923 Al, the content of which is incorporated by reference into this application, describes a sensor element for temperature measurement with a thin-film NTC thermistor.

[0012] The object of the present invention is to describe a sensor element, a method for manufacturing a sensor element, and a use of a sensor element with improved properties.

[0013] This problem is solved by a sensor element, a method for manufacturing a sensor element and a use of the sensor element according to the independent claims.

[0014] A sensor element is described according to one aspect. The sensor element is suitable for measuring a temperature. The sensor element is a temperature sensor. In particular, the sensor element is a thin-film NTC temperature sensor.

[0015] The sensor element has at least one support. Preferably, the sensor element has exactly one support. The support comprises a support material, preferably silicon, silicon carbide, or glass (silicatic or borosilicate glass). Alternatively, the support material can also comprise AIN or Al₂O₃. P2024, 0930 WO N 8 September 2025

[0016] 3

[0017] The carrier has a top and a bottom surface. The top surface is electrically insulating. Preferably, an electrically insulating layer, for example SiO2 or SiA1N4, is formed on the top surface of the carrier. The insulating layer is formed directly on the top surface of the carrier. The insulating layer can consist of one or more layers.

[0018] The sensor element further comprises at least one functional layer. The substrate mechanically stabilizes the functional layer. The functional layer only partially covers the substrate or the insulating layer on the top side of the substrate. In particular, the functional layer does not extend to an edge region of the substrate.

[0019] The thickness of the functional layer is between 50 nm and 1 pm, preferably between 100 nm and 500 nm, and particularly preferably between 250 nm and 400 nm. The functional layer is a thin-film functional layer. This means that the functional layer is deposited onto the substrate as a thin layer and is not, for example, soldered or glued on.

[0020] The functional layer comprises a material (functional material) that exhibits a specific electrical characteristic. The functional layer comprises a material with a temperature-dependent electrical resistance. Preferably, the functional layer comprises an NTC ceramic.

[0021] Preferably, the NTC ceramic is based on an oxide material in the perovskite or spinel structure type. Alternatively, the functional layer can be based on a carbide or nitride material in the wurtzite structure type. P2024, 0930 WO N 8. September 2025

[0022] 4. Another alternative is a thin film of vanadium oxide or SiC.

[0023] The sensor element also has first and second electrodes for electrical contacting the functional layer or areas of the functional layer.

[0024] For example, the sensor element has at least two first electrodes and at least two second electrodes. However, the sensor element can also have at least one first electrode and at least two second electrodes, or at least two first electrodes and at least one second electrode. Preferably, the sensor element has a plurality of first electrodes and a plurality of second electrodes. The first and second electrodes have opposite polarity.

[0025] The sensor element further comprises a plurality of contact pads for electrical contacting the sensor element. In particular, the sensor element comprises at least three contact pads. The contact pads are directly electrically and mechanically connected to the electrodes. Each contact pad is directly connected to a portion of exactly one of the electrodes.

[0026] Overall, the sensor element is very compact, allowing it to be embedded directly into an electrical system as a discrete component. In this context, "discrete" means that the sensor element can be integrated into electrical structures as a compact and self-contained system. P2024, 0930 WO N 8 September 2025

[0027] 5

[0028] For example, the sensor element has a maximum edge length between 200 pm and 1000 pm. The thickness of the sensor element is < 100 pm, preferably < 80 pm. For example, the thickness of the sensor element is 50 pm. Preferably, the component is designed for direct integration into a MEMS structure and / or a SESUB structure.

[0029] The functional layer comprises numerous areas (hereinafter also referred to as sensitive areas). For example, the functional layer may have two, three, five, ten, or more areas. These areas of the functional layer are to be understood as the contact areas / sensitive areas of the sensor element. All areas together constitute the functional area / functional layer of the sensor element. However, depending on the desired nominal resistance of the sensor element, not all areas necessarily contribute to its final function.

[0030] The sensor element has a variable nominal resistance. This means that the sensor element can be operated with different nominal resistances. For this purpose, the various areas of the functional layer can be contacted separately (i.e., independently of each other), depending on the desired nominal resistance. In other words, the nominal resistance of the sensor element depends on the contacted areas (in particular, the number and / or nature of the areas) of the functional layer. The more areas of the functional layer are contacted, i.e., the larger the final functional area of ​​the sensor element, the higher the nominal resistance of the sensor element. This provides a particularly flexible sensor element that can be used for a wide variety of applications. P2024, 0930 WO N 8 September 2025

[0031] 6

[0032] According to one embodiment, the areas are connected in series. In other words, the electrodes, contact pads, and areas of the functional layer are designed and arranged such that the sensor element has a series connection of the functional layer areas. This allows different nominal resistances of the sensor element to be achieved easily, without the need for trimming the electrodes and / or functional layer.

[0033] According to one embodiment, the regions are at least partially spatially separated from one another. In other words, the regions of the functional layer can represent discrete, unconnected (i.e., not mechanically interacting) sections of the functional layer. Each region can be designed and arranged, or connected with electrodes and contact pads, such that it is electrically contacted by exactly one first and exactly one second electrode. However, this does not preclude the possibility that each first / second electrode can contact more than one region.

[0034] Alternatively, the areas can also be at least partially contiguous. In other words, it is possible for two or more areas to represent (spatially or mechanically) connected sections of the functional layer. In this case, the respective area can be designed and arranged such that it is electrically contacted by at least one first and at least one second electrode. This means that several sensitive areas grouped together to form a contiguous area can be electrically and mechanically connected to multiple first and second electrodes. P2024, 0930 WO N 8 September 2025

[0035] 7

[0036] However, the connection of two or more areas of the functional layer can also have an impact on the resistance compared to separate areas, which must be taken into account in the design of the sensor element.

[0037] According to one embodiment, the respective first electrode and / or the respective second electrode is designed and arranged such that it contacts more than one region of the functional layer. For example, a first / second electrode can contact two, three, or more spatially / mechanically separated regions of the functional layer. Likewise, a first / second electrode can contact two, three, or more spatially / mechanically connected regions of the functional layer. In other words, the multiple regions of the functional layer contacted by the respective first electrode and / or the respective second electrode can be configured as a contiguous region or as discrete individual regions.

[0038] According to one embodiment, the functional layer regions have different shapes, areas, and / or thicknesses. For example, the functional layer regions can have a rectangular or square shape, or even a honeycomb shape. The shape of the regions can vary along the series interconnection. Likewise, the regions can vary in size (area) along the series interconnection, for example, becoming progressively smaller or larger. A variation in the thickness (extent in the stacking direction) of the regions along the series interconnection is also possible.

[0039] The different shapes, surfaces / sizes and / or thicknesses affect the nominal resistance of the sensor element. P2024, 0930 WO N September 8, 2025

[0040] 8

[0041] By varying the individual parameters of the sensitive areas, the nominal resistance of the sensor element can be made particularly flexible. Preferably, the nominal resistance can be varied within a range of 20% to 500%.

[0042] According to one embodiment, each first electrode and each second electrode has at least one electrode finger, preferably a plurality of electrode fingers. Electrode fingers of electrodes of different polarities are arranged alternately with each other (interdigital structure of the electrodes). The structure of the individual electrodes is to be understood as flexible. Thus, the electrode fingers of different first / second electrodes can have different lengths and / or thicknesses. Electrode fingers belonging to a specific first / second electrode can also have different lengths and / or thicknesses.

[0043] Furthermore, the number of electrode fingers of each electrode can vary along the series connection. The distance between the electrode fingers of each electrode can also vary along the series connection. This facilitates the variable design of the nominal resistance. In particular, this allows for a variable nominal resistance in the range of 10% to 1000% without affecting the B-value of the functional layer, i.e., the thermal sensitivity index, in any way. Preferably, the nominal resistance can be varied in a range of 20% to 500%.

[0044] According to one embodiment, the nominal resistance of the sensor element changes depending on which contact pads, in particular which two contact pads from the plurality of contact pads, are contacted. Depending on the contacted P2024, 0930 WO N 8 September 2025

[0045] 9

[0046] The contact pad increases or decreases the area of ​​the contacted functional layer, i.e., the number of contacted areas. This allows the sensor element to be operated with a desired, specific nominal resistance.

[0047] According to one embodiment, the functional layer is arranged on the substrate. The functional layer can be arranged directly on the substrate or on the insulating layer on the substrate. This means that in this case, no further component of the sensor element is arranged between the substrate and the functional layer or between the insulating layer and the functional layer. In this embodiment, the electrodes are formed directly on the functional layer.

[0048] Alternatively, the electrodes can also be arranged directly on the substrate or insulating layer. In this case, the functional layer is formed directly on the electrodes.

[0049] According to one embodiment, the sensor element has a protective layer. The protective layer can be made of oxides, nitrides, ceramics, glasses, or plastics. The protective layer completely covers one top surface of the sensor element, except for the contact pads or partial areas of the electrodes. For this purpose, the protective layer has recesses at the location of the contact pads. The protective layer has a thickness between 50 nm and 1 pm, preferably between 200 nm and 600 nm, ideally between 400 nm and 500 nm. The protective layer improves the long-term stability of the sensor element. P2024, 0930 WO N 8 September 2025

[0050] 10

[0051] According to another aspect, a method for manufacturing a sensor element is described. Preferably, the method is used to manufacture the sensor element described above, and in particular, a plurality of sensor elements. All properties disclosed with respect to the sensor element or the method are also disclosed with respect to the respective other aspect, and vice versa, even if the respective property is not explicitly mentioned in the context of the respective aspect. The method comprises the following steps:

[0052] A) Provision of a substrate material for forming a support. Preferably, the substrate material comprises Si, SiC, or glass. Alternatively, the substrate material can comprise AIN or Al₂O₃. Preferably, the substrate material comprises Si. The support has a top and a bottom surface. The other components of the sensor element are subsequently formed on the top surface.

[0053] For the sake of clarity, it should be mentioned here that in parallel processing, the carrier in the form of a wafer is provided in this step, from which the individual sensor elements are separated in a final step.

[0054] Optionally, following the provision of the carrier, an electrically insulating layer, preferably SiO2, is formed on the top side of the carrier.

[0055] B) Forming or depositing a plurality of first and second electrodes on the substrate, in particular on the top side of the substrate. In this step, at least three electrodes are deposited, for example, a first electrode P2024, 0930 WO N 8, September 2025

[0056] 11 and two second electrodes or two second electrodes and one first electrode. Preferably, a plurality of first electrodes and a plurality of second electrodes are deposited.

[0057] Deposition is achieved through a PVD (physical vapor deposition) process, a CVD (chemical vapor deposition) process, or electroplating. Alternatively, deposition can also be carried out using an ALD (atomic layer deposition) process. The first and second electrodes feature thin-film electrodes.

[0058] Alternatively, step B) can also be performed only after the following step C), meaning that in this case the electrodes are applied directly to the functional layer.

[0059] C) Application, preferably sputtering, of a functional material to at least a portion of the electrodes to form a functional layer. The functional layer has several areas (sensitive areas) that may be spatially separated from each other, but may also be partially contiguous.

[0060] The functional material preferably comprises an NTC ceramic based on an oxide material of the perovskite or spinel structure type. Alternatively, the functional material can also be based on a carbidal or nitridic material of the wurtzite structure type. Alternatively, the functional material can comprise or be a thin film of vanadium oxide or SiC.

[0061] The functional layer is formed as a thin film layer.

[0062] The use of thin-film technology makes it possible to P2024, 0930 WO N 8 September 2025

[0063] 12. to reduce the form factor of the sensor element so that it can be incorporated into a wide variety of possible applications, while still ensuring fast response times and installation near hot spots.

[0064] The functional layer is deposited as a full-surface thin film and then structured in a further process step, e.g., by lithography, thereby creating the multitude of areas. These areas can be rectangular, square, hexagonal, or octagonal, for example, and differ from one another in shape, size / area, and / or thickness. After deposition, the NTC layer is not yet fully crystallized.

[0065] Alternatively, as already mentioned, step C) can also be performed before step B), meaning that the functional layer is applied directly to the substrate and then the electrodes are applied to the functional layer.

[0066] D) Sintering of the functional layer. This serves to develop the NTC properties of the functional material and is carried out at temperatures up to 1000°C. Preferably, sintering is carried out at temperatures between 500°C and 800°C, advantageously at 600°C.

[0067] According to one embodiment, the method further comprises the following additional steps:

[0068] E) Applying a protective layer to the top surface of the sensor element. The protective layer completely covers the top surface except for several partial areas. The protective layer is used for structuring either P2024, 0930 WO N 8 September 2025

[0069] 13

[0070] (a) applied over the entire surface and the free areas created by a subsequent process such as lithography or laser structuring or

[0071] (b) applied directly in a structured manner by using a mask during the deposition process.

[0072] F) Forming contact pads in the areas free of the protective layer for electrical contacting the sensor element. In this step, a plurality of contact pads, in particular at least three contact pads, are formed. Each contact pad is directly connected to a terminal area of ​​one of the electrodes.

[0073] The contact pads can contain Cu, Au, Ni, Cr, Ag, Ti, W, Pd, or Pt. Preferably, the contact pads contain Au. Preferably, the contact pads have a layered structure of Au and Ti, with Ti being applied as an adhesion layer beneath the Au layer. Preferably, the contact pads have a thickness of > 5 pm.

[0074] According to one embodiment, the method involves the parallel production of a large number of sensor elements. The method further comprises the following step:

[0075] G) Separating or singulating the sensor elements to form the final, i.e., ready-to-use, sensor elements. The sensor elements have a variable nominal resistance.

[0076] On the customer side, different circuits and thus different nominal resistances of the respective sensor element can then be tested in a prototyping or optimization step. Different contact pads can be used in this process. P2024, 0930 WO N 8 September 2025

[0077] The nominal resistance of the sensor element changes depending on which two contact pads are contacted. Depending on the contact pad, the number of contacted areas of the functional layer varies. This allows the sensor element to be operated with a desired, specific nominal resistance, making it particularly versatile.

[0078] According to another aspect, a use of a sensor element is described. Preferably, a use of the sensor element mentioned above is described. All properties disclosed with respect to the sensor element, the method, or the use are also disclosed with respect to the respective other aspect, and vice versa, even if the respective property is not explicitly mentioned in the context of the respective aspect.

[0079] The sensor element is used in such a way that it has a specific nominal resistance, which is set by electrically connecting two specific contact pads from the multitude of available contact pads. By connecting specific contact pads, the different areas of the functional layer can be contacted separately (i.e., independently of each other), depending on the desired nominal resistance. The nominal resistance of the sensor element depends on the contacted areas (in particular, the number and / or characteristics of these areas) of the functional layer. The more

[0080] Areas of the functional layer are contacted; that is, the larger the final functional area of ​​the sensor element, the higher the nominal resistance of the sensor element. P2024, 0930 WO N 8 September 2025

[0081] 15

[0082] The drawings described below are not to be considered as being to scale. Rather, individual dimensions may be enlarged, reduced, or distorted for better illustration.

[0083] Elements that are identical or that perform the same function are designated with the same reference symbols.

[0084] They show:

[0085] Figure 1 shows an exploded view of a sensor element according to the prior art,

[0086] Figure 2 shows a sectional view of the sensor element according to Figure 1 (prior art) ,

[0087] Figure 3 shows a top view of a partial area of ​​a sensor element according to the invention in a first embodiment,

[0088] Figure 4 shows a top view of a partial area of ​​a sensor element according to the invention in a further embodiment,

[0089] Figure 5 shows a top view of a partial area of ​​a sensor element according to the invention in a further embodiment,

[0090] Figure 6 shows a top view of a partial area of ​​a sensor element according to a further embodiment of the invention, P2024, 0930 WO N 8 September 2025

[0091] 16

[0092] Figure 7 shows a top view of a partial area of ​​a sensor element according to the invention in a further embodiment.

[0093] Figures 1 and 2 show a representation of a sensor element 1 according to the prior art. The sensor element 1 serves to illustrate a basic structure of the sensor element 100 described below (Figures 3 to 7). For a detailed description of the essential features of the sensor element 1 according to Figures 1 and 2, reference is made to German patent application DE 10 2020 122 923 A1.

[0094] The sensor element 1 is an NTC thin-film temperature sensor and has a substrate 2 with a top surface 11 and a bottom surface 12. The top surface 11 of the substrate 2 has an insulating layer 3, for example, comprising SiO2. The sensor element 1 further has at least two electrodes 4a, 4b. The two electrodes 4a, 4b are positioned apart from each other on the insulating layer 3 of the substrate 2 and have thin metal films.

[0095] Electrodes 4a and 4b are designed as interdigital thin-film electrodes. Specifically, each electrode 4a and 4b has a planar end region 6 and a region with at least one electrode finger 5. The region with the electrode fingers 5 is located in a central region of the support 2. The planar end region 6 and the region with the electrode fingers 5 merge seamlessly. The two electrodes 4a and 4b interlock in the region of the electrode fingers 5 within the central region of the support 2, forming an interdigital structure. P2024, 0930 WO N September 8, 2025

[0096] 17

[0097] The sensor element 1 further comprises a functional layer 7 with a top surface 14 and a bottom surface 15. The functional layer 7 is an NTC thin film. The functional layer 7 only partially covers the insulating layer 3 on the top surface 11 of the carrier 2. Preferably, the functional layer 7 is applied at least partially to the electrodes 4a, 4b. As can be seen from Figures 1 and 2, the electrodes 4a, 4b are formed between the carrier 2 and the functional layer 7, in particular on a bottom surface 15 of the functional layer 7. The functional layer 7 lies directly on the area with the electrode fingers 5.

[0098] The sensor element 1 further comprises at least two contact pads 10 for electrical contacting the sensor element 1.

[0099] The sensor element 1 can further comprise a protective layer 8. The protective layer 8 is applied over the NTC thin film and the electrodes 4a, 4b. The protective layer 8 completely covers one top surface of the sensor element 1, with the exception of the contact pads 10. There are openings / recesses 9 in the protective layer 8 through which the respective contact pad 10 comes into contact with the electrodes 4a, 4b. Alternatively, the flat end region 6 of the electrodes 4a, 4b themselves can also serve as a contact pad (not explicitly shown).

[0100] Due to the compact design of the individual components of the sensor element 1, the sensor element 1 is suitable for integration into MEMS or SESUB structures.

[0101] The basic structure shown in Figures 1 and 2 is based on the principle of connecting individual resistors in parallel. In the construction of sensor element 1 according to Figures 1 and 2, the resistance cannot be adapted to the specific component. Therefore, sensor element 1 has a specific, non-adjustable nominal resistance.

[0102] Figures 3 to 7 show a top view of a partial area of ​​a sensor element 100 according to the invention. The sensor element 100 has essentially the same components as the sensor element 1 according to Figures 1 and 2. The basic structure of the sensor element 100 corresponds to the structure of the sensor element 1 of Figures 1 and 2, as already mentioned above. For details of the components and the operation of the sensor element 100, reference is therefore made to the above description or to document DE 10 2020 122 923 A1. Unless otherwise indicated, the reference numerals given in connection with Figures 1 and 2 shall also apply in the following.

[0103] Unlike sensor element 1 according to Figures 1 and 2, sensor element 100 according to Figures 3 to 7 can be implemented with different nominal resistances. In other words, sensor element 100 has a variable nominal resistance. This means that sensor element 100 can be operated with different nominal resistances, depending on customer requirements.

[0104] To ensure a variable nominal resistance, functional layer 7 has a plurality of areas 70, for example, two, three, five, or ten areas 70. The areas 70 are sensitive sections of the single functional layer 7. The areas 70 can be contacted separately, i.e., independently of each other, as described in detail below.

[0105] Furthermore, the sensor element 100 has a plurality of electrodes 4a, 4b. Preferably, the sensor element 100 has a P2024, 0930 WO N 8 September 2025

[0106] A plurality of first electrodes 4a and a plurality of second electrodes 4b are present. The first and second electrodes 4a, 4b have opposite polarities. Each first and second electrode 4a, 4b has a structure with electrode fingers 5 and a connection or end region 6, as described in relation to Figures 1 and 2.

[0107] At least one first electrode 4a and at least one second electrode 4b are each in direct electrical and mechanical contact with a region 70 of the functional layer 7. As can be seen from Figures 3 to 7, one electrode 4a, 4b can contact several regions 70 simultaneously (see, for example, the upper right electrode 4b in Figure 3, which contacts the uppermost and the middle region 70 of the functional layer 7, i.e., two regions 70 of the functional layer 7).

[0108] In the embodiments shown in Figures 3 to 6, the functional layer regions 70 are spatially separated from one another. This means that there is no mechanical interaction between the regions 70. Each region 70 is contacted by exactly one first electrode 4a and exactly one second electrode 4b (however, as described above, one electrode 4a, 4b can contact several regions 70).

[0109] However, it is also possible that the regions 70 are at least partially contiguous, as can be seen in Figure 7. In Figure 7, each pair of regions 70 represents interconnected sections of the functional layer 7. The respective contiguous region 70 is contacted by two first electrodes 4a and two second electrodes 4b, as can be seen in Figure 7. Self- P2024, 0930 WO N 8 September 2025

[0110] 20 understandable, but more than two areas 70 can also be formed in a connected manner and accordingly more than two first and more than two second electrodes 4a, 4b can contact the connected area.

[0111] The sensor element 100 further comprises a plurality of contact pads 10a to lOf (in particular at least three contact pads), wherein each contact pad 10a to lOf is directly connected to the end region 6 of one of the electrodes 4a, 4b. Each contact pad 10a to lOf is electrically and mechanically connected to exactly one electrode 4a, 4b. The number of electrodes 4a, 4b therefore corresponds to the number of contact pads 10a to lOf.

[0112] The areas 70 of functional layer 7 are connected in series. In other words, the electrodes 4a, 4b, the contact pads 10a to 10of, and the areas 70 of functional layer 7 are arranged such that the sensor element 100 has a series connection of the areas 70 to form functional layer 7. This allows for different nominal resistances of the sensor element 100.

[0113] The sensor element 100 can be operated with different nominal resistances. For this purpose, the various areas 70 of the functional layer 7 are arranged and connected to the electrodes 4a, 4b / contact pads 10a to 10of in such a way that they can be contacted separately (i.e., independently of each other) or together via a series connection, depending on the desired nominal resistance.

[0114] In other words, the nominal resistance of the sensor element 100 depends on the contacted areas 70 of functional layer 7. Therefore, the resistance of the sensor element 100 changes depending on the circuit. The more areas 70 of P2024, 0930 WO N 8 September 2025

[0115] functional layer 7 is contacted, i.e. the larger the final or active functional area of ​​the sensor element 100 is, the greater the nominal resistance of the sensor element 100.

[0116] The contacting of specific B:areas 70 is effected by the electrical connection of two specific contact pads 10a, 10b, 10c, lOd, lOe, lOf from the plurality of contact pads 10a to lOf. The nominal resistance of the sensor element 100 depends on the number and / or the nature of the contacted areas 70 of the functional layer 7.

[0117] For example, the sensor element 100 can have a resistance of 10 kΩ by contacting the contact pads 10a top left and 10b top right in Figure 3, while contacting the contact pads 10a (top left) and lOd (bottom right) in Figure 3 results in a resistance of 30 kΩ.

[0118] The nominal resistance of the sensor element 100 can be influenced not only by the contacted contact pad and thus by the number of contacted areas 70, but also by the size or area and / or thickness of the areas 70. The size / area of ​​the areas 70 can vary along the series connection, as can be seen, for example, in Figures 4 and 6. Figure 4 shows that the first / uppermost area 70 has a larger area than the other areas 70.

[0119] The same applies to the thickness of the areas 70. The thickness of the areas 70 can also change along the series connection. A variation in the shape of the areas 70 is also conceivable. For example, individual areas 70 can be rectangular and P2024, 0930 WO N 8 September 2025

[0120] 22 others, for example, may be square in shape (not explicitly shown).

[0121] The nominal resistance of the sensor element 100 can also be influenced by the electrode structure. For example, the electrode fingers 5 of different first / second electrodes 4a, 4b can have different lengths and / or thicknesses compared to each other. Electrode fingers 5 belonging to a specific first / second electrode 4a, 4b can also have different lengths and / or thicknesses among themselves (not explicitly shown).

[0122] Alternatively or additionally, the number of electrode fingers 5 of each electrode 4a, 4b can vary along the series connection. For example, at the beginning of the series connection, an electrode 4a, 4b with two electrode fingers 5 can be provided, and at the end of the series connection, an electrode 4a, 4b with four electrode fingers 5, or vice versa. Configurations with a wide variety of electrode fingers 5 are conceivable.

[0123] In addition, the distance between electrode fingers 5 of the respective electrode 4a, 4b along the series connection can also vary (see, for example, Figures 4 and 7).

[0124] Furthermore, it is possible that electrode fingers 5 are formed on opposite sides of the end region 6 (see Figures 5, 6 and 7) or only on one side of the end region 6 (see Figures 3 and 4), depending on the structure of the series connection and / or the structure and arrangement of the regions 70. P2024, 0930 WO N 8 September 2025

[0125] The different structures of regions 70 and electrodes 4a, 4b increase the variability of the nominal resistance. In particular, this allows for a variable nominal resistance in the range of 10% to 1000% without affecting the B-value of functional layer 7. Preferably, the nominal resistance can be varied in a range of 20% to 500%.

[0126] To utilize the available space more efficiently and to have more resistance variations on the same element site, the various configurations according to Figures 3, 4, 5 and 6 can be combined, as shown in Figure 7. This variation also includes the possibility of contiguous areas 70 of the functional layer, as already explained above.

[0127] The following describes a method for manufacturing the sensor element 100. Preferably, the method is used to manufacture a plurality of sensor elements 100 according to one of the embodiments described above (see Figures 3 to 7). All features described in connection with the sensor element 100 therefore also apply to the method and vice versa.

[0128] In a first step A), a support material is provided for forming the support 2 described above. Preferably, the support material comprises Si, SiC, GaN, or glass. Alternatively, the support material can comprise SiaN4, AIN, or Al2O3. The support 2 has a top surface 11 and a bottom surface 12.

[0129] Subsequently, an electrically insulating layer 3 is formed on the top surface 11 of the carrier 2. P2024, 0930 WO N 8 September 2025

[0130] For example, the insulating layer 3 contains SiO2. Ideally, an insulating layer 3 with a thickness of up to 1.5 pm is produced on the top surface 11 of the support 2.

[0131] In a further step B), a large number of first and second electrodes 4a, 4b are formed / deposited on the substrate 2. The deposition is carried out by a PVD or CVD process or electroplating.

[0132] The electrodes 4a, 4b can be single-layered or multi-layered and contain, for example, Cu, Au, Ni, Cr, Ag, Ti, Ta, W, Pd, or Pt. The electrodes 4a, 4b are designed as thin-film electrodes. Each electrode 4a, 4b has a flat end region 6 and at least one electrode finger 5.

[0133] The structuring of electrodes 4a, 4b is generally achieved via a lift-off process. The electrode fingers 5 of electrodes 4a, 4b can have different lengths and / or thicknesses. Alternatively or additionally, adjacent electrode fingers 5 of the same or different electrodes 4a, 4b can have different distances between them.

[0134] In a further step C), a functional material is applied to form a functional layer 7. This is done, for example, by sputtering or a spin-coating process. The functional material is first applied over the entire surface and then structured in a further process (for example, by wet chemical etching, dry etching, or laser structuring) so that a multitude of regions 70 are created. Preferably, the functional layer 7 has a thickness between 50 nm and 1 pm, preferably P2024, 0930 WO N 8. September 2025

[0135] 25 between 100 nm and 500 nm, particularly preferably between 250 nm and 400 nm.

[0136] Alternatively, step C) can also be carried out before step B), so that the functional material 7 is sputtered directly onto the insulating layer 3 of the carrier 2 and then the electrodes 4a , 4b are applied to the functional layer 7 (not explicitly shown).

[0137] The functional material features an NTC ceramic based on an oxide material of the perovskite or spinel structure type. Alternatively, the functional material can also be based on a carbide or nitride material. In another alternative, the functional material comprises or consists of thin films of vanadium oxide or SiC.

[0138] The functional layer 7 only partially covers the top surface of the carrier 2 and the electrodes 4a, 4b. In particular, the areas 70 of the functional layer 7 are only located on the electrode fingers 5. The end area 6 of the respective electrode 4a, 4b is free of the areas 70 of the functional layer 7.

[0139] In a further step D), the functional layer 7 is subjected to heat treatment to form the structure or properties.

[0140] In a next step E), a protective layer 8 is formed. The protective layer 8 can comprise oxides, nitrides, ceramics, glasses, or polymers and is produced by a PVD or CVD process and structured by wet chemical etching or dry etching. The protective layer 8 has a thickness of < 10 pm, preferably < 5 pm, and particularly preferably < 1 pm. Ideally, the protective layer 8 has a thickness of < 1.5 pm and completely covers the top surface of the sensor element 100, with the exception of the contact pads 10a to 10of applied in the following step and the planar end regions 6 of the electrodes 4a, 4b. In particular, a recess 9 is provided in the protective layer 8 at the location of the flat end areas 6 (see Figures 1, 2) to enable electrical contact between contact pad 10a to lOf and electrode 4a, 4b.

[0141] Subsequently, in step F), contact pads 10a to lOf are formed on at least a partial area of ​​the electrodes 4a, 4b. Depending on the number of electrodes 4a, 4b, at least three contact pads 10a to lOf are formed. Each contact pad 10a to lOf is formed directly on the flat end region 6 of an electrode 4a, 4b.

[0142] In one embodiment, the contact pads 10a to lOf have a layered structure of Ti and Au. Ti serves as an adhesion layer beneath the Au. The contact pads 10a to lOf have a thickness of > 5 pm. In particular, the contact pads 10a to lOf protrude beyond the surface 13 of the finished sensor element 100. Alternatively, bumps can be formed instead of the contact pads.

[0143] In a further step G), the sensor elements 100 are separated.

[0144] The final sensor element 100 has a maximum edge length L of less than 1000 pm. The final, isolated sensor element 100 has a variable nominal resistance, meaning it can be operated with different nominal resistances. P2024, 0930 WO N 8. September 2025

[0145] 27. Two specific contact pads can be used for this purpose, thereby contacting specific areas 70 of the functional layer 7, depending on the desired nominal resistance. In other words, the nominal resistance of the sensor element 100 depends on the contacted areas 70 (in particular, the number and / or characteristics of the areas) of the functional layer 7. The more areas 70 of the functional layer 7 are contacted, i.e., the larger the final functional area of ​​the sensor element 100, the greater the nominal resistance of the sensor element 100.

[0146] The description of the items listed here is not limited to the individual specific versions. Rather, the characteristics of the individual versions can be combined with each other as desired – insofar as this is technically feasible.

[0147] P2024, 0930 WO N 8. September 2025

[0148] 28

[0149] Reference number list

[0150] 1 sensor element

[0151] 2 carriers

[0152] 3 I insulating layer

[0153] 4a First electrode

[0154] 4b Second electrode

[0155] 5 electrode fingers

[0156] 6 End area

[0157] 7 functional layer

[0158] 8 protective layer

[0159] 9 recess

[0160] 10 contact pads

[0161] 11 Top of the carrier

[0162] 12 Underside of the carrier

[0163] 13 Top side of the sensor element

[0164] 14 Top side of the functional layer

[0165] 15 Underside of the functional layer

[0166] 100 sensor elements

[0167] 10a, b, c, d, e, f contact pad

[0168] D Thickness of the sensor element

[0169] L Edge length of the carrier / sensor element d Distance between electrode fingers

Claims

P2024, 0930 WO N September 8, 2025 Patent claims 1. Sensor element (100) comprising a temperature measuring element - a carrier (2) with a top (11) and a bottom (12) , wherein the top (11) is electrically insulating, - at least one functional layer (7) which has a material with a temperature-dependent electrical resistance, - a plurality of first and second electrodes (4a, 4b) for electrical contacting the functional layer (7) , - at least three contact pads (10a to lOf) for electrical contacting the sensor element (100) , wherein the sensor element (100) has a variable nominal resistance and wherein the at least one functional layer (7) has several areas (70) which are contacted separately, so that the nominal resistance of the sensor element (100) depends on the contacted areas (70) of the functional layer (7) .

2. Sensor element (100) according to claim 1, wherein the areas (70) are connected in series.

3. Sensor element (100) according to claim 1 or 2, wherein the areas (70) are at least partially spatially separated from each other and / or wherein the respective area (70) is designed and arranged such that it is electrically contacted by exactly one first and exactly one second electrode (4a, 4b).

4. Sensor element (100) according to one of the preceding claims, P2024, 0930 WO N 8 September 2025 wherein the areas (70) are at least partially interconnected and / or wherein the respective area (70) is designed and arranged in such a way that it is electrically contacted by at least one first and at least one second electrode (4a, 4b).

5. Sensor element (100) according to one of the preceding claims, wherein the respective first electrode (4a) and / or the respective second electrode (4b) is designed and arranged such that it contacts more than one area (70) of the functional layer (7).

6. Sensor element (100) according to one of the preceding claims, wherein the areas (70) have different shapes and / or surfaces and / or thicknesses.

7. Sensor element (100) according to one of the preceding claims, wherein the respective electrode (4a, 4b) has at least one electrode finger (5) and wherein the electrode fingers (5) of electrodes (4a, 4b) of different polarity are arranged alternately to each other.

8. Sensor element (100) according to claim 7, wherein the electrode fingers (5) of different electrodes (4a, 4b) have different lengths and / or thicknesses.

9. Sensor element (100) according to claim 7 or 8, wherein the respective electrode (4a, 4b) has at least two electrode fingers (5) and wherein the electrode fingers (5) P2024, 0930 WO N 8 September 2025 of an electrode (4a, 4b) have different lengths and / or thicknesses.

10. Sensor element (100) according to one of claims 7 to 9 and claim 2, wherein a number of electrode fingers (5) of the respective electrode (4a, 4b) varies along the series connection.

11. Sensor element (100) according to one of claims 7 to 10 and claim 2, wherein a distance between electrode fingers (5) of the respective electrode (4a, 4b) varies along the series connection.

12. Sensor element (100) according to one of the preceding claims, wherein the nominal resistance changes depending on which two contact pads (10a, 10b, 10c, lOd, lOe, lOf) of the at least three contact pads (10a to lOf) are contacted.

13. Sensor element (100) according to one of the preceding claims, further comprising a protective layer (8) wherein the protective layer (8) at least partially covers a top surface (13) of the sensor element (100).

14. Sensor element (100) according to one of the preceding claims, wherein the functional layer (7) comprises an NTC ceramic based on an oxide material in the perovskite or spinel structure type, or wherein the functional layer (7) comprises an NTC ceramic based on a carbide or nitride material in the wurtzite structure type, or wherein P2024, 0930 WO N 8 September 2025 the functional layer a thin film of vanadium oxide or SiC is present.

15. Sensor element (100) according to one of the preceding claims, wherein a thickness (D) of the sensor element (100) is 50 pm < D < 100 pm.

16. A method for manufacturing at least one sensor element (100) comprising the following steps: A) Providing a carrier material for the training of a carrier ( 2 ) ; B) Forming a plurality of first electrodes (4a) and second electrodes (4b) on the support (2) ; C) Applying a functional material to at least a partial area of ​​the first and second electrodes (4a, 4b) to form a functional layer (7) , wherein the functional layer (7) has a plurality of areas (70); D) Sintering of the functional layer (7) .

17. The method of claim 16, further comprising the following steps: E) Applying a protective layer (8) to a top surface of the sensor element (100), wherein the protective layer (8) completely covers the top surface except for a plurality of sub-areas; F) Forming at least three contact pads (10a to lOf) in the partial areas free from the protective layer (8) for electrical contacting the sensor element (100) .

18. Method according to one of claims 16 or 17, wherein the method enables a plurality of sensor elements to be (100) is produced and the process continues P2024, 0930 WO N September 8, 2025 shows the following steps: G) Singling out the sensor elements (100) .

19. Method according to any one of claims 16 to 18, wherein the method produces a sensor element (100) according to any one of claims 1 to 15.

20. Use of a sensor element (100) according to any one of claims 1 to 15, wherein the nominal resistance of the sensor element (100) is set by an electrical connection of two specific contact pads (10a, 10b, 10c, lOd, lOe, lOf) of the at least three contact pads (10a to lOf).

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