Sensorelement

Abstract

Sensor element (100) for non-contact temperature measurement comprising: - at least one carrier (2) with a top (11) and a bottom (12); - at least one first functional layer (7a) for non-contact temperature measurement of an object and at least one second functional layer (7b) for contact measurement of an ambient temperature, wherein the respective functional layer (7a, 7b) comprises a material with a temperature-dependent electrical resistance and wherein the functional layers (7a, 7b) are arranged separately from each other on the carrier (2); - at least one upper electrode (50), wherein a first contact area (c1) is formed between the upper electrode (50) and one of the two functional layers (7a, 7b); - at least one lower electrode (40), wherein a second contact area (c2) is formed between the lower electrode (40) and the functional layer (7a, 7b) which is in contact with the upper electrode (50).wherein the respective functional layer (7a, 7b), the at least one upper electrode (50) and the at least one lower electrode (40) are designed and arranged such that a certain electrical resistance of the sensor element (100) is achieved.

Description

The present invention relates to a sensor element, in particular a temperature sensor for contactless temperature measurement.In order to integrate passive devices, such as sensors, capacitors, protection devices or heaters, into electrical systems, the dimensions must be adapted for modern packaging designs, which are in the micrometer and even nanometer scale range. To achieve this degree of miniaturization, the devices are deposited as thin films on supporting structures with electrical connections and are described as a discrete device. These novel components can be integrated, for example, into MEMS (Micro Electro Mechanical System) structures.According to the prior art, temperatures for monitoring and regulation in a wide variety of applications are predominantly measured with ceramic thermistor elements (NTC), silicon temperature sensors (KTY), platinum temperature sensors (PRTD) or thermocouples (TC). In this case, the NTC thermistors are the most widely used because of the low production costs. Another advantage over thermocouples and metallic resistive elements, such as Pt elements, is the pronounced negative resistance-temperature characteristic.In contactless temperature measurement of an object temperature with an infrared sensor, measuring the ambient temperature of the functional element (e.g. thermopile, bolometer, etc.) in the sensor is necessary. An inaccurate temperature measurement of the ambient temperature at the functional element leads to errors in interpreting the measurement value. A separate element for measuring the ambient temperature is required in addition to the functional element.Thus, the current solution of ambient temperature measurement in the prior art in contactless temperature sensors, such as thermopiles, is also an NTC chip. This separate NTC chip must be installed in an additional process step and is therefore at a distance from the functional element that is a few / greater.It is an object of the present invention to describe an improved sensor element.This object is achieved by a sensor element according to the independent claim.According to one aspect, a sensor element is described. The sensor element is suitable for contactless measurement of a temperature. The sensor element is an IR (infrared) temperature sensor. In particular, the sensor element is a TF (thin film) IR-NTC temperature sensor.The sensor element has at least one carrier. The sensor element preferably has exactly one carrier. The support comprises a support material, preferably silicon, silicon carbide or glass (silicate or borosilicate glass). Alternatively, the carrier material can also comprise AlN or Al 2 O 3.The carrier has an upper side and a lower side. The top side is designed to be electrically insulating. Preferably, an insulating layer / insulating layer, for example SiO 2 or Si 3 N 4, is formed on the upper side of the carrier. The insulating layer is formed directly on the upper side of the carrier and can be constructed from one or more layers.The sensor element further comprises at least one first functional layer. The first functional layer is designed and arranged for contactless temperature measurement. In particular, the temperature of an object is measured contactless with the first functional layer on the basis of its emitted radiation.The first functional layer is formed on the carrier, in particular on the insulating layer. The carrier mechanically stabilizes the first functional layer. The first functional layer is arranged in a first region / IR region of the carrier or of the sensor element. The first region / IR region is also referred to below as an IR sensor.The sensor element further comprises at least one second functional layer. The second functional layer is designed for measuring, in particular for contact-type measurement, an ambient temperature. In particular, the second functional layer is formed and arranged for measuring the temperature of the carrier.The second functional layer is formed on the carrier, in particular on the insulating layer. The carrier mechanically stabilizes the second functional layer. The second functional layer is arranged in a second region / reference region of the carrier or of the sensor element. The second region / reference region is also referred to below as a reference sensor.The first and second function layers are thin films (TF). A thickness of the respective functional layer is between 50 nm and 1 μm, preferably between 100 nm and 500 nm, particularly preferably between 250 nm and 400 nm.The respective functional layer comprises a material (functional material) which has a specific electrical characteristic. The respective functional layer comprises a material having a temperature-dependent electrical resistance. The respective functional layer preferably comprises an NTC ceramic.The NTC ceramic is preferably based on an oxidic material of perovskite or spinel structure type. Alternatively, the respective functional layer can be constructed on the basis of a carbide or a nitride material. A further alternative is thin films of vanadium oxide or SiC.The two functional layers are arranged spatially separated from one another on a single carrier. The carrier thus has two sensitive regions. In other words, according to the invention, two sensors (IR sensor and reference sensor) are combined in a smallest space on a single chip.There is no direct contact between the two functional layers. The two functional layers / sensors can be formed, for example, next to one another on the carrier. Alternatively, the second functional layer can also surround the first functional layer. In other words, the reference sensor may be formed around the IR sensor.By combining two sensitive areas on a single chip, the ambient temperature can be measured in the immediate vicinity of the IR sensor. This provides a particularly precise and compact sensor element.The sensor element further comprises at least one upper electrode, for example exactly one upper electrode. The upper electrode may be formed in the first region (IR region) or in the second region (reference region) of the sensor element.The upper electrode is arranged at least partially directly above the functional layer of the relevant region (i.e. above the first or the second functional layer). The upper electrode is arranged at least partially on an upper side of the relevant functional layer. Between the upper electrode and the relevant functional layer, a contact region (first or upper contact region) is formed.Ideally, the sensor element has at least two upper electrodes, in particular at least one first upper electrode (upper electrode of the IR sensor / in the first region) and at least one second upper electrode (upper electrode of the reference sensor / in the second region).Of course, the sensor element can also comprise more than two upper electrodes, for example three, four or more upper electrodes. The plurality of upper electrodes can be formed either all in one region (IR region or reference region) or also in both regions of the sensor element. The (respective) top electrode may comprise one or more layers of thin film metals, the materials comprising e.g. Cu, Au, Ni, Cr, Ag, Ti, W, Pd or Pt.In the case of at least two upper electrodes, the respective upper electrode is arranged directly above the respective functional layer. In particular, the at least one first upper electrode is arranged above the first functional layer. The at least one second upper electrode is arranged above the second functional layer.Between the respective upper electrode and the respective functional layer, a contact region (i.e. the first contact region) is formed. In other words, there is a direct electrical and mechanical contact between the respective upper electrode and the respective functional layer.The sensor element further comprises at least one lower electrode, for example exactly one lower electrode. The lower electrode may be formed in the first region (IR region) or in the second region (reference region) of the sensor element. If exactly one lower electrode and one upper electrode are present, the lower electrode is arranged in the same region (IR region or reference region) as the one upper electrode.The lower electrode is arranged in the relevant region (first or second region) at least partially below the functional layer. The lower electrode is arranged at least partially on an underside of the functional layer.That is, upper and lower electrodes are formed on different sides of the respective functional layer (upper and lower sides of the functional layer). Between the lower electrode and the relevant functional layer, a contact region (second or lower contact region) is formed.Ideally, the sensor element has at least two lower electrodes. The sensor element then has in particular at least one first lower electrode (lower electrode of the IR sensor / in the first region) and at least one second lower electrode (lower electrode of the reference sensor / in the second region).Of course, the sensor element can also comprise more than two lower electrodes, e.g. three, four or more lower electrodes. The plurality of lower electrodes can be formed either all in one region (IR region or reference region) or else in both regions of the sensor element.The respective lower electrode may comprise single or multiple layers of thin film metals, the materials comprising e.g. Cu, Au, Ni, Cr, Ag, Ti, W, Pd or Pt. The respective lower electrode can be arranged directly on the upper side of the carrier or on the insulating layer.The (respective) lower electrode is arranged at least partially directly below the respective functional layer. In the case of at least two lower electrodes, the at least one first lower electrode is arranged at least partially below the first functional layer. The at least one second lower electrode is arranged at least partially below the second functional layer.Between the respective lower electrode and the respective functional layer, a contact region (i.e. the second contact region) is formed. In other words, there is a region with direct electrical and mechanical contact between the respective lower electrode and the respective functional layer.The respective or relevant functional layer is arranged at least partially between the respective lower electrode and the respective upper electrode (sandwich structure or stack structure). In particular, the first region and / or the second region of the sensor element have an electrode(s)-NTC electrode(s) stack structure.The sensor element has a specific electrical rated resistance. More precisely, the sensor element has two rated resistances (one for the IR sensor / IR range and one for the reference sensor / reference range), even if these should ideally be the same. In the following, "rated resistance" is understood to mean the rated resistance of the respective region (IR sensor / first region or reference sensor / second region).The first / second functional layer, the at least one upper electrode and the at least one lower electrode are designed and / or arranged and / or connected in such a way that a specific electrical rated resistance can be achieved. In other words, the respective functional layer, the lower electrode and / or the upper electrode have a specific material, a specific contact region and / or a specific position with respect to one another in order to control the resistance of the sensor element or of the respective region.In this way, a very precise sensor element is provided.Overall, the sensor element is furthermore of very compact design, i.e. it has a miniaturized design, so that it can be embedded directly in an electrical system as a discrete component. In this context, the term "discrete" means that the sensor element can be integrated into electrical structures as a compact and self-contained system.For example, the sensor element has a maximum edge length (length or width) of 2000 μm, preferably ≤1500 μm. A thickness of the sensor element (extension in a stacking direction) is <1000 μm, preferably <700 μm, particularly preferably <300 μm. For example, the component is designed for direct integration into a MEMS structure.The two sensors combined in one sensor element (IR sensor and reference sensor) make it possible to determine the ambient temperature in the immediate vicinity of the IR sensor. Thus, no further NTC chip is necessary, which would have to be mounted in an additional process step. A very compact, cost-effective, durable and precise sensor element is thus provided.According to one exemplary embodiment, the sensor element has at least one upper and at least one lower electrode, which are formed either in the IR region or in the reference region. In addition, the sensor element can have at least two interdigital electrodes in the other region of the sensor element for the electrical contacting of that functional layer which is free of contact with the upper electrode and the lower electrode. The two interdigital electrodes are formed at least partially under the relevant functional layer. Alternatively, the interdigital electrodes can also be formed on the relevant functional layer.Furthermore, in this case, the sensor element can have two contact elements, wherein in each case one contact element is arranged directly on at least one partial region of one of the interdigital electrodes. The contact elements serve for the electrical contacting of the sensor element.The respective interdigital electrode is designed as a thin-film electrode. The respective interdigital electrode has a flat end region, wherein at least one contact element is arranged on the flat end region of at least one of the electrodes. The respective interdigital electrode also has a plurality of electrode fingers, which form an interdigital structure with the electrode fingers of the other interdigital electrode.According to one exemplary embodiment, the sensor element has a cavity in the carrier. In other words, a cavity is formed in the carrier. In one embodiment, the cavity penetrates the carrier completely. In an alternative embodiment, an underside of the carrier is free of a cavity. Consequently, the underside of the carrier has a smooth course in this embodiment. In other words, the cavity does not completely penetrate the carrier. The cavity is formed directly below the insulating layer. The insulating layer covers the cavity in the upward direction (membrane structure).The cavity is formed in the first region / IR region of the carrier or of the sensor element. The cavity is located in the region of the first functional layer. In particular, the cavity is located at least partially below the first functional layer.The cavity may have a smaller area than an area of the first functional layer. In this context, "surface" is to be understood as an extent perpendicular to a stacking direction / a thickness of the sensor element. Preferably, the cavity and the first functional layer take up the same area. Ideally, the area of the cavity is larger than the area of the first functional layer.The cavity is designed and arranged for thermal decoupling of the first functional layer (and all further components of the sensor element formed on the first functional layer) from the carrier. As a result, there are fewer thermal losses to the carrier and a maximized temperature change at the first functional layer is made possible. Thus, the change in resistance is also maximized.A complete decoupling of the first functional layer and the environment is, however, not possible. Thus, there is always a loss of heat to the environment. Therefore, the temperature of the first functional layer will deviate from that of the object to be measured. In this case, the higher the temperature difference between the first functional layer and the environment, the greater the thermal losses. Therefore, there is a need for a reference sensor (second region) for measuring the ambient temperature.In addition, the heat transport via solids is significantly faster than via gases, which means that the main heat loss takes place via the carrier. Consequently, the influence of the carrier is dominant compared to the rest of the environment. Therefore, it is of particular interest to determine the temperature of the carrier (and thus of the environment) in order to be able to make a correction by the thermal losses. This takes place via the reference sensor / the second functional layer in the immediate vicinity of the IR sensor.According to one exemplary embodiment, a region of the carrier below the second functional layer is free of a cavity. In other words, no cavity is formed in the second region / reference region. In other words, the reference sensor does not have a cavity (in the carrier).A cavity decouples the functional layer from the carrier. The reaction time of the functional layer to changes in the carrier is thus delayed and more easily impaired by other influences. Without cavity, the thermal interaction between the second functional layer and the carrier is thus improved and the temperature response time and stability are optimized. The thin-film structure of the functional layer has a significantly lower heat capacity than that of the carrier. This has a negligible influence on the carrier temperature. Thus, a very accurate measurement of the carrier temperature is also possible.Overall, a fast, accurate and stable ambient temperature can be determined by the embodiment of the reference sensor without a cavity. At the same time, the mechanical stability is improved and design options are only minimally restricted. Thus, the first and second functional layers (IR sensor and reference sensor) can be closer together compared to the prior art, there is no weight limit for the membrane at the reference sensor, etc. For example, the reference sensor can also surround the IR sensor for a more uniform determination of the ambient temperature.According to an embodiment, the sensor element further comprises at least one insulating layer. The sensor element may also include two, three, four, or a plurality of insulating layers. Alternatively, however, the sensor element can also be free of an insulating layer.The insulating layer includes an insulating material. The at least one insulating layer comprises a thin, non-conductive material, e.g., oxides, nitrides, ceramics, glasses and polymers. The insulating layer may include, for example, SiO 2.There are the following possibilities where an insulating layer can be applied: 1. between carrier and respective lower electrode; in other words, the above-mentioned insulating layer on the carrier constitutes an insulating layer, and / or 2. between lower electrode and respective (first and second) functional layer, and / or 3. between the respective functional layer and the upper electrode, and / or 4. between the upper electrode and a contact pad connected to the upper electrode.Accordingly, there may be between zero and four insulating layers.In other words, the insulating layer may at least partially cover an upper side of the sensor element. Additionally or alternatively, the insulating layer may at least partially cover an upper side of the respective lower electrode. Additionally or alternatively, the insulating layer can at least partially cover the top side of the carrier (=insulator layer or insulating layer on the top side of the carrier). The insulating layer can improve the long-term stability of the sensor element.The insulating layer may include at least one window. The insulating layer may comprise more than one window, e.g. two or more windows. The at least one window forms a recess in the insulating layer. The window is designed and arranged in such a way that electrical contact is possible between the (respective) upper electrode / the (respective) lower electrode and the respective functional layer. According to one exemplary embodiment, the sensor element furthermore has at least one, preferably exactly one, absorber layer. The absorber layer is formed in the first region / IR region. The second region (reference region) is free of an absorber layer.The absorber layer is formed above the first functional layer as viewed in a stacking direction of the sensor element. The absorber layer is formed on the insulating layer, in particular directly on the insulating layer.The absorber layer is preferably formed congruently with the first functional layer. This means that an area of the absorber layer is as large as an area of the first functional layer. Alternatively, the absorber layer can also partially project beyond the first functional layer (on one side or on both sides) or be smaller than this.The absorber layer comprises a material which absorbs infrared radiation. Preferably, the absorber layer consists of an IR radiation absorbing material. Materials for the absorber layer include, for example, thin metal layers, dielectric materials (e.g., silicon oxide, silicon nitride, aluminum nitride, etc.), nanoporous metals or polymers (e.g., polyimide resins, polymers with dispersed carbon particles, etc.).The temperature of an object is measured contactless with the first functional layer / the IR sensor based on its emitted radiation. The radiation is absorbed by the absorber layer, as a result of which its temperature changes. The absorber layer is in thermal contact with the first functional layer. As a result, the temperature of the first functional layer changes. This results in a change in the resistance of the material.According to one exemplary embodiment, the sensor element further comprises at least one, preferably exactly one, reflector layer. The reflector layer is formed in the second region / reference region. The first region (IR region) is free of a reflector layer.The reflector layer is formed above the second functional layer as viewed in a stacking direction of the sensor element. The reflector layer is formed on the insulating layer. In particular, the reflector layer is formed directly on the insulating layer.The reflector layer can be configured congruently with the second functional layer. This means that an area of the reflector layer is as large as an area of the second functional layer. Alternatively, the reflector layer can, however, also partially project beyond the second functional layer (on one side or on both sides) or be smaller than this.The reflector layer comprises a material which reflects infrared radiation. Preferably, the reflector layer consists of a material reflecting IR radiation. The reflector layer preferably comprises metallic materials having a sufficient thickness. For example, the same material as used for the upper electrode may be used for the reflector layer. For example, the reflector layer comprises Au.The effect of IR radiation on the reference sensor is minimized by the reflector layer. Since the reflector layer reflects IR radiation, the temperature of the second functional layer does not change, or only slightly changes, by IR radiation incident on the reflector layer. This results in no or only a slight change in the resistance of the material of the second functional layer due to the incident IR radiation. The reflector layer consequently ensures reliable functioning of the reference sensor / the second functional layer. This results in the provision of a very precise sensor element.According to an embodiment, one of the upper electrodes functions as a reflector layer. In particular, an upper electrode formed above the second functional layer (i.e. in the second region / reference region) is designed such that it simultaneously assumes the function of a contact pad and the function of the reflector layer. An additional reflector layer is thus omitted. The number of process steps for producing the sensor element can thus be reduced. A particularly cost-effective sensor element with a simplified structure is thus provided.According to an embodiment, the sensor element comprises at least two contact pads, for example three, four or more contact pads. These can be arranged either in the first region or in the second region or distributed over the two regions of the sensor element. Preferably, the sensor element comprises at least two first contact pads (upper electrodes) and at least two second contact pads (lower electrodes). The contact pads facilitate the electrical connection of the sensor element to the outside world.The respective upper electrode can serve as a contact pad (i.e. as a first contact pad) of the sensor element for the electrical contacting of the sensor element. In this case, an additional / separate contact pad connected to the respective upper electrode is superfluous. The respective top electrode and the contact pad may form a single component of the sensor element.Alternatively, the sensor element may also have separate contact pads electrically connected to the respective upper electrode. In this case, the respective upper electrode and the respective contact pad represent different material layers of the sensor element.The respective lower electrode can also serve as a contact pad (i.e. as a second contact pad) of the sensor element. In this case, an additional / separate contact pad connected to the respective lower electrode is superfluous. The respective lower electrode and the contact pad may form a single component of the sensor element. This case is particularly suitable for wire bonding. When an insulating layer is provided on the upper surface of the lower electrode, the lower electrode may be connected to a wire via a window in the insulating layer.Alternatively, the sensor element comprises an additional / separate contact pad electrically connected to the respective lower electrode. If an insulating layer is present on the upper side of the lower electrode, the respective (second) contact pad is connected to the respective lower electrode via a window in the insulating layer.According to one exemplary embodiment, the resistance of the sensor element is determined / controlled by the size of the contact region between respective upper electrode and respective (i.e. first / second) functional layer, i.e. by the size of the respective first contact region.For this purpose, the contact region between the respective lower electrode and the respective functional layer (second contact region) must have at least the same size as the contact region between the respective upper electrode and the respective functional layer (first contact region). Preferably, the second contact area is larger than the first contact area.The larger contact area should be at least as large as the smaller. Ideally, the larger contact region should have an additional extension / width which corresponds to >3 times the thickness of the respective functional layer. Ideally, the size / width of the second contact region is greater than or equal to the size / width of the first contact region plus 3 times the thickness of the respective functional layer.The size of the first contact region may be controlled by the size of a window disposed in the insulating layer on the top surface of the sensor element. According to an embodiment, a resistance of the sensor element is controlled by an area of the respective upper electrode. This can be done, for example, by the window size in the insulating layer being larger than the area of the respective upper electrode or if no insulating layer is present between respective upper electrode and respective functional layer.According to one exemplary embodiment, a resistance of the sensor element is determined / controlled by the size of the contact region between the respective lower electrode and the respective functional layer (i.e. the second contact region). In this case, the second contact area is smaller than the first contact area.In the ideal case, the size / width of the first contact region is greater than or equal to the size of the second contact region plus three times the thickness of the respective functional layer.The size of the second contact region may be controlled by a lower electrode manufacturing method, i.e., during manufacture of the sensor element. Additionally or alternatively, the size of the second contact region may be controlled by the size of a window arranged in an insulating layer at least partially deposited between the respective lower electrode and the respective functional layer.According to one exemplary embodiment, a resistance of the sensor element is controlled / determined jointly by the respective upper electrode and the respective lower electrode. The resistance may be limited by the size of the respective upper electrode and the size of the respective lower electrode.In particular, the resistance is determined by the size of the first contact region and at the same time by the size of the second contact region. Additionally or alternatively, the resistance of the sensor element can be controlled / determined by a position of the respective upper electrode and the respective lower electrode relative to one another, in particular by an overlap region between respective upper electrode and respective lower electrode, more precisely by an overlap region between first contact region and second contact region.According to an embodiment, the sensor element comprises at least two lower electrodes and at least four upper electrodes. These can be arranged either in the first region or in the second region or distributed over the two regions of the sensor element. The resistance of the sensor element can be determined / controlled by the size of the first contact regions.Alternatively or additionally, the resistance of the sensor element can be determined / controlled by a size of the second contact regions.Alternatively or additionally, the resistance of the sensor element can be determined / controlled by a relative position of the upper electrodes and the lower electrodes and in particular by a size of the overlap regions between the upper electrodes and the lower electrodes, more precisely by the size of the overlap regions between the first contact regions and the second contact regions.According to an embodiment, the sensor element comprises a plurality of upper electrodes, for example a plurality of first upper electrodes (upper electrodes of the IR sensor) and a plurality of second upper electrodes (upper electrodes of the reference sensor). In addition, the sensor element includes a plurality of lower electrodes, for example, a plurality of first lower electrodes (lower electrodes of the IR sensor) and a plurality of second lower electrodes (lower electrodes of the reference sensor). The upper electrodes and the lower electrodes are connected in series. This has the result that the current flows through the respective functional layer a plurality of times, as if a plurality of smaller resistors were connected in series, which leads to a greater overall resistance of the sensor element.The final resistance of the sensor element (rated resistance) can be determined by the size of the first contact areas and / or by the size of the second contact areas. Additionally or alternatively, the resistance of the sensor element can be determined / controlled by a relative position of the upper electrodes and the lower electrodes and in particular by the size of the overlap areas between the upper electrodes and the lower electrodes, more precisely by a size of the overlap areas between the first contact areas and the second contact areas.Additionally or alternatively, the resistance of the sensor element may be determined / controlled by a number of series connected resistors. This means that the resistance is controlled by controlling the number of current passages through the respective functional layer.According to one embodiment, the sensor element has a close resistance tolerance, i.e. a small deviation range from the rated resistance. In order to achieve the tight resistance tolerance, the sensor element comprises at least one additional contact pad.The additional contact pad is connected to at least one of the upper electrodes in order to further adjust the final resistance of the sensor element. In particular, the additional contact pad enables an additional / intermediate connection of at least one of the upper electrodes connected in series. An undesired / too frequent current flow through the functional layer, which would increase the overall resistance of the sensor element, can thus be avoided.Preferably, the additional contact pad extends beyond a surface of the respective functional layer. In particular, the additional contact pad is not arranged directly above the respective functional layer, but can be laterally offset.According to one embodiment, the sensor element has a close resistance tolerance, i.e. a small deviation range from the rated resistance. To achieve the close resistance tolerance, the sensor element also includes trim electrodes. The trim electrodes are additional electrodes that allow additional electrical connections of the top electrodes.The trimming electrodes are connected to upper electrodes (in particular only to certain upper electrodes). The trim electrodes connect certain top electrodes connected in series and omit other top electrodes. Undesired / excessively frequent current flow through the functional layer, which would increase the overall resistance of the sensor element, can thus be avoided.Preferably, the trimming electrodes are not arranged directly above the respective functional layer, but laterally offset.According to an embodiment, at least one of the trimming electrodes is trimmed, i.e. the electrode material is at least partially removed, e.g. by laser cutting, sawing or grinding, in order to fine tune the resistance of the final sensor element. By this change in geometry, the resistance can be changed so that it better matches the rated resistance.According to an embodiment, the sensor element comprises a plurality of upper electrodes (for example a plurality of first upper electrodes and a plurality of second upper electrodes) and at least two lower electrodes (first lower electrode / lower electrode of the IR sensor and second lower electrode / lower electrode of the reference sensor). The upper electrodes are connected in parallel.Alternatively, the sensor element may also include at least two upper electrodes (for example, first upper electrode and second upper electrode) and a plurality of lower electrodes. The lower electrodes are connected in parallel.Alternatively, the sensor element may include a plurality of upper electrodes and a plurality of lower electrodes. These may be arranged either in the first region or in the second region or distributed over the two regions of the sensor element. The upper electrodes and the lower electrodes are connected in parallel.The resistance of the sensor element may be determined / controlled by the size of the respective first contact regions and / or by the size of the respective second contact regions. Additionally or alternatively, the resistance of the sensor element may be determined / controlled by a number of upper electrodes and lower electrodes connected in parallel.According to one embodiment, the sensor element has a close resistance tolerance. This means that the sensor element has a very small deviation range from the rated resistance. To achieve the close resistance tolerance, the sensor element further comprises trimming electrodes.The trimming electrodes are connected to the upper electrodes (in particular to all the upper electrodes) in a row or a circle or a spiral. The trimming electrodes may also be connected to any desired upper electrodes. Preferably, the trimming electrodes are not arranged directly above the respective functional layer, but laterally offset. At least one of the trim electrodes may be further trimmed, e.g., with a laser, to fine tune the resistance of the final sensor element, thereby eliminating certain resistances.According to one exemplary embodiment, the respective upper electrode can be transparent. In particular, the upper electrode in the first region / the upper electrode of the IR sensor can be transparent. For example, the upper electrode of the IR sensor comprises ITO (indium tin oxide). The reflection of IR radiation can thus be reduced and the sensitivity of the IR sensor can be increased.According to an embodiment, the electrodes (upper and lower electrodes) formed in the first region have a specific structure for heat decoupling. In other words, the at least one lower electrode and at least one upper electrode of the IR sensor are formed and arranged such that a heat transport between the carrier and the first functional layer is minimized. Consequently, the electrodes in the first region can have a different structure than the electrodes in the second region despite an analogous layer structure (electrode-NTC electrode structure).Preferably, the upper electrode is formed as narrow or thin as possible in a connection region between a bonding region (coupling region between upper electrode / sensor element and an external application) and a connection region (coupling region between upper electrode and first functional layer). Alternatively or additionally, the upper electrode can be designed as long as possible in the connection region. For example, the upper and / or the lower electrode of the IR sensor can be partially formed in meandering fashion in order to achieve optimum heat decoupling.According to a further aspect, a use of a sensor element is described. The sensor element is in particular the IR sensor element described above. All features described in connection with the sensor element also apply to the use of the sensor element. The sensor element is used for temperature monitoring and / or temperature control, e.g. in the automobile sector or in so-called smart wearables (electronic objects that can be worn directly on the body, for example fitness trackers, smart glasses, earphones, smart watches, etc.). Since the sensor element has a specific electrical rated resistance and a close resistance tolerance, very precise monitoring and / or regulation is made possible.The drawings described below are not to be understood as true to scale. Rather, for better representation, individual dimensions can be depicted in enlarged, reduced or distorted form.Elements that are the same as or that perform the same function are denoted by the same reference numerals.The following are shown: FIG. 1 shows a sectional illustration of the sensor element according to the invention, FIG. 2 shows a sectional illustration of the sensor element according to the invention according to a further exemplary embodiment, FIG. 3 shows a sectional illustration of the sensor element according to the invention according to a further exemplary embodiment, FIG. 4 shows a schematic plan view of a sensor element according to the invention according to a further exemplary embodiment. FIG. 5 shows a perspective view of a partial region of a sensor element according to the invention, FIG. 6 shows a sectional illustration of the partial region from FIG. 5, FIG. 7 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 8 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 9 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 10 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 11 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 12 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 13 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 14 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 15 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 16 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 17 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 18 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 19 shows a schematic plan view of the partial region according to FIGS. 17, 18, FIG. 20 shows a schematic plan view of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 21 shows a schematic plan view of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 22 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 23 shows a sectional illustration of a partial region of a sensor element according to the invention according to a further exemplary embodiment, FIG. 24 shows a schematic plan view of the partial region according to FIGS. 22, 23, FIG. 25 shows a schematic plan view of a sensor element according to the invention according to a further exemplary embodiment, FIG. 26 shows a sectional illustration of the sensor element according to the invention according to a further exemplary embodiment, FIG. 27 is a perspective view of a portion of the sensor element of FIG. 26.FIGS. 1 to 27 show exemplary embodiments of a sensor element 100 according to the invention. The sensor element 100 is an NTC thin-film temperature sensor. The sensor element 100 is designed for contactless temperature measurement of an object and has a close resistance tolerance. The sensor element 100 is a TF IR-NTC temperature sensor with a specific rated resistance.The sensor element 100 has an upper side 1 aand a lower side 1 b. The sensor element 100 further comprises a carrier 2 having an upper side 11 and a lower side 12. The upper side 11 of the carrier 2 has an insulating layer or insulating layer 8, for example comprising SiO 2. A thickness of the insulating layer / insulating layer 8 may be between 50 nm and 1 μm, preferably between 250 nm and 600 nm. Ideally, the thickness is 500 nm. The support 2 is preferably a rectangle and may be square.A thickness T (extension in a stacking direction S) of the sensor element 100 is <1000 μm, preferably <700 μm, particularly preferably <300 μm (see FIGS. 1 and 6 ). For example, sensor element 100 is designed for direct integration into a MEMS structure.The sensor element 100 and thus also the carrier 2 have a first region B 1 and a second region B 2 (see, for example, FIGS. 1 and 4 ). The first region B 1 is IRsensitive (IR sensor 101) and the second region B 2 is ambient temperature sensitive (reference sensor 102). The sensor element 100 thus combines two sensitive regions on a single chip. An additional NTC chip for determining a reference temperature is thus superfluous.In the exemplary embodiments according to FIGS. 1 to 3, the two regions B 1 and B 2 are located at a spatial distance next to one another on the carrier 2. In particular, the region lying between B1 and B2 is free of functional material.In an alternative embodiment (FIG. 4 ), the second region B 2 can, however, also surround the first region B 1. In other words, the reference sensor 102 then surrounds the IR sensor 101. In this embodiment, too, a region lying between the regions B 1, B 2 is free of functional elements of the sensor element 100.The temperature of an object is measured contactless with the IR sensor 101 on the basis of its emitted radiation. The IR sensor 101 comprises a functional material (first functional layer 7a), which in the embodiments shown in FIGS. 1 to 14 is formed directly on at least a partial region of a lower electrode 40 (first lower electrode 40). The first functional layer 7 ais an NTC thin film.Between the first functional layer 7 aand the first lower electrode 40, a contact region c 2 (second and lower contact regions c 2, respectively) is formed. In this region, there is a direct / direct electrical and mechanical contact between the lower electrode 40 and the first functional layer 7 a. The lower electrode 40 may itself function as a contact pad 40 aor may be connected to a separate contact pad 40 a, as will be described in detail later.The IR sensor 101 further comprises an upper electrode (first upper electrode 50) in the embodiments shown in Figs. 1 to 14. This is connected directly to the first functional layer 7a in a contact region (first or upper contact region c1). In this region there is consequently a direct / direct electrical and mechanical contact between the first upper electrode 50 and the first functional layer 7 a. The first upper electrode 50 may function as a contact pad 50 aor may be connected to a separate contact pad 50 a, as will be described in detail later.The sensor element 100 has an insulating layer 8 mentioned above. The insulating layer 8 may include a plurality of regions / portions, as will be explained later. An (IR) absorber layer 21 is located on the insulating layer. The absorber layer 21 is congruent with the first functional layer 7 ain this exemplary embodiment. That is to say that absorber layer 21 and first functional layer 7 ahave the same area (same extent in the x-y direction, that is to say extent perpendicular to the stacking direction S of sensor element 100 / perpendicular to the z direction).However, the absorber layer 21 can also be larger than the first functional layer 7 aand can partially protrude beyond the latter (not explicitly illustrated). Alternatively, the absorber layer 21 can also be smaller than the first functional layer 7 a(not explicitly shown).The absorber layer 21 is thermally coupled to the first functional layer 7 aand comprises an IR radiation-absorbing material. For example, the absorber layer 21 includes a metal thin film, a dielectric material (e.g., silicon oxide, silicon nitride, or aluminum nitride), a nonporous metal, or a polymer (e.g., a polyimide resin or a carbon particle dispersed polymer).The absorber layer 21 is located exclusively in the first region B 1, that is to say in the region of the IR sensor 101. This means that no IR radiation absorbing material is formed on the insulating layer 8 in the second region B 2.The IR radiation impinging on the absorber layer 21 is absorbed by the absorber layer 21, as a result of which a temperature change of the absorber layer 21 occurs. Due to the thermal coupling with the first functional layer 7 a, this leads to a change in resistance at the first functional layer 7 a.The IR sensor 101 furthermore has a cavity 20 in the carrier 2. The cavity 20 is formed only in the first region B 1. It does not expand either into the second region B2 or into the region lying between B1 and B2. In particular, the second region B 2 (reference sensor 102) is completely free of a cavity in the carrier 2.The cavity 20 penetrates the carrier 2 completely in the embodiment shown. In the embodiments according to FIGS. 1 to 3, the cavity 20 is formed directly under the insulating layer / insulating layer 8.Alternatively, the cavity 20 can also be designed such that it only partially penetrates the carrier 2 (not explicitly shown). In this case, the cavity does not extend from the top side 11 to the bottom side 12 of the carrier 2. the cavity 2 is formed starting from the bottom side 12 of the carrier 2. Thus, should the cavity 20 not penetrate the carrier 2 completely, some carrier material is still in direct contact with the insulating layer 8.As seen in the stacking direction S, the cavity 20 is located below the first functional layer 7 a. In the exemplary embodiment shown, an area (extent perpendicular to the stacking direction, i.e. in the x-y direction) of the cavity 20 is approximately as large as an area of the first functional layer 7 a. The area of the cavity 20 can, however, also be smaller or larger than the area of the first functional layer 7 a(not explicitly illustrated).The cavity 20 ensures that the first functional layer 7 ais thermally decoupled from the carrier 2. As a result, there are fewer thermal losses to the carrier 2 and a maximized temperature change at the first functional layer 7 ais made possible. Thus, the resistance change of the first functional layer 7 ais also maximized.In the immediate vicinity of the first functional layer 7 a, the second functional layer 7 bis formed on the carrier 2. This is part of the reference sensor 102. The second functional layer 7 bis an NTC thin film. The reference sensor 102 is designed to measure an ambient temperature and in particular a temperature of the carrier 2. The reference sensor 102 acts as a contact-type sensor.The reference sensor 102 measures the temperature in the direct environment to the IR sensor 101. Since a complete decoupling of the IR sensor 101 (and in particular of the first functional layer 7 a) from the environment is not possible, there are always losses of heat to the environment. Therefore, the temperature of the first functional layer 7a will deviate from that of the object to be measured. In this case, the higher the temperature difference between the first functional layer 7 aand the environment, the greater the thermal losses.Therefore, there is a need for a reference sensor 102 for measuring the ambient temperature. In addition, the heat transport via solids is significantly faster than via gases, which means that the main heat loss takes place via the carrier 2. Thus, the influence of the carrier 2 is dominant in comparison with the rest of the environment. It is therefore of particular interest to determine the temperature of the carrier 2 (and thus of the environment) in order to be able to carry out a correction by the thermal losses.The reference sensor 102 comprises a functional material (second functional layer 7 b), which in the embodiments shown in FIGS. 1 to 14 is formed directly on at least a partial region of a lower electrode 40 (second lower electrode). Between the second functional layer 7 band the second lower electrode, a contact region c 2 (second or lower contact region c 2) is formed. In this region, there is a direct / direct electrical and mechanical contact between the lower electrode 40 and the second functional layer 7 b. The second lower electrode 40 may function as a contact pad 40 aor may be connected to a separate contact pad 40 a, as will be described in detail later.The reference sensor 102 has an upper electrode (second upper electrode 50) in the embodiments shown in FIGS. 1 to 4. This is connected directly to the second functional layer 7b in a contact region (first or upper contact region c1). In this region, there is a direct / direct electrical and mechanical contact between the upper electrode 50 and the second functional layer 7 b. The second upper electrode 50 may function as a contact pad 50 aor may be connected to a separate contact pad 50 a, as will be described in detail later.In addition, a reflector layer 22 is also formed on the insulating layer 8. In this exemplary embodiment, the reflector layer 22 is congruent with the second functional layer 7 b. That is to say that the reflector layer and the second functional layer 7 bhave an area of the same size (same extent in the x-y direction, that is to say extent perpendicular to the stacking direction S of the sensor element 100).However, the reflector layer 22 can also be larger than the second functional layer 7 band may partially protrude beyond the latter (not explicitly illustrated). Alternatively, the reflector layer 22 can also be smaller than the second functional layer 7 b(not explicitly shown).The reflector layer 22 comprises a material reflecting IR radiation. For example, the reflector layer 22 comprises an Au layer of sufficient thickness to reflect IR radiation.The reflector layer 22 is situated exclusively in the second region B 2, that is to say in the region of the reference sensor 102. It does not protrude into the region lying between B1 and B2. In particular, the first region B 1 (IR sensor 101) is free of a component reflecting the IR radiation.The layer structure of sensor element 100, and in particular the electrode structure and insulating layer(s) 8, is illustrated in greater detail below in connection with FIGS. 5 to 24. For the sake of simplicity, the figures here show essentially only a partial region of sensor element 100, i.e., only first region B 1 (IR sensor 101) or second region B 2 (reference sensor 102), which is intended to be made clear by the use of reference numerals 7 a / 7 b(i.e., first or second functional layer 7 a, 7 b).However, the structure described in connection with FIGS. 5 to 24 is present in both regions (IR sensor 101 / first region B 1 and reference sensor 102 / second region B 2) of sensor element 100. Ideally, in the embodiments shown in FIGS. 1 to 24, in particular the electrode structure of the two regions B 1 and B 2 is constructed analogously in order to configure IR sensor 101 and reference sensor 102 as similarly as possible.In an alternative embodiment (see FIGS. 26 and 27 in this regard), however, the IR sensor 101 and the reference sensor 102 can also have different electrode structures. Thus, the IR sensor 101 could have, for example, the electrode structure described below and the reference sensor 102 could have two lower electrodes in the form of an interdigital structure (interdigital electrodes 4) and two contact elements 10, or vice versa, as will be described later in connection with FIGS. 26 and 27, respectively.As already mentioned, the sensor element 100 according to FIGS. 1 to 3 has exactly two upper electrodes 50 (first and second upper electrodes 50) and exactly two lower electrodes 40 (first and second lower electrodes 40). Specifically, each region B 1, B 2 of the sensor element 100 includes a lower electrode 40 and an upper electrode 50.Of course, the sensor element 100 can also comprise more upper electrodes 50 / lower electrodes 40, as is described in the embodiments in connection with FIGS. 17 to 24.The respective upper electrode 50 / lower electrode 40 may comprise individual or multiple layers of thin-film metals, wherein the materials may be Cu, Au, Ni, Cr, Ag, Ti, W, Pd or Pt.The respective lower electrode 40 is arranged directly / directly on the upper side 11 of the carrier 2 (FIGS. 5 and 6 ) or on the insulating layer 8 arranged on the upper side 11 of the carrier 2 (see FIG. 7 ). The respective lower electrode 40 is arranged between the carrier 2 and the respective functional layer 7 a, 7 b. The respective lower electrode 40 is arranged directly below the respective functional layer 7 a, 7 b. In other words, the respective lower electrode 40 is at least partially in direct electrical and mechanical contact with the respective functional layer 7 a, 7 b.Between the respective lower electrode 40 and the respective functional layer 7 a, 7 b, the contact region c 2 (second or lower contact region c 2) is formed. The second contact region c 2 is the region in which the respective functional layer 7 a, 7 blies directly on the respective lower electrode 40.The respective upper electrode 50 is arranged on the upper side of the respective functional layer 7 a, 7 b, i.e. above the functional layer 7 a, 7 b. In other words, the respective functional layer 7 a, 7 bis embedded between the upper electrode 50 and the lower electrode 40.The respective upper electrode 50 is at least partially in direct electrical and mechanical contact with the respective functional layer 7 a, 7 b. Between the respective upper electrode 50 and the functional layer 7 a, 7 b, the contact region c 1 (first or upper contact region c 1) is formed. The first contact region c 1 is the region in which the upper electrode 5 rests directly on the functional layer 7 a, 7 b.As already mentioned, there may be a plurality of insulating layers 8. In the embodiment of FIGS. 5 to 7, the sensor element 100 further comprises an insulating layer 8 disposed on an upper surface 1a of the sensor element 1. This insulating layer 8 covers the upper side 1 aat least partially, as can be seen, for example, from FIG. 6. An insulating layer 8 further covers an upper surface of each lower electrode 40 except for the contact region c 2 between the lower electrode 40 and each functional layer 7 a, 7 b. An insulating layer 8 also covers an upper surface of each of the function layers 7 a, 7 b, except for the contact region c 1 between the upper electrode 50 and the function layer 7 a, 7 b.The respective insulating layer 8 includes windows or recesses 70. Since there may be a plurality of insulating layers 8, there may also be a plurality of windows 70. A window 70 is located between the lower electrode 40 and the functional layer 7 a, 7 b(FIG. 7 ). A further window may be located between the lower electrode 40 and contact pad 40 a(see FIG. 3 ). A further window 70 can be located between the upper electrode 50 and the functional layer 7 a, 7 b. A window 70 may also be located between the upper electrode 50 and the contact pad 50 a(see FIGS. 1 and 2 ). And theoretically, the windows 70 may all be present simultaneously. Only because one insulating layer 8 has a window 70, that is, not that another insulating layer 8 may not have one or more windows 70.These windows 70 are designed and arranged to allow direct contact between the upper electrode 50 and the functional layer 7 a, 7 band / or between the lower electrode 40 and the functional layer 7 a, 7 band / or between the lower electrode 40 and the contact pad 40 a, etc. In particular, in FIGS. 5 to 7, a window 70 is arranged directly below the upper electrode 50 in order to enable electrical contact between the upper electrode 50 and the functional layer 7 a, 7 bin the first contact region c 1. Another window 70 is disposed directly above the lower electrode 40 to allow electrical contact between the lower electrode 40 and a contact pad 40 a.The respective insulating layer 8 may improve the long-term stability of the sensor element 100, in particular when the insulating layer 8 is disposed on an outer surface of the sensor element 100. An insulating layer thickness is between 50 nm to 1 μm, preferably 200 nm to 600 nm and ideally between 400 nm to 500 nm.The respective insulating layer 8 comprises a thin, non-conductive material, for example comprising oxides, nitrides, ceramics, glasses and / or polymers.As already mentioned, an insulating layer 8 covers the top side 1 aof the sensor element 100 with the exception of the contact pads 40 a, 50 a. The contact pads 40 a, 50 a facilitate the electrical contacting of the sensor element 100 and have a thickness of >100 nm, preferably >1 μm and ideally >5 μm. The contact pads 40 a, 50 acomprise single- or multi-layer thin-film metals with materials such as Cu, Au, Ni, Cr, Ag, Ti, W, Pd or Pt.The contact pads 40 a, 50 aare directly connected to the electrodes 40, 50. In the embodiment of Figures 5-7, the contact pad 40a is directly connected to the lower electrode 40 via the window / recess 70. In addition, in this embodiment, the upper electrode 50 directly functions as the contact pad 50 a. In other words, there is no additional first contact pad 50a connected to the upper electrode 50, as seen in Figs. 5 to 7.In an alternative embodiment (not explicitly shown), the lower electrode 40 can also function directly as contact pad 40 a. In other words, in this case, there is no additional second contact pad 40 aconnected to the lower electrode 40.In an alternative embodiment (see FIG. 8 ), a special electrode material may be used to contact the functional layer 7 a, 7 band the upper electrode 50 to improve adhesion. In other words: In the embodiment according to FIG. 8, a separate first contact pad 50 ais provided, which electrically and mechanically contacts the upper electrode 50. The materials of the upper electrode 50 and the first contact pad 50 amay be different.In either case (FIGS. 5 to 8 ), the upper electrode 50 is directly connected to the top surface of the function layer 7 aor 7 bvia the window 70 in the insulating layer 8 to form the contact region c 1.As can be seen from FIGS. 6 to 8, the current flow F takes place from the second contact pad 40 ato the lower electrode 4 and further to the functional layer 7 a, 7 band via the functional layer 7 a, 7 bto the upper electrode 50, 50 a.The sensor element 100 has a specific resistance (rated resistance). In the embodiment according to FIGS. 4 to 8, the resistance is determined and in particular limited by a size of the first contact region c1, i.e. the contact region between upper electrode 50 and functional layer 7a or 7b.In order to limit the resistance by the first contact region c 1, the second contact region c 2 must have at least the same size as the first contact region c 1. Preferably, the second contact area c2 is larger than the first contact area c1, as shown in Figs. 4 to 8. In particular, a width of the second contact region c 2 (extent of the second contact region c 2 perpendicular to the stacking direction S) is equal to or greater than a width of the first contact region c 1 plus three times the thickness t of the respective functional layer 7 aand 7 b: c 2≥c 1+3 t.The size / width of the first contact region c 1 is determined by the size of the window 70 disposed in the insulating layer 8 directly below the upper electrode 50. The larger the window 70 is, the larger the first contact area c 1 is. The larger the first contact area c 1, the lower the resistance of the sensor element 100.If the window size is larger than the size of the area of the first contact pad 50 aand / or if an insulating layer 8 (not explicitly shown) is absent, the resistance of the sensor element 100 can also be controlled via the area of the upper electrode 50, wherein in the embodiment according to FIGS. 4 to 6 the resistance is also controlled via an area of the upper electrode 50, since the upper electrode 50 functions as the first contact pad 50 a.FIGS. 9 and 10 show a sectional illustration of a partial region of the sensor element 100 according to a further embodiment. In this embodiment, the electric resistance is controlled by the respective lower electrode 40. In particular, the resistance is determined by the size or the width of the second contact region c 2. The larger the contact area c 2, the smaller the resistance of the sensor element 100.For determining / controlling the resistance through the second contact region c 2, the first contact region c 1 must have at least the same size as the second contact region c 2. Preferably, the first contact area c 1 is larger than the second contact area c 2 (see FIGS. 9 and 10 ). In particular, a width of the first contact region c 1 (extent of the first contact region c 1 perpendicular to the stacking direction S) is equal to or greater than a width of the second contact region c 2 plus three times the thickness t of the respective functional layer 7 aand 7 b: c 1≥c 2+3 t.In this embodiment, the size of the second contact region c 2 is controlled by the manufacture of the sensor element 100, particularly, the manufacture of the lower electrode 40.As can be seen from the embodiment in FIG. 10, the lower electrode 40 is deposited starting from the carrier 2. The contact region c2 can now be defined either by the structure of the lower electrode 40 or, as shown, by a window 70 in an insulating layer 8. To create this window 70, a SiO 2- layer is deposited and, for example, a hole is etched into the SiO 2. The functional layer 7 aand 7 bis then deposited over the hole. The lower electrode 40 is thus a planar layer and the functional layer 7 aand 7 bfills the window 70. Subsequently, a further SiO 2- layer / insulating layer 8 is deposited and a further window 70 is provided for the upper electrode / contact pad 50, 50 a.It should be noted that the figures shown are a very rough description of the layer structure and the windows actually lead to a gradation in the layers lying above, the layer thickness remaining the same irrespective of the position.FIGS. 11 and 12 show a sectional illustration of a partial region of the sensor element 100 according to a further embodiment. In this embodiment, the resistance is controlled by each of the upper electrode 50 and the lower electrode 40. More specifically, the resistance is controlled by a size of the (respective) first contact region c 1 between the upper electrode 50 and the functional layer 7 aand 7 band by the size of the (respective) second contact region c 2 between the lower electrode 40 and the functional layer 7 aand 7 b.The control of the resistor is effected here analogously to the embodiments according to FIGS. 4 to 10, i.e. via the size of the contact regions c1, c2. In addition, the resistance can be controlled by the position of the first contact region c 1 and the second contact region c 2 with respect to one another, in particular by an overlap region o perpendicular to the stacking direction S between the first and second contact regions c 1, c 2, as illustrated in FIGS. 11 and 12. The larger the overlap region o, the lower the resistance.Here too, as already described in connection with FIGS. 4 to 6, there are a plurality of insulating layers 8 and windows 70. as already described above, the insulating layer 8 may be present between respective lower electrode 40 and respective functional layer 7 a, 7 bto control the size of the second contact region c 2 via a window 70 in the insulating layer 8.By controlling the size of the contact regions c 1, c 2 and / or the position of the contact regions c 1, c 2 with respect to one another, the rated resistance of the sensor element 100 can be precisely controlled.Also in this embodiment, the upper electrode 50 may function as the first contact pad 50 aas shown in FIGS. 11 and 12. Alternatively, the upper electrode 50 and the first contact pad 50 amay also be made of separate material layers, as illustrated in FIG. 8.FIGS. 13 to 16 show a sectional illustration of a partial region of the sensor element 100 according to a further embodiment. In this embodiment, the functional layer 7 aand 7 bis respectively embedded between two upper electrodes 50 and one lower electrode 40, i.e. two upper electrodes 50 are respectively formed in the first region B 1 and in the second region B 2.This causes the current to flow through the NTC multiple times (see current flow F). The current flows through the left upper electrode 50 (left in FIG. 13 ) through the functional layers 7 aand 7 bto the lower electrode 40. There, the current flows through the functional layer 7 aand 7 bto the upper electrode 50.The resistance of the sensor element 100 can be controlled in the same manner as in the above-described embodiments, either by changing / controlling the first contact region c 1, the second contact region c 2, or by varying the position and size of the contact regions c 1, c 2. Here, too, the upper electrode 50 may be an additional layer (see FIGS. 15, 16 ) or may be integrally provided with the first contact pad 50 a, i.e. the upper electrode 50 functions as the first contact pad 50 a, as shown in FIGS. 11, 12.FIGS. 17 and 18 show a sectional illustration of a partial region of the sensor element 100 according to a further embodiment. In this embodiment, a plurality of upper electrodes 50 and a plurality of lower electrodes 40 are used per area B 1 / B 2 and connected in series. Thus, for the IR sensor 101 and for the reference sensor 102, a plurality of upper electrodes 50 and lower electrodes 40 are present in each case and thus a plurality of first contact regions c 1 and second contact regions c 2, which can also be of different sizes.The specific structure results in the current flowing multiple times through the respective functional layer 7 a, 7 bas if multiple smaller resistors were connected in series, which leads to a larger total resistance (see current flow F in FIGS. 17, 18 ).In this embodiment, two factors affect the final resistance of the sensor element 100:First, the first and second contact regions c1, c2 mentioned in the above-described embodiments. For example, the resistance may be controlled via the size of the first contact regions c 1 by the design of the top electrodes 50 or the size of the window 70 in the insulating layer 8, or by the second contact regions c 2, or by the size and position of both the first and second contact regions c 1, c 2 simultaneously, as described above. The upper electrodes 50 may in turn either be an additional layer (not explicitly shown) or simultaneously function as first contact pads 50 a.The other factor for controlling the resistance is the number of resistors connected in series. By limiting the series-connected resistors, the total resistance of the sensor element 100 can be determined.This also allows fine tuning of the resistor after production is completed. Fine tuning can achieve the result that the finished sensor element 100 has a very small deviation range from the rated resistance.There are two possibilities for fine tuning:One possibility is to provide trimming electrodes 80 as shown in Fig. 19. Trim electrodes 80 are separate / additional electrodes connected to particular top electrodes 50 arranged in a row. Alternatively, the trimming electrodes 80 can also be connected to specific, circularly or spirally arranged upper electrodes or to any desired upper electrodes (not explicitly shown). The trimming electrodes 80 are also connected to a contact pad 50a as seen in Fig. 19. The trimming electrodes 80 act as short-circuiting electrodes. They connect certain / some upper electrodes 50 and omit other upper electrodes 50 disposed between the connected upper electrodes 50.The more frequently the current flows through the respective functional layer 7 a, 7 b(current flow F, FIG. 18 ), the higher the final resistance of the sensor element 100. By inserting the trimming electrodes 80, the current can be prevented from flowing through the functional layer 7a or 7b more frequently than provided. Specifically, for the embodiment shown in FIG. 19, this means that the upper row of upper electrodes 50 can be jumped further to the right with the aid of trimming electrodes 80, so that a current flow F through functional layer 7 aand 7 band upper electrodes 50 arranged therebetween can be avoided. In this case, the total resistance can be reduced.For further fine tuning and depending on the measured resistance, the trimming electrodes 80 connected to the upper electrode 50 can additionally be cut off, for example with a laser. This means that electrode material of the trimming electrodes 80 is at least partially removed for fine tuning the resistance of the finished sensor element 100, e.g. by laser cutting, sawing or grinding.In Fig. 19 as an example, cutting the leftmost terminal would increase the resistance by the smallest step, and each other cut terminal would increase the resistance further. This enables very good fine tuning to the rated resistance of the sensor element 100.Ideally, the trimming electrodes 80 are not arranged directly above the respective functional layer 7 a, 7 b, but laterally, as illustrated in FIG. 19. In other words, the trimming electrodes 80 are not arranged directly above the top side of the functional layer 7 aand 7 b, respectively.The embodiment in FIG. 19 also shows that all upper electrodes 50 contact the lower electrode 40 via the respective functional layer 7 a, 7 b. However, this is not required, and only a part of the upper electrodes 50 may be disposed on the respective functional layer 7 a, 7 band contact the lower electrode 40, as shown in FIG. 20, for example. This would be of particular interest for trimming electrodes by laser cutting, as this allows even smaller steps in fine tuning the resistor.The second way to fine tune the resistance of sensor element 100 is to provide additional contact pads 90 that are connected to top electrodes 50 at other locations. This is illustrated in FIG. 21. The additional contact pads 90 are another way to directly contact (certain) top electrodes 50 without having to insert trim electrodes 80.Depending on which additional contact pads 90 are used for the second connection, the resistance may be fine tuned to achieve the target / rated resistances. In the embodiment shown, the first contact pad 50a would be the left electrode and the second contact pad would be either the upper left contact pad 90 (lowest resistance), the upper right contact pad 90 (slightly higher resistance) or the right contact pad 90 (highest resistance) for fine tuning to the target resistances. Ideally, the contact pads 50 a, 90, which are provided for the electrical contacting of the sensor element 100 with an external source, are not completely located above the respective functional layer 7 a, 7 b, but rather protrude beyond the functional layer 7 a, 7 b, as illustrated in FIG. 21.FIGS. 22 and 23 show a sectional illustration of a partial region of the sensor element 100 according to a further embodiment. In this embodiment, a plurality of upper electrodes 50 and one lower electrode 40 are provided per area B 1 / B 2 and connected in parallel. As a result, the current can flow at a plurality of points simultaneously through the respective functional layer 7 a, 7 b, as illustrated in FIGS. 22, 23 (see current flow F).Here, too, two factors influence the total resistance of the sensor element 100:On the one hand, as described in the preceding embodiments, the size and the relative position of the contact regions c 1, c 2. The second factor is the number of electrodes 40, 50 connected in parallel. In this embodiment, it is also possible to trim the electrodes and fine tune the resistance after the sensor element 100 is manufactured. An example of fine tuning is shown in Fig. 24.The sensor element 100 illustrated in FIG. 24 includes a lower electrode 40 and a plurality of upper electrodes 50 per region B 1 / B 2. Also in this embodiment, trimming electrodes 80 are inserted which are connected to all the upper electrodes 50 of a region B1 / B2 in a row. The trimming electrodes 80 may be trimmed by laser cutting to adjust the final resistance of the sensor element 100, thereby obtaining a sensor element 100 having a small range of deviation from the rated resistance. By laser cutting trim electrodes 80, individual resistors may be removed, thereby increasing the overall resistance of sensor element 100. The adjustment is preferably carried out in a region which is not directly above the respective functional layer 7 a, 7 b.The lower electrode 40 can also be divided into a plurality of electrodes for the respective region B 1 / B 2, wherein the parallel connection is maintained. Alternatively, the structure can also be embodied in mirror image form with a plurality of lower electrodes 40 and one large upper electrode 50 per region B 1 / B 2 (not explicitly shown). In this case, the upper electrode 50 may be divided into a plurality of electrodes while maintaining the parallel connection.In the exemplary embodiment shown in FIG. 1, the sensor element 100 has a separate reflector layer 22, as described above. In particular, the reference sensor 102 comprises a reflector layer 22 in addition to the contact pads 40 a, 50 aof the reference sensor 102.Alternatively, as shown in FIG. 2, one of the contact pads (here contact pad 50 a) of the reference sensor 102 can also assume the function of the reflector layer 22. In other words, one of the contact pads of the reference sensor 102 may be configured to reflect IR radiation (IR radiation reflecting contact pad 50 a, 22 in FIG. 2 ). A separate reflector layer 22 is omitted in this case.For this purpose, one of the contact pads of the reference sensor 102, i.e. a contact pad in the second region B 2, is formed such that it extends over the insulating layer 8 at least partially over the surface. Unlike the remaining contact pads 40 a, 50 a, the contact pad functioning as a reflector layer is thus located at least partially on the insulating layer 8.The contact pad functioning as a reflector layer is formed in such a way that its surface approximately corresponds to the surface of the second functional layer 7 band is preferably larger than the surface of the second functional layer 7 b. A thickness of the reflected contact pad may also be adapted, in particular enlarged, in comparison to the remaining contact pads of the sensor element 100. In contrast to the other contact pads, the contact pad functioning as a reflector layer has IR radiation reflecting properties.In an embodiment, one of the contact pads 40 a, 50 aof the IR sensor 101 and one of the contact pads 40 a, 50 aof the reference sensor 102 may also be combined into a single contact pad (combined contact pad 103, FIG. 3 ). Thus, the sensor element 100 according to FIG. 3 has a total of two lower electrodes 40 and three contact pads 40 a, 50 a, 103. In this case, the combined contact pad 103 is electrically conductive and mechanically connected to the two lower electrodes 40.Combining the two upper electrodes 50 (upper electrode 50 of the IR sensor 101 and upper electrode 50 of the reference sensor 102) to form a combined electrode is also possible (not explicitly shown).In an embodiment, the upper electrode 50 / the upper contact pad 50 aof the IR sensor 101 is transparent. For example, the top electrode / contact pad 50 amay include ITO. The reflection of IR radiation can thus be reduced and the sensitivity of the IR sensor 101 can be increased.In the exemplary embodiment according to FIG. 25, the electrodes 40, 50 of the first region B 1 (IR sensor 101) also have a specific structure which serves for the heat decoupling between the carrier 2 and the first functional layer 7 a. In other words, the structure of each upper electrode 50 / lower electrode 40 may be different depending on the position thereof on the substrate 2 (first region B 1 and second region B 2, respectively), although both regions B 1 and B 2 have an electrode NTC layer structure.In the IR sensor region (first region B 1), the aim is to achieve a maximum possible temperature difference by the radiated light. Since the sandwich structure (lower electrode 40 - functional layer 7a - upper electrode 50) results in large areas with metal contacts having good thermal conductivity, it is desirable to provide thermal decoupling.The heat conduction between carrier 2 and first functional layer 7 acan be reduced as much as possible by virtue of the upper electrode 50 having a narrow (preferably <5 μm, ideally <1 μm) electrical connection region 105 between a bonding region 104 (i.e. a coupling region between upper electrode 50, 50 a / sensor element 100 and an external application) and the first functional layer 7 a. In other words, in a connection region 105 between the bonding region 104 and a connection region 106 to the first functional layer 7 a, the upper electrode 50 is formed to be long and narrow (width <5 μm, ideally <1 μm). The upper electrode 50 may also be wound in the connection region 105. For example, the upper electrode 50 has a meandering structure in the connection region 105.The upper electrode 50 of the IR sensor 101 is thus designed with different structures and has in particular a plurality of regions:at least one flat region (bonding region 104): large-area, for example square;at least one long and narrow, for example also wound / meandering, region (connecting region 105): small-area, preferably wound;a connection region 106 in which the upper electrode 50 is directly connected to the first functional layer 7 a:The size of the area is between the area of the bonding portion 104 and the connection portion 105, for example, a square shape.The regions 104, 105, 106 of the upper electrode 50 merge directly into one another. The connection region 105 is formed between the bonding region 104 and the connection region 106.Likewise, the lower electrode 40 of the IR sensor 101 / of the first region B 1 can also be designed in a structured manner in order to achieve good heat decoupling. As can be seen from FIG. 25, the lower electrode 40 can also have a long, narrow, for example wound (meandering) region (connecting region 107), which directly adjoins a large-area region of the lower electrode 40. The influence of the carrier 2 on the IR sensor region / first functional layer 7 acan thus be further minimized.FIG. 26 shows a sectional illustration of the sensor element 100 according to a further exemplary embodiment. The sensor element 100 has the above-described structure including the upper electrode 50 and the lower electrode 40 (sandwich structure) in the reference region B 2. An alternative electrode structure is formed in the IR region B 1.In particular, the sensor element 100 has two interdigital electrodes 4 in the first region B 1 (IR sensor 101), as can be seen from FIG. 27. The two interdigital electrodes 4 are formed on the insulating layer 8 of the carrier 2 at a distance from one another and have thin metal films.The interdigital electrodes 4 are formed as interdigital thin-film electrodes. They each have a flat end region 6 and a region with electrode fingers 5. The region with the electrode fingers 5 is formed in each case in a central region of the carrier 2 and in particular of the first region B 1. The planar end region 6 and the region with the electrode fingers 5 merge into one another. The two interdigital electrodes 4 each engage in one another in the region of the electrode fingers 5 in the central region of the carrier 2 and form an interdigital structure there. The IR sensor 101 further comprises two contact elements 10. The interdigital electrodes 4 are contacted via windows 70 in the insulating layer 8 by means of the contact elements 10.As an alternative to the embodiment shown, the IR sensor 101 can also have the stack structure described in connection with FIGS. 1 to 25 comprising the lower electrode 40-first functional layer 7 a-upper electrode 50, and the reference sensor 102 can have the contacting via interdigital electrodes 4 and contact elements 10 according to FIGS. 26, 27 (not explicitly shown).The IR sensor element 100 described in connection with FIGS. 1 to 27 can be used for contactless temperature measurement. The sensor element 100 is used for temperature monitoring and / or temperature control, e.g. in the automobile sector or in so-called smart wearables (electronic objects that can be worn directly on the body, for example fitness trackers, smart glasses, earphones, smart watches, etc.). Since the sensor element 100 has a specific electrical rated resistance and a narrow resistance tolerance, a very precise monitoring and / or regulation of the temperature is made possible.The description of the subject matter provided herein is not limited to the particular specific embodiments. Rather, the features of the individual embodiments can be combined with one another as desired, insofar as technically expedient.List of reference characters100 Sensor element 1 a: upper side of the sensor element 1 b: lower side of the sensor element 2: carrier 4: interdigital electrode 5: electrode finger 6: end region 7 a: first functional layer 7 b: second functional layer 8: insulating layer 10: contact element 11: upper side of the carrier 12: lower side of the carrier 20: cavity 21: absorber layer 22: reflector layer 40: lower electrode 40 a: second contact pad 50: upper electrode 50 a: first contact pad 70: window 80: trimming electrode 90: additional contact pad 101: IR sensor 102: reference sensor 103: combined contact pad 104: bonding region 105: connecting region 106: connection region 107: connecting region S: stacking direction B 1: first region / IR region of the carrier / of the sensor element B 2: second region / reference region of the carrier / of the sensor element T: thickness of the sensor element t: thickness the functional layer o overlap region between the upper electrode and the lower electrode c 1 contact region between the upper electrode and the functional layer / first or upper contact region c 2 contact region between the lower electrode and the functional layer / second or lower contact region F current flow

Claims

Sensor element (100) for contactless measurement of a temperature, comprising - at least one carrier (2) with an upper side (11) and a lower side (12), - at least one first functional layer (7a) for contactless temperature measurement of an object and at least one second functional layer (7b) for contact-type measurement of an ambient temperature, wherein the respective functional layer (7a, 7b) comprises a material with a temperature-dependent electrical resistance and wherein the functional layers (7a, 7b) are arranged on the carrier (2) separately from one another, - at least one upper electrode (50), wherein a first contact region (c1) is formed between the upper electrode (50) and one of the two functional layers (7a, 7b), - at least one lower electrode (40), wherein a second contact region (c2) between the lower electrode (40) and that functional layer (7a, 7 b), which is in contact with the upper electrode (50), wherein the respective functional layer (7 a, 7 b), the at least one upper electrode (50) and the at least one lower electrode (40) are configured and arranged such that a specific electrical resistance of the sensor element (100) is achieved.Sensor element (100) according to Claim 1, further comprising: - at least two interdigital electrodes (4) for electrically contacting that functional layer (7a, 7b) which is free of contact with the upper electrode (50) and the lower electrode (40), - at least two contact elements (10) for electrically contacting the sensor element (100), wherein in each case one contact element (10) is arranged directly on at least one sub-region of one of the interdigital electrodes (4).Sensor element (100) according to Claim 1, having - at least two upper electrodes (50), wherein in each case a first contact region (c1) is formed between one of the upper electrodes (50) and a functional layer (7a, 7b), and - at least two lower electrodes (40), wherein in each case a second contact region (c2) is formed between one of the lower electrodes (40) and a functional layer (7a, 7b), wherein the respective functional layer (7a, 7b) is arranged at least partially between at least one of the at least two lower electrodes (40) and at least one of the at least two upper electrodes (50).Sensor element (100) according to one of the preceding claims, wherein the first functional layer (7a) is formed in a first region (B1) of the carrier (2) and wherein the second functional layer (7b) is formed in a second region (B2) of the carrier (2).Sensor element (100) according to one of the preceding claims, wherein the second functional layer (7b) is formed and arranged for measuring a temperature of the carrier (2).Sensor element (100) according to one of the preceding claims, further comprising an insulating layer (8) on the upper side (11) of the carrier (2) and a cavity (20) in the carrier (2), wherein the cavity (20) is located below the insulating layer (8) and wherein the cavity (20) is formed in a first region (B1) of the sensor element (100) and at least partially below the first functional layer (7a).Sensor element (100) according to one of the preceding claims, wherein a region of the carrier (2) below the second functional layer (7b) is free of a cavity.Sensor element (100) according to one of the preceding claims, further comprising an insulating layer (8), wherein the insulating layer (8) at least partially covers an upper side (1a) of the sensor element (100) and / or at least partially covers an upper side of the respective lower electrode (4) and / or at least partially covers an upper side (11) of the carrier (2).Sensor element (100) according to one of the preceding claims, further comprising at least one absorber layer (21), wherein the absorber layer (21) is formed above the first functional layer (7a) as viewed in a stacking direction (S) of the sensor element (100).The sensor element (100) according to claim 8 and claim 9, wherein the absorber layer (21) is formed on the insulating layer (8).Sensor element (100) according to Claim 9 or 10, wherein the absorber layer (21) is in thermal contact with the first functional layer (7a).Sensor element (100) according to one of Claims 9 to 11, wherein the absorber layer (21) comprises a material which absorbs infrared radiation.Sensor element (100) according to one of the preceding claims, further comprising at least one reflector layer (22), wherein the reflector layer (22) is formed above the second functional layer (7b) as viewed in a stacking direction (S) of the sensor element (100).The sensor element (100) according to claim 13 and claim 8, wherein the reflector layer (22) is formed on the insulating layer (8).Sensor element (100) according to claim 13 or 14, wherein the reflector layer (22) comprises a material which reflects infrared radiation.The sensor element (100) according to any one of claims 13 to 15, wherein one of the upper electrodes (50) functions as a reflector layer (22).Sensor element (100) according to one of Claims 8 to 16, having at least one window (70), wherein the at least one window (70) represents a cutout in the at least one insulating layer (8), wherein the at least one window (70) is designed and arranged to enable an electrical connection between the respective lower electrode (40) and the respective functional layer (7a, 7b) and / or between the respective upper electrode (50) and the respective functional layer (7a, 7b).Sensor element (100) according to one of the preceding claims, wherein the upper electrode (50) functions as a first contact pad (50a) of the sensor element (100) for electrically contacting the sensor element (1) and / or wherein the sensor element (100) has at least one first contact pad (50a) electrically connected to the upper electrode (50).Sensor element (100) according to one of the preceding claims, wherein the lower electrode (40) functions as a second contact pad (40a) of the sensor element (100) and / or wherein the sensor element (100) comprises at least one second contact pad (40a) electrically connected to the lower electrode (40).The sensor element (100) of claim 18, wherein a resistance of the sensor element (100) is determined by an area of the first contact pad (50a).Sensor element (100) according to one of the preceding claims, wherein a resistance of the sensor element (100) is determined by a size of the first contact region (c1) formed between the respective upper electrode (50) and the respective functional layer (7a, 7b).Sensor element (100) according to claim 21, wherein the second contact area (c2) has at least the same size as the first contact area (c1).Sensor element (100) according to claim 21 or 22, wherein a width of the second contact region (c2) is equal to or greater than a width of the first contact region (c1) plus three times a functional layer thickness (t): c2 ≥ c1 + 3t.Sensor element (100) according to one of Claims 21 to 23, wherein the size of the first contact region (c1) is determined by a size of a window (70) arranged in an insulating layer (8) on an upper side (1a) of the sensor element (100).The sensor element (100) according to any one of claims 1 to 19, wherein a resistance of the sensor element (100) is determined by a size of the second contact region (c2), and wherein the second contact region (c2) is smaller than the first contact region (c1).The sensor element (100) according to claim 25, wherein a width of the first contact region (c1) is equal to or greater than a width of the second contact region (c2) plus three times a functional layer thickness (t): c1 ≥ c2 + 3t.Sensor element (100) according to claim 25 or 26, wherein the size of the second contact area (c2) is determined by a manufacturing process of the lower electrode (40) and / or by a size of a window (70) arranged in an insulating layer (8) arranged at least partially on the top side of the lower electrode (40).Sensor element (100) according to one of Claims 1 to 19, wherein a resistance of the sensor element (100) is determined by a size of the first contact region (c1) and by a size of the second contact region (c2) and / or by a position of the first contact region (c1) and the second contact region (c2) with respect to one another.Sensor element (100) according to Claim 28, wherein the resistance of the sensor element (100) is determined by a size of an overlap region (o) between the first contact region (c1) and the second contact region (c2).Sensor element (100) according to one of Claims 1 to 19, having at least two upper electrodes (50), wherein a resistance of the sensor element (100) is controlled by a size of the respective first contact region (c1) and / or by a size of the respective second contact region (c2) and / or by a relative position of respective first contact region (c1) and respective second contact region (c2) and / or by a size of overlap regions (o) between respective first contact region (c1) and respective second contact region (c2).Sensor element (100) according to one of claims 1 to 19, comprising a plurality of upper electrodes (50) and a plurality of lower electrodes (40) connected in series, wherein a resistance is determined - by a size of the respective first contact area (c1) and / or - by a size of the respective second contact area (c2) and / or - by a relative position of first contact areas (c1) and second contact areas (c2) and / or - by a size of overlap areas (o) between first contact areas (c1) and second contact areas (c2) and / or - by a number of resistors connected in series.The sensor element (100) according to claim 31, having a close resistance tolerance, wherein the sensor element (100) further comprises at least one additional contact pad (90) connected to at least one of the upper electrodes (50) for fine tuning the resistance of the sensor element (100), wherein the additional contact pad (90) extends beyond a surface of the respective functional layer (7a, 7b).The sensor element (100) of claim 31 having a close resistance tolerance, the sensor element (100) further comprising trimming electrodes (80) connected to particular top electrodes (50), wherein at least one of the trimming electrodes (80) is cut with a laser to fine tune the resistance of the final sensor element (100).Sensor element (100) according to any of claims 1 to 19, comprising a plurality of parallel-connected upper electrodes (50) and at least two lower electrodes (40), or comprising at least two upper electrodes (50) and a plurality of parallel-connected lower electrodes (40), or comprising a plurality of parallel-connected upper electrodes (50) and a plurality of parallel-connected lower electrodes (40), wherein a resistance of the sensor element (100) is determined - by a size of the first contact regions (c1) and / or - by a size of the second contact regions (c2) and / or - by a number of parallel-connected upper electrodes (50) and lower electrodes (40).The sensor element (100) of claim 34, having a close resistance tolerance, wherein the sensor element (100) further comprises trimming electrodes (80) connected to the top electrodes (50) in a row, and wherein at least one of the trimming electrodes (80) is cut by a laser to fine tune the resistance of the final sensor element (100).Sensor element (100) according to one of Claims 4 to 35, wherein the first region (B1) represents an IR sensor (101) and the second region (B2) represents a reference sensor (102), and wherein the second region (B2) surrounds the first region (B1).Sensor element (100) according to one of claims 4 to 36, wherein the first region (B1) has an electrode-NTC electrode stack structure and / or wherein the second region (B2) has an electrode-NTC electrode stack structure.Sensor element (100) according to one of claims 4 to 37, wherein the at least one lower electrode (40) and / or at least one upper electrode (50) formed in the first region (B1) has a specific structure for heat decoupling.Sensor element (100) according to one of Claims 4 to 38, wherein the at least one upper electrode (50) formed in the first region (B1) is transparent.

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