Magnetoresistiver Sensor

Abstract

Magnetoresistive sensor (200; 500; 600), comprising: comprising at least one xMR sensor element (100) formed from a layer stack a magnetically free layer (116) with a magnetically free vortex magnetization, and at least one reference layer (110) with a reference magnetization in a predetermined direction; and magnetically free layers (216A, 216B) with a magnetically free vortex magnetization arranged along the predetermined direction on opposite sides of the xMR sensor element (100) and laterally adjacent to the xMR sensor element (100), wherein the magnetoresistive sensor (500; 600) comprises a 2-dimensional matrix arrangement (500; 600) of a plurality of xMR sensor elements (100) and laterally adjacent magnetically free layers (216A, 216B), wherein a lateral distance between an xMR sensor element (100) and laterally adjacent magnetically free layers (216A, 216B) is less in the predetermined direction than in a direction perpendicular to the predetermined direction.

Description

Technical field

[0001] The present disclosure relates in general to magnetoresistive sensors and in particular to magnetoresistive sensors with a magnetically free vortex magnetization of the magnetically free layer. background

[0002] Magnetoresistive effects encompass a number of different physical phenomena, all of which share the common feature that the electrical resistance of a magnetoresistive element can be changed by the behavior of an external magnetic field acting upon it. Techniques that utilize magnetoresistive effects are sometimes referred to as "xMR techniques," where the "x" indicates that multiple effects can be addressed, such as the GMR effect (Giant Magnetoresistive effect), the TMR effect (Tunnel Magnetoresistive effect), or the AMR effect (Anisotropic Magnetoresistive effect), to name just a few. xMR effects can be applied to a wide variety of field-based sensors, for example, to measure rotation, angle, etc.In some applications, especially safety-relevant applications, it is necessary for these sensors to operate reliably and at a high level of accuracy.

[0003] The orientation of a magnetic reference layer or reference system in magnetoresistive sensors defines a sensitive axis for detecting external magnetic fields. For some applications, it is crucial that the magnetoresistive sensor responds only to external magnetic fields along this axis. A problem arises with vortex-based magnetoresistive sensors, i.e., sensors with a magnetically free layer with vortex magnetization and a misaligned reference system. An x-sensor (reference layer with reference magnetization in the x-direction) will then also respond to y-fields, for example, because the vortex magnetization of the magnetically free layer is affected by x- and y-fields equally. Further stabilizing the orientation of the reference layer or reference system is not trivial, as the magnetization is also influenced by mechanical stresses (inverse magnetostrictive effect).

[0004] Therefore, there is a need for magnetoresistive vortex- or vortex-based magnetoresistive sensors with improved sensitivity in a predetermined direction. Summary

[0005] According to a first aspect, a magnetoresistive sensor is proposed. The proposed magnetoresistive sensor comprises at least one magnetoresistive sensor element formed from a stack of layers. The magnetoresistive sensor element has a magnetically free layer with magnetically free vortex magnetization and at least one reference layer with a reference magnetization in a predetermined direction. The predetermined direction corresponds to a sensitive axis of the magnetoresistive sensor element (e.g., the x- or y-axis). The magnetoresistive sensor further comprises magnetically free layers with magnetically free vortex magnetization arranged along the predetermined direction on opposite sides of the magnetoresistive sensor element and laterally adjacent to the magnetoresistive sensor element.

[0006] The use of adjacent magnetically free layers with magnetically free vortex magnetization next to the magnetoresistive sensor element can increase its sensitivity in the predetermined direction (e.g., x-direction) and decrease its sensitivity in perpendicular directions (e.g., y-direction). Additionally, the reference layer or reference system of the magnetoresistive sensor element can be stabilized by a stray field generated by the adjacent magnetically free layers.

[0007] According to some embodiments, the adjacent magnetically free layers have a larger (aspect) ratio of thickness to diameter than the magnetically free layer of the magnetoresistive sensor element.

[0008] According to some embodiments, the magnetically free layer of the magnetoresistive sensor element and the adjacent magnetically free layers have identical thickness-to-diameter ratios. Thus, the thickness and diameter of the magnetically free layer of the magnetoresistive sensor element and the adjacent magnetically free layers can differ, but each has the same ratio to the other.

[0009] According to some embodiments, the magnetically free layer of the magnetoresistive sensor element and the adjacent magnetically free layers have identical geometric dimensions. The thickness and diameter of the magnetically free layer of the magnetoresistive sensor element and the adjacent magnetically free layers can therefore also be identical. This simplifies the manufacturing of the magnetoresistive sensor.

[0010] According to some embodiments, the lateral distance between the magnetoresistive sensor element and an adjacent magnetically free layer is less than twice the diameter of the magnetoresistive sensor element and / or the adjacent magnetically free layer. The distance between the magnetoresistive sensor element and an adjacent magnetically free layer should be small enough that the magnetoresistive sensor element can still "see" the stray field of the adjacent magnetically free layers. This allows the adjacent magnetically free layers to act as magnetic flux concentrators along the predetermined direction.

[0011] In some embodiments, the magnetoresistive sensor element is electrically connected, while the adjacent magnetically free layers are electrically unconnected (not connected), i.e., without current. The layer stack can therefore additionally include electrodes that supply the magnetoresistive sensor element with an electrical signal. The adjacent magnetically free layers, however, do not need to be electrically connected to act as magnetic flux concentrators for the magnetoresistive sensor element located between them.

[0012] According to some embodiments, the adjacent magnetically free layers are formed in the same layer of the layer stack as the magnetically free layer of the magnetoresistive sensor element. For example, the adjacent magnetically free layers can be part of adjacent (but unenergized) magnetoresistive sensor elements formed in the same layer stack as the intervening magnetoresistive sensor element. This simplifies the fabrication of the magnetoresistive sensor. The adjacent magnetoresistive sensor elements are preferably electrically unpowered (not connected), i.e., without current.

[0013] In some embodiments, the adjacent magnetically free layers are formed in different layers than the magnetically free layer of the magnetoresistive sensor element. For example, starting from a common substrate, the adjacent magnetically free layers can be located higher or lower in the vertical direction (z-direction) than the magnetically free layer of the magnetoresistive sensor element. Therefore, the adjacent magnetically free layers do not require a complete xMR layer stack like the interposed magnetoresistive or xMR sensor element.

[0014] In some embodiments, the magnetically free layer of the magnetoresistive sensor element and the adjacent magnetically free layers are each designed in a circular disk shape. Providing magnetically free layers with a circular disk structure can lead to the spontaneous formation of a closed-flux magnetization pattern (vortex magnetization) in the respective magnetically free layers.

[0015] According to some embodiments, the magnetoresistive sensor comprises a two-dimensional (2D) matrix arrangement of a plurality of (electrically connected) magnetoresistive sensor elements. Each magnetoresistive sensor element has laterally adjacent magnetically free layers (not electrically connected). The magnetoresistive sensor elements and the laterally adjacent magnetically free layers of the matrix arrangement span, for example, an xy-plane. The lateral distance between a magnetoresistive sensor element and its laterally adjacent magnetically free layers is smaller in the predetermined direction (e.g., x-direction) than in a direction perpendicular to the predetermined direction (e.g., y-direction).

[0016] According to some embodiments, the at least one magnetoresistive sensor element is designed as a TMR sensor element, with a tunnel barrier layer between the magnetically free layer and the reference system.

[0017] According to another aspect, a magnetoresistive sensor is proposed, comprising a two-dimensional matrix arrangement of a plurality of (electrically connected) magnetoresistive sensor elements and laterally adjacent magnetically free layers (electrically unconnected). Each magnetoresistive sensor element has a magnetically free layer with a magnetically free vortex magnetization and a reference layer with a reference magnetization in a predetermined direction. The matrix arrangement includes magnetically free layers with a magnetically free vortex magnetization arranged along the predetermined direction on opposite sides of each magnetoresistive sensor element and laterally adjacent to the magnetoresistive sensor element. These layers can act as magnetic flux concentrators along the predetermined direction.The lateral distance between a magnetoresistive sensor element and laterally adjacent magnetically free layers is smaller in the predetermined direction than in a direction perpendicular to that predetermined direction. Therefore, the distance between rows of the two-dimensional matrix arrangement differs from the distance between columns of the two-dimensional matrix arrangement.

[0018] A magnetically free vortex magnetization responds linearly to any external magnetic field in the plane. The linear range and sensitivity can be defined by the aspect ratio (thickness / diameter) of the vortex-magnetized free layer. Therefore, an adjacent vortex-magnetized free layer can be used for linear B-field shielding or B-field concentration. To reduce the influence of y-fields on an x-sensor, adjacent vortex-magnetized free layers can be placed along the x-axis next to the magnetoresistive sensor element. This concentrates the x-component of the external B-field onto the magnetoresistive sensor while simultaneously shielding the y-component of the external B-field. Character description

[0019] Some examples of devices and / or methods are explained in more detail below with reference to the accompanying figures. These show: Fig. 1A a schematic representation of a layer stack of a magnetoresistive sensor element; Fig. 1B a schematic representation of a magnetoresistive sensor element with a magnetically free layer with vortex magnetization; Fig. 1C an opposing inclination of the reference system of a left and right sensor element in one package; Fig. 2A a schematic top view of a magnetoresistive sensor according to the present disclosure and external magnetic field in x-direction; Fig. 2B a schematic top view of a magnetoresistive sensor according to the present disclosure and external magnetic field in the y-direction; Fig. 3A a drop in stray field strength in the x-direction; Fig. 3B a decrease in stray field strength in the y-direction; Fig. 4 an increase in the sensitivity of a magnetoresistive sensor in the x-direction and a decrease in the sensitivity of the magnetoresistive sensor in the y-direction; Fig. 5A a schematic representation of a magnetoresistive sensor with two magnetoresistive sensor elements according to an embodiment of the present disclosure; Fig. 5B a schematic representation of a magnetoresistive sensor with two magnetoresistive sensor elements according to a further embodiment of the present disclosure; Fig. 6A a schematic representation of a magnetoresistive sensor with a plurality of magnetoresistive sensor elements in a matrix arrangement according to an embodiment of the present disclosure; and Fig. 6B a schematic representation of a magnetoresistive sensor with a plurality of magnetoresistive sensor elements in a matrix arrangement according to a further embodiment of the present disclosure. Description

[0020] Some examples are now described in more detail with reference to the accompanying figures. However, other possible examples are not limited to the features of these detailed embodiments. These may include modifications of the features, as well as equivalents and alternatives to the features. Furthermore, the terminology used herein to describe certain examples should not be considered restrictive for other possible examples.

[0021] Identical or similar reference symbols throughout the description of the figures refer to identical or similar elements or features, which may be implemented in an identical or modified form, while providing the same or a similar function. Furthermore, the thickness of lines, layers, and / or areas in the figures may be exaggerated for clarity.

[0022] When two elements A and B are combined using "or," this is to be understood as revealing all possible combinations, i.e., only A, only B, and A and B, unless explicitly defined otherwise in a specific case. As an alternative formulation for the same combinations, "at least one of A and B" or "A and / or B" can be used. This applies equivalently to combinations of more than two elements.

[0023] When a singular form, e.g., "ein, eine" and "der, die, das," is used, and the use of only a single element is neither explicitly nor implicitly defined as mandatory, further examples may also use multiple elements to implement the same function. If a function is subsequently described as being implemented using multiple elements, further examples may implement the same function using a single element or a single processing entity.It is further understood that the terms "include", "comprehensive", "exhibit" and / or "exhibit" when used describe the presence of the specified features, integers, steps, operations, processes, elements, components and / or a group thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, processes, elements, components and / or a group thereof.

[0024] Fig. Figure 1A shows an example of a layer stack of a magnetoresistive sensor element 100 according to one or more embodiments.

[0025] The magnetoresistive sensor element 100 can, for example, be a TMR sensor element with a bottom-pinned spin valve (BSV) configuration. GMR sensor elements are also possible. Furthermore, the magnetoresistive sensor element 100 can be arranged on a semiconductor substrate (not shown) of a magnetoresistive sensor. When described in a Cartesian coordinate system with pairwise perpendicular coordinate axes x, y, and z, the layers of the layer stack extend laterally in an xy-plane spanned by the x- and y-axes. Thus, lateral dimensions (e.g., lateral distances, lateral cross-sectional areas, lateral surfaces, lateral extents, lateral displacements, etc.) can refer to dimensions in the xy-plane, and vertical dimensions to dimensions in the z-direction, perpendicular to the xy-plane. For example, the vertical extent of a layer in the z-direction can be referred to as the layer thickness.

[0026] The layer stack of the magnetoresistive sensor element 100 comprises at least one reference layer with a reference magnetization (e.g., a reference direction in the case of GMR or TMR technology). The reference magnetization is a magnetization direction that provides a sensor direction corresponding to a sensor axis of the magnetoresistive sensor element 100. The reference layer, and consequently the reference magnetization, defines a sensor plane. The sensor plane can be defined, for example, by the xy-plane. Thus, the x-direction and the y-direction can be described as "in-plane" with respect to the sensor plane, and the z-direction can be described as "out-of-plane" with respect to the sensor plane.

[0027] Accordingly, in the case of a GMR or TMR sensor element, the resistance of the magnetoresistive sensor element 100 is minimal when the magnetically free magnetization of a magnetically free layer points in exactly the same direction as the reference magnetization (e.g., the reference direction), and the resistance of the magnetoresistive sensor element 100 is maximal when the magnetically free magnetization of the magnetically free layer points in exactly the opposite direction to the reference magnetization. The orientation of the magnetically free magnetization of the magnetically free layer is variable in the presence of an external magnetic field. Thus, the resistance of the magnetoresistive sensor element 100 can vary based on the influence of the external magnetic field on the magnetically free magnetization of the magnetically free layer.

[0028] From bottom to top, the magnetoresistive sensor element 100 can include an optional seed layer 102, which can be used to influence and / or optimize stack growth. In some embodiments, the seed layer 102 can be made of copper, tantalum, ruthenium, or a combination thereof. In the example shown, a natural antiferromagnetic (NAF) layer 104 is formed or otherwise arranged on the seed layer 102. The NAF layer 104 can be made of platinum-manganese (PtMn), iridium-manganese (IrMn), nickel-manganese (NiMn), or the like. The thickness of the NAF layer can, for example, be in the range of 5 nm to 50 nm.

[0029] Furthermore, a pinned layer (PL) 106 can be formed or otherwise arranged on the NAF layer 104. The pinned layer 106 can be made of a ferromagnetic material, such as cobalt-iron (CoFe) or cobalt-iron-boron (CoFeB). The contact between the NAF layer 104 and the pinned layer 106 can produce an effect known as the exchange bias effect, which causes the magnetization of the pinned layer 106 to align in a preferred direction (e.g., in the x-direction, as shown). The magnetization of the pinned layer 106 can be referred to as pinned magnetization. The pinned layer 106 can exhibit a linear magnetization pattern in the xy-plane (e.g., a homogeneous alignment in one direction) that is permanently fixed.

[0030] The magnetoresistive sensor element 100 also comprises a non-magnetic layer (NML) referred to as the coupling layer 108. In one possible embodiment, the coupling layer 108 can, for example, comprise ruthenium, iridium, copper, copper alloys, or similar materials. Other materials (e.g., paramagnets) are also possible. A magnetic (e.g., ferromagnetic) reference layer (RL) 110 can be formed on the coupling layer 108 or arranged otherwise. The thickness of the pinned layer 106 and the magnetic reference layer 110 can be in the range of 1 nm to 10 nm.

[0031] Accordingly, the coupling intermediate layer 108 can be arranged between the pinned layer 106 and the magnetic reference layer 110 to spatially separate the pinned layer 106 and the magnetic reference layer 110 in the vertical direction. Furthermore, the coupling intermediate layer 108 can provide an interlayer exchange coupling (e.g., an antiferromagnetic Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling) between the pinned layer 106 and the magnetic reference layer 110 to form an artificial antiferromagnet. As a result, the magnetization of the magnetic reference layer 110 can align and be held in a direction that is antiparallel or opposite to the magnetization of the pinned layer 106 (e.g., in the x-direction, as shown). The magnetization of the magnetic reference layer 110 can be referred to as the reference magnetization.

[0032] Since the NAF layer 104 is configured to align and fix the magnetization of the pinned layer 106 in a specific direction, and the coupling intermediate layer 108 is configured to align and fix the magnetization of the magnetic reference layer 110 in an opposite direction, the NAF layer 104 can be said to maintain the magnetization of the pinned layer 106 (e.g., a fixed magnetization) in a first magnetic orientation and the magnetization of the magnetic reference layer 110 (e.g., a fixed reference magnetization) in a second magnetic orientation. The magnetic reference layer 110 can have a linear magnetization pattern in a specific direction in the xy-plane if the pinned layer 106 has a linear magnetization pattern in an antiparallel direction.Thus, the NAF layer 104, the pinned layer 106, the coupling intermediate layer 108 and the magnetic reference layer 110 form a magnetic reference layer system 112 of the magnetoresistive sensor element 100.

[0033] The magnetoresistive sensor element 100 additionally comprises a barrier layer 114 (e.g., a tunnel barrier) arranged vertically between the reference layer system 112 and a magnet-free layer 116. The barrier layer 114 can, for example, be formed on the magnetic reference layer 110 of the reference layer system 112 or arranged otherwise, and the magnet-free layer 116 can be formed on the barrier layer 114 or arranged otherwise.

[0034] The barrier layer 114 can be made of a non-magnetic material. In some embodiments, the barrier layer 114 can be an electrically insulating tunnel barrier layer. For example, the barrier layer 114 can be a tunnel barrier layer used to generate a TMR effect. The barrier layer 114 can be made of magnesium oxide (MgO) or another material with similar properties.

[0035] The material of the magnetically free layer 116 can be an alloy of a ferromagnetic material, such as CoFe, CoFeB, or NiFe. The magnetically free layer 116 has a magnetically free magnetization that is variable in the presence of an external magnetic field. Therefore, the magnetically free layer 116 can be referred to as a sensor layer, since changes in the magnetically free magnetization are used to determine a measured quantity. Furthermore, in a ground state, the magnetically free magnetization has a standard magnetic orientation (such as a vortex magnetization). The ground state is a state in which the influence of the external magnetic field on the magnetically free layer 116 is either non-existent or negligibly small. In some embodiments, the magnetoresistive sensor element 100 can comprise a magnetically free system that includes a plurality of layers (e.g.,The magnetically free system contains two or more magnetically free layers that, in combination, act as a magnetically free layer. In this case, the magnetically free layers of the magnetically free system are magnetically coupled to each other. The magnetically free system can therefore function as a single magnetically free layer, but it can also consist of multiple layers. The magnetically free system has a magnetically free magnetization, which is variable in the presence of an external magnetic field.

[0036] A cover layer 118, e.g. made of tantalum (Ta), tantalum nitride (TaN), ruthenium (Ru), titanium (Ti), titanium nitride (TiN), platinum (Pt) or similar, can be formed on the magnetically free layer 116 or otherwise arranged to form an upper layer of the magnetoresistive sensor element 100.

[0037] The nucleation layer 102 can serve as a lower electrode or establish electrical contact with a lower electrode (not shown) of the magnetoresistive sensor element 100. The top layer 118 can establish electrical contact with an upper electrode (not shown) of the magnetoresistive sensor element 100. The barrier layer 114 can be configured to allow electrons to tunnel between the reference layer system 112 and the magnetically free layer 116 when a bias voltage is applied to the electrodes of the magnetoresistive sensor element 100 (not shown) to generate a magnetoresistive effect (e.g., a TMR effect).

[0038] As mentioned above, it serves Fig. 1A is merely an example of a magnetoresistive sensor element. Other examples can be found in the description in Fig. 1 differ. The number and arrangement of the in Fig. The components shown in Figure 1A are an example. In practice, the magnetoresistive sensor element can have 100 additional elements or layers, fewer elements, different elements, or elements arranged differently than those shown. Fig. Included in 1A as shown.

[0039] Fig. Figure 1B shows a simplified perspective view of the magnetoresistive sensor element 100, in which the magnetically free layer 116 is disk-shaped to spontaneously (i.e., automatically) develop a vortex magnetization in the ground state. The disk-shaped magnetically free layer 116 has a diameter D, which can range, for example, from several hundred nm to 10 µm. The magnetically free layer 116 also has a thickness T in the range of, for example, 1 nm to 100 or 200 nm. Providing a layer with this structure can lead to the spontaneous formation of a closed-flux magnetization pattern in the magnetically free layer 116. The occurrence of such a field can also be called a vortex state or a vortex configuration.In other words, the vortex state can be achieved by selecting a disk thickness T in the range of, for example, 10 nm to 200 nm and a disk diameter D between 100 nm and 3 µm. The vortex spin valve structure is not limited to the TMR effect; it can also be realized, for example, via a GMR structure.

[0040] In a differential magnetoresistive magnetic field sensor for measuring differential external magnetic fields in the x-direction, for example, two magnetoresistive sensor elements 100 adjacent in the x-direction can be provided, ideally each having a reference layer 110 magnetized in the positive or negative x-direction. The orientation of the magnetic reference layer 110 or the reference system 112 of magnetoresistive sensors determines the sensitive axis for detecting external magnetic fields. For some applications, it is crucial that the magnetoresistive sensor responds only to external magnetic fields along this axis. For example, a differential magnetic field sensor for measuring differential external magnetic fields in the x-direction should only respond to external magnetic fields along the x-axis. A problem arises for vortex or...vortex-based magnetoresistive sensors with a non-ideally aligned reference layer 110 or a non-ideally aligned reference system 112.

[0041] Fig. Figure 1C schematically shows a differential magnetoresistive magnetic field sensor 150 for measuring differential external magnetic fields in the x-direction. Both magnetoresistive sensor elements 100A and 100B of the differential magnetic field sensor 150 each have a non-ideally aligned reference system. While the reference magnetization of the left magnetoresistive sensor element 100A has a desired component in the positive x-direction and an undesired component in the positive y-direction, the reference magnetization of the right magnetoresistive sensor element 100B has a desired component in the positive x-direction and an undesired component in the negative y-direction. Thus, the vortex-based magnetic field sensor 150 also reacts to y-fields, for example, because the vortex magnetization of the respective magnetically free layer 116 of the sensor elements 100A and 100B is influenced by x- and y-fields in the same way.Stabilizing the orientation of the reference system 112 is not trivial, since the magnetization is also influenced by mechanical stresses (inverse magnetostrictive effect).

[0042] The Fig. Figure 2A shows a schematic top view of a magnetoresistive sensor 200 according to an exemplary embodiment.

[0043] The magnetoresistive sensor 200 comprises at least one layer stack (see Fig. 1A, Fig. 1B) formed magnetoresistive sensor element 100. The magnetoresistive sensor element 100 has a magnetically free layer 116 with a magnetically free vortex magnetization and at least one reference layer 110 with a linear reference magnetization (mainly) in a predetermined direction (here: x-direction). As mentioned above, the actual direction of the reference magnetization may deviate from the ideal direction (here: x-direction) (for example, due to mechanical stresses). To control the orientation of the reference layer 110, orTo stabilize the reference system 112 of the magnetoresistive sensor element 100, the magnetoresistive sensor 200 has magnetically free layers 216A, 216B arranged along the predetermined direction (desired sensitivity direction) on opposite sides of the magnetoresistive sensor element 100 and laterally adjacent to the magnetoresistive sensor element 100, each with a magnetically free vortex magnetization.

[0044] The magnetically free layers 216A and 216B, located to the left and right of the magnetoresistive sensor element 100, increase its measurement sensitivity in the x-direction and decrease it in the y-direction. Additionally, the reference layer 110, or the reference system 112 of the magnetoresistive sensor element 100, is stabilized by the stray field 210 generated by the magnetically free layers 216A and 216B. The orientation of the magnetically free magnetization of the respective magnetically free layers 216A (left), 116 (center), and 216B (right) follows the external magnetic field B. ext . Thus, a linear stray field 210 is formed in the x-direction between the adjacent magnetically free layers 216A (left) and 216B (right), which increases the sensitivity of the magnetoresistive sensor element 100 in the x-direction.

[0045] The stray field 210 generated by the adjacent magnetically free layers 216A, 216B in the presence of an external magnetic field in the y-direction is in Fig. Figure 2B shows that in the region of the magnetoresistive sensor element 100 between the adjacent magnetically free layers 216A, 216B, the stray field 210 runs in the opposite direction to the external magnetic field B. ext , so that the sensitivity of the magnetoresistive sensor element 100 is reduced in the y-direction.

[0046] According to exemplary embodiments of the present disclosure, both the magnetically free layer 116 of the magnetoresistive sensor element 100 and the adjacent magnetically free layers 216A, 216B (within the limits of manufacturing tolerances) have identical thickness (T) to diameter (D) ratios. This allows the magnetically free layer 116 of the magnetoresistive sensor element 100 and the adjacent magnetically free layers 216A, 216B to respond to an external magnetic field B. ext behave almost identically and their respective magnetically free magnetization is equally affected by the external magnetic field Bext is influenced. The magnetically free layer 116 of the magnetoresistive sensor element 100 and the adjacent magnetically free layers 216A, 216B can have identical geometric dimensions in the x, y, and z directions (within the limits of manufacturing tolerances).

[0047] According to embodiments of the present disclosure, the magnetically free layers 216A, 216B are each equidistant from a geometric center of the magnetically free layer 116 of the magnetoresistive sensor element 100. That is, the magnetically free layers 216A, 216B are arranged symmetrically along the x-axis (or y-axis) with respect to the magnetoresistive sensor element 100, through which an axis of symmetry 220 runs in the y-direction (or x-direction). The lateral distance (e.g., in the x-direction) between the magnetoresistive sensor element 100 and an adjacent magnetically free layer 216A, 216B is less than twice the diameter (2*D) of the magnetoresistive sensor element 100 or the adjacent magnetically free layer 216A, 216B.The lateral distance can be measured in the predetermined direction, for example, from the center of the magnetically free layer 116 of the magnetoresistive sensor element 100 to the center of the respective adjacent magnetically free layer 216A, 216B, so that the lateral distance between the magnetoresistive sensor element 100 and an adjacent magnetically free layer 216A, 216B can lie between D and 2D. A distance of D would mean that the magnetoresistive sensor element 100 and the adjacent magnetically free layer 216A, 216B are directly adjacent (without a gap). A distance of 2D would mean a gap of D between the magnetoresistive sensor element 100 and the adjacent magnetically free layer 216A, 216B.

[0048] A decay of the stray field 210 in the x-direction for an adjacent magnetically free layer 216A, 216B with a diameter D = 1 µm and a thickness T = 80 nm, which is x-magnetized by an external magnetic field, is observed in Fig. Figure 3A shows a decay of the stray field 210 in the x-direction for an adjacent magnetically free layer 216A, 216B with a diameter D = 1 µm and a thickness T = 80 nm, magnetized by an external magnetic field y-magnetized. Fig. 3B shown. If the influence of the stray field 210 on the magnetoresistive sensor element 100 is to be as large as possible, a small lateral distance between the magnetoresistive sensor element 100 and an adjacent magnetically free layer 216A, 216B is advantageous.

[0049] The Fig. Figure 4 shows the influence of the proposed concept with the adjacent magnetically free layers 216A, 216B (as magnetic flux concentrators) on the sensitivity of a vortex-magnetized magnetoresistive sensor element 100. By arranging the adjacent magnetically free layers 216A, 216B to the left and right of the magnetoresistive sensor element 100, its sensitivity in the x-direction can be increased from 0.9% / mT to 1.10% / mT (curve 410) and in the y-direction decreased from 0.9% / mT to 0.85% / mT (curve 420). The Fig. The simulation shown in 4 is based on identically dimensioned magnetically free layers 116, 216A, 216B with a respective diameter D = 750 nm, a thickness T = 80 nm and a spacing of 250 nm.

[0050] Fig. Figure 5A schematically shows a sensor arrangement 500 in which two magnetoresistive sensors 200A and 200B are arranged laterally adjacent in the x-direction on a common substrate. The two magnetoresistive sensors 200A and 200B can, for example, form a differential magnetic field sensor 500.

[0051] A left magnetoresistive sensor 200A of the sensor arrangement 500 comprises at least one consisting of a layer stack (see Fig. 1A, Fig. 1B) formed xMR sensor element 100A. The xMR sensor element 100A has a magnetically free layer 116 (not shown) with a magnetically free vortex magnetization and at least one reference layer 110 (not shown) with a linear reference magnetization in a predetermined sensitivity direction (e.g., x-direction). To stabilize the orientation of the reference layer 110 of the xMR sensor element 100A, the magnetoresistive sensor 200A has magnetically free layers 216A, 216B, each with a magnetically free vortex magnetization, arranged along the predetermined sensitivity direction on opposite sides of the xMR sensor element 100A and laterally adjacent to the xMR sensor element 100A. The xMR sensor element 100A is thus embedded between the adjacent magnetically free layers 216A, 216B along the predetermined sensitivity direction.

[0052] A right magnetoresistive sensor 200B of the sensor arrangement 500 comprises at least one consisting of a layer stack (see Fig. 1A, Fig. 1B) formed xMR sensor element 100B. The xMR sensor element 100B has a magnetically free layer 116 (not shown) with a magnetically free vortex magnetization and at least one reference layer 110 (not shown) with a linear reference magnetization in the predetermined sensitivity direction (e.g., x-direction). To stabilize the orientation of the reference layer 110 of the xMR sensor element 100B, the magnetoresistive sensor 200B has magnetically free layers 216A, 216B, each with a magnetically free vortex magnetization, arranged along the predetermined sensitivity direction on opposite sides of the xMR sensor element 100B and laterally adjacent to the xMR sensor element 100B. The xMR sensor element 100B is thus also embedded between adjacent magnetically free layers 216A, 216B along the predetermined sensitivity direction.

[0053] In the sensor arrangement 500 of the Fig. 5A The adjacent magnetically free layers 216A, 216B can be formed in the same layer of the layer stack as the magnetically free layer 116 of the respective xMR sensor element 100A, 110B. For example, the adjacent magnetically free layers 216A, 216B can be part of adjacent and electrically disconnected (i.e., unpowered) xMR sensor elements. At a minimum, the adjacent magnetically free layers 216A, 216B can be formed in layers on the same side (e.g., above) of electrode 520 as the magnetically free layer 116 of the respective xMR sensor element 100A, 110B.

[0054] The distance between the right magnetically free layer 216B of the left sensor 200A and the left magnetically free layer 216A of the right sensor 200B is greater than the distance between the xMR sensor element 100A and its left and right adjacent magnetically free layers 216A, 216B, or than the distance between the xMR sensor element 100B and its left and right adjacent magnetically free layers 216A, 216B.

[0055] A lower electrode 520 forms a substrate for the xMR sensor elements 100A, 100B and the respective adjacent magnetically free layers 216A, 216B. While the xMR sensor elements 100A, 100B are additionally connected to a respective upper electrode layer 510 and thus electrically connected via the upper and lower electrodes 510, 520 in a CPP configuration (CPP: Current Perpendicular to Plane), the respective adjacent magnetically free layers 216A, 216B are not connected to the respective upper electrode 510. The magnetically free layers 216A, 216B are therefore not electrically connected and thus carry no current. Instead, they serve as magnetic flux concentrators along the predetermined sensitivity direction.

[0056] Fig. Figure 5B shows an alternative embodiment of the sensor arrangement 500, in which the adjacent magnetically free layers 216A, 216B are formed in different layers than the magnetically free layer 116 of the respective xMR sensor element 100A, 110B. Fig. The adjacent magnetically free layers 216A and 216B are formed in layers on the opposite side (e.g., below) of electrode 520, similar to the magnetically free layer 116 of the respective xMR sensor element 100A or 110B. Here too, the adjacent magnetically free layers 216A and 216B are not (electrically) connected. They serve as magnetic flux concentrators along the predetermined sensitivity direction.

[0057] Fig. Figure 6A schematically shows a sensor arrangement 600A according to a further embodiment.

[0058] The sensor arrangement 600A comprises a 2-dimensional matrix arrangement of a plurality of xMR sensor elements 100A, 100B, 100C arranged in the y-direction. Magnetically free layers 216A, 216B are arranged adjacent to each of the xMR sensor elements 100A, 100B, 100C to the left and right in the x-direction. Fig. Figure 6A shows an example matrix with three rows and three columns. Each row forms a magnetoresistive (partial) sensor 200 with an xMR sensor element 100 embedded in the x-direction between adjacent magnetically free layers 216A, 216B. A first row of the matrix arrangement forms a first (partial) sensor 200A with a first xMR sensor element 100A embedded in the x-direction between adjacent magnetically free layers 216A, 216B. A second row forms a second (partial) sensor 200B with a second xMR sensor element 100B embedded in the x-direction between adjacent magnetically free layers 216A, 216B. A third row forms a third (partial) sensor 200C with a third xMR sensor element 100C embedded in the x-direction between adjacent magnetically free layers 216A, 216B.A first column of the matrix arrangement is formed by the three magnetically free layers 216A of the (sub-)sensors 200A, 200B, and 200C, arranged vertically in the y-direction. A second column is formed by the three xMR sensor elements 100A, 100B, and 100C of the (sub-)sensors 200A, 200B, and 200C, arranged vertically in the y-direction. A third column is formed by the three magnetically free layers 216B of the (sub-)sensors 200A, 200B, and 200C, arranged vertically in the y-direction. The distance dx between columns of the matrix arrangement adjacent in the x-direction is less than the distance dy between rows adjacent in the y-direction. In other words, the lateral distance between an xMR sensor element 100 and laterally adjacent magnetically free layers 216A, 216B in the x-direction is smaller than in the y-direction.

[0059] Fig. Figure 6B schematically shows a sensor arrangement 600B according to a further embodiment.

[0060] The sensor arrangement 600B comprises a two-dimensional matrix arrangement of a plurality of xMR sensor elements 100A, 100B and magnetically free layers 216A, 216B adjacent to each of these laterally in the x-direction. Here, each xMR sensor element 100A, 100B is formed from two xMR sensor elements that are immediately adjacent in the x-direction. Magnetically free layers 216A, 216B are arranged adjacent to each of the xMR sensor elements 100A, 100B, 100C to the left and right in the x-direction. Fig.Figure 6B shows an example matrix with two rows and four columns. Each row forms a magnetoresistive sensor 200 with an xMR sensor element 100 embedded in the x-direction between adjacent magnetically free layers 216A, 216B. In contrast to the previous embodiments, here an xMR sensor element 100 is formed by two xMR sensor elements arranged adjacent in the x-direction. That is, here two xMR sensor elements arranged adjacent in the x-direction are embedded in the x-direction between adjacent magnetically free layers 216A, 216B. A first row forms a first (partial) sensor 200A with a first xMR sensor element 100A (formed by two xMR sensor elements arranged adjacent in the x-direction) that is embedded in the x-direction between adjacent magnetically free layers 216A, 216B.A second row forms a second (partial) sensor 200B with a second xMR sensor element 100B (formed by two xMR sensor elements arranged adjacent in the x-direction), which is embedded in the x-direction between adjacent magnetically free layers 216A, 216B. A first column is formed by the two magnetically free layers 216A of sensors 200A, 200B, which are located one below the other in the y-direction. Two further columns are formed by the xMR sensor elements 100A, 100B of sensors 200A, 200B, which are located one below the other in the y-direction. A fourth column is formed by the two magnetically free layers 216B of sensors 200A, 200B, which are located one below the other in the y-direction. A distance dx between columns adjacent in the x-direction is less than a distance dy between rows adjacent in the y-direction.In other words, the lateral distance dx between an xMR sensor element 100 and the laterally adjacent magnetically free layers 216A, 216B is smaller in the x-direction than in the y-direction. While the xMR sensor elements 100A, 100B between the upper electrode 510 and the lower electrode 520 are electrically connected (energized), the magnetically free layers 216A, 216B, which act as shields or magnetic field concentrators, are not connected (unenergized). This can also be achieved, for example, by appropriate additional circuitry.

[0061] In summary, the exemplary implementations involve additional vortex disks in the vicinity of an xMR sensor.

[0062] The aspects and features described in connection with one of the previous examples can also be combined with one or more of the further examples to replace an identical or similar feature of that further example or to additionally introduce the feature into the further example.

[0063] It is further understood that the disclosure of several steps, processes, operations, or functions disclosed in the description or claims should not be interpreted as necessarily occurring in the described sequence, unless explicitly stated in a specific case or required for technical reasons. Therefore, the preceding description does not restrict the execution of multiple steps or functions to a specific sequence. Furthermore, in other examples, a single step, function, process, or operation may include and / or be broken down into multiple sub-steps, functions, processes, or operations.

[0064] If certain aspects described in the preceding sections relate to a device or system, these aspects should also be understood as a description of the corresponding procedure. For example, a block, device, or functional aspect of the device or system may correspond to a feature, such as a process step, of the corresponding procedure. Similarly, aspects described in relation to a procedure should also be understood as a description of a corresponding block, element, property, or functional feature of that device or system.

[0065] The following claims are hereby included in the detailed description, each claim being a separate example. It should also be noted that—although a dependent claim may refer to a specific combination with one or more other claims—other examples may include a combination of the dependent claim with the subject matter of any other dependent or independent claim. Such combinations are hereby explicitly proposed unless it is stated in a specific case that a particular combination is not intended. Furthermore, features of a claim are also to be included for each other independent claim, even if that claim is not directly defined as dependent on that other independent claim.

Claims

[1] Magnetoresistive sensor (200; 500; 600), comprising: comprising at least one xMR sensor element (100) formed from a layer stack a magnetically free layer (116) with a magnetically free vortex magnetization, and at least one reference layer (110) with a reference magnetization in a predetermined direction; and magnetically free layers (216A, 216B) with a magnetically free vortex magnetization arranged along the predetermined direction on opposite sides of the xMR sensor element (100) and laterally adjacent to the xMR sensor element (100), wherein the magnetoresistive sensor (500; 600) comprises a 2-dimensional matrix arrangement (500; 600) of a plurality of xMR sensor elements (100) and laterally adjacent magnetically free layers (216A, 216B), wherein a lateral distance between an xMR sensor element (100) and laterally adjacent magnetically free layers (216A, 216B) is less in the predetermined direction than in a direction perpendicular to the predetermined direction. [2] Magnetoresistive sensor (200; 500; 600) according to claim 1, wherein the magnetically free layer (116) of the xMR sensor element (100) and the adjacent magnetically free layers (216A, 216B) have identical thickness-to-diameter ratios. [3] Magnetoresistive sensor (200; 500; 600) according to claim 2, wherein the magnetically free layer (116) of the xMR sensor element (100) and the adjacent magnetically free layers (216A, 216B) have identical geometric dimensions. [4] Magnetoresistive sensor (200; 500; 600) according to any of the preceding claims, wherein a lateral distance between the xMR sensor element (100) and an adjacent magnetically free layer (216A, 216B) is less than 2 times the diameter of the xMR sensor element (100) or the adjacent magnetically free layer (216A, 216B). [5] Magnetoresistive sensor (200; 500; 600) according to any of the preceding claims, wherein the xMR sensor element (100) is electrically connected and the adjacent magnetically free layers (216A, 216B) are electrically unconnected. [6] Magnetoresistive sensor (200; 500; 600) according to any of the preceding claims, wherein the adjacent magnetically free layers (216A, 216B) are formed in the same layer of the layer stack as the magnetically free layer (116) of the xMR sensor element (100). [7] Magnetoresistive sensor (200; 500; 600) according to any one of claims 1 to 5, wherein the adjacent magnetically free layers (216A, 216B) are formed in different layers than the magnetically free layer (116) of the xMR sensor element (100). [8] Magnetoresistive sensor (200; 500; 600) according to one of the preceding claims, wherein the magnetically free layer (116) of the xMR sensor element (100) and the adjacent magnetically free layers (216A, 216B) are each formed in a circular disk shape. [9] Magnetoresistive sensor (200; 500; 600) according to one of the preceding claims, wherein the at least one xMR sensor element (100) is designed as a TMR sensor element. [10] Magnetoresistive sensor (500; 600), comprising: a 2-dimensional matrix arrangement (500; 600) consisting of a plurality of xMR sensor elements (100) and laterally adjacent magnetically free layers (216A, 216B), wherein each xMR sensor element (100) has a magnetically free layer (116) with a magnetically free vortex magnetization and a reference layer (110) with a reference magnetization in a predetermined direction, wherein the matrix arrangement comprises magnetically free layers (216A, 216B) arranged along the predetermined direction on opposite sides of each xMR sensor element (100) and laterally adjacent to the xMR sensor element (100) with a magnetically free vortex magnetization, wherein a lateral distance between an xMR sensor element (100) and laterally adjacent magnetically free layers (216A, 216B) is less in the predetermined direction than in a direction perpendicular to the predetermined direction.

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