MAGNETORESISTIVER SENSOR

Abstract

The present disclosure provides a magnetoresistive (xMR) sensor having increased immunity to the presence of a transverse magnetic field by using a combination of differential biasing across the sensing layers of the sensing elements, sensing elements with different sensitivities, and different reference magnetization directions. The xMR sensor comprises two or more arrays of sensing elements, each array comprising multiple sensing elements. The sensing elements within each array may be arranged in pairs, with the sensing elements within each pair having sensing layers magnetically biased in antiparallel directions. The sensing elements within each array are also provided with different respective sensitivities.The sensing elements with the lowest sensitivity are provided with a reference layer magnetized in a first direction, and the sensing elements in the remaining arrays are provided with a reference layer magnetized in a direction antiparallel to the first direction.

Description

Field of the invention

[0001] The present disclosure relates to a magnetoresistive sensor. More particularly, the present disclosure relates to a magnetoresistive sensor with enhanced immunity to the presence of a transverse magnetic field. background

[0002] Magnetoresistive (xMR) sensors are highly sensitive magnetic field sensors that enable the measurement of a single field component. Fig. As illustrated in Figures 1A-B, a typical xMR stack 1, such as a giant magnetoresistive (GMR) or tunneling magnetoresistive (TMR) stack, is typically formed from an antiferromagnetic layer 10 and a reference structure 12 designed to establish a fixed magnetization direction that does not rotate within the operating range of the sensor. This fixed magnetization direction defines the sensing axis of the entire sensing device.

[0003] The sensing layer 14 (also referred to as the free layer) is a ferromagnetic layer that can rotate freely in the presence of an external magnetic field. The output of the sensing device is determined by the angle between the sensing layer 14 and the reference structure 12, from which information about the magnetic field strength of an external magnetic field can be derived. A minimum and maximum resistance state is obtained when the sensing layer 14 and the reference structure 12 have parallel and antiparallel saturation states, respectively. Brief description

[0004] The present disclosure provides a magnetoresistive (xMR) sensor that has increased immunity to the presence of a transverse magnetic field, that is, a magnetic field applied in a plane in a direction orthogonal to the sensing direction of the sensor, which can adversely affect the sensitivity of the sensor. The present disclosure aims to achieve this by using a combination of a differential bias across the sensing layers of the sensing elements, sensing elements with different sensitivities (e.g., using different aspect ratios), and different reference magnetization directions. The xMR sensor comprises two or more arrays of sensing elements, each array comprising multiple sensing elements.As an example, the sensing elements within each array may be arranged in pairs, with the sensor elements within each pair having sensing layers magnetically biased in antiparallel directions, for example, by an exchange bias provided by an additional antiferromagnetic layer to thereby provide the differential bias. The sensing elements within each array are also provided with different respective sensitivities, which may be achieved by one or more of different aspect ratios, different sensing layer compositions, different soft pinning on the sensing layer of each array, and an additional external bias on one or more of the arrays.The sensing elements with the lowest sensitivity are provided with a reference layer magnetized in a first direction, which defines the sensing direction of the xMR sensor. The sensing elements in the remaining arrays are then provided with a reference layer magnetized in a direction antiparallel to the first direction. By constructing an xMR sensor with sensing elements that have different sensitivity levels and different tolerances to transverse fields, an xMR sensor with improved immunity to transverse fields is provided.

[0005] A first aspect of the present disclosure provides a magnetoresistive field sensor system comprising one or more magnetoresistive field sensors, each magnetoresistive field sensor comprising: a first sensor array of magnetoresistive sensing elements having a first sensitivity, each of the magnetoresistive elements in the first array comprising a sensing layer to which a first bias field is applied and a reference structure magnetized in a first reference magnetization direction, and at least one second sensor array of magnetoresistive sensing elements having a second sensitivity, the second sensitivity being higher than the first sensitivity, each of the magnetoresistive elements in the second array comprising a sensing layer to which a second bias field is applied and a reference structure magnetized in a second reference magnetization direction,wherein the second reference magnetization direction is opposite to the first reference magnetization direction.,

[0006] Therefore, the present disclosure provides a magnetoresistive sensor that combines differential biasing with sensing elements having different sensitivities and opposite reference directions to thereby reduce the effect of transverse magnetic fields. By using arrays of sensors with different sensitivities and opposite reference directions, the resulting magnetoresistive sensor ensures a wider and more robust operating range than those that use only differential biasing to reduce the effect of transverse fields. Therefore, the present invention provides an improved magnetoresistive sensor with increased immunity to transverse fields.

[0007] In some arrangements, the first sensor array may comprise magnetoresistive elements having a first aspect ratio to thereby provide the first sensitivity, and the second sensor array may comprise magnetoresistive elements having a second aspect ratio to thereby provide the second sensitivity. That is, the size of the sensor elements is varied to provide different levels of sensitivity, with sensors having a higher aspect ratio providing lower sensitivity.However, it will be appreciated that the sensitivity of the sensing elements may be varied by other means, for example, by using sensing elements with different xMR stack arrangements, by applying different bias fields to the sensing layer to provide a different degree of soft pinning, or by applying an additional external bias field to one or more of the sensing elements (e.g., by a field generated by an electromagnet or a permanent magnet) to thereby vary the sensitivity.

[0008] In some arrangements, the first sensor array may comprise a first number of magnetoresistive sensing elements, and the second sensor array may comprise a second number of magnetoresistive sensing elements. Preferably, the first number of magnetoresistive sensing elements may differ from the second number of magnetoresistive sensing elements. That is, each sensor array may have a different number of sensing elements, for example, depending on the respective sensitivity of the sensing elements.

[0009] In some cases, the first and second numbers of sensing elements may be determined by a respective weighted value, with each weighted value indicating the percentage of a sensor output provided by the respective array. For example, sensor elements with the highest sensitivity are generally more susceptible to transverse fields and therefore represent a smaller percentage of the magnetic sensor output. As such, the sensor array including sensing elements with the higher sensitivity may include a smaller number of sensing elements than the sensor array(s) including sensing elements with a relatively lower sensitivity.

[0010] In some arrangements, the first and second bias fields may be induced by differential sensing layer bias. For example, the first and second sensor arrays may comprise respective pairs of magnetoresistive sensing elements with soft-pinned antiparallel sensing layers. In such arrangements, the sensing layers of the respective pairs of magnetoresistive sensing elements may be soft-pinned by an antiferromagnetic layer.

[0011] In other arrangements, the first and second bias fields may be induced by one or more permanent magnets or an electromagnet.

[0012] In some arrangements, each magnetoresistive field sensor may further comprise a third array of magnetoresistive sensing elements having a third sensitivity, the third sensitivity being higher than the second sensitivity, each of the magnetoresistive elements in the third array comprising a sensing layer having a third bias field applied thereto and a reference structure magnetized in the second reference magnetization direction. It is also understood that each magnetoresistive field sensor may comprise any number of sensor arrays having varying sensitivity levels and bias fields applied thereto.

[0013] In some arrangements, the third sensor array may comprise magnetoresistive elements having a third aspect ratio to thereby provide the third sensitivity.

[0014] In some arrangements, the third bias field may be induced by differential sensing layer bias. For example, the third sensor array may comprise respective pairs of magnetoresistive sensing elements with soft-pinned antiparallel sensing layers. In such cases, the sensing layers of the respective pairs of magnetoresistive sensing elements may be soft-pinned by an antiferromagnetic layer.

[0015] In other arrangements, the third bias field can be induced by one or more permanent magnets or an electromagnet.

[0016] In some arrangements, the first reference magnetization direction may define the sensing direction of the one or more magnetoresistive field sensors.

[0017] In some arrangements, the magnetoresistive field sensor system may comprise a first set of magnetoresistive field sensors connected in a first Wheatstone bridge arrangement.

[0018] Furthermore, the system may further comprise a second set of magnetoresistive field sensors connected in a second Wheatstone bridge arrangement, wherein the second Wheatstone bridge arrangement is rotated by 90° relative to the first Wheatstone bridge arrangement.

[0019] The magnetoresistive sensing elements can be tunneling magnetoresistive sensing elements or giant magnetoresistive sensing elements. Short description of the drawings

[0020] The present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1A an example of a typical magnetoresistive sensor stack; Fig. 1B shows an example of the magnetization direction in the layers of a linearized sensor element; Fig. 2 an example of the shape and detection direction of a typical magnetoresistive element; Fig. 3A-B further illustrate the influence of a transverse field on a typical magnetoresistive sensing device; Fig. 4A-C show the effect of a transverse field on a typical magnetoresistive sensing device in the presence of a bias field; Fig. 5A-B illustrate an example of a pair of magnetoresistive sensor elements according to the present disclosure; Fig. 6A further illustrates an example of a magnetoresistive sensor element according to the present disclosure; Fig. 6B shows the effect of the sensing layer structure on the bias field; Fig. 7A-C illustrate the influence of a transverse field on a magnetoresistive sensing device having a first sensitivity according to the present disclosure; Fig. 8A-C illustrate the influence of a transverse field on a magnetoresistive sensing device having a second sensitivity according to the present disclosure; Fig. 9A-C illustrate the influence of a transverse field on a magnetoresistive sensing device having a third sensitivity according to the present disclosure; Fig. 10 the effect of a transverse field on magnetoresistive sensing devices with varying sensitivities; Fig. 11A-C illustrate an example of sensor optimization according to the present disclosure; Fig. 12A-B illustrate an effect of a transverse field on an optimized magnetoresistive sensor according to the present disclosure; Fig. 13 shows a first example of a pair of sensing elements with differential sensing layer bias; Fig. 14 shows a second example of a pair of sensing elements with differential sensing layer bias; Fig. 15 illustrates an exemplary magnetic sensor according to the present disclosure; Fig. 16 illustrates another exemplary magnetic sensor according to the present disclosure; Fig. 17 illustrates another exemplary magnetic sensor according to the present disclosure; Fig. 18 further illustrates an exemplary magnetic sensor according to the present disclosure; Fig. 19 further shows an example of a magnetic sensor according to the present disclosure; Fig. 20 illustrates an exemplary method of manufacturing a magnetic sensor according to the present disclosure; Fig. 21 illustrates another exemplary method of manufacturing a magnetic sensor according to the present disclosure; Fig. 22A-D illustrate a portion of a method for manufacturing a magnetic sensor according to the present disclosure; Fig. 23A-E illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure; Fig. 24A-D illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure; Fig. 25A-B illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure; Fig. 26A-G illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure; Fig. 27A-G illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure; Fig. 28A-C illustrate another portion of a method of manufacturing a magnetic sensor according to the present disclosure. Detailed description

[0021] Magnetoresistive (xMR) sensors are highly sensitive magnetic field sensors that enable the measurement of a single field component. Such magnetic sensing devices are particularly useful for detecting and measuring the magnetic field generated by an electric current flow and can thus be used to detect and measure the electric currents themselves. Such magnetic sensing devices can therefore be used in a wide variety of applications, such as automotive, medical, industrial control, consumer, and many other applications where current sensing is required.

[0022] As discussed above, a typical xMR stack used in xMR sensing devices will comprise a reference structure and a sensing layer, where the output of the sensing device is given by the angle between the sensing layer and the reference structure.

[0023] Typically, a linear response between the saturation states is obtained when the magnetization direction of the sensing layer 14 and that of the reference structure 12 are perpendicular or nearly perpendicular in the absence of an external field, as in Fig. 1B. The magnetization direction of the reference structure 12 is defined by exchange bias coupling (unidirectional coupling). Linearization can then be achieved (i.e., such that the magnetization direction of the sensing layer 14 is perpendicular to that of the reference structure 12) in a variety of ways. As an example, linearization can be achieved through the shape anisotropy of the sensing layer 14 (uniaxial linearization). Here, the shape anisotropy is determined by the geometry of the sensing elements. For example, high shape anisotropy is obtained in sensing elements with a high aspect ratio, where the length of the sensing element is significantly larger than the width of the sensing element. That is, a sensing element that is much longer than its width or height will automatically magnetize in the direction of its length without the need to apply an external magnetic field.As another example, linearization can be achieved by applying a bias field perpendicular to the sensing axis (unidirectional linearization), for example, using a magnetic field generated by a permanent magnet.

[0024] In the presence of a transverse magnetic field (i.e., a magnetic field applied in the plane of the magnetoresistive sensor film in a direction perpendicular to the sensor's sensing axis), the sensitivity of a standalone sensor changes. The nature of the sensitivity change depends on the linearization strategy. For example, with uniaxial linearization, the sensor sensitivity decreases with increasing absolute transverse field. For unidirectional linearization, the sensitivity decreases as the sum of the bias field and the transverse field increases. In both cases, this can lead to uncertainty in sensor measurements in the presence of a transverse magnetic field.

[0025] Fig. Figures 2 and 3A-3B illustrate how the sensitivity is affected by a transverse field for sensing devices that have undergone uniaxial linearization. In this example, the sensing layer 14 of the xMR stack 1, which has a high aspect ratio and low sensitivity, comprises a first ferromagnetic layer 20, which in this case is a cobalt-iron-boron (CoFeB) layer, and a second ferromagnetic layer 22, which in this case is nickel-iron (NiFe), to thereby provide the required shape anisotropy H k .

[0026] The sensor response, µ0. H || where µ0 is the magnetic permeability and H || the magnetic field is parallel to the detection axis, is independent of the transverse field polarity, as in Fig. However, as shown in Figure 3A, there is a continuous nonlinear decrease in sensitivity when the absolute transverse field (µ0. H⊥ ) increases, where H ⊥ the transverse magnetic field is perpendicular to the detection axis. Furthermore, the sensitivity error increases with increasing transverse field. In this context, the sensitivity error can be calculated as follows: SErr=SH⊥−SH⊥=0SH⊥=0 where S H⊥ the sensor sensitivity with a transverse field of non-zero and S H⊥=0 the sensor sensitivity in the absence of a transverse field.

[0027] Fig. Figures 4A-C illustrate how the sensitivity is affected by a transverse field for detecting devices that have undergone unidirectional linearization. In this example, a bias field (H Vorspannung ) to the detection layers of xMR sensor elements, which have an aspect ratio of 20 × 1.0µm 2 have, created. Fig. Figure 4A shows the effect of applying a transverse field with the same polarity as the sensor layer bias field, showing that the sensitivity decreases with increasing transverse field. Fig. Figure 4B shows the effect of applying a transverse field with the opposite polarity to the sensor layer bias field, from which it can be seen that the sensitivity increases with increasing transverse field up to H Vorspannung + H ⊥ = 0, after which the sensitivity begins to decrease. As shown in Fig. As shown in Figure 4C, when a combination of xMR sensor elements is connected in series with a differential sensing layer bias field, the influence of the transverse field on the sensitivity is reduced.

[0028] However, there are several disadvantages when implementing only a differential bias field to reduce the effect of any transverse fields. First, using a differential bias field from an electromagnet does not create a large working area free of transverse field disturbances and requires a constant current to be applied. Likewise, the integration of permanent magnets is not compatible with applications in harsh environments, and the magnets can easily become magnetized under a high external field. Additionally, combining pairs of sensors with the same characteristics and an antiparallel sensing layer bias does not provide complete transverse field compensation, as the transverse field's influence on sensitivity is nonlinear.

[0029] The present disclosure therefore seeks to provide an xMR magnetic field sensor that provides a wide and robust operating range and has a sensor arrangement capable of providing improved attenuation of the transverse field effect.

[0030] In particular, the present disclosure provides a magnetoresistive sensing device that combines multiple pairs of sensors having a differential sensing layer bias, different sensitivities, and opposite reference directions (i.e., the magnetization direction of the reference structure), thereby reducing the effect of transverse fields. In some cases, the differential sensing layer bias is provided by exchange bias coupling between the sensing layer and an adjacent antiferromagnetic layer. However, it is understood that the differential sensing layer bias could be provided using any suitable differential sensing layer technique, for example, applying an external bias field with permanent magnets or an electromagnet.

[0031] The magnetoresistive sensor described here offers several advantages, including greater robustness to harsh environments, a wider cross-field immunity window with lower output errors, reduced susceptibility to repinning, and it does not necessarily require multiple dies and / or different film types for fabrication.

[0032] Fig. Figure 5A illustrates an xMR stack 3 of a sensing element that can be used according to the present disclosure. As before, the xMR stack 3 includes an antiferromagnetic layer 30 and a reference structure 32 configured to establish a fixed magnetization direction that does not rotate within the operating range of the sensor. In this example, the sensing layer 34 includes a ferromagnetic region 36 and an antiferromagnetic layer 38 to effectively provide a soft-pinned sensing layer 34.

[0033] The xMR stack 3 also includes a bottom electrode 40 for electrically connecting the xMR stack 3 and a cap layer 42 for protecting the xMR stack 3. Furthermore, a non-magnetic spacer 44 is provided between the reference structure 32 and the sensing layer 34. In the case of a GMR stack, the non-magnetic spacer 44 can be formed from any suitable metal material, for example, copper. In the case of a TMR stack, the non-magnetic spacer 44 can be formed from any suitable oxide material, for example, magnesium oxide (MgO) or aluminum oxide (Al2O3).

[0034] Fig. Figure 5B illustrates a pair of sensing elements 3A, 3B according to the present disclosure. In this example, the magnetization directions of the reference structures 32A, 32B are fixed in the same direction, while the ferromagnetic layers 36A, 36B have antiparallel magnetization directions.

[0035] Fig. Figure 6A further illustrates the Fig. 5A-5B. As before, the ferromagnetic region 36 of the sensing layer 34 comprises a first ferromagnetic layer 50 and a second ferromagnetic layer 52. The first and second ferromagnetic layers 50, 52 may be formed from any suitable ferromagnetic materials, such as CoFeB, NiFe, or cobalt-iron (CoFe). The antiferromagnetic layer 38 may comprise any suitable antiferromagnetic material, such as iridium-manganese (IrMn) or platinum-manganese (PtMn).

[0036] The two ferromagnetic layers 50, 52 are coupled to the antiferromagnetic layer 38 by an exchange bias, and thereby the magnetization direction of the ferromagnetic region 36 is soft-pinned in a specific direction. By providing a pair of sensing elements with antiparallel magnetization directions (as in Fig. 5B), a differential sensing layer bias is provided. The amplitude of the exchange bias can be tuned by the ferromagnetic and antiferromagnetic material. For example, as in Fig. 6B (R. Ferreira et al., Large Area and Low Aspect Ratio Linear Magnetic Tunnel Junction with a Soft-Pinned Sensing Layer, IEEE Transactions on Magnetics, Vol. 48, No. 11, 2012), the amplitude of the pinning field (i.e., the bias field) can be increased or decreased by varying the thickness of a layer of non-magnetic material, for example, ruthenium, between the ferromagnetic region 36 and the antiferromagnetic region 38.

[0037] The exchange bias field H Bsp. is unidirectional, resulting in a transverse field polarity-dependent sensor output when one or more pairs of sensing elements are implemented in a magnetoresistive sensing device. The sensitivity of the sensing device increases when ⌈HExample+H⊥⌉ decreases, and thus the cross-field immunity window is determined by H Bsp.The detection device still operates above this value, but with a higher sensitivity variation, as the sensitivity of both detection elements decreases (as described below with reference to Fig. 10).

[0038] Although the above describes the use of pairs of sensing elements with ferromagnetic regions 36 soft-pinned in antiparallel directions, it will of course be understood that the differential bias may be provided by other methods described herein (e.g., by applying an external bias field using permanent magnets), in which case the antiferromagnetic layer 38 may be omitted from the xMR stack 32.

[0039] The Fig. Figures 7-9 illustrate the effect of a transverse field on xMR sensing devices with sensing elements having differential soft-pinned sensing layers and the change in this effect when the sensitivity of the sensing elements is varied by changing the aspect ratio. In this regard, it should be understood that the xMR sensing devices may have any number of sensing elements connected in series or parallel.

[0040] The Fig. 7A-C illustrate the effect of a transverse field on xMR sensing devices with sensing elements with a first sensitivity determined by an aspect ratio of 20×1.0µm 2 is provided. Fig. Figure 7A shows the sensitivity when the transverse field and the sensing layer exchange field have the same polarity. Fig. Figure 7B shows the sensitivity when the transverse field and the sensing layer exchange field have opposite polarities. Fig. Figure 7C shows the effect of connecting a uniform combination of xMR sensing elements with antiparallel sensing layer exchange fields in series to thereby provide pairs of xMR sensing elements with the differential soft-pinned sensing layers. As can be seen from Fig. As can be seen in Figure 7C, the sensitivity variation is significantly reduced by implementing a different soft-pinned sensing layer arrangement.

[0041] The Fig. 8A-C illustrate the effect of a transverse field on xMR detectors with detector elements having a second sensitivity determined by an aspect ratio of 20×1.5µm 2 is provided. Fig. Figure 8A shows the sensitivity when the transverse field and the sensing layer exchange field have the same polarity. Fig. Figure 8B shows the sensitivity when the transverse field and the sensing layer exchange field have opposite polarities. Fig. Figure 8C shows the effect of connecting a uniform combination of xMR sensing elements with antiparallel sensing layer exchange fields in series to thereby provide pairs of xMR sensing elements with the differential soft-pinned sensing layers. As can be seen from Fig. As can be seen in Figure 8C, the sensitivity variation is again significantly reduced by implementing a different arrangement of a soft-pinned sensing layer, and the overall sensitivity is increased by using a smaller aspect ratio.

[0042] The Fig. 9A-C illustrate the effect of a transverse field on xMR detectors with detector elements having a third sensitivity determined by an aspect ratio of 20×2.0µm 2 is provided. Fig. Figure 9A shows the sensitivity when the transverse field and the sensing layer exchange field have the same polarity. Fig. Figure 9B shows the sensitivity when the transverse field and the sensing layer exchange field have opposite polarities. Fig. Figure 9C shows the effect of connecting a uniform combination of xMR sensing elements with antiparallel sensing layer exchange fields in series to thereby provide pairs of xMR sensing elements with the differential soft-pinned sensing layers. As can be seen from Fig. As can be seen in Figure 9C, the sensitivity variation is again significantly reduced by implementing a different soft-pinned sensing layer arrangement, and the overall sensitivity is further increased by the reduced aspect ratio.

[0043] Fig. Figure 10 shows the sensitivity error for each of the Fig. 7C, Fig. 8C and Fig. 9C compared to that of the sensor output shown in the Fig. 3A-B shown typical xMR sensor. Fig. Figure 10 shows that the use of xMR sensing elements with antiparallel sensing layer exchange fields reduces the sensitivity error when a transverse field is present. While arrays comprising sensing elements with higher aspect ratios provide lower sensitivity, the sensitivity error is lower for such arrays.

[0044] Therefore, the present disclosure proposes a combination of differential sensing layer sensing elements with different sensitivities to improve the cross-field immunity. To achieve this, a combination of differential sensing layer sensing elements with different pinning directions (i.e., reference directions) is also implemented, since a combination of differential sensing layer sensing elements with different sensitivities and the same reference direction results in an arrangement in which all sensing elements have a relatively low sensitivity. In this regard, as indicated by the Fig. 7C, Fig. 8C, Fig. 9C and Fig. As illustrated in Figure 10, all sensing elements still exhibit some cross-field sensitivity, with the sensing elements with higher sensitivity exhibiting a larger sensitivity error, resulting in reduced sensitivity across all sensing elements. By combining sensing elements of different sensitivities with different reference directions, the sensitivity to cross-fields in some of the sensor elements is effectively reversed, thereby canceling out the effect of the cross-field in the other sensing elements.

[0045] An example of an optimized combination of differential detection layer detection elements will now be described with reference to the Fig. 11A-C and 12A-B.

[0046] In this example, differential sensing layer sensing elements with three different sensitivities are combined. In this example, three different aspect ratios are used to provide the three different sensitivities, with the sensing elements with the lowest sensitivity (i.e., the highest aspect ratio) and the highest sensitivity (i.e., the lowest aspect ratios) having antiparallel reference structures. The differential sensing layer sensing elements with the highest aspect ratio (e.g., 20×1.0µm 2 ) define the detection direction based on the magnetization direction of their reference structures, as shown by Fig. 11A. The differential sensing layer sensing elements with the lowest aspect ratios (e.g., 20×1.5µm 2 and 20×2.0µm 2) have the opposite detection direction (i.e., antiparallel pinning direction) to mitigate the nonlinear increase in sensitivity error, as shown in the Fig. 11B-C is shown

[0047] As in Fig. As shown in Figure 12A, the combination of a differential soft-pinned sensing layer with different aspect ratios and opposite reference directions results in improved immunity to transverse fields. Each array of differential sensing layer sensing elements has a percentage W width (W 1.0 , W 1.5 and W 2.0 ) of the final output generated by a full array of sensing elements in series to achieve the optimal immunity to transverse fields, which depends on the combination of aspect ratios implemented. In Fig. 12A, the optimal ratio of outputs is 75% for the sensing elements with an aspect ratio of 20×1.0µm 2 , 10% for the detection elements with an aspect ratio of 20x1.5 µm 2 and 15% for the detection elements with an aspect ratio of 20x2.0 µm 2 . The sensor elements with a higher aspect ratio and a lower sensitivity error make a larger contribution to the output signal. As in Fig. As shown in Figure 12B, the sensitivity error of this combination of soft-pinned differential sensing elements provides negligible or nearly negligible sensitivity error in the presence of a transverse field equal to or below the strength of the bias field, with a relatively small error in sensitivity seen only at stronger transverse fields (e.g., above 6mT).

[0048] Although the above example uses different aspect ratios to provide sensing elements with varying sensitivities, it should be understood that the sensing elements can be provided with different sensitivities in a variety of ways. For example, the sensitivities can be varied by using sensing elements with different xMR stack arrangements, including, for example, different sensing layer compositions, or by applying different bias fields to the sensing layer to provide a different degree of soft pinning. As another example, the sensitivities can be varied by applying an additional external field to one or more of the sensing elements (e.g., a field generated by an electromagnet or a permanent magnet) to thereby vary the bias field.

[0049] For example, in Fig. 11, the lower aspect ratio sensors can be replaced by higher aspect ratio sensing elements, but comprising an xMR stack with a lower bias field in the sensing layer to provide increased sensitivity, or by reducing the bias field by a field generated by an electromagnet or permanent magnet in the opposite direction, while still achieving the same increased immunity. This array of sensing elements can be implemented as a standalone magnetic sensor array or in a Wheatstone bridge configuration, as described below, to achieve improved performance in terms of background signal reduction and thermal response.A similar strategy can be applied in a range of transverse fields higher than the exchange bias field; when the output of both sensing elements in each differential sensor pair is captured, a post-processing circuit can determine which sensing element provides the correct value.

[0050] Although the above examples have aspect ratios of 20×1µm 2 , 20×1.5µm 2 and 20×2.0µm 2 provide, it is obvious that these are exemplary and any suitable aspect ratio can be used.

[0051] Fig. Figure 13 shows an example 100 of a pair of tunneling magnetoresistive (TMR) sensing elements with differential sensing layer bias. In this example, a first TMR sensing element 102 and a second TMR sensing element 104 are disposed on a first electrical contact 106, each having further electrical contacts 108, 110 disposed across the top surface for electrically connecting the sensing elements 102, 104 in a circuit. As shown in Fig. 13, both sensing elements 102, 104 have reference structures pinned in the same direction and opposite bias fields, H bias , on.

[0052] Fig. Figure 14 shows an example 200 of a pair of giant magnetoresistive (GMR) sensing elements with differential sensing layer bias. In this example, a first GMR sensing element 202 and a second GMR sensing element 204 are disposed between and in contact with electrical contacts 206, 208, and 210, thereby connecting the sensing elements 202, 204 in a circuit. Both sensing elements 202, 204, in turn, have reference structures pinned in the same direction and opposite bias fields, H bias , on.

[0053] In the examples of Fig. 13 and Fig. 14, the bias field is induced by exchange biasing using sensing layers that are soft-pinned in opposite directions. However, it is understood that the bias field can also be induced externally by permanent magnets or an electromagnet. That is, the differential bias of the sensing layers can be provided by soft-pinning the sensing layer, as described with reference to Fig. 5A, Fig. 5B and Fig. 6A, or by a bias field generated by permanent magnets or an electromagnet.

[0054] Fig. Figure 15 illustrates an exemplary magnetic sensor 300 comprising multiple arrays of sensing elements, wherein the arrays of sensing elements have a differential sensing layer bias, different sensitivities, and a varying reference magnetization direction. It should be understood that the pairs of sensing elements within each array may be TMR- or GMR-based sensing elements, as indicated by the Fig. 13 and Fig. 14 is illustrated.

[0055] The magnetic sensor 300 includes a first sensor array 310, a second sensor array 320, and a third sensor array 330, each including sensing elements connected in series; however, it should be understood that the sensing elements of each array may also be connected in parallel. The first sensor array 310 includes a plurality of sensing elements having a first sensitivity, shown here as a first pair of sensing elements 312, a second pair of sensing elements 314, a third pair of sensing elements 316, and a fourth pair of sensing elements 318. The second sensor array 320 includes a plurality of sensing elements having a second sensitivity, shown here as a first pair of sensing elements 322, a second pair of sensing elements 324, a third pair of sensing elements 326, and a fourth pair of sensing elements 328.The third sensor array 330 includes a plurality of sensing elements having a third sensitivity, shown here as a first pair of sensing elements 332, a second pair of sensing elements 334, a third pair of sensing elements 336, and a fourth pair of sensing elements 338. It should be understood that each pair of sensing elements 312-338 has a similar configuration to that shown in FIGS. Fig. 13 and Fig. 14 (i.e., 100 and 200). In this example, the sensitivities of the sensing elements in each sensor array 310, 320, and 330 are defined by the aspect ratio therein, however, it will be appreciated that the different sensitivities may be provided by any other means, as described above. The arrows within each pair of sensing elements represent the pinning direction of the reference structure (i.e., the reference magnetization direction), and the illustrated size of each pair of sensing elements represents the relative difference between the sensitivities and / or the amplitude of the bias fields. In this regard, a smaller sensing element represents a lower sensitivity (i.e., a higher aspect ratio) and / or a higher bias field, and a larger sensing element represents a higher sensitivity (i.e.,a lower aspect ratio) and / or a lower bias field. It can therefore be seen that the first sensitivity of the first sensor array 310 is lower than the second sensitivity of the second sensor array 320, which in turn is lower than the third sensitivity of the third sensor array 330.

[0056] Although four pairs of sensing elements are shown in each sensory array, it should be understood that any number of sensing elements may be included in each sensor array depending on the percentage weighting W of each sensitivity, as described further below.

[0057] Since the first sensor array 310 comprises sensing elements with the lowest sensitivity (i.e., the highest aspect ratio), it defines the sensing direction, as determined by the reference magnetization direction. The first sensor array 310 is called N AInclude detection elements that have a first percentage W A of the magnetic sensor output. The second and third sensor arrays 320, 330 attenuate the cross-field effect with an antiparallel pinning direction and a higher sensitivity (i.e., a lower aspect ratio). The second sensor array 320 is N B Include recording elements that represent a percentage W B of the magnetic sensor output, and the third sensor array 330 will represent N C Include detection elements that have a first percentage W C of the magnetic sensor output. Because the sensing elements of the second and third sensor arrays 320, 330 have higher sensitivity, they are more susceptible to transverse fields, and thus these sensor arrays will typically represent a smaller percentage of the magnetic sensor output.

[0058] Although in Fig. 15, three sensor arrays are shown, it is understood that a magnetic sensor according to the present disclosure can be implemented with two or more sensor arrays comprising at least a first sensor array defining the sensing direction and at least one further sensor array with antiparallel pinning direction to improve the attenuation of the cross-field effect. The magnetic sensor is thus implemented by combining sensor arrays i (where i is the number of sensor arrays) with a weight W i (Σ = 1) is formed.

[0059] The magnetic sensor 300 may operate in a single-ended mode (i.e., as a single magnetic sensor), or it may be arranged in a Wheatstone bridge arrangement comprising multiple magnetic sensors, as shown in Fig. 16 is shown. Fig. Figure 16 shows a magnetic sensing device 400 comprising a plurality of magnetic sensors 402, 404, 406, and 408 connected in a Wheatstone bridge configuration. Each of the magnetic sensors 402, 404, 406, and 408 comprises two or more sensor arrays as described herein, for example, each of the magnetic sensors 402, 404, 406, and 408 having the configuration of the Fig. 15 shown magnetic sensor 300.

[0060] If the magnetic sensing device 400 is arranged in a Wheatstone bridge configuration, it will be important that each sensor array within the magnetic sensors 402, 404, 406, and 408 provides the same resistance value. In this example, the optimal weighting (i.e., the percentage W) for each aspect ratio used can be obtained by numerically combining the simulated response of each type of sensing element to thereby determine a combination of those sensor elements that provide the required resistance value. Therefore, in the case where the sensitivity of each array is varied by using sensing elements with different aspect ratios, the weightings W can be compensated with respect to the resistance value of each aspect ratio. Referring again to the case of a TMR-based magnetic sensor (e.g., magnetic sensor 300, as shown in Fig. 15, the pairs of TMR sensing elements as in Fig. 13) with three arrays of sensing elements, the areas of 20×1.0µm 2 , 20×1.5µm 2 and 20×2.0µm 2 with the same weightings as those determined with reference to Fig. 12A, the total number of sensing elements per array can be calculated as shown in Table 1 below. Table 1 Sensor Array Size (µm 2 ) Widerstand N Gewicht (%) Gesamt 1 20x1.0 R1.0=NR×AA1.0=N1.0R 4 75 30 2 20x1.5 R1,5=23N1,5R 6 10 6 3 20x2.0 R2,0=12N2,0R 8 15 12

[0061] In Table 1, R × A is the resistance time area product of the TMR film, A 1,0 , 1,5, 2,0 is the area of a detection element of a given size in the array, N 1,0 , 1,5 , 20 is the number of detection elements of a given size in the array, and R 1,0, 1,5, 2,0 is the total resistance of combinations of sensing elements of a given size in the array.

[0062] Therefore, in the case of the Fig. 15, the first sensor array 310 would comprise 15 pairs of sensing elements (30 total), the second sensor array 320 would comprise 3 pairs of sensing elements (6 total), and the third sensor array 330 would comprise 6 pairs of sensing elements (12 total) to ensure that the same resistance value and optimal weighting is provided across each sensor array.

[0063] Again, the case of a GMR-based magnetic sensor (e.g., magnetic sensor 300, as shown in Fig. 15, the pairs of GMR sensing elements as shown in Fig. 14) with three arrays of sensing elements, the areas of 20×1.0µm 2 , 20×1.5µm 2 and 20×2.0µm 2 with the same weightings as those determined with reference to Fig. 12A, as another example, the total number of sensing elements per array can be calculated as shown in Table 2 below. Table 2 Sensor Array Size (µm 2 ) Widerstand N Gewicht (%) Gesamt 1 20x1.0 R1,0=NRSchichtIw=N1,0R 4 75 30 2 20x1.5 R1,5=23N1,5R 6 10 6 3 20x2.0 R2,0=12N2,0R 8 15 12

[0064] In Table 2, R sheet is the sheet resistance of the GMR film, l is the length of a sensing element in the array, w is the width of a sensing element in the region, N 1,0, 1,5, 2,0 is the number of detection elements of a given size in the array, and R 1,0, 1,5, 2,0 is the total resistance of combinations of sensing elements of a given size in the array.

[0065] Of course, the number of sensor elements provided in Tables 1 and 2 is exemplary, and any number of sensing elements may be used according to the weighting. For example, the number of elements may be multiples of the above sums (i.e., {5, 1, 2}; {60, 12, 24}, etc.).

[0066] In some applications, it may be necessary to monitor an external magnetic field in two or more directions. In such cases, a magnetic sensing device 500 comprising two Wheatstone bridge assemblies 510, 520 may be provided to sense and measure an external magnetic field in both the x- and y-directions. The first Wheatstone bridge 510 again comprises four magnetic sensors 512, 514, 516, and 518, with the sensing direction (denoted by the arrows), as defined by the first sensor array within each sensor, pinned to the y-direction. The second Wheatstone bridge 520 also comprises four magnetic sensors 522, 524, 526, and 528, but in this case, the sensing direction (denoted by the arrows), as defined by the first sensor array within each sensor, is pinned to the x-direction.It is obvious that a third Wheatstone bridge can also be implemented to monitor the magnetic field in the z-direction. It is also understood that each of the magnetic sensors of each Wheatstone bridge can be configured as the one described with reference to . Fig. 15. It is also understood that when connecting the magnetic sensors in a Wheatstone bridge, each sensor of the bridge may comprise a different combination of sensing elements. In this case, the individual magnetic sensors may not completely attenuate transverse fields, but may provide the required transverse field attenuation in a half- or full-bridge. As an example, two magnetic sensors may be connected in a first half-bridge that undercompensates for transverse fields (e.g., each magnetic sensor comprising a first array comprising 4 sensing elements, a second array comprising 6 sensor elements, and a third array comprising 7 sensor elements), and two further magnetic sensors may be connected in a second half-bridge that overcompensates for transverse fields (e.g.,each magnetic sensor comprises a first array comprising 4 sensing elements, a second array comprising 6 sensing elements, and a third array comprising 9 sensing elements), so that when connected in a full bridge the required compensation is provided.

[0067] Fig. 18 illustrates an exemplary layout of a magnetic sensing device 600, which includes a first magnetic sensor 610 configured to measure the magnetic field in the y-direction and a second magnetic sensor 620 configured to measure the magnetic field in the x-direction. In this regard, the first and second magnetic sensors 610, 620 may be configured as the Fig. 17, wherein each magnetic sensor 612 comprises two or more sensor arrays, such as those shown in Fig. 15. The first and second magnetic sensors 610, 620 may be disposed on the same sensor die or on separate sensor dies, which may then be disposed on an ASIC (application specific integrated circuit) die 602 formed on a laminate substrate, such as a printed circuit board (PCB) substrate, ceramic substrate, or any suitable substrate type.

[0068] Fig. 19 illustrates an exemplary layout of a magnetic sensing device 700 according to the present disclosure that utilizes pairs of TMR sensing elements 702 electrically connected via a bottom electrode 704, similar to that shown in Fig. 13. A contact 706 is also provided for connecting the TMR sensing elements 702 to the circuit components. Each array is provided with a flux concentrator 708 for adjusting the magnetization direction of the reference layer. Each pair of TMR sensing elements is also provided with a further flux concentrator 710 for adjusting the magnetization direction of the sensing layers, which in turn adjusts the exchange bias field. It should be understood that the further flux concentrator 710 is removed after the pinning process has been performed. An example of this is given in U.S. Patent No. 10,151,806.

[0069] Fig. Figure 20 is a flowchart illustrating a method 800 for manufacturing the sensor elements of a GMR-based magnetic sensor according to the present disclosure. In a first step 802, an area-wide GMR stack (e.g., the one shown in Fig. 5A) is deposited onto a substrate. For example, the substrate may comprise an application-specific integrated circuit (ASIC) die formed on a laminate substrate, such as a printed circuit board (PCB) substrate, ceramic substrate, or any suitable substrate type.

[0070] At step 804, the overall GMR stack is patterned into two or more arrays of sensing elements, for example, using ion beam etching techniques, with each array being patterned such that the sensing elements within a given array have a specific aspect ratio. The arrays of sensing elements are also patterned to provide an even number of sensing elements. In the next step 806, the metal contacts for connecting the sensing elements in series are provided. This can be done by applying a lift-off resist coating, depositing the metal material, and then performing the lift-off process to create the metal contacts.

[0071] At step 808, a first layer of passivation material may be deposited to protect the GMR sensing elements. A magnetic annealing process 810 is then performed to adjust the magnetization directions of the reference layer and the sensing layer of the GMR sensing elements. This can be done by local heating and / or magnetic field or using a non-wafer-based solution. It will be appreciated that the magnetization direction of the reference layer (i.e., the reference direction) can be adjusted using a variety of methods.

[0072] At step 812, additional coil biasing may be performed, for example, by plating the surface with a metallic material. In this context, an electromagnet may be fabricated to increase the bias field to increase the transverse field range (i.e., the amount of transverse field that can be attenuated), or alternatively, the electromagnet may be used to generate the bias field, thereby providing the differential bias of the sensing layer. Similarly, at 814, another layer of passivation material may be deposited.

[0073] Finally, at step 816, bond pads are patterned into the sensing device, for example, using a wet etch, to electrically connect the GMR sensing device.

[0074] Fig. Figure 21 is a flowchart illustrating a method 900 for manufacturing the sensor elements of a TMR-based magnetic sensor according to the present disclosure. In a first step 902, a full-surface TMR stack (e.g., the one shown in Fig. 5A, the xMR stack 3) is deposited onto a substrate. For example, the substrate may comprise an application-specific integrated circuit (ASIC) die formed on a laminate substrate, such as a printed circuit board (PCB) substrate, ceramic substrate, or any suitable substrate type. It should be understood that in this case of a TMR stack, the TMR film within the stack also comprises a tunnel barrier layer positioned between the reference layer and the sense layer.

[0075] At step 904, the overall TMR stack is patterned into two or more arrays of sensing elements, for example, using ion beam etching techniques, with each array being patterned such that the sensing elements within a given array have a specific aspect ratio. The arrays of sensing elements are also patterned to provide an even number of sensing elements, with each pair of sensing elements connected in series by a bottom electrode.

[0076] The process of structuring the TMR stack is Fig. 22-23 shown in more detail. The Fig. 22A-D illustrate the process by which the bottom electrode of the TMR stack is patterned. Fig. Figure 22D shows the area-wide TMR stack, which includes a substrate 1000 at the base (typically formed of silicon), followed by a layer of an intermetal dielectric (IMD) oxide 1002, such as silicon oxide, a bottom electrode 1004, and a TMR film 1006 (i.e., comprising the reference layers, the tunnel barrier layer, and the sensing layers). To begin the process, a photoresist 1008 is applied to the stack, which is then used to etch (e.g., using ion beam etching) through a portion of the TMR film 1006 and the bottom electrode 1004, as in Fig. 22B. The photoresist material 1008 is then removed as shown in Fig. 22C-D. In this respect, Fig. 22D is a top view in which two lengths of the TMR film 1006 (with a bottom electrode 1004 underneath) have been left on the substrate 1002.

[0077] The Fig. 23A-E illustrate the process by which the TMR film 1006 is patterned into pairs of sensing elements. As in Fig. 23A, a pair of TMR sensing elements is formed by first depositing a lift-off coating 1010A-B and a photoresist coating 1012A-B. As shown in Fig. 23B, the TMR film 1006 is then etched to leave two TMR sensing elements defined by portions 1006A-B.

[0078] In the next step 906, which is further Fig. 23C, a layer of passivation material 1014 is deposited to protect the TMR elements 1006A-B and ensure that the sidewalls do not short-circuit. As shown in Fig. 23D, the lift-off coating 1010A-B is then used to remove the photoresist coating 1012A-B and the passivation material 1014 thereon. In this regard, Fig. 23E is a top view wherein two arrays of sensing elements, 1006A-B and 1006C-D, respectively (each with a bottom electrode 1004AB underneath), have been left on the substrate 1002. Although shown as having the same size, it will be appreciated that the sensing elements of the two arrays, 1006A-B and 1006C-D, may be provided with different aspect ratios in accordance with the present disclosure to thereby provide different sensitivities.

[0079] At step 908, further indicated by the Fig. 24A-D, metal contacts are formed over the TMR sensing elements 1006A-B, thereby providing a top electrode. As shown in Fig. 24A, a lift-off coating 1016 and a photoresist coating 1018 are first applied. A metal layer 1020 (such as tantalum or gold) is deposited over the stack, as shown in Fig. 24B, thereby forming the metal contacts. As shown in Fig. 24C, the lift-off coating 1016 is then used to remove the photoresist coating 1018 and the metal 1020 thereon. Fig. 24D thus shows the top view with the metal contacts 1020 now formed over the sensing elements.

[0080] At step 910, further indicated by the Fig. 25A-B, a layer of passivation material 1022 is deposited over the entire substrate.

[0081] At step 912, magnetically annealing both the reference layers and the sense layers to adjust their magnetization directions. Fig. 26A-G illustrate a method by which the reference layer can be magnetically annealed using a flux concentrator. Fig. 26A-C and 26E-G show a side view, so that each of the TMR sensing elements 1006 shown is an element in its respective array. First, as in Fig. 26A, a seed layer 1024 is deposited. Then, as shown in Fig. 26B, a photoresist coating 1026 is applied such that only a portion of the seed layer 1024 is exposed. A flux concentrator 1028 is plated in the exposed portion, and the photoresist coating 1026 is removed, as shown in Fig. 26C. The flux concentrator 1028 is positioned so that it lies between two arrays of sensing elements (with the first sensing elements 1006A, 1006C shown). Fig. Figure 26D provides a top view showing the plated flux concentrator 1028.

[0082] As in Fig. 26E, the seed layer 1024 is etched such that the only remaining portion lies directly beneath the flux concentrator 1028. As shown in Fig. 26F, an out-of-plane magnetic field, as illustrated by arrow A, is applied to magnetically anneal the reference layer so that the magnetization directions are fixed in a particular direction. By placing the flux concentrator 1028 between two arrays of sensing elements 1006A, 1006C, the reference layers of the sensing elements 1006A, 1006C of each array are magnetized in opposite directions. Therefore, the stack can be rotated relative to the out-of-plane magnetic field to ensure that the magnetization direction of the array comprising the sensing elements with the lowest sensitivity is set in a particular direction. Once this is complete, the seed layer 1024 and the flux concentrator 1028 are removed (e.g., by etching), as shown in Fig. 26G. It is obvious that the magnetization direction of the reference layer (ie, the reference direction) can be adjusted using a variety of methods.

[0083] Fig. 27A-G illustrate a method by which the sensing layers can be magnetically annealed using a flux concentrator. First, as in Fig. 27A, a seed layer 1030 is deposited. Then, as shown in Fig. 27B, a photoresist coating 1032 is applied such that only a portion of the seed layer 1030 is exposed. A flux concentrator 1034 is plated in the exposed portion, and the photoresist coating 1032 is removed, as shown in Fig. 27C. The flux concentrator 1034 is positioned to lie between respective pairs of sensing elements 1006A-B. Fig. Figure 27D provides a top view showing the plated flux concentrator 1034.

[0084] As in Fig. 27E, the seed layer 1030 is etched such that the only remaining portion lies directly beneath the flux concentrator 1034. As shown in Fig. 27F, an out-of-plane magnetic field, as shown by arrow B, is applied to magnetically anneal the sensing layers so that the magnetization directions are fixed in a particular direction. By placing the flux concentrator 1034 between pairs of sensing elements 1006A-B, the sensing layers of each pair of sensing elements 1006A-B are soft-pinned in antiparallel directions, thereby providing the differential soft-pinned sensing layers. Once this is complete, the seed layer 1030 and the flux concentrator 1034 are removed (e.g., by etching), as shown in Fig. 27G is shown.

[0085] At step 914, additional coil biasing may be performed, for example, by plating the surface with a metal material (not shown). In this context, an electromagnet may be fabricated to increase the bias field to increase the cross-field range (i.e., the amount of cross-field that can be attenuated), or alternatively, the electromagnet may be used to generate the bias field, thereby providing the differential bias of the sensing layer. Similarly, at 916, another layer of passivation material (not shown) may be deposited.

[0086] Finally, at step 918, and as further indicated by Fig. 28C, bond pads are patterned into the sensing device, for example, using a wet etch, to electrically connect the TMR sensing device. As shown in Fig. 28A, a photoresist coating 1036 is applied, exposing only the portions of the passivation layer 1022 to be removed. As shown in Fig. 28B, the passivation layer 1022 is etched to expose portions of the metal contacts 1020, and the photoresist coating 1036 is removed. This is further illustrated in Fig. 28C, in which portions of the metal contacts 1020 are exposed as bond pads to electrically connect the TMR sensing device.

[0087] Various modifications, whether by addition, deletion and / or substitution, may be made to any of the embodiments described above to provide further embodiments, each and / or all of which are intended to be within the scope of the appended claims. Applications

[0088] Any of the principles and advantages discussed herein may be applied to other systems, not just those described above. Some embodiments may include a subset of features and / or advantages set forth herein. The elements and acts of the various embodiments described above may be combined to provide additional embodiments. The acts of the methods discussed herein may be performed in any order, as appropriate. Furthermore, the acts of the methods discussed herein may be performed in series or in parallel, as appropriate. Although circuits are illustrated in specific arrangements, other equivalent arrangements are possible.

[0089] Any of the principles and advantages discussed herein may be implemented in connection with any other systems, devices, or methods that may benefit from any of the teachings herein. For example, any of the principles and advantages discussed herein may be implemented in connection with any device requiring shielding from stray magnetic fields from a magnetic sensor system including a magnetic sensor.

[0090] Aspects of this disclosure may be implemented in various electronic devices or systems. For example, phase correction methods and sensors implemented according to any of the principles and advantages discussed herein may be included in various electronic devices and / or in various applications. Examples of electronic devices and applications may include, but are not limited to, servos, robots, aircraft, submarines, toothbrushes, biomedical measurement devices, and parts of consumer electronic products such as semiconductor dies and / or packaged modules, electronic test equipment, etc. Furthermore, the electronic devices may include unfinished products, including those for industrial, automotive, and / or medical applications.

[0091] Unless the context clearly requires otherwise, the words "comprise," "comprising," "include," "including," and the like, throughout the specification and claims, are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is, in the sense of "including, but not limited to." The words "coupled" or "connected," as generally used herein, refer to two or more elements that may be either directly connected or connected through one or more intermediate elements. While the various schematics shown in the figures represent example arrangements of elements and components, additional intervening elements, devices, features, or components may be present in an actual embodiment (assuming that the functionality of the illustrated circuitry is not adversely affected).The words "based on," as used herein, are intended to include generally "based only on" and "based at least in part on." Furthermore, the words "herein," "foregoing," "hereinafter," and words of similar import, when used in this application, are intended to refer to this application as a whole and not to any specific portions of this application. Where the context permits, words in the detailed description that use the singular or the plural may also include the plural or the singular, respectively. The word "or," with reference to a list of two or more items, is intended to cover all of the following interpretations of the word: any of the list items, all of the list items, and any combination of the list items. Any numerical values or distances provided herein are intended to include similar values within an error of measurement.

[0092] Although specific embodiments have been described, these embodiments have been presented only as examples and are not intended to limit the scope of the disclosure. Indeed, the novel devices, systems, and methods described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes may be made to the form of the methods and systems described herein without departing from the spirit of the disclosure. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 10 151, 806

[0068] Zitierte Nicht-Patentliteratur

[0000] R. Ferreira et al., Large Area and Low Aspect Ratio Linear Magnetic Tunnel Junction with a Soft-Pinned Sensing Layer, IEEE Transactions on Magnetics, Band 48, Nr. 11, 2012

[0036]

Claims

[1] Magnetoresistive field sensor system, comprising: one or more magnetoresistive field sensors, each magnetoresistive field sensor comprising: a first sensor array of magnetoresistive sensing elements having a first sensitivity, each of the magnetoresistive elements in the first array comprising a sensing layer to which a first bias field is applied and a reference structure magnetized in a first reference magnetization direction; and at least a second sensor array of magnetoresistive sensing elements having a second sensitivity, the second sensitivity being higher than the first sensitivity, wherein each of the magnetoresistive elements in the second array comprises a sensing layer to which a second bias field is applied and a reference structure magnetized in a second reference magnetization direction, the second reference magnetization direction being opposite to the first reference magnetization direction. [2] The magnetoresistive field sensor system of claim 1, wherein the first sensor array comprises magnetoresistive elements having a first aspect ratio to thereby provide the first sensitivity, and the second sensor array comprises magnetoresistive elements having a second aspect ratio to thereby provide the second sensitivity. [3] The magnetoresistive field sensor system of claim 1 or 2, wherein the first sensor array comprises a first number of magnetoresistive sensing elements and the second sensor array comprises a second number of magnetoresistive sensing elements. [4] The magnetoresistive field sensor system of claim 3, wherein the first number of magnetoresistive sensing elements is different from the second number of magnetoresistive sensing elements. [5] A magnetoresistive field sensor system according to claim 3 or 4, wherein the first and second numbers of sensing elements are determined by a respective weighted value, each weighted value indicating the percentage of a sensor output provided by the respective array. [6] A magnetoresistive field sensor system according to any one of the preceding claims, wherein the first and second bias fields are induced by differential sensing layer bias. [7] The magnetoresistive field sensor system of claim 6, wherein the first and second sensor arrays comprise respective pairs of magnetoresistive sensing elements with soft-pinned antiparallel sensing layers. [8] A magnetoresistive field sensor system according to claim 7, wherein the sensing layers of the respective pairs of magnetoresistive sensing elements are soft-pinned by an antiferromagnetic layer. [9] A magnetoresistive field sensor system according to any one of claims 1 to 5, wherein the first and second bias fields are induced by one or more permanent magnets or an electromagnet. [10] A magnetoresistive field sensor system according to any one of the preceding claims, wherein each magnetoresistive field sensor further comprises a third array of magnetoresistive sensing elements having a third sensitivity, the third sensitivity being higher than the second sensitivity, each of the magnetoresistive elements in the third array comprising a sensing layer to which a third bias field is applied and a reference structure magnetized in the second reference magnetization direction. [11] The magnetoresistive field sensor system of claim 10, wherein the third sensor array comprises magnetoresistive elements having a third aspect ratio to thereby provide the third sensitivity. [12] A magnetoresistive field sensor system according to claim 10 or 11, wherein the third bias field is induced by differential sensing layer bias. [13] The magnetoresistive field sensor system of claim 12, wherein the third sensor array comprises respective pairs of magnetoresistive sensing elements with soft-pinned antiparallel sensing layers. [14] A magnetoresistive field sensor system according to claim 13, wherein the sensing layers of respective pairs of magnetoresistive sensing elements are soft-pinned by an antiferromagnetic layer. [15] A magnetoresistive field sensor system according to claim 10 or 11, wherein the third bias field is induced by one or more permanent magnets or an electromagnet. [16] A magnetoresistive field sensor system according to any one of the preceding claims, wherein the first reference magnetization direction defines the sensing direction of the one or more magnetoresistive field sensors. [17] A magnetoresistive field sensor system according to any one of the preceding claims, wherein the magnetoresistive field sensor system comprises a first set of magnetoresistive field sensors connected in a first Wheatstone bridge arrangement. [18] The magnetoresistive field sensor system of claim 17, further comprising a second set of magnetoresistive field sensors connected in a second Wheatstone bridge arrangement, the second Wheatstone bridge arrangement being rotated 90° relative to the first Wheatstone bridge arrangement. [19] A magnetoresistive field sensor system according to any one of the preceding claims, wherein the magnetoresistive sensing elements are tunnel magnetoresistive sensing elements or giant magnetoresistive sensing elements.

Images