MAGNETIC FIELD SENSOR, METHOD FOR PRODUCING SAME, AND METHOD FOR MEASURING A MAGNETIC FIELD

Abstract

The present disclosure relates to a magnetic field sensor, in particular an angle sensor, including a magnetoresistive sensor component and a spin-orbit torque, SOT, sensor component.

Claims

1. A magnetic field sensor comprising a magnetoresistive sensor component; and a spin-orbit torque (SOT) sensor component.

2. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component and the SOT sensor component are configured to measure an external magnetic field redundantly.

3. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component and the SOT sensor component are monolithically integrated on a common substrate.

4. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component and the SOT sensor component are integrated in a common layer stack composed of magnetic and nonmagnetic layers.

5. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component is galvanically isolated from the SOT sensor component .

6. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component is formed within a layer stack in layers above the SOT sensor component.

7. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component and the SOT sensor component are arranged in a common chip package.

8. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component has at least one Wheatstone bridge circuit.

9. The magnetic field sensor as claimed in claim 1, wherein the SOT sensor component has at least one Hall cross arrangement.

10. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component is configured as a first angle sensor and the SOT sensor component is configured as a second angle sensor, wherein the magnetoresistive sensor component and the SOT sensor component are each configuredin to measure sine component of an angle of rotation of a rotating external magnetic field and a cosine component of the angle of rotation of the rotating external magnetic field.

11. The magnetic field sensor as claimed in claim 1, wherein the SOT sensor component is configured to determine measurement drifts of the magnetoresistive sensor component.

12. The magnetic field sensor as claimed in claim 1, wherein the magnetoresistive sensor component has one or more of a giant magnetoresistance (GMR) sensor component or a tunnel magnetoresistance (TMR) sensor component.

13. The magnetic field sensor as claimed in claim 1, wherein the SOT sensor component is formed from a ferromagnet/heavy metal heterostructure.

14. A method for measuring a magnetic field, comprising measuring the magnetic field using a magnetoresistive sensor component; and measuring the magnetic field using a spin-orbit torque (SOT) sensor component.

15. The method as claimed in claim 14, wherein measuring the magnetic field using the a magnetoresistive sensor component includes measuring, using the a magnetoresistive sensor component, a sine component of an angle of rotation of the magnetic field and a cosine component of the angle of rotation of the magnetic field; and wherein measuring the magnetic field using the SOT sensor component includes measuring, using the SOT sensor component, the sine component of the angle of rotation of the magnetic field and the cosine component of the angle of rotation of the magnetic field.

16. The method as claimed in claim 14, further comprising: correcting a measurement shift over a lifetime of the magnetoresistive sensor component using the SOT sensor component.

17. A method for producing a magnetic field sensor comprising forming a magnetoresistive sensor component on a substrate; and forming a spin-orbit torque (SOT) sensor component on the substrate.

18. The method (60) as claimed in claim 17, wherein the magnetoresistive sensor component and the SOT sensor component are formed in a common layer stack composed of magnetic and nonmagnetic layers.

19. The method as claimed in claim 17, wherein the magnetoresistive sensor component is galvanically isolated from the SOT sensor component by an MgO layer.

20. The method as claimed in claim 17, wherein the magnetoresistive sensor component is formed within a layer stack in layers above the SOT sensor component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Some examples of devices and/or methods are explained in greater detail merely by way of example below with reference to the accompanying figures, in which:

[0033] FIG. 1 shows a magnetic angle sensor in accordance with the present disclosure;

[0034] FIG. 2 shows a layer stack comprising an MR sensor component and a SOT sensor component;

[0035] FIG. 3 shows a layer stack comprising an SOT sensor component and two series-connected MR sensor components;

[0036] FIG. 4 shows a contacting concept for an SOT sensor component;

[0037] FIG. 5 shows an SOT cosine Hall cross and an SOT sine Hall cross; and

[0038] FIG. 6 shows a method for producing an angle sensor in accordance with the present disclosure.

DETAILED DESCRIPTION

[0039] Some examples will now be described more thoroughly with reference to the accompanying figures. However, further possible examples are not restricted to the features of these implementations described in detail. These may have modifications of the features and counterparts and alternatives to the features. Furthermore, the terminology used herein for describing specific examples is not intended to be limiting for further possible examples.

[0040] Throughout the description of the figures, identical or similar reference signs refer to identical or similar elements or features which can be implemented in each case identically or else in modified form, while they provide the same or a similar function. In the figures, furthermore, the thicknesses of lines, layers and/or regions may be exaggerated for elucidation purposes.

[0041] If two elements A and B are combined using an “or”, this should be understood such that all possible combinations are disclosed, e.g. only A, only B, and A and B, unless expressly defined otherwise in an individual case. As alternative wording for the same combinations, it is possible to use “at least from A and B” or “A and/or B”. That applies equivalently to combinations of more than two elements.

[0042] If a singular form, e.g. “a, an” and “the” is used and the use of only a single element is defined neither explicitly nor implicitly as obligatory, further examples can also use a plurality of elements in order to implement the same function. If a function is described below as being implemented using a plurality of elements, further examples can implement the same function using a single element or a single processing entity. Furthermore, it goes without saying that the terms “comprises”, “comprising”, “has” and/or “having” in their usage 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 the addition of one or more other features, integers, steps, operations, processes, elements, components and/or a group thereof.

[0043] FIG. 1 shows a magnetic angle sensor 10 in accordance with one example implementation of the present disclosure. The magnetic angle sensor 10 comprises an MR sensor component 12 and an SOT sensor component 14. Both the MR sensor component 12 and the SOT sensor component 14 can each be configured to measure an angle of a rotating external magnetic field 16 and to output corresponding angle signals. In this case, both sensor components 12, 14 are configured to measure the same external rotating magnetic field 16.

[0044] The magnetic angle sensor 10 can be a dual-die angle sensor, in which MR sensor component 12 and SOT sensor component 14 are provided on different semiconductor dies in a common chip package 18. In some implementations, the magnetic angle sensor 10 is a single-die angle sensor, in which MR sensor component 12 and SOT sensor component 14 are provided on a single semiconductor die, e.g. are also fabricated monolithically on a common semiconductor substrate jointly in a common semiconductor fabrication process. In accordance with both concepts, the MR sensor component 12 and the SOT sensor component 14 can be provided in a common chip package 18 and can thus form a redundantly constructed magnet angle sensor 10 having two angle sensor components for measuring the rotating magnetic field 16.

[0045] In principle, AMR, GMR, or TMR sensor components are suitable as the MR sensor component 12. In some implementations, the MR sensor component 12 is configured as a GMR or TMR sensor component, since an inherent lifetime drift of the GMR or TMR sensor component 12 can then be compensated for by the SOT sensor component 14, which is more stable in this regard.

[0046] GMR or TMR sensor components may be formed on a layer stack composed of magnetic and nonmagnetic layers on a (semiconductor) substrate. In this case, one part of the layer stack is formed by a so-called reference system having a fixed reference magnetization, and another part by a free layer, the magnetization of which changes with the external magnetic field 16 depending on the angle of rotation thereof. An electrical resistance of the MR sensor component changes depending on the direction or the angle of the magnetization of the free layer with respect to the reference magnetization.

[0047] In the case of the single-die concept, the SOT sensor component 14 can additionally be integrated in the MR layer stack by the SOT sensor component 14 being formed in layers above or below the layer stack of the MR sensor component 12. However, it is also conceivable to form the SOT sensor component 14 laterally or horizontally next to the MR sensor component 12 on the common (semiconductor) substrate.

[0048] FIG. 2 shows an example layer stack 20 in which the MR sensor component 12 and the SOT sensor component 14 are formed jointly. In the example shown, the MR sensor component 12 is a TMR sensor component. However, a similar integration concept also applies to a GMR sensor component.

[0049] The TMR layer stack comprises at the top a magnetic layer 21, the free layer (FL), an underlying spacer layer 22 (e.g. MgO) and a reference system 23 lying in turn under the spacer layer 22. Typical materials for the FL layer 21 and the reference system 23 are Ni, Co, Fe and their alloys such as NiFe, CoFe or CoFeB. An electrode 24 (e.g. a Cu layer) of the TMR sensor component 12, the electrode being situated under the reference system 23, can be used to connect two TMR resistance elements of a (Wheatstone) bridge circuit from below. A top electrode of a TMR resistance element can be brought into contact for example with the respective FL layer 21 (see FIG. 3). This results in a so-called CPP configuration for the TMR resistance elements of the MR sensor component 12.

[0050] The SOT sensor component 14 can be contacted from below for example with the aid of through contacts (through a substrate). The SOT sensor component 14 can comprise two layers 26, 27 below the TMR layer stack or the electrode 24, a (ferro)magnetic layer 26 (Ni, Co, Fe, NiFe, CoFe or CoFeB) and an SO layer 27 underneath. The magnetic layer 26 has the same function as the FL layer 21 of the MR sensor component 12. The SO layer 27 can comprise heavy metals, such as e.g. Pt, W, Ta, etc. Although the entire layer stack 20 can be deposited in a single step, the two sensors 12, 14 remain galvanically isolated by a thick lower magnesium oxide layer (MgO) 25 between the layers 24 and 26. FIGS. 3 and 4 show top via contacts 31 of the MR sensor component 12 and bottom via contacts 41 of the SOT sensor component 14. By virtue of the top electrodes 31 and the bottom electrode 24, a CPP configuration results for the MR sensor component 12. By virtue of the bottom electrodes 41, a CIP configuration results for the SOT sensor component 14.

[0051] The functional principle of an MR angle sensor will be described briefly. The MR sensor component 12 can comprise two Wheatstone bridges, namely a sine bridge and cosine bridge. All eight MR measuring resistors of these two bridges (four per bridge) are embodied physically identically and, in some implementations, in a circular fashion in order to reduce the shape anisotropy. However, a magnetization direction of the reference systems 23 in the resistors of the sine bridge is rotated by 90° (orthogonally) with respect to the cosine bridge. Respective voltage output signals of these bridges can be written as follows:

[00001]$V_{\sin }-V_{01}\sin \theta$

[00002]$V_{\cos }=V_{02}\cos \theta$

[00003]${\theta }_{sens}={\tan }^{-1}\left(\frac{V_{\sin }}{V_{\cos }}\right)$

[0052] In this case, θ denotes an angle between the magnetization of the free layer 21 and the reference layer 23. By measuring the voltage signals V.sub.sin and V.sub.cos, it is possible to calculate the angle θ of the applied magnetic field 16 in accordance with equation (3).

[0053] The functional principle of an SOT angle sensor will be described briefly. As is shown in FIG. 5, the SOT sensor component 14 can comprise two identically configured rectangular Hall crosses 50-sin, 50-cos, one of which functions as a sine signal transmitter and the other as a cosine signal transmitter. The functioning of such an SOT angle sensor is described in detail for example in Luo et al., “Magnetic angular position sensor enabled by spin-orbit torque”, Appl. Phys. Lett. 112, 262405 (2018). The spin-orbit torque (SOT) is induced by the spin-orbit interaction or the Rashba effect at the interface of dissimilar materials, that is to say the interface between the layers 26, 27. The Hall crosses 50-sin, 50-cos are fabricated from a ferromagnet/heavy metal heterostructure 26, 27 and are arranged together with the MR resistance elements of the MR angle sensor 12 in the layer stack 20 on a common (semiconductor) substrate. In contrast to the MR sensor component 12, the SOT sensor component 14 comprising the Hall crosses 50-sin, 50-cos has only one (ferro)magnetic layer 26, which is analogous to the free layer 21 of the MR sensor component 12. The orthogonal current flow directions x, y in the two Hall crosses 50-sin, 50-cos make them sensitive to the orthogonal components x, y of the external magnetic field 16 in the x-y-plane. The current flow generates a sinusoidal signal having a periodicity of 180° on account of the planar Hall effect (PHE) and the anomalous Hall effect (AHE). A differential sine or cosine signal (periodicity 360°) is generated by virtue of current flowing in opposite directions. The signals thus obtained can be used for evaluating the angle θ of the magnetic field 16 in the x-y-plane using the same equations (equ. 1-3).

[0054] The SOT sensor component 14 has an angle periodicity of 360° and has substantially no lifetime drift of its performance. However, an output signal requires complex post-processing in order to obtain the angle information. Therefore, a standalone SOT sensor is associated with a certain complexity. A combination of SOT technology with TMR/GMR technology means significant progress, however. In the case of the combined SOT and TMR/GMR sensor 10, the TMR/GMR sensor 12 functions as the main sensor, while the SOT sensor 14 is used for evaluating the phase shifts during the lifetime. Compensation of the drifts makes it possible to maintain the performance of the TMR/GMR sensor 12 over the entire lifetime. The integrated sensor 10 will therefore have similar capabilities to conventional GMR/TMR sensors, but with a significantly better performance during its lifetime.

[0055] In summary, example implementations of the present disclosure concern monolithic integration of SOT sensors with GMR or TMR sensors in a single-stack coating process. The production of the combined sensor 10 does not require a new integration concept and is therefore cost-effective in comparison with the dual-die sensor concept. FIG. 6 shows a schematic flow diagram of a corresponding production method 60.

[0056] The method 60 for producing the magnetic field sensor 10 comprises forming 61 an MR sensor component 12 on a substrate and forming 62 an SOT sensor component 14 on the substrate. In this case, the MR sensor component 12 and the SOT sensor component 14 can be monolithically integrated on the substrate, for example in the form of the layer stack 20.

[0057] Although the detailed description has been given in regard to angle sensors, it will be apparent to the person skilled in the art that the proposed concept is also applicable to other applications of magnetic field sensors in which a redundant magnetic field measurement is advantageous.

[0058] The aspects and features that have been described in association with a specific one of the examples above can also be combined with one or more of the further examples in order to replace an identical or similar feature of this example or in order additionally to introduce the feature into the further example.

[0059] It furthermore goes without saying that the disclosure of a plurality of steps, processes, operations or functions disclosed in the description or the claims should not be interpreted as being mandatorily in the order described, unless this is explicitly indicated or absolutely necessary for technical reasons in an individual case. Therefore, the preceding description does not limit the implementation of a plurality of steps or functions to a specific order. Furthermore, in further examples, an individual step, an individual function, an individual process or an individual operation can include a plurality of partial steps, partial functions, partial processes or partial operations and/or be subdivided into them.

[0060] Where some aspects in the preceding sections have been described in association with the device or a system, these aspects should also be understood as a description of the corresponding method. In this case, for example, a block, a device or a functional aspect of a device or of the system can correspond to a feature, for instance a method step, of the corresponding method. Analogously thereto, aspects described in association with a method should also be understood as a description of a corresponding block, a corresponding element, a property or a functional feature of a corresponding device or a corresponding system.

[0061] The claims that follow are hereby incorporated in the detailed description, where each claim can be representative of a separate example by itself. Furthermore, it should be taken into consideration that - although a dependent claim refers in the claims to a specific combination with one or more other claims - other examples can also encompass a combination of the dependent claim with the subject of any other dependent or independent claim. Such combinations are hereby explicitly proposed, provided that in an individual case no indication is given that a specific combination is not intended. Furthermore, features of a claim are also intended to be included for any other independent claim, even if this claim is not directly defined as being dependent on this other independent claim.