magnetoresistive sensor

Abstract

This invention provides a magnetoresistive sensor, comprising: a first magnetic tunnel junction; and a second magnetic tunnel junction electrically connected to the first magnetic tunnel junction; the first and second magnetic tunnel junctions each have a first length in a first direction, and the free layers of the first and second magnetic tunnel junctions each have a second length in a second direction, the first and second directions being perpendicular to each other, and the second direction being the thickness direction of the first and second magnetic tunnel junctions; the first and second lengths of the first magnetic tunnel junction have a first ratio, and the first and second lengths of the second magnetic tunnel junction have a second ratio, wherein the first ratio is greater than the second ratio. This application solves the problem that existing magnetoresistive sensors are difficult to use for leakage current and low current monitoring while ensuring a wide measurement range.

Description

Technical Field

[0001] This invention relates to the field of magnetoresistive sensor technology, and more specifically, to a magnetoresistive sensor. Background Technology

[0002] Tunnel magnetoresistive (TMR) sensors, characterized by high sensitivity, low power consumption, and low temperature drift, represent the mainstream development direction in magnetic sensing. They have a broad application base in industrial automation, automotive electronics, and new energy fields. Specifically, in the new energy and electric vehicle sectors, contactless current measurement based on TMR has received widespread attention and is already in extensive industrial use. Its core principle is that the magnetic field generated by the current acts on the sensing layer (free layer) of the magnetic tunnel junction in the TMR magnetic sensor, changing its direction and thus altering the resistance.

[0003] However, no sensor component can simultaneously possess both high sensitivity and a wide measurement range. For example, while Hall sensors have a very wide magnetic field measurement range (up to Tesla's), their sensitivity is relatively low, making them difficult to use for magnetic field detection below 10 Oe; and while TMR magnetic sensors have high sensitivity, their detection range is often below 100 Oe.

[0004] In recent years, novel Z-axis sensitive TMR magnetic sensors have gradually found applications, offering a wider magnetic field response range. Z-axis sensitive TMR magnetic sensors typically fix the reference layer magnetization direction in the out-of-plane direction (z-axis), while the free layer magnetization direction can rotate with the external magnetic field. Furthermore, in the ground state, the free layer magnetization orientation is in the in-plane direction (xy plane). Although this cross structure exhibits z-axis sensitivity, the free layer, with its in-plane magnetization direction in the ground state, possesses a large anisotropic field (H0). k It requires a large out-of-plane magnetic field to pull it to rotate outwards, thus it cannot maintain a high sensitivity. Therefore, it is difficult to use for leakage current and low current monitoring. Summary of the Invention

[0005] The main objective of this invention is to provide a magnetoresistive sensor to solve the problem that existing magnetoresistive sensors are difficult to use for leakage current and low current monitoring while ensuring a wide measurement range.

[0006] To achieve the above objectives, this application provides a magnetoresistive sensor, comprising: a first magnetic tunnel junction; a second magnetic tunnel junction electrically connected to the first magnetic tunnel junction; the first and second magnetic tunnel junctions each having a first length in a first direction, and the free layers of the first and second magnetic tunnel junctions each having a second length in a second direction, the first direction being perpendicular to the second direction, and the second direction being the thickness direction of the first and second magnetic tunnel junctions; the first length and the second length of the first magnetic tunnel junction having a first ratio, and the first length and the second length of the second magnetic tunnel junction having a second ratio, wherein the first ratio is greater than the second ratio.

[0007] Optionally, the second length of the first magnetic tunnel junction is equal to the second length of the second magnetic tunnel junction.

[0008] Optionally, the first ratio is greater than 10.

[0009] Optionally, the second ratio is less than 2.

[0010] Optionally, the first magnetic tunnel junction and the second magnetic tunnel junction are obtained by etching the same stacked film layer.

[0011] Optionally, the magnetization direction of the free layer of the first magnetic tunnel junction and the magnetization direction of the free layer of the second magnetic tunnel junction are parallel to the first direction, respectively, and the magnetization direction of the reference layer of the first magnetic tunnel junction and the magnetization direction within the reference layer of the second magnetic tunnel junction are parallel to the second direction, respectively.

[0012] Optionally, the magnetoresistive sensor includes a first sensing unit and a second sensing unit electrically connected. The first sensing unit includes a plurality of first magnetic tunnel junctions, and the second sensing unit includes a plurality of second magnetic tunnel junctions. The plurality of first magnetic tunnel junctions are connected in series and / or in parallel, and the plurality of second magnetic tunnel junctions are connected in series and / or in parallel.

[0013] Optionally, the magnetization direction of the free layer of each first magnetic tunnel junction is parallel to the magnetization direction of the free layer of each second magnetic tunnel junction, and the magnetization direction of the reference layer of each first magnetic tunnel junction is parallel to the magnetization direction of the reference layer of each second magnetic tunnel junction.

[0014] Optionally, the multiple first magnetic tunnel structures form a Wheatstone bridge structure; and / or, the multiple second magnetic tunnel structures form a Wheatstone bridge structure.

[0015] Optionally, the plurality of first magnetic tunnel junctions and the plurality of second magnetic tunnel junctions form a Wheatstone bridge structure, and the first magnetic tunnel junctions and the second magnetic tunnel junctions are two adjacent arms of the Wheatstone bridge structure.

[0016] Applying the technical solution of this invention, the first magnetic tunnel junction and the second magnetic tunnel junction each have a first length in a first direction, and the free layer of the first magnetic tunnel junction and the free layer of the second magnetic tunnel junction each have a second length in a second direction. The first length and the second length of the first magnetic tunnel junction have a first ratio, and the first length and the second length of the second magnetic tunnel junction have a second ratio, with the first ratio being greater than the second ratio. The first direction is perpendicular to the second direction, and the second direction is the thickness direction of the first and second magnetic tunnel junctions. Based on this, the first magnetic tunnel junction has a wide measurement range, and the second magnetic tunnel junction has high sensitivity. Therefore, the magnetoresistive sensor of this application, having both the electrically connected first and second magnetic tunnel junctions, can possess both a wide measurement range and high sensitivity. Thus, this application solves the problem that existing magnetoresistive sensors are difficult to use for leakage current and small current monitoring while ensuring a wide measurement range. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A schematic diagram showing the relationship between δN (shape anisotropy coefficient) and t / D (the ratio of the second length to the first length) of a magnetic tunnel junction is shown.

[0019] Figure 2 A schematic diagram of the magnetic field response curves of a first magnetic tunnel junction and a second magnetic tunnel junction according to an embodiment of the present invention is shown.

[0020] Figure 3 A cross-sectional structural schematic diagram of a first magnetic tunnel junction according to an embodiment of the present invention is shown;

[0021] Figure 4 A cross-sectional structural schematic diagram of a second magnetic tunnel junction according to an embodiment of the present invention is shown;

[0022] Figure 5 A schematic diagram showing the arrangement of a plurality of first magnetic tunnel junctions in a magnetoresistive sensor according to a first embodiment of the present invention is shown;

[0023] Figure 6 A schematic diagram showing the arrangement of a plurality of second magnetic tunnel junctions in a magnetoresistive sensor according to a first embodiment of the present invention is shown;

[0024] Figure 7 A schematic diagram of a Wheatstone bridge structure composed of a plurality of first magnetic tunnels of a magnetoresistive sensor according to a second embodiment of the present invention is shown.

[0025] Figure 8 A schematic diagram of a Wheatstone bridge structure composed of a plurality of second magnetic tunnels of a magnetoresistive sensor according to a second embodiment of the present invention is shown.

[0026] Figure 9 A schematic diagram of a Wheatstone bridge structure composed of a plurality of first magnetic tunnel junctions and a plurality of second magnetic tunnel structures of a magnetoresistive sensor according to a third embodiment of the present invention is shown.

[0027] Figure 10 A schematic diagram of the magnetic field response curve of a magnetoresistive sensor according to a third embodiment of the present invention is shown.

[0028] The above figures include the following reference numerals:

[0029] 10. Reference layer; 20. Spacer layer; 30. Free layer. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] As described in the background section, existing magnetoresistive sensors often cannot simultaneously achieve both high sensitivity and a wide measurement range. For example, Z-axis sensitive TMR magnetoresistors typically fix the magnetization direction of the reference layer in the out-of-plane direction (z-axis), while the magnetization direction of the free layer can rotate with an external magnetic field. Furthermore, in the ground state, the magnetization orientation of the free layer is in the in-plane direction (xy plane). Although this cross structure has z-axis sensitivity, the free layer with an in-plane magnetization direction in the ground state has a large anisotropic field (Hk), requiring a large out-of-plane magnetic field to pull it to rotate outwards. Therefore, it cannot maintain high sensitivity. Therefore, it is difficult to use it for leakage current and low current monitoring. Therefore, there is an urgent need for a new magnetoresistive sensor that can be used for leakage current and low current monitoring while having a wide range.

[0034] In some optional embodiments, a magnetoresistive sensor is provided, comprising: a first magnetic tunnel junction; a second magnetic tunnel junction electrically connected to the first magnetic tunnel junction; the first and second magnetic tunnel junctions each having a first length in a first direction, and the free layers of the first and second magnetic tunnel junctions each having a second length in a second direction, the first direction being perpendicular to the second direction, and the second direction being the thickness direction of the first and second magnetic tunnel junctions; the first length and the second length of the first magnetic tunnel junction having a first ratio, and the first length and the second length of the second magnetic tunnel junction having a second ratio, wherein the first ratio is greater than the second ratio.

[0035] Specifically, both the first magnetic tunnel junction and the second magnetic tunnel junction can be Z-axis sensitive magnetic tunnel junctions. That is, the second direction mentioned above can be the Z-axis direction.

[0036] Furthermore, the free layer of a Z-axis sensitive magnetic tunnel junction flips under the influence of a perpendicularly applied magnet, thereby altering the tunnel magnetoresistance. It is important to note that the change in tunnel magnetoresistance is directly related to the deflection angle of the free layer's magnetization direction. Moreover, the magnetic field corresponding to the free layer's deflection from the in-plane direction to the perpendicular direction (saturation) is determined by the demagnetizing field, i.e., δN*4πM. S , of which M S This represents the saturation magnetization. For example... Figure 1 As shown, the vertical axis is δN (shape anisotropy coefficient), and the horizontal axis is t / D (the ratio of the second length to the first length). In the critical case, when the first length of the magnetic tunnel junction (first magnetic tunnel junction or second magnetic tunnel junction) in the first direction is less than the second length of the free layer of the magnetic tunnel junction in the second direction, the free layer of the magnetic tunnel junction will tend to be arranged along the Z-axis direction without an external magnetic field.

[0037] For the first magnetic tunnel junction of this application, its first length in the first direction can be much greater than the second length of its free layer in the second direction; for the second magnetic tunnel junction of this application, its first length in the first direction can be close to the second length of its free layer in the second direction. Based on this, according to the relevant theory of magnet demagnetization, the δN of the second magnetic tunnel junction will be significantly smaller than that of the first magnetic tunnel junction, thus the free layer of the second magnetic tunnel junction will deflect along the in-plane direction to the magnetic field value (δN*4πM) corresponding to the vertical direction (saturation). S The free layer of the second magnetic tunnel junction will be significantly reduced. As a result, compared with the free layer of the first magnetic tunnel junction, the free layer of the second magnetic tunnel junction is more likely to be arranged along the Z-axis in the absence of an external magnetic field. Consequently, the free layer of the second magnetic tunnel junction can be flipped under the influence of a smaller vertical external magnetic field, resulting in higher sensitivity of the magnetoresistive sensor.

[0038] Applying the technical solution of this invention, the first magnetic tunnel junction and the second magnetic tunnel junction each have a first length in a first direction, and the free layer of the first magnetic tunnel junction and the free layer of the second magnetic tunnel junction each have a second length in a second direction. The first length and the second length of the first magnetic tunnel junction have a first ratio, and the first length and the second length of the second magnetic tunnel junction have a second ratio. The first ratio is greater than the second ratio. The first direction is perpendicular to the second direction, and the second direction is the thickness direction of the first and second magnetic tunnel junctions. Based on this, the first magnetic tunnel junction has a wide measurement range, and the second magnetic tunnel junction has high sensitivity. Therefore, the magnetoresistive sensor of this application, having both the electrically connected first and second magnetic tunnel junctions, can possess both a wide measurement range and high sensitivity. Thus, this application solves the problem that existing magnetoresistive sensors are difficult to use for leakage current and small current monitoring while ensuring a wide measurement range. For example, Figure 2 As shown, the vertical axis represents the resistance (R) of the first magnetic tunnel junction and the second magnetic tunnel junction, and the horizontal axis represents the response range of the independent vertical magnetic field (H) of the first magnetic tunnel junction (first tunnel junction) and the second magnetic tunnel junction (second tunnel junction).

[0039] Optionally, the above-mentioned magnetoresistive sensor is a giant magnetoresistive sensor or a tunneling magnetoresistive sensor.

[0040] Furthermore, it is known to those skilled in the art that, as Figure 3 (The arrows in the diagram indicate the direction of magnetization) and Figure 4 As shown (the arrows in the figure indicate the magnetization direction), the first magnetic tunnel junction and the second magnetic tunnel junction may respectively include a reference layer 10, a spacer layer 20 and a free layer 30 stacked together.

[0041] Optionally, the constituent materials of the reference layer 10 include, but are not limited to, one or more of CoFeB, FeB and CoFe forming a multilayer film structure with one or more of Co / Pt multilayer film, Co / Pd multilayer film and Co / Ni multilayer film.

[0042] Optionally, the spacer layer 20 may be composed of materials including, but not limited to, MgO, Al2O3, HfO2, MgAlO, CuO, and Cu. Optionally, the thickness of the spacer layer 20 may be between 0.5 and 3 nm.

[0043] Optionally, the constituent materials of the free layer 30 include, but are not limited to, a multi-element alloy composed of two or more elements selected from Co, Fe, Ni, Cr, V, Mn, C, and B. Optionally, the thickness of the free layer 30 is between 2 and 100 nm.

[0044] In some alternative implementations, in order to give the first magnetic tunnel junction a large magnetic response width, the first ratio is greater than 10.

[0045] Specifically, in this embodiment, the ratio of the first length of the first magnetic tunnel junction in the first direction to the second length of the free layer of the first magnetic tunnel junction in the second direction is greater than 10. This allows the free layer of the first magnetic tunnel junction to have a larger anisotropic field in the in-plane direction, requiring a stronger out-of-plane magnetic field to rotate the magnetization direction of the free layer to a perpendicular state. Therefore, the magnetoresistive sensor has a larger range and can detect a stronger magnetic field.

[0046] In some alternative implementations, in order to reduce the anisotropic field of the free layer of the second magnetic tunnel junction and lower the saturation magnetic field value, so that the second magnetic tunnel junction has a more sensitive magnetic response capability, the second ratio is less than 2.

[0047] Specifically, in this embodiment, the ratio of the first length of the second magnetic tunnel junction in the first direction to the second length of the free layer of the second magnetic tunnel junction in the second direction is less than 2. This allows the free layer to be more inclined to align in the vertical direction when there is no external magnetic field. Therefore, the second magnetic tunnel junction is more sensitive to smaller out-of-plane magnetic fields and can detect weaker magnetic field changes, thereby improving the sensitivity of the magnetoresistive sensor.

[0048] In some alternative implementations, in order for the first magnetic tunnel junction and the second magnetic tunnel junction to have similar magnetization behavior under the same magnetic field strength, the second length of the first magnetic tunnel junction is equal to the second length of the second magnetic tunnel junction.

[0049] Furthermore, by setting the second length of the free layer in the second direction of the first magnetic tunnel junction to be equal to the second length of the free layer in the second direction of the second magnetic tunnel junction, the process can be simplified, allowing the free layers of the first and second magnetic tunnel junctions to use the same deposition and processing conditions, thereby helping to improve production efficiency and reduce costs. Moreover, the performance of the first and second magnetic tunnel junctions can be better matched.

[0050] Furthermore, by making the second length of the free layer of the first magnetic tunnel junction equal to the second length of the free layer of the second magnetic tunnel junction in the second direction, more design freedom can be provided for the magnetoresistive sensor. For example, when adjusting the sensitivity and range of the magnetoresistive sensor, only the first length of the first magnetic tunnel junction in the first direction and the first length of the second magnetic tunnel junction in the first direction need to be changed, without the need to additionally adjust the thickness of the free layers of the first and second magnetic tunnel junctions, thus simplifying the design process.

[0051] In some alternative embodiments, in order to make the first magnetic tunnel junction and the second magnetic tunnel junction have exactly the same properties at the material level, the first magnetic tunnel junction and the second magnetic tunnel junction are obtained by etching the same stacked film layer.

[0052] Specifically, in the above embodiments, using the same material for the first magnetic tunnel junction and the second magnetic tunnel junction can make the behavior of the first magnetic tunnel junction and the second magnetic tunnel junction more consistent when responding to a magnetic field.

[0053] In some alternative embodiments, in order for the first magnetic tunnel junction and the second magnetic tunnel junction to be used to detect an external magnetic field in the Z-axis direction, the magnetization direction of the free layer of the first magnetic tunnel junction and the magnetization direction of the free layer of the second magnetic tunnel junction are respectively parallel to a first direction, and the magnetization direction of the reference layer of the first magnetic tunnel junction and the magnetization direction within the reference layer of the second magnetic tunnel junction are respectively parallel to a second direction.

[0054] Furthermore, the magnetoresistive sensor includes an electrically connected first sensing unit (such as...) Figure 5 As shown in the figure, the arrows indicate the magnetization direction) and the second sensing unit (such as... Figure 6 As shown in the figure (the arrows indicate the magnetization direction), the first induction unit includes multiple first magnetic tunnel junctions 100 (e.g., ...). Figure 5 As shown), the second sensing unit includes multiple second magnetic tunnel junctions 200 (such as...). Figure 6 As shown, multiple first magnetic tunnel junctions 100 are connected in series and / or in parallel, and multiple second magnetic tunnel junctions 200 are connected in series and / or in parallel. The series or parallel connection is achieved by connecting the upper and lower metal layers of the magnetic tunnel junctions.

[0055] Of course, the first sensing region may also include only one first magnetic tunnel junction; the second sensing region may also include only one second magnetic tunnel junction.

[0056] In the above embodiments, the first sensing region includes multiple first magnetic tunnel junctions, thereby possessing a high critical magnetic field (anisotropic field) and providing a wide measurement range. The second sensing region includes multiple second magnetic tunnel junctions, thereby being sensitive to weak magnetic fields and enabling highly sensitive magnetic field detection. In summary, by integrating the first and second sensing regions into the magnetoresistive sensor, the entire detection range from weak to strong magnetic fields can be covered simultaneously without sacrificing sensitivity or range. Furthermore, the series or parallel connection of multiple first magnetic tunnel junctions in the first sensing region enhances the signal output, improves the signal-to-noise ratio of the magnetoresistive sensor, and reduces the impact of potential performance fluctuations of a single first magnetic tunnel junction on the entire magnetoresistive sensor, thus enhancing its stability and reliability. Similarly, the series or parallel connection of multiple second magnetic tunnel junctions in the second sensing region enhances the signal output, improves the signal-to-noise ratio of the magnetoresistive sensor, and reduces the impact of potential performance fluctuations of a single second magnetic tunnel junction on the entire magnetoresistive sensor, thus enhancing its stability and reliability.

[0057] In some alternative embodiments, the magnetization direction of the free layer of each first magnetic tunnel junction in the first sensing region is parallel to the magnetization direction of the free layer of each second magnetic tunnel junction in the second sensing region, and the magnetization direction of the reference layer of each first magnetic tunnel junction in the first sensing region is parallel to the magnetization direction of the reference layer of each second magnetic tunnel junction in the second sensing region.

[0058] It is understandable that the magnetization directions of the multiple first magnetic tunnel junctions in the first sensing region and the multiple second magnetic tunnel junctions in the second sensing region are aligned. Therefore, when a magnetic field acts on the multiple first and multiple second magnetic tunnel junctions in the same direction, they will exhibit the same magnetoresistance change. This means that when the external magnetic field changes, the magnetic tunnel junctions in both the first and second sensing regions will produce a resistance change related to the direction of the magnetic field, thereby enhancing the overall output signal of the magnetoresistive sensor and helping to improve signal quality and signal-to-noise ratio.

[0059] Furthermore, the multiple first magnetic tunnel junctions in the first sensing region and the multiple second magnetic tunnel junctions in the second sensing region differ in size and magnetic field response characteristics. The consistency of the magnetization direction enables the first sensing region and the second sensing region to be seamlessly connected when measuring magnetic fields of different intensities, jointly providing continuous and high-precision detection from low magnetic fields to high magnetic fields.

[0060] In some alternative embodiments, the plurality of first magnetic tunnels in the first sensing region are structured as a Wheatstone bridge structure, such as... Figure 7 As shown (arrows in the figure indicate magnetization directions); and / or, multiple second magnetic tunnel structures in the second induction region form a Wheatstone bridge structure, such as... Figure 8 As shown (the arrows in the figure indicate the magnetization direction). It should be noted that the Wheatstone bridge structure has two input terminals (In+ and In-) and two output terminals (Out+ and Out-).

[0061] Specifically, in order to make the multiple first magnetic tunnel structures in the first sensing region form a Wheatstone bridge structure, the magnetization direction of the reference layer of a portion of the multiple first magnetic tunnel junctions in the first sensing region is antiparallel to the magnetization direction of the reference layer of another portion of the multiple first magnetic tunnel junctions.

[0062] It should be noted that the aforementioned portion of the first magnetic tunnel junction and the aforementioned other portion of the first magnetic tunnel junction each include at least two first magnetic tunnel junctions, and the magnetization direction of the reference layer of the aforementioned portion of the first magnetic tunnel junction and the magnetization direction of the reference layer of the aforementioned other portion of the first magnetic tunnel junction are respectively parallel to the Z-axis. For example, as shown... Figure 7 As shown, the magnetization direction of the reference layer of at least two first magnetic tunnel junctions (A and D) in one portion of the first magnetic tunnel junctions is upward along the Z-axis, while the magnetization direction of the reference layer of at least two first magnetic tunnel junctions (B and C) in another portion of the first magnetic tunnel junctions is downward along the Z-axis. Therefore, the at least two first magnetic tunnel junctions in one portion and the at least two first magnetic tunnel junctions in the other portion can constitute a Wheatstone bridge structure. Furthermore, the magnetization directions of the reference layers of the two first magnetic tunnel junctions on adjacent arms of the Wheatstone bridge structure are opposite.

[0063] Similarly, in order to make the multiple second magnetic tunnel structures in the second sensing region form a Wheatstone bridge structure, the magnetization direction of the reference layer of a portion of the multiple second magnetic tunnel junctions in the second sensing region is antiparallel to the magnetization direction of the reference layer of another portion of the multiple second magnetic tunnel junctions.

[0064] It should also be noted that the aforementioned portion of the second magnetic tunnel junction and the aforementioned portion of the second magnetic tunnel junction each include at least two second magnetic tunnel junctions, and the magnetization direction of the reference layer of the aforementioned portion of the second magnetic tunnel junction and the aforementioned portion of the second magnetic tunnel junction are respectively parallel to the Z-axis. For example, as shown... Figure 8As shown, the magnetization direction of the reference layer of at least two second magnetic tunnel junctions (B and C) in one portion of the second magnetic tunnel junctions is downward along the Z-axis, while the magnetization direction of the reference layer of at least two second magnetic tunnel junctions (A and D) in another portion of the second magnetic tunnel junctions is upward along the Z-axis. Therefore, at least two second magnetic tunnel junctions in one portion and at least two second magnetic tunnel junctions in the other portion can constitute a Wheatstone bridge structure. Furthermore, the magnetization directions of the reference layers of the two second magnetic tunnel junctions on adjacent arms of the Wheatstone bridge structure are opposite.

[0065] In some alternative implementations, such as Figure 9 As shown, a plurality of first magnetic tunnel junctions (A and D) in the first sensing region and a plurality of second magnetic tunnel junctions (B and C) in the second sensing region constitute a Wheatstone bridge structure, and the first magnetic tunnel junctions and the second magnetic tunnel junctions are two adjacent arms of the Wheatstone bridge structure.

[0066] In this embodiment, the plurality of first magnetic tunnel junctions in the first sensing region include at least two first magnetic tunnel junctions, and the plurality of second magnetic tunnel junctions in the second sensing region include at least two second magnetic tunnel junctions. Further, in order to form a Wheatstone bridge structure with the plurality of first magnetic tunnel junctions in the first sensing region and the plurality of second magnetic tunnel junctions in the second sensing region, the magnetization direction of the reference layer of the at least two first magnetic tunnel junctions in the first sensing region is opposite to the magnetization direction of the reference layer of the at least two second magnetic tunnel junctions in the second sensing region. Thus, one of the at least two first magnetic tunnel junctions and one of the at least two second magnetic tunnel junctions form a Wheatstone half-bridge structure, and the other of the at least two first magnetic tunnel junctions and the other of the at least two second magnetic tunnel junctions form a Wheatstone half-bridge structure. Furthermore, it is important to note that when the magnetic tunnel junction on one arm of the Wheatstone half-bridge structure is the aforementioned first magnetic tunnel junction, the magnetic tunnel junction on the other arm of the Wheatstone half-bridge structure adjacent to the aforementioned arm is the aforementioned second magnetic tunnel junction. It should be noted that each Wheatstone half-bridge in the Wheatstone bridge structure has one input terminal (In+ or In-) and one output terminal (Out+ or Out-).

[0067] For example, such as Figure 9As shown, the magnetization direction of the reference layer of at least two first magnetic tunnel junctions (A and D) in the first induction region is upward along the Z-axis, and the magnetization direction of the reference layer of at least two second magnetic tunnel junctions (B and C) in the second induction region is downward along the Z-axis. In this case, the at least two first magnetic tunnel junctions and the aforementioned at least two second magnetic tunnel junctions form at least two Wheatstone half-bridge structures. Specifically, a first Wheatstone half-bridge structure is formed by one of the at least two first magnetic tunnel junctions and one of the at least two second magnetic tunnel junctions. This first Wheatstone half-bridge structure includes two adjacent arms, with the magnetic tunnel junction on one arm being the aforementioned first magnetic tunnel junction and the magnetic tunnel junction on the other arm being the aforementioned second magnetic tunnel junction. A second Wheatstone half-bridge structure is formed by the other of the at least two first magnetic tunnel junctions and the other of the at least two second magnetic tunnel junctions. This second Wheatstone half-bridge structure includes two adjacent arms, with the magnetic tunnel junction on one arm being the aforementioned first magnetic tunnel junction and the magnetic tunnel junction on the other arm being the aforementioned second magnetic tunnel junction. Furthermore, it should be noted that when the first and second Wheatstone half-bridge structures constitute a Wheatstone bridge structure, the arm with the first magnetic tunnel junction in the first Wheatstone half-bridge structure needs to be adjacent to the arm with the second magnetic tunnel junction in the second Wheatstone half-bridge structure.

[0068] In summary, as Figure 10 As shown, the vertical axis represents the output (Out+ or Out-), and the horizontal axis represents the vertical magnetic field (H). Since the magnetoresistive sensor has both the first magnetic tunnel junction and the second magnetic tunnel junction, its magnetic field response range (vertical magnetic field H) can be consistent with the magnetic field response range of the first magnetic tunnel junction, and its magnetic field response sensitivity can be consistent with the sensitivity of the second magnetic tunnel junction.

[0069] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0070] Applying the technical solution of this invention, the first magnetic tunnel junction and the second magnetic tunnel junction each have a first length in a first direction, and the free layer of the first magnetic tunnel junction and the free layer of the second magnetic tunnel junction each have a second length in a second direction. The first length and the second length of the first magnetic tunnel junction have a first ratio, and the first length and the second length of the second magnetic tunnel junction have a second ratio, with the first ratio being greater than the second ratio. The first direction is perpendicular to the second direction, and the second direction is the thickness direction of the first and second magnetic tunnel junctions. Based on this, the first magnetic tunnel junction has a wide measurement range, and the second magnetic tunnel junction has high sensitivity. Therefore, the magnetoresistive sensor of this application, having both the electrically connected first and second magnetic tunnel junctions, can possess both a wide measurement range and high sensitivity. Thus, this application solves the problem that existing magnetoresistive sensors are difficult to use for leakage current and small current monitoring while ensuring a wide measurement range.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A magnetoresistive sensor, characterized in that, include: First magnetic tunnel junction; The second magnetic tunnel junction is electrically connected to the first magnetic tunnel junction. The first magnetic tunnel junction and the second magnetic tunnel junction each have a first length in a first direction, and the free layer of the first magnetic tunnel junction and the free layer of the second magnetic tunnel junction each have a second length in a second direction. The first direction is perpendicular to the second direction, and the second direction is the thickness direction of the first magnetic tunnel junction and the second magnetic tunnel junction. The first length and the second length of the first magnetic tunnel junction have a first ratio, and the first length and the second length of the second magnetic tunnel junction have a second ratio, wherein the first ratio is greater than the second ratio.

2. The magnetoresistive sensor according to claim 1, characterized in that, The second length of the first magnetic tunnel junction is equal to the second length of the second magnetic tunnel junction.

3. The magnetoresistive sensor according to claim 1, characterized in that, The first ratio is greater than 10.

4. The magnetoresistive sensor according to claim 1, characterized in that, The second ratio is less than 2.

5. The magnetoresistive sensor according to claim 1, characterized in that, The first magnetic tunnel junction and the second magnetic tunnel junction are obtained by etching the same stacked film layer.

6. The magnetoresistive sensor according to any one of claims 1 to 5, characterized in that, The magnetization direction of the free layer of the first magnetic tunnel junction and the magnetization direction of the free layer of the second magnetic tunnel junction are respectively parallel to the first direction, and the magnetization direction of the reference layer of the first magnetic tunnel junction and the magnetization direction within the reference layer of the second magnetic tunnel junction are respectively parallel to the second direction.

7. The magnetoresistive sensor according to claim 6, characterized in that, The magnetoresistive sensor includes a first sensing unit and a second sensing unit electrically connected. The first sensing unit includes a plurality of first magnetic tunnel junctions, and the second sensing unit includes a plurality of second magnetic tunnel junctions. The plurality of first magnetic tunnel junctions are connected in series and / or in parallel, and the plurality of second magnetic tunnel junctions are connected in series and / or in parallel.

8. The magnetoresistive sensor according to claim 7, characterized in that, The magnetization direction of the free layer of each first magnetic tunnel junction is parallel to the magnetization direction of the free layer of each second magnetic tunnel junction, and the magnetization direction of the reference layer of each first magnetic tunnel junction is parallel to the magnetization direction of the reference layer of each second magnetic tunnel junction.

9. The magnetoresistive sensor according to claim 6, characterized in that, The plurality of first magnetic tunnel structures form a Wheatstone bridge structure; and / or, the plurality of second magnetic tunnel structures form a Wheatstone bridge structure.

10. The magnetoresistive sensor according to claim 6, characterized in that, The plurality of first magnetic tunnel junctions and the plurality of second magnetic tunnel junctions form a Wheatstone bridge structure, and the first magnetic tunnel junctions and the second magnetic tunnel junctions are two adjacent arms of the Wheatstone bridge structure.

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