Tunnel magnetoresistance sensor and annealing method for tunnel magnetoresistance sensor

Abstract

Embodiments of the present application provide a tunnel magnetoresistance sensor and an annealing method of the tunnel magnetoresistance sensor. The tunnel magnetoresistance sensor comprises a first half-bridge circuit or a first full-bridge circuit. The first half-bridge circuit comprises one half-bridge structure, and the first full-bridge circuit comprises two parallel half-bridge structures. In the half-bridge structure, one bridge arm comprises a first number of first magnetic tunnel junctions and a second number of second magnetic tunnel junctions in series, and the first number is not equal to the second number. Another bridge arm comprises the second number of first magnetic tunnel junctions and the first number of second magnetic tunnel junctions in series. Diagonal bridge arms of the full-bridge circuit are the same. Long axes of the first magnetic tunnel junction and the second magnetic tunnel junction have a first included angle and a second included angle with a preset direction respectively. The long axes of the first magnetic tunnel junction and the second magnetic tunnel junction have opposite components in the preset direction. The first half-bridge circuit or the first full-bridge circuit is used for converting a magnetic signal of an external magnetic field into a first voltage signal, so as to realize single-chip integration of the tunnel magnetoresistance sensor.

Description

Technical Field

[0001] This application relates to the semiconductor field, and more particularly to a tunnel magnetoresistive sensor and an annealing method for the tunnel magnetoresistive sensor. Background Technology

[0002] Magnetoresistive magnetic sensors, such as tunnel magnetoresistive (TMR) sensors, are widely used in current detection, position detection, and magnetic field measurement due to their advantages such as high sensitivity, low power consumption, and miniaturization. Typical TMR sensors can employ half-bridge or full-bridge circuits. A half-bridge circuit consists of one half-bridge structure, while a full-bridge circuit consists of two parallel half-bridge structures. Each half-bridge structure includes two arms, and each arm contains one or more magnetic tunnel junctions (MTJs) connected in series. The resistance of the MTJ varies with the angle between the free layer magnetic moment direction and the fixed layer magnetic moment direction.

[0003] Tunnel magnetoresistive (TMG) sensors impose strict requirements on the pinning direction of the fixation layer of the magnetic tunnel junction in the bridge arm: typically, the pinning directions of the fixation layers of the TMG in adjacent bridge arms must be opposite. When the TMG senses an external magnetic field, the resistance values ​​of the TMG in adjacent bridge arms should change differently, thus converting the magnetic signal of the external magnetic field into a voltage signal output. However, in actual manufacturing processes, wafer-level overall annealing is usually required to set the pinning direction of the fixation layer. However, overall annealing tends to make the pinning directions of the fixation layers of the TMG in adjacent bridge arms tend to be consistent, resulting in similar resistance values ​​of the TMG in adjacent bridge arms, making it difficult to effectively convert the magnetic signal of the external magnetic field into a voltage signal output.

[0004] There are several solutions in the industry to achieve opposite pinning directions for the fixed layers of magnetic tunnel junctions in adjacent arms. For example, external magnetic flux structures or magnetic bias structures (such as soft magnetic focusing structures or permanent magnet bias structures) are used to apply local magnetic fields in different directions to adjacent arms. This approach increases the structural complexity and packaging cost of the tunnel magnetoresistive sensor and is not conducive to miniaturization and high integration. Alternatively, the film stack structure of the magnetic tunnel junction can be improved or laser local annealing or local heating-assisted processes can be used. These two methods are complex and it is difficult to guarantee yield and consistency. Another approach is to use a discrete manufacturing scheme, first manufacturing multiple devices with different pinning directions, and then combining them through packaging to form a tunnel magnetoresistive sensor. However, this approach cannot achieve true monolithic integration and is difficult to meet the requirements of high integration and miniaturization. Summary of the Invention

[0005] This application provides a tunnel magnetoresistive sensor and an annealing method for the tunnel magnetoresistive sensor, which enables monolithic integration of the tunnel magnetoresistive sensor without the need for an external magnetic flux gathering structure, a magnetic bias structure, a local annealing process, an improved film stack structure of the magnetic tunnel junction, or independent device manufacturing.

[0006] In a first aspect, embodiments of this application provide a tunnel magnetoresistive sensor, including: a first half-bridge circuit or a first full-bridge circuit, wherein the first half-bridge circuit includes a half-bridge structure, and the first full-bridge circuit includes two parallel half-bridge structures.

[0007] In the half-bridge structure of the first half-bridge circuit or the first full-bridge circuit, one bridge arm includes a first number of first magnetic tunnel junctions and a second number of second magnetic tunnel junctions connected in series, and the other bridge arm includes the second number of first magnetic tunnel junctions and the first number of second magnetic tunnel junctions connected in series, wherein the first number and the second number are not equal; the diagonal bridge arms of the full-bridge circuit are the same.

[0008] The major axis of the first magnetic tunnel junction has a first angle with a preset direction, and the major axis of the second magnetic tunnel junction has a second angle with the preset direction. The major axes of the first magnetic tunnel junction and the second magnetic tunnel junction have components with opposite directions in the preset direction.

[0009] The first half-bridge circuit or the first full-bridge circuit is used to convert the magnetic signal of the external magnetic field into a first voltage signal.

[0010] In some embodiments, the tunnel magnetoresistive sensor further includes: a second half-bridge circuit corresponding to the first half-bridge circuit, or a second full-bridge circuit corresponding to the first full-bridge circuit; the second half-bridge circuit includes a half-bridge structure, and the second full-bridge circuit includes two parallel half-bridge structures.

[0011] In the half-bridge structure of the second half-bridge circuit or the second full-bridge circuit, each bridge arm includes a third number of the first magnetic tunnel junctions and the third number of the second magnetic tunnel junctions.

[0012] The second half-bridge circuit or the second full-bridge circuit is used to convert the magnetic signal of the external magnetic field into a second voltage signal, and the tunnel magnetoresistive sensor outputs a third voltage signal based on the first voltage signal and the second voltage signal.

[0013] In some embodiments, the tunnel magnetoresistive sensor further includes: a computational circuit, wherein the input terminals of the computational circuit are respectively used to receive the first voltage signal and the second voltage signal, and the output terminal of the computational circuit is used to output the third voltage signal.

[0014] In some embodiments, the film structure of the first magnetic tunnel junction and the second magnetic tunnel junction, from top to bottom, includes:

[0015] Top electrode and / or metal layer, second antiferromagnetic layer, free layer, barrier layer, fixed layer, first antiferromagnetic layer, bottom electrode.

[0016] In some embodiments, a reference layer and a coupling layer are further included from top to bottom between the barrier layer and the fixed layer, and a seed layer is further included between the first antiferromagnetic layer and the bottom electrode.

[0017] The tunneling magnetoresistive sensor provided in this application embodiment is constructed by a first half-bridge circuit comprising a single half-bridge structure or a first full-bridge circuit comprising two parallel half-bridge structures. One arm of the half-bridge structure includes a first number of first magnetic tunnel junctions connected in series and a second number of second magnetic tunnel junctions, which is unequal to the first number. The other arm includes a second number of first magnetic tunnel junctions connected in series and a first number of second magnetic tunnel junctions. The major axes of the first and second magnetic tunnel junctions have opposite components in a predetermined direction. Furthermore, the diagonal arms of the full-bridge circuit have identical structures, enabling the first half-bridge circuit or... The first full-bridge circuit can convert the magnetic signal of the external magnetic field into a first voltage signal. Therefore, by the asymmetrical complementary distribution of the number of the first magnetic tunnel junctions and the second magnetic tunnel junctions in the adjacent bridge arms, and combined with the design that the long axis of the first magnetic tunnel junction and the long axis of the second magnetic tunnel junction have opposite components in the preset direction, the fixing direction of each magnetic tunnel junction in the adjacent bridge arms can be reversed by overall annealing. Thus, the tunnel magnetoresistive sensor can be monolithically integrated without relying on external magnetic flux gathering structure, magnetic bias structure, local annealing process, or improving the film stack structure of the magnetic tunnel junction or independently manufacturing devices.

[0018] Furthermore, the complementary arrangement of the first and second magnetic tunnel junctions in adjacent bridge arms effectively cancels out stray magnetic fields between the magnetic tunnel junctions, making the resistance change of each bridge arm more linear with the change of the external magnetic field, thereby further improving the detection accuracy and anti-interference capability of the tunnel magnetoresistive sensor. By adjusting the ratio of the first and second magnetic tunnel junctions in each bridge arm, the net magnetic response amplitude of the bridge arm can be adjusted, and the sensitivity can be adjusted proportionally to adapt to different ranges or different application scenarios.

[0019] In addition, the operational circuit can process the first voltage signal, effectively suppress noise, compensate for the inherent nonlinear error of the bridge arm, and support online calibration. This enables the output of the bridge arm to have both linear compensation capability and achieve high consistency, high linearity, low offset, adjustable sensitivity, and online calibration function, thereby enabling the construction of a high-performance, monolithically integrated tunnel magnetoresistive sensor structure.

[0020] Secondly, embodiments of this application provide an annealing method for a tunnel magnetoresistive sensor, applied to the tunnel magnetoresistive sensor as described in the first aspect, comprising:

[0021] The temperature of the tunnel magnetoresistive sensor is controlled to be greater than a first temperature, and a first magnetic field is applied along a first direction to pin the fixed layer magnetic moment of the first magnetic tunnel junction in the tunnel magnetoresistive sensor to a second direction, and to pin the fixed layer magnetic moment of the second magnetic tunnel junction in the tunnel magnetoresistive sensor to a third direction; wherein, the second direction has a first angle with a preset direction, the third direction has a second angle with the preset direction, and the fixed layer magnetic moment of the first magnetic tunnel junction and the fixed layer magnetic moment of the second magnetic tunnel junction have components with opposite directions in the preset direction;

[0022] The temperature of the tunnel magnetoresistive sensor is controlled to be greater than a second temperature and less than a first temperature. A second magnetic field is applied along the first direction to pin the free layer magnetic moment of the first magnetic tunnel junction to the first direction and to pin the free layer magnetic moment of the second magnetic tunnel junction to the first direction.

[0023] In some embodiments, after applying the first magnetic field along the first direction, the method further includes:

[0024] After the first magnetic field has been applied for a first duration, the application of the first magnetic field is stopped.

[0025] After a second duration following the cessation of applying the first magnetic field, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature.

[0026] In some embodiments, after applying the first magnetic field along the first direction, the method further includes:

[0027] After the first magnetic field has been applied for a first duration, the application of the first magnetic field is stopped.

[0028] The control of the temperature of the tunnel magnetoresistive sensor to be greater than a second temperature and less than the first temperature includes:

[0029] After a second duration following the cessation of applying the first magnetic field, the temperature of the tunnel magnetoresistive sensor is controlled to be greater than the second temperature and less than the first temperature.

[0030] In some embodiments, after applying the second magnetic field along the first direction, the method further includes:

[0031] After the second magnetic field is applied for a third duration, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature, and the application of the second magnetic field is stopped after the temperature of the tunnel magnetoresistive sensor reaches room temperature.

[0032] In some implementations, the magnetic field strength of the second magnetic field is less than that of the first magnetic field.

[0033] The tunnel magnetoresistive sensor and its annealing method provided in this application control the temperature of the tunnel magnetoresistive sensor to be higher than a first temperature and apply a first magnetic field along a first direction to pin the fixed layer magnetic moment of the first magnetic tunnel junction in the tunnel magnetoresistive sensor to a second direction and pin the fixed layer magnetic moment of the second magnetic tunnel junction in the tunnel magnetoresistive sensor to a third direction. The second direction has a first angle with a preset direction, and the third direction has a second angle with the preset direction. The major axis of the first magnetic tunnel junction and the major axis of the second magnetic tunnel junction have opposite components in the preset direction, which can realize differentiated reverse pinning of the fixed layer magnetic moments of the first and second magnetic tunnel junctions, effectively solving the problem of the consistency of the magnetic moment direction of the fixed layer in the magnetic tunnel junction in the traditional annealing process. On this basis, the temperature of the tunnel magnetoresistive sensor is controlled to be higher than a second temperature and lower than a first temperature, and a second magnetic field along the first direction is applied to pin the free layer magnetic moment of the first magnetic tunnel junction to the first direction and pin the free layer magnetic moment of the second magnetic tunnel junction to the first direction, thereby ensuring that the magnetic moment of the free layer is uniformly pinned to the first direction at a lower temperature.

[0034] Therefore, the tunnel magnetoresistive sensor provided in this application embodiment can be made so that the fixing direction of each magnetic tunnel junction in the adjacent bridge arm is opposite through overall annealing, so that it does not need to rely on external magnetic flux gathering structure, magnetic bias structure, local annealing process, nor does it need to improve the film stack structure of magnetic tunnel junction or manufacture devices independently.

[0035] Furthermore, the complementary arrangement of the first and second magnetic tunnel junctions in adjacent bridge arms effectively cancels out stray magnetic fields between the magnetic tunnel junctions, making the resistance change of each bridge arm more linear with the change of the external magnetic field, thereby further improving the detection accuracy and anti-interference capability of the tunnel magnetoresistive sensor. By adjusting the ratio of the first and second magnetic tunnel junctions in each bridge arm, the net magnetic response amplitude of the bridge arm can be adjusted, and the sensitivity can be adjusted proportionally to adapt to different ranges or different application scenarios.

[0036] In addition, the annealing process, which controls the temperature in stages and applies the external magnetic field in steps, can accurately distinguish the pinning process thresholds of the fixed layer and the free layer, effectively avoiding mutual interference between the high and low temperature annealing processes. This not only preserves the stable pinning effect of the magnetic moment of the fixed layer, but also makes the direction of the magnetic moment of the free layer controllable. Attached Figure Description

[0037] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0038] Figure 1 A schematic diagram of a full-bridge circuit provided in this application embodiment. Figure 1 ;

[0039] Figure 2 A schematic diagram of a half-bridge circuit provided in an embodiment of this application. Figure 1 ;

[0040] Figure 3 A schematic diagram illustrating the fixing layer stapling direction of each magnetic tunnel junction in an adjacent bridge arm, provided in an embodiment of this application;

[0041] Figure 4 A schematic diagram of a bridge arm provided in an embodiment of this application. Figure 1 ;

[0042] Figure 5 A schematic diagram of a bridge arm provided in an embodiment of this application. Figure 2 ;

[0043] Figure 6 A schematic diagram showing the angle between the major axis of a first magnetic tunnel junction and a preset direction, provided for an embodiment of this application;

[0044] Figure 7 A schematic diagram showing the angle between the major axis of a second magnetic tunnel junction and a preset direction, provided for an embodiment of this application;

[0045] Figure 8 A schematic diagram of the film structure of a first magnetic tunnel junction and a second magnetic tunnel junction provided in the embodiments of this application. Figure 1 ;

[0046] Figure 9 A schematic diagram of the film structure of a first magnetic tunnel junction and a second magnetic tunnel junction provided in the embodiments of this application. Figure 2 ;

[0047] Figure 10 This is a schematic diagram of a series connection of magnetic tunnel junctions in a bridge arm, provided in an embodiment of this application.

[0048] Figure 11 A schematic diagram of a half-bridge circuit provided in an embodiment of this application. Figure 2 ;

[0049] Figure 12 A schematic diagram of a full-bridge circuit provided in this application embodiment. Figure 2 ;

[0050] Figure 13 A schematic diagram of a bridge arm provided in an embodiment of this application. Figure 3 ;

[0051] Figure 14 A schematic diagram of a bridge arm provided in an embodiment of this application. Figure 4;

[0052] Figure 15 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 1 ;

[0053] Figure 16 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 2 ;

[0054] Figure 17 A schematic diagram of the fixed layer magnetic moment direction of a first magnetic tunnel junction provided in this application embodiment. Figure 1 ;

[0055] Figure 18 A schematic diagram of the fixed layer magnetic moment direction of a second magnetic tunnel junction provided in this application embodiment. Figure 1 ;

[0056] Figure 19 A schematic diagram of the fixed layer magnetic moment direction of a first magnetic tunnel junction provided in this application embodiment. Figure 2 ;

[0057] Figure 20 A schematic diagram of the fixed layer magnetic moment direction of a second magnetic tunnel junction provided in this application embodiment. Figure 2 ;

[0058] Figure 21 A schematic diagram of the free layer magnetic moment direction of a first magnetic tunnel junction provided in an embodiment of this application;

[0059] Figure 22 This is a schematic diagram of the free layer magnetic moment direction of a second magnetic tunnel junction provided in an embodiment of this application;

[0060] Figure 23 A schematic diagram showing the direction of the free layer magnetic moment and the direction of the fixed layer magnetic moment of a first magnetic tunnel junction provided in an embodiment of this application;

[0061] Figure 24 A schematic diagram showing the direction of the free layer magnetic moment and the direction of the fixed layer magnetic moment of a second magnetic tunnel junction provided in an embodiment of this application;

[0062] Figure 25 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 3 .

[0063] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0064] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0065] The tunnel magnetoresistive sensor may include a full-bridge circuit or a half-bridge circuit.

[0066] The full-bridge circuit includes two parallel half-bridge structures, such as... Figure 1 As shown, the first half-bridge structure 101 and the second half-bridge structure 102 are respectively. Each half-bridge structure includes two bridge arms connected in series. Among them, the bridge arms connected to the power supply are the first bridge arm 201 and the second bridge arm 202. In the figure, V is used as the reference. DD The power supply voltage is indicated; the bridge arms connected to the ground point GND are the third bridge arm 203 and the fourth bridge arm 204. That is, the first half-bridge structure 101 includes the first bridge arm 201 and the third bridge arm 203, the second half-bridge structure 102 includes the second bridge arm 202 and the fourth bridge arm 204, and the full-bridge circuit includes the first bridge arm 201, the second bridge arm 202, the third bridge arm 203, and the fourth bridge arm 204.

[0067] Each of the first bridge arm 201, the second bridge arm 202, the third bridge arm 203, and the fourth bridge arm 204 contains one or more magnetic tunnel junctions.

[0068] Reference Figure 1 As illustrated, the midpoint between the first bridge arm 201 and the third bridge arm 203 in the first half-bridge 101 is the output terminal Vout1, and the midpoint between the second bridge arm 202 and the fourth bridge arm 204 in the second half-bridge 102 is the output terminal Vout2. The voltage between the two output terminals Vout1 and Vout2 is the voltage signal obtained by converting the magnetic signal of the induced external magnetic field by the multiple magnetic tunnel junctions in the full-bridge circuit.

[0069] A half-bridge circuit includes a half-bridge structure, such as... Figure 2 As shown, the half-bridge structure includes a fifth bridge arm 301 and a sixth bridge arm 302. The figure illustrates the two output terminals Vout1 and Vout2 of the sixth bridge arm 302 as voltage signals. The voltage between the two output terminals Vout1 and Vout2 is the voltage signal obtained by the multiple magnetic tunnel junctions in the half-bridge circuit converting the magnetic signal of the external magnetic field sensed by the external magnetic field.

[0070] The fifth bridge arm 301 and the sixth bridge arm 302 can have the same structure as the first bridge arm 201 and the third bridge arm 203 mentioned above; or, the fifth bridge arm 301 and the sixth bridge arm 302 can also have the same structure as the second bridge arm 202 and the fourth bridge arm 204 mentioned above; or, depending on the design requirements, a structure composed of other numbers of magnetic tunnel junctions can be adopted.

[0071] To realize the tunnel magnetoresistive sensor composed of a half-bridge or full-bridge circuit, enabling it to convert the sensed magnetic signal into a voltage signal, the fixing directions of the magnetic tunnel junctions in adjacent arms of the half-bridge or full-bridge circuit must be opposite. Figure 3 For example, when a tunnel magnetoresistive sensor senses an external magnetic field, the pinning directions of the fixing layers of the magnetic tunnel junctions in adjacent arms are opposite, causing different changes in the resistance of the magnetic tunnel junctions in adjacent arms of the full-bridge circuit; that is, the resistance of one arm increases, and the resistance of the other arm decreases. For instance, the resistance of the first arm 201 increases, the resistance of the second arm 202 decreases, the resistance of the third arm 203 decreases, and the resistance of the fourth arm 204 increases. This allows a differential voltage signal to be output between the two output terminals Vout1 and Vout2. The implementation principle of a tunnel magnetoresistive sensor based on a half-bridge circuit is similar, also requiring the fixing directions of the two arms to be opposite in order to convert the external magnetic field signal into a voltage signal.

[0072] In actual manufacturing, wafer-level devices typically require overall annealing to set the pinning direction of the fixing layers of magnetic tunnel junctions. However, overall annealing can easily cause the pinning directions of the fixing layers of magnetic tunnel junctions in adjacent arms to become consistent. This results in similar resistance changes in the magnetic tunnel junctions in each arm when an external magnetic field is applied, making it difficult to effectively convert the magnetic signal from the external magnetic field into a voltage signal output.

[0073] There are several solutions in the industry for achieving opposite pinning directions of the fixing layers of magnetic tunnel junctions in adjacent arms. One approach involves using an external magnetic flux structure or magnetic bias structure (such as a soft magnetic focusing structure or a permanent magnet bias structure) to apply local magnetic fields in different directions to adjacent arms of the tunnel magnetoresistive sensor. This reverses the pinning directions of the fixing layers of each magnetic tunnel junction, resulting in different resistance changes in the magnetic tunnel junctions in adjacent arms, thus converting the magnetic signal from the external magnetic field into a voltage signal output. However, this approach typically increases the structural complexity and packaging cost of the tunnel magnetoresistive sensor and hinders its miniaturization and high integration.

[0074] In another implementation, the film stack structure of the magnetic tunnel junction can be improved, or laser local annealing or local heating-assisted processes can be used to make the pinning direction of the fixing layer of each magnetic tunnel junction in adjacent arms opposite, thereby causing different changes in the resistance of each magnetic tunnel junction in adjacent arms, realizing the conversion of the magnetic signal of the external magnetic field into a voltage signal output. However, this process is more complex, and it is difficult to guarantee the yield and consistency.

[0075] In another implementation, a discrete manufacturing approach can be used. Multiple magnetic tunnel junction devices with different pinning directions are first fabricated, and then combined through a packaging stage to form a tunnel magnetoresistive sensor. This directly achieves opposite pinning directions for the magnetic tunnel junctions in adjacent arms, converting the magnetic signal from the external magnetic field into a voltage signal output. However, this method cannot achieve true monolithic integration and is difficult to adapt to the current application requirements of high integration and miniaturization of devices.

[0076] In summary, even though the above-mentioned implementation methods can, to some extent, ensure that the pinning directions of the fixing layers of each magnetic tunnel junction in adjacent arms are opposite, the tunnel magnetoresistive sensor integrated based on this method will increase the overall structural complexity and packaging cost, and will not be conducive to device miniaturization and high integration, making it difficult to meet the current application requirements of high integration and miniaturization of devices; or, there may be problems with complex processes and difficulty in guaranteeing yield and consistency.

[0077] Furthermore, tunnel magnetoresistive sensors are susceptible to interference from stray magnetic fields. Under the influence of this interference, the voltage signal output by the tunnel magnetoresistive sensor is prone to significant zero-point offset, and the linearity between the induced magnetic signal and the resistance changes of each magnetic tunnel junction in adjacent bridge arms is poor. For example, when the external magnetic field strength changes slightly, the resistance of each magnetic tunnel junction in adjacent bridge arms may fluctuate significantly. Additionally, the sensitivity of tunnel magnetoresistive sensors is either not adjustable or has a limited adjustment range, making it difficult to meet the performance requirements of high-precision applications.

[0078] Therefore, this application provides a tunnel magnetoresistive sensor, which includes a first half-bridge circuit or a first full-bridge circuit. The first half-bridge circuit includes one half-bridge structure, and the first full-bridge circuit includes two parallel half-bridge structures. The first full-bridge circuit can be referred to... Figure 1 The full-bridge circuit shown can be referenced in the first half-bridge circuit. Figure 2 The half-bridge circuit shown.

[0079] A half-bridge structure may include two arms, see reference. Figure 4 One arm of the bridge includes a first number of first magnetic tunnel junctions 401 connected in series and a second number of second magnetic tunnel junctions 402, which is not equal to the first number; Reference Figure 5The other arm includes a second number of first magnetic tunnel junctions 401 and a first number of second magnetic tunnel junctions 402 connected in series.

[0080] In each bridge arm, adjacent magnetic tunnel junctions can be connected in series via a metal layer 801 and a bottom electrode 808 or a seed layer 903. (Reference) Figure 4 and Figure 5 The metal layer 801 of a magnetic tunnel junction is electrically connected to the metal layer 801 of the adjacent left magnetic tunnel junction. The metal layer 801, as the conductive connection structure at the top of the magnetic tunnel junction, has the characteristics of high conductivity and low contact resistance. This enables seamless conduction between the circuits at the top of the adjacent left magnetic tunnel junctions, effectively reducing contact resistance and thus reducing signal transmission loss of the bridge arm.

[0081] Furthermore, the bottom electrode 808 of the magnetic tunnel junction is electrically connected to the corresponding bottom electrode 808 of the adjacent right-side magnetic tunnel junction. If a seed layer 903 exists in the magnetic tunnel junction, the seed layer 903 also needs to be electrically connected accordingly. The bottom electrode 808 serves as the bottom conductive layer of the magnetic tunnel junction, and the seed layer 903, located above the bottom electrode 808, is used as an auxiliary functional layer for matching the growth of the magnetic tunnel junction thin film. It possesses conductivity adaptability and structural transition, and can optimize the bonding strength and conductivity matching degree between the magnetic tunnel junction and the bottom electrode 808. Therefore, through the cooperative connection of the bottom electrode 808 and the seed layer 903, stable conduction of the bottom circuit of the adjacent right-side magnetic tunnel junction can be achieved.

[0082] Reference Figure 6 As shown, the major axis of the first magnetic tunnel junction 401 has a first angle with the preset direction. , refer to Figure 7 As shown, the major axis of the second magnetic tunnel junction 402 has a second angle with the preset direction. The embodiments in this application do not limit the first included angle. Second angle The specific angle values ​​and magnitudes only require that the major axes of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 have components in opposite directions in a preset direction. Preferably, the first included angle... Second angle Complementary, i.e., the first included angle Second angle The sum of the degrees is 180 degrees.

[0083] For example, refer to Figure 1 The full-bridge circuit shown, if the first bridge arm 201 is Figure 4 The bridge arm shown is the second bridge arm 202. Figure 5 The bridge arm shown; if the first bridge arm 201 is Figure 5 The bridge arm shown is the second bridge arm 202. Figure 4 The bridge arm shown. If the third bridge arm 203 is... Figure 4 The bridge arm shown is the fourth bridge arm 204. Figure 5 The bridge arm shown; if the third bridge arm 203 is Figure 5 The bridge arm shown is the fourth bridge arm 204. Figure 4 The bridge arm shown.

[0084] For example, refer to Figure 2 The half-bridge circuit shown, if the fifth bridge arm 301 is Figure 4 The bridge arm shown is the sixth bridge arm 302. Figure 5 The bridge arm shown; if the fifth bridge arm 301 is Figure 5 The bridge arm shown is the sixth bridge arm 302. Figure 4 The bridge arm shown.

[0085] Furthermore, in the embodiments of this application, the diagonal arms of the full-bridge circuit are identical. That is, when the tunnel magnetoresistive sensor includes a first full-bridge circuit, the two diagonal arms of the first full-bridge circuit have the same magnetic tunnel junction series structure and quantity ratio. (Refer to...) Figure 1 The first bridge arm 201 and the fourth bridge arm 202 are diagonal bridge arms, each including a first number of first magnetic tunnel junctions 401 connected in series and a second number of second magnetic tunnel junctions 402 that is not equal to the first number; the second bridge arm 202 and the third bridge arm 203 are diagonal bridge arms, each including a second number of first magnetic tunnel junctions 401 connected in series and a first number of second magnetic tunnel junctions 402.

[0086] It should be noted that, Figure 4 and Figure 5 The number of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is illustrated using an example of 4 for the first quantity and 2 for the second quantity. In practical applications, the number of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 can be set as needed, as long as the first quantity and the second quantity are not equal. Furthermore, in this embodiment, the membrane structure of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is the same; the use of "first" and "second" to indicate the magnetic tunnel junctions is only to distinguish their arrangement in the bridge arm.

[0087] Since the tilt angles of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 are complementary, the fixed layer magnetic moments of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 can be pinned in opposite directions. The method of achieving the opposite pinning direction through overall annealing will be described in subsequent embodiments.

[0088] When an external magnetic field is applied, the resistance values ​​of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 in each bridge arm change differently. The resistance of the first magnetic tunnel junction 401 increases, and the resistance of the second magnetic tunnel junction 402 decreases, or the resistance of the first magnetic tunnel junction 401 decreases, and the resistance of the second magnetic tunnel junction 402 increases. In the same bridge arm, the resistance changes of one first magnetic tunnel junction 401 and one second magnetic tunnel junction 402 can approximately cancel each other out. However, since the number of first magnetic tunnel junctions 401 and second magnetic tunnel junctions 402 in the same bridge arm is not equal, the resistance changes cannot completely cancel each other out, thus causing the resistance value of each bridge arm to change when an external magnetic field is applied. Since the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 in the two arms of the same half-bridge structure are complementary, the resistance of one arm increases and the resistance of the other arm decreases in the same half-bridge structure. Moreover, the resistance changes of the diagonal arms in the full-bridge circuit are the same, so that the half-bridge circuit or the full-bridge circuit can convert the magnetic signal of the sensed external magnetic field into the first voltage signal.

[0089] Furthermore, the greater the difference in the number of first magnetic tunnel junctions 401 and second magnetic tunnel junctions 402 in the same bridge arm, the less the resistance change is canceled out, and the greater the change in the resistance value of the bridge arm. This results in a greater change in the conversion of the magnetic signal from the external magnetic field into the first voltage signal. Therefore, the sensitivity of the first voltage signal output by the tunnel magnetoresistive sensor can be controlled by adjusting the difference in the number of first magnetic tunnel junctions 401 and second magnetic tunnel junctions 402. This allows the tunnel magnetoresistive sensor to be adapted to different application scenarios, such as high-precision detection of weak external magnetic fields and wide-range detection of strong external magnetic fields.

[0090] Meanwhile, the complementary arrangement of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 in the adjacent bridge arms effectively cancels out the stray magnetic field of the magnetic tunnel junction. This makes the change in resistance of each bridge arm more linear with the change in magnetic signal of the external magnetic field, further improving the detection accuracy and anti-interference capability of the tunnel magnetoresistive sensor.

[0091] Figure 4 and Figure 5 The membrane structure of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 can be referred to Figure 8 .like Figure 8 As shown, the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402, from top to bottom, include a metal layer 801 and / or a top electrode 802, a second antiferromagnetic layer 803, a free layer 804, a barrier layer 805, a fixed layer 806, a first antiferromagnetic layer 807, and a bottom electrode 808. Figure 4 and 5The tunnel magnetoresistive sensor formed by the bridge arm shown is a double-pinned tunnel magnetoresistive sensor, wherein the magnetic moment direction of the free layer 804 is pinned by the second antiferromagnetic layer 803, and the magnetic moment direction of the fixed layer 806 is pinned by the first antiferromagnetic layer 807.

[0092] Optional, see reference Figure 9 Between the barrier layer 805 and the fixed layer 806, from top to bottom, a reference layer 901 and a coupling layer 902 may be included. Between the first antiferromagnetic layer 807 and the bottom electrode 808, a seed layer 903 may be included. The coupling layer 902 is used to achieve antiferromagnetic coupling between the reference layer 901 and the fixed layer 806, and the seed layer 903 is used to improve the crystal orientation and surface smoothness of the thin films on it, thereby enhancing the consistency of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402.

[0093] Based on the above embodiments, the series connection of each magnetic tunnel junction in the first bridge arm 201, the second bridge arm 202, the third bridge arm 203, or the fourth bridge arm 204 is as described above. Figure 10 .like Figure 10 As shown in the figure, this example uses six magnetic tunnel junctions connected in series. The bottom electrode 808 and seed layer 903 of one magnetic tunnel junction are electrically connected to the bottom electrode 808 and seed layer 903 of the adjacent right-hand magnetic tunnel junction. At the same time, the metal layer 801 of this magnetic tunnel junction is electrically connected to the metal layer 801 of the adjacent left-hand magnetic tunnel junction. And so on, to achieve the sequential series connection of the six magnetic tunnel junctions.

[0094] It should be noted that, Figure 10 The use of six magnetic tunnel junctions connected in series is merely illustrative and does not constitute a limitation on the number of magnetic tunnel junctions in a bridge arm. In practical applications, the number of magnetic tunnel junctions in each bridge arm can be adjusted according to specific design requirements, but the series connection method between the magnetic tunnel junctions is the same as the principle illustrated.

[0095] In some embodiments, when the tunnel magnetoresistive sensor includes a first half-bridge circuit, the tunnel magnetoresistive sensor further includes a second half-bridge circuit corresponding to the first half-bridge circuit. The second half-bridge circuit includes a half-bridge structure, which is referenced to... Figure 11 As shown, the second half-bridge circuit includes two bridge arms, namely the seventh bridge arm 111 and the eighth bridge arm 112; or, if the tunnel magnetoresistive sensor includes the first full-bridge circuit, the tunnel magnetoresistive sensor also includes a second full-bridge circuit corresponding to the first full-bridge circuit, as shown in the figure. Figure 12 As shown, the second full-bridge circuit includes two parallel half-bridge structures, namely the third half-bridge structure 121 and the fourth half-bridge structure 122 shown in the figure. The third half-bridge structure 121 includes the ninth bridge arm 123 and the tenth bridge arm 124, and the fourth half-bridge structure 122 includes the eleventh bridge arm 125 and the twelfth bridge arm 126.

[0096] Reference Figure 13 and Figure 14 As shown, in the half-bridge structure of the second half-bridge circuit or the second full-bridge circuit, each bridge arm includes a third number of first magnetic tunnel junctions 401 and a third number of second magnetic tunnel junctions 402. Since the number of first magnetic tunnel junctions 401 and second magnetic tunnel junctions 402 in the same bridge arm is equal, the resistance changes of the first magnetic tunnel junctions 401 and second magnetic tunnel junctions 402 in adjacent bridge arms cancel each other out, causing the output of the second half-bridge circuit or the second full-bridge circuit to approach zero, retaining only the residual voltage signal caused by process mismatch, temperature drift, and other factors. That is, the second half-bridge circuit or the second full-bridge circuit is used to convert the magnetic signal of the external magnetic field into a second voltage signal, which mainly characterizes the zero-point drift.

[0097] The tunnel magnetoresistive sensor outputs a third voltage signal based on the first and second voltage signals. This third voltage signal is obtained by calibrating the first voltage signal output by the first half-bridge circuit or the first full-bridge circuit using the second voltage signal.

[0098] Optionally, the tunnel magnetoresistive sensor also includes a computational circuit. The input terminals of the computational circuit are used to receive a first voltage signal output from a first half-bridge circuit and a second voltage signal output from a second half-bridge circuit, or a first voltage signal output from a first full-bridge circuit and a second voltage signal output from a second full-bridge circuit. The output terminal of the computational circuit is used to output a third voltage signal. By differentially processing the first and second voltage signals, the zero-point drift interference inherent in the first voltage signal is canceled out, thereby outputting a calibrated third voltage signal that accurately reflects the actual magnetic field magnitude. This enables online offset detection and compensation, improving the temperature drift robustness and long-term stability of the tunnel magnetoresistive sensor.

[0099] The arithmetic circuit can be configured with one or more of the following arithmetic functions: differential arithmetic, proportional arithmetic, weighted arithmetic, signal amplification arithmetic, and normalization processing. In practical applications, the appropriate function can be selected according to the requirements, and the specific structure of the arithmetic circuit is not limited.

[0100] When the arithmetic circuit is configured with differential arithmetic function, the output third voltage signal can be the difference between the first voltage signal and the second voltage signal.

[0101] When the arithmetic circuit is configured with a proportional operation function, the output third voltage signal can be the first voltage signal minus k times the second voltage signal. Here, k is a preset proportional coefficient.

[0102] When the arithmetic circuit is configured with a weighted operation function, weighting coefficients can be configured for the first voltage signal and the second voltage signal respectively, and then a difference operation can be performed to output the third voltage signal, which is a times the first voltage signal minus b times the second voltage signal. Here, a and b are the weighting coefficients corresponding to the first voltage signal and the second voltage signal, respectively.

[0103] When the operational circuit is configured with both differential operation and signal amplification operation functions, the result of the differential operation can be multiplied by the gain coefficient G, and the output third voltage signal is equal to G multiplied by the difference between the first voltage signal and the second voltage signal. This increases the amplitude of the third voltage information so that it reaches the amplitude range that subsequent circuits can process.

[0104] When the arithmetic circuit is configured with both differential arithmetic and normalization processing functions, the third voltage signal obtained after differential arithmetic can be adjusted to a preset standard voltage range, for example, the output third voltage signal can be mapped to between 0 and 3.3 volts.

[0105] In addition, the above-mentioned calculation functions can be implemented through analog circuits, or the analog signals can be converted from analog to digital and then the corresponding numerical calculations can be completed through digital circuits.

[0106] Figure 15 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 1 .like Figure 15 As shown, the annealing method includes:

[0107] S1501. Control the temperature of the tunnel magnetoresistive sensor to be greater than a first temperature, and apply a first magnetic field along a first direction to pin the magnetic moment of the fixing layer 806 of the first magnetic tunnel junction 401 in the tunnel magnetoresistive sensor to a second direction, and pin the magnetic moment of the fixing layer 806 of the second magnetic tunnel junction 402 in the tunnel magnetoresistive sensor to a third direction; wherein, the second direction has a first angle with the preset direction, the third direction has a second angle with the preset direction, and the magnetic moments of the fixing layer 806 of the first magnetic tunnel junction 401 and the fixing layer 806 of the second magnetic tunnel junction 402 have components with opposite directions in the preset direction.

[0108] The first temperature is the critical temperature at which the magnetic moment pinning state of the fixed layer 806 in the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is released. When the temperature of the tunnel magnetoresistive sensor is greater than the first temperature, the magnetic moment pinning of the fixed layer 806 is released, and it can be reoriented under the action of the first magnetic field in the first direction.

[0109] S1502, control the temperature of the tunnel magnetoresistive sensor to be greater than the second temperature and less than the first temperature, apply a second magnetic field along the first direction to pin the magnetic moment of the free layer 804 of the first magnetic tunnel junction 401 to the first direction, and pin the magnetic moment of the free layer 804 of the second magnetic tunnel junction 402 to the first direction.

[0110] The second temperature is the critical temperature at which the magnetic moment pinning state of the free layer 804 in the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is released. At this second temperature, the magnetic moment direction of the free layer 804 can be reset by the second magnetic field in the first direction, while the pinning state of the fixed layer 806 remains unchanged because the second temperature does not reach the first temperature. The magnetic field strength of the second magnetic field is less than that of the first magnetic field.

[0111] In one implementation, a segmented cooling annealing process is provided, such as... Figure 16 As shown, Figure 16 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 2 The annealing method includes:

[0112] S1601. Control the temperature of the tunnel magnetoresistive sensor to be greater than a first temperature, and apply a first magnetic field along a first direction.

[0113] When the temperature of the tunnel magnetoresistive sensor exceeds a first temperature, the pinning state of the fixing layer 806 of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is released. After applying a first magnetic field in a first direction, the magnetic moments of the fixing layers 806 of both the first and second magnetic tunnel junctions 401 and 402 turn in the first direction. The directions of the magnetic moments of the fixing layers 806 are as follows: Figure 17 The arrow of the first magnetic tunnel junction 401 and Figure 18 The arrow in the second magnetic tunnel junction 402 is shown.

[0114] S1602. After the first magnetic field has been applied for a first duration, the application of the first magnetic field is stopped.

[0115] After the first magnetic field is stopped, due to the difference in tilt angle between the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402, the magnetic moment direction of the fixed layer 806 of the first magnetic tunnel junction 401, as shown... Figure 19 As shown, rotate along an acute angle to the major axis direction of the first magnetic tunnel junction 401, i.e., the second direction; the magnetic moment direction of the fixed layer 806 of the second magnetic tunnel junction 402, as shown... Figure 20 As shown, rotate along an acute angle to the major axis direction of the second magnetic tunnel junction 402, i.e., the third direction.

[0116] S1603. After the second duration of the first magnetic field is stopped, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature so as to pin the magnetic moment of the fixing layer 806 of the first magnetic tunnel junction 401 in the tunnel magnetoresistive sensor to the second direction and the magnetic moment of the fixing layer 806 of the second magnetic tunnel junction 402 in the tunnel magnetoresistive sensor to the third direction.

[0117] During the temperature cooling process of the tunnel magnetoresistive sensor, the magnetic moment of the fixed layer 806 of the first magnetic tunnel junction 401 or the second magnetic tunnel junction 402 induces the magnetic moment of the first antiferromagnetic layer 807 to be in the opposite direction to the magnetic moment of the fixed layer 806. The magnetic moment of the first antiferromagnetic layer 807, in turn, pins the direction of the magnetic moment of the fixed layer 806.

[0118] S1604. Control the temperature of the tunnel magnetoresistive sensor to be greater than the second temperature and less than the first temperature, and apply a second magnetic field along the first direction.

[0119] When the temperature of the tunnel magnetoresistive sensor is greater than the second temperature but less than the first temperature, the pinning state of the free layer 804 of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is released. After applying the second magnetic field in the first direction, the magnetic moments of the free layer 804 of both the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 turn towards the first direction. The directions of the magnetic moments of the free layer 804 are as follows: Figure 21 The arrow of the first magnetic tunnel junction 401 and Figure 22 The arrow in the second magnetic tunnel junction 402 is shown.

[0120] S1605. After the second magnetic field is applied for a third duration, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature. After the temperature of the tunnel magnetoresistive sensor reaches room temperature, the application of the second magnetic field is stopped, so as to pin the magnetic moment of the free layer 804 of the first magnetic tunnel junction 401 in the first direction and pin the magnetic moment of the free layer 804 of the second magnetic tunnel junction 402 in the first direction.

[0121] After the tunnel magnetoresistive sensor is cooled to room temperature, the magnetic moment of the free layer 804 of the first magnetic tunnel junction 401 or the second magnetic tunnel junction 402 induces the magnetic moment of the second antiferromagnetic layer 803 to be in the opposite direction to the magnetic moment of the free layer 804. The magnetic moment of the second antiferromagnetic layer 803, in turn, pins the direction of the magnetic moment of the free layer 804, i.e., pins it in the first direction. For example... Figure 23 As shown, the magnetic moment direction of the free layer 804 of the first magnetic tunnel junction 401 is parallel to... Figure 19 The magnetic moment directions of the fixed layer 806 in the middle are at a certain angle. ;like Figure 24 As shown, the magnetic moment direction of the free layer 804 of the second magnetic tunnel junction 402 is parallel to... Figure 20 The magnetic moment directions of the fixed layer 806 in the middle are at a certain angle. .

[0122] In another implementation, such as Figure 25 As shown, Figure 25 A flowchart illustrating an annealing method for a tunnel magnetoresistive sensor provided in this application embodiment. Figure 3 The annealing method includes:

[0123] S2501. Control the temperature of the tunnel magnetoresistive sensor to be greater than a first temperature, and apply a first magnetic field along a first direction.

[0124] S2502. After the first magnetic field is applied for a first duration, the application of the first magnetic field is stopped so as to pin the magnetic moment of the fixing layer 806 of the first magnetic tunnel junction 401 in the tunnel magnetoresistive sensor to the second direction, and pin the magnetic moment of the fixing layer 806 of the second magnetic tunnel junction 402 in the tunnel magnetoresistive sensor to the third direction.

[0125] S2503. After a second duration following the cessation of applying the first magnetic field, the temperature of the tunnel magnetoresistive sensor is controlled to be greater than the second temperature and less than the first temperature, and a second magnetic field is applied along the first direction.

[0126] Since the temperature of the fixing layer 806 of the magnetic tunnel junction does not reach the first temperature, the magnetic moment pinning direction of the fixing layer 806 of the magnetic tunnel junction in each arm is not affected when a second magnetic field strength less than the first magnetic field strength is applied.

[0127] S2504. After the second magnetic field is applied for a third duration, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature. After the temperature of the tunnel magnetoresistive sensor reaches room temperature, the application of the second magnetic field is stopped, so as to pin the magnetic moment of the free layer 804 of the first magnetic tunnel junction 401 in the first direction and pin the magnetic moment of the free layer 804 of the second magnetic tunnel junction 402 in the first direction.

[0128] The implementation principles of S2501 to S2504 in this embodiment are the same as those of S1601 to S1605 described above, and will not be repeated here.

[0129] The annealing method for a tunnel magnetoresistive sensor provided in this application embodiment controls the temperature of the tunnel magnetoresistive sensor to be higher than a first temperature, and applies a first magnetic field along a first direction to pin the magnetic moment of the fixing layer 806 of the first magnetic tunnel junction 401 in the tunnel magnetoresistive sensor to a second direction, and pins the magnetic moment of the fixing layer 806 of the second magnetic tunnel junction 402 in the tunnel magnetoresistive sensor to a third direction. The second direction has a first angle with a preset direction, and the third direction has a second angle with the preset direction. The major axis of the first magnetic tunnel junction 401 and the major axis of the second magnetic tunnel junction 402 have components with opposite directions in the preset direction. Differential reverse pinning of the magnetic moments of the fixed layer 806 in the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 is achieved, effectively solving the problem of the consistency of the magnetic moment direction of the fixed layer 806 in the magnetic tunnel junction in the traditional annealing process. On this basis, the temperature of the tunnel magnetoresistive sensor is controlled to be greater than a second temperature and less than a first temperature, and a second magnetic field along the first direction is applied to pin the magnetic moment of the free layer 804 of the first magnetic tunnel junction 401 and the magnetic moment of the free layer 804 of the second magnetic tunnel junction 402 to the first direction, thereby ensuring that the magnetic moment of the free layer 804 is uniformly pinned to the first direction at a lower temperature.

[0130] Therefore, the tunnel magnetoresistive sensor provided in this application embodiment can be made so that the fixing layer 806 of each magnetic tunnel junction in the adjacent bridge arm is pinned in opposite directions by the overall annealing method, so that it does not need to rely on external magnetic flux gathering structure, magnetic bias structure and local annealing process, nor does it need to improve the film stack structure of magnetic tunnel junction or manufacture devices independently.

[0131] Furthermore, it effectively cancels stray magnetic fields between magnetic tunnel junctions, making the resistance change of each bridge arm more linear with the change of the external magnetic field, thereby further improving the detection accuracy and anti-interference capability of the tunnel magnetoresistive sensor; by adjusting the ratio of the first magnetic tunnel junction 401 and the second magnetic tunnel junction 402 in each bridge arm, the net magnetic response amplitude of the bridge arm can be adjusted, and the sensitivity can be adjusted proportionally to adapt to different ranges or different application scenarios.

[0132] In addition, the annealing process, which controls the temperature in stages and applies the external magnetic field in steps, can accurately distinguish the pinning process thresholds of the fixed layer 806 and the free layer 804, effectively avoiding mutual interference between the high and low temperature annealing processes. This not only preserves the stable pinning effect of the magnetic moment of the fixed layer 806, but also makes the direction of the magnetic moment of the free layer 804 controllable.

[0133] The division of units involved in the embodiments of this application is merely a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0134] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0135] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0136] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0137] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0138] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A tunnel magnetoresistive sensor, characterized in that, include: The first half-bridge circuit or the first full-bridge circuit, wherein the first half-bridge circuit includes a half-bridge structure, and the first full-bridge circuit includes two parallel half-bridge structures. In the half-bridge structure of the first half-bridge circuit or the first full-bridge circuit, one bridge arm includes a first number of first magnetic tunnel junctions and a second number of second magnetic tunnel junctions connected in series, and the other bridge arm includes the second number of first magnetic tunnel junctions and the first number of second magnetic tunnel junctions connected in series, wherein the first number and the second number are not equal; the diagonal bridge arms of the full-bridge circuit are the same. The major axis of the first magnetic tunnel junction has a first angle with a preset direction, and the major axis of the second magnetic tunnel junction has a second angle with the preset direction. The major axes of the first magnetic tunnel junction and the second magnetic tunnel junction have components with opposite directions in the preset direction. The first half-bridge circuit or the first full-bridge circuit is used to convert the magnetic signal of the external magnetic field into a first voltage signal. After annealing the tunnel magnetoresistive sensor by applying a magnetic field along the first direction, the fixed layer magnetic moment of the first magnetic tunnel junction is pinned to the long axis direction of the first magnetic tunnel junction, the fixed layer magnetic moment of the second magnetic tunnel junction is pinned to the long axis direction of the second magnetic tunnel junction, and the free layers of both the first and second magnetic tunnel junctions are pinned to the first direction.

2. The tunnel magnetoresistive sensor according to claim 1, characterized in that, Also includes: A second half-bridge circuit corresponding to the first half-bridge circuit, or a second full-bridge circuit corresponding to the first full-bridge circuit; The second half-bridge circuit includes a half-bridge structure, and the second full-bridge circuit includes two parallel half-bridge structures. In the half-bridge structure of the second half-bridge circuit or the second full-bridge circuit, each bridge arm includes a third number of the first magnetic tunnel junctions and the third number of the second magnetic tunnel junctions. The second half-bridge circuit or the second full-bridge circuit is used to convert the magnetic signal of the external magnetic field into a second voltage signal, and the tunnel magnetoresistive sensor outputs a third voltage signal based on the first voltage signal and the second voltage signal.

3. The tunnel magnetoresistive sensor according to claim 2, characterized in that, Also includes: The arithmetic circuit has input terminals for receiving the first voltage signal and the second voltage signal, respectively, and output terminals for outputting the third voltage signal.

4. The tunnel magnetoresistive sensor according to any one of claims 1-3, characterized in that, The film structures of the first magnetic tunnel junction and the second magnetic tunnel junction, from top to bottom, include: Top electrode and / or metal layer, second antiferromagnetic layer, free layer, barrier layer, fixed layer, first antiferromagnetic layer, bottom electrode.

5. The tunnel magnetoresistive sensor according to claim 4, characterized in that, From top to bottom, the barrier layer and the fixed layer also include a reference layer and a coupling layer, and the first antiferromagnetic layer and the bottom electrode also include a seed layer.

6. An annealing method for a tunnel magnetoresistive sensor, characterized in that, The tunnel magnetoresistive sensor according to any one of claims 1-5 comprises: The temperature of the tunnel magnetoresistive sensor is controlled to be greater than a first temperature, and a first magnetic field is applied along a first direction to pin the fixed layer magnetic moment of the first magnetic tunnel junction in the tunnel magnetoresistive sensor to a second direction, and to pin the fixed layer magnetic moment of the second magnetic tunnel junction in the tunnel magnetoresistive sensor to a third direction; wherein, the second direction has a first angle with a preset direction, the third direction has a second angle with the preset direction, and the fixed layer magnetic moment of the first magnetic tunnel junction and the fixed layer magnetic moment of the second magnetic tunnel junction have components with opposite directions in the preset direction; The temperature of the tunnel magnetoresistive sensor is controlled to be greater than a second temperature and less than a first temperature. A second magnetic field is applied along the first direction to pin the free layer magnetic moment of the first magnetic tunnel junction to the first direction and to pin the free layer magnetic moment of the second magnetic tunnel junction to the first direction.

7. The method according to claim 6, characterized in that, After applying the first magnetic field along the first direction, the method further includes: After the first magnetic field has been applied for a first duration, the application of the first magnetic field is stopped. After a second duration following the cessation of applying the first magnetic field, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature.

8. The method according to claim 6, characterized in that, After applying the first magnetic field along the first direction, the method further includes: After the first magnetic field has been applied for a first duration, the application of the first magnetic field is stopped. Controlling the temperature of the tunnel magnetoresistive sensor to be greater than a second temperature and less than the first temperature includes: After a second duration following the cessation of applying the first magnetic field, the temperature of the tunnel magnetoresistive sensor is controlled to be greater than the second temperature and less than the first temperature.

9. The method according to any one of claims 6-8, characterized in that, After applying the second magnetic field along the first direction, the method further includes: After the second magnetic field is applied for a third duration, the temperature of the tunnel magnetoresistive sensor is cooled to room temperature, and the application of the second magnetic field is stopped after the temperature of the tunnel magnetoresistive sensor reaches room temperature.

10. The method according to any one of claims 6-8, characterized in that, The magnetic field strength of the second magnetic field is less than that of the first magnetic field.

Images