Method for manufacturing a magnetic laminated body and a magnetic sensor, and device for manufacturing a magnetic laminated body

Abstract

A laminated film (601) is formed comprising a ferromagnetic layer (631) and an antiferromagnetic layer (66), the ferromagnetic layer (631) and the antiferromagnetic layer (66) being in contact with each other in a first direction (step S1). A magnetically fixed layer (63), having a fixed magnetization direction with respect to an external magnetic field, is formed from the ferromagnetic layer (631) by applying a magnetic field to the laminated film (601) in the first direction (step S2). After the magnetic field has ceased to be applied, the magnetic laminated body (6) is formed by heating the laminated film (601) to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer (66) (step S3).

Description

AREA

[0001] The present disclosure relates to a method for manufacturing a magnetic laminated body, a magnetic sensor and a device for manufacturing a magnetic laminated body. BACKGROUND

[0002] JP2018-6598A describes a magnetic sensor comprising a magnetically free layer whose magnetization direction changes with respect to an external magnetic field, a magnetically fixed layer whose magnetization direction is fixed with respect to the external magnetic field, and a non-magnetic layer positioned between the magnetically free layer and the magnetically fixed layer. The magnetization direction of the magnetically fixed layer reverses when exposed to a strong magnetic field, and the magnetization direction may remain fixed in the reversed direction. To prevent this, a technique is known in which an antiferromagnetic layer is provided to strongly fix the magnetization direction of the magnetically fixed layer by means of exchange coupling between the antiferromagnetic layer and the magnetically fixed layer, as described in JP2015-207625A. SUMMARY

[0003] The aim of the present disclosure is to provide a method for producing a magnetic laminated body which enables a simplification of a device for magnetizing a magnetically fixed layer and for heating an antiferromagnetic layer.

[0004] The method for producing a magnetic laminated body of the present disclosure comprises the following steps: forming a laminated film comprising a ferromagnetic layer and an antiferromagnetic layer, wherein the ferromagnetic layer and the antiferromagnetic layer are in contact with each other in a first direction; applying a magnetic field in the first direction to the laminated film in order to form a magnetically fixed layer from the ferromagnetic layer, the direction of magnetization of which is fixed with respect to an external magnetic field; and after cessation of the application of the magnetic field, heating the laminated film to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer. BRIEF DESCRIPTION OF THE DRAWINGS The Fig. 1A and Fig. Figure 1B shows schematic drawings of a magnetic sensor according to a first embodiment. The Fig. 2A and Fig. Figure 2B shows a schematic drawing illustrating a method for magnetizing a magnetically fixed layer and a method for heating a laminated film of the material described in the figures. Fig. 1A and Fig. Show the magnetic sensor shown in 1B. Fig. Figure 3 is a schematic drawing of a device for applying a magnetic field to the [unclear text]. Fig. 1A and Fig. 1B shown magnetic sensor and for heating it. The Fig. 4A and Fig. Figure 4B shows schematic drawings of a magnetic sensor according to a second embodiment. Fig. Figure 5 is a drawing of the structure of a laminated film in the second embodiment. Fig. Figure 6 is a schematic drawing of a magnetic sensor according to a third embodiment. The Fig. Figures 7A-7D are schematic drawings illustrating a method for magnetizing a magnetically fixed layer and a method for heating a laminated film of the in Fig. The 6 magnetic sensors shown are shown. Fig. Figure 8 is a schematic drawing of a magnetic sensor according to a fourth embodiment. The Fig. Figures 9A-9D are schematic drawings illustrating a method for magnetizing a magnetically fixed layer and a method for heating a laminated film of the in Fig. The magnetic sensor shown is 8. The Fig. 10A and Fig. 10B are diagrams showing the measurement results of the magnetization curves in the examples and comparison examples. DETAILED DESCRIPTION

[0005] A magnetically fixed layer of a magnetic sensor must be magnetized, and for the purpose of exchange coupling, an antiferromagnetic layer must be heated to a temperature equal to or higher than the blocking temperature. In the magnetic sensor described in JP2018-6598A, the magnetization direction of the magnetically fixed layer is aligned with the stacking direction of the magnetically free layer, the non-magnetic layer, and the magnetically fixed layer. Therefore, the magnetization of the magnetically fixed layer and the heating of the antiferromagnetic layer must occur from the same direction. However, since magnetization and heating are performed in the same process, a device for magnetizing and heating is complex.

[0006] Exemplary embodiments of the present disclosure are described below with reference to the drawings. In the following description and the drawings, the direction (first direction) in which the multiple layers of the magnetic laminated body 6 and the laminated film 601 are stacked is referred to as the Z-direction. The direction from the magnetic laminated body 6 or the laminated film 601 to the upper electrode layer 5 is referred to as the +Z-direction. The direction from the magnetic laminated body 6 or the laminated film 601 to the lower electrode layer 7 or to the substrate is referred to as the -Z-direction. The first direction signifies either the +Z-direction or the -Z-direction. The direction orthogonal to the Z-direction is referred to as the X-direction. Although the X-direction is shown in the drawing for simplicity, the X-direction can be any direction orthogonal to the Z-direction.Unless otherwise indicated, white arrows in the drawings show the magnetization directions of the first magnetically fixed layer 63 and the second magnetically fixed layer 65. A bold line with an arrow indicates the magnetization direction of the magnetically unaffected layer 61 in a state where no external magnetic field is applied (hereinafter referred to as the zero magnetic field state). First embodiment

[0007] Fig. Figure 1a shows the schematic configuration of the magnetic sensor 1 according to a first embodiment. The magnetic sensor 1 can comprise a magnetic field sensing element 2. The magnetic field sensing element 2 can comprise a silicon substrate (not shown), a magnetic laminated body 6, and upper and lower electrode layers 5, 7, which supply a sensor current to the magnetic laminated body 6. The upper electrode layer 5, the magnetic laminated body 6, and the lower electrode layer 7 can be arranged on the substrate in the order upper electrode layer 5, magnetic laminated body 6, and lower electrode layer 7 in the -Z direction. Although not shown in the figure, further layers can be located between the lower electrode layer 7 and the substrate, and the lower electrode layer 7 can be separated from the substrate.The upper electrode layer 5 and the lower electrode layer 7 can be formed by a multilayer film or the like, composed of conductors such as Ta, Cu and Ru.

[0008] The magnetically laminated body 6 can comprise a magnetically free layer 61, a non-magnetic layer 62, a first magnetically fixed layer 63, and an antiferromagnetic layer 66. These layers can be arranged in the following order in the -Z direction from the upper electrode layer 5 to the lower electrode layer 7: magnetically free layer 61, non-magnetic layer 62, first magnetically fixed layer 63, and antiferromagnetic layer 66. Adjacent layers can be in contact with each other. In other words, the first magnetically fixed layer 63 can be a magnetically fixed layer in contact with the antiferromagnetic layer 66. These layers can also be stacked in reverse order.In particular, the layers can be arranged in the sequence antiferromagnetic layer 66, first magnetically fixed layer 63, non-magnetic layer 62 and magnetically free layer 61 in the -Z direction from the upper electrode layer 5 to the lower electrode layer 7.

[0009] The magnetically free layer 61 can be a magnetic layer whose magnetization direction changes depending on an external magnetic field. The magnetically free layer 61 can consist of ferromagnetic materials such as Ni, Fe, Co, an alloy of two or more of these materials, or an amorphous alloy produced by adding B or Si to the alloy. The magnetization direction of the magnetically free layer 61 can be oriented orthogonally to the Z-direction in the zero-magnetic field state.

[0010] The non-magnetic layer 62 can comprise an insulating layer such as MgO or Al₂O₃. The magnetic field sensor element 2 in this embodiment can function as a tunnel magnetoresistive element (TMR element). The non-magnetic layer 62 can also comprise a non-magnetic metal layer such as copper or silver. In this case, the magnetic field sensor element 2 can function as a giant magnetoresistive element (GMR element). TMR elements tend to provide a higher output power than GMR elements.

[0011] The first magnetically fixed layer 63 can be a magnetic layer whose magnetization direction is fixed in the Z-direction. The first magnetically fixed layer 63 can be formed from a material with large perpendicular magnetic anisotropy, such as a multilayer film of Co, a multilayer film of Pd, or a multilayer of Co-film and Ni-film. The first magnetically fixed layer 63 can be formed as in Fig. 1A may be magnetized in the +Z direction, but it can also be magnetized in the -Z direction.

[0012] The antiferromagnetic layer 66 can be made of IrMn or of antiferromagnetic materials such as PtMn and FeRh. The antiferromagnetic layer 66 can stabilize the magnetization direction of the first magnetically fixed layer 63 in the zero-magnetic-field state. In particular, the first magnetically fixed layer 63 can be exchange-coupled with the antiferromagnetic layer 66 and fixed in the same direction as the magnetization direction during magnetization and annealing. If a strong magnetic field is applied in the Z-direction opposite to the magnetization direction of the first magnetically fixed layer 63, the magnetization direction of the first magnetically fixed layer 63 can be temporarily reversed. If the magnetization direction of the first magnetically fixed layer 63 remains reversed, the slope of the output can be reversed (e.g.,(An output curve trending upwards to the right can become an output curve trending downwards to the right). However, the magnetization direction of the first magnetically fixed layer 63 can revert to its original direction when the zero magnetic field state is reached. Therefore, the magnetization direction of the first magnetically fixed layer 63 can be easily stabilized in the zero magnetic field state, and it is less likely that the output will reverse.

[0013] When an external magnetic field, including a component in the Z-direction, is applied to the magnetically free layer 61, the magnetization direction of the magnetically free layer 61 can tilt in the Z-direction. This tilt can change the angle between the magnetization direction of the magnetically free layer 61 and the magnetization direction of the first magnetically fixed layer 63, and the electrical resistance of the magnetic laminated body 6 can change due to the magnetoresistive effect. The intensity of the Z-direction component of the external magnetic field can be measured by detecting the change in the electrical resistance of the magnetic laminated body 6, and in this way, the magnetic sensor 1 of this embodiment can detect the magnetic field in the Z-direction.

[0014] Fig. Figure 1B shows the schematic structure of a variant of the magnetic sensor 1 of the first embodiment. In the zero-magnetic field state, the magnetization direction of the magnetically free layer 61 can exhibit a vortex shape in a plane perpendicular to the Z-direction. The magnetization state of the magnetically free layer 61 in the zero-magnetic field state can be determined by the balance between the exchange energy and the static magnetization energy of the magnetically free layer 61. In general, vortex shapes are more likely to occur when the saturation magnetization is high. In the zero-magnetic field state, the center of the vortex, referred to as the core, can be located in the center of the magnetically free layer 61, and the magnetization direction can describe a concentric circle around the core.When an external magnetic field is applied in the Z-direction, the overall magnetization direction can be inclined in the Z-direction, leading to a magnetoresistive effect similar to that in the first embodiment. Since, in this case, the magnetically free layer 61 has a vortex shape in the zero-magnetic-field state, sensitivity fluctuations when exposed to a magnetic field other than that in the Z-direction can be easily suppressed. Method for manufacturing a magnetic sensor 1

[0015] Next, a manufacturing process for the magnetic sensor 1 of this embodiment will be described with reference to the Fig. 2A to 3 described. Fig. Figure 2A is a schematic drawing showing part of the manufacturing process of the magnetic sensor 1 of this embodiment, and Fig. Figure 2B is a schematic drawing showing part of the manufacturing process of the magnetic sensor in comparison example 1. In the Fig. 2A and Fig. 2B, dashed arrows indicate magnetic fields and hatched arrows indicate local heating. Although the Fig. 2A and Fig. While Figure 2B shows only a multilayer film 601, the magnetic sensor 1 can be manufactured in units of wafers 8 in which a plurality of multilayer films 601 are formed. The magnetic sensors of this embodiment and of Comparative Example 1 can have the same structure, but the manufacturing processes can be different.

[0016] To manufacture the magnetic sensor 1, the lower electrode layer 7, the laminated film 601 and the upper electrode layer 5 can first be successively placed on the wafer 8 (see Fig. 3), which is a substrate, are formed (step S1). The laminated film 601 can be formed by sequentially forming an antiferromagnetic layer 66, a ferromagnetic layer 631, a non-magnetic layer 62, and a magnetically free layer 61 in the +Z direction on the lower electrode layer 7. The ferromagnetic layer 631 is magnetized to become the first magnetically fixed layer 63, but at this stage, the ferromagnetic layer 631 is not magnetized and therefore differs from the first magnetically fixed layer 63. The ferromagnetic layer 631 and the antiferromagnetic layer 66 can be in contact with each other in the Z direction. The manufacturing process described above can apply to both this embodiment and Comparative Example 1.

[0017] In this embodiment, a magnetization process (step S2), in which a magnetic field is applied to the laminated film 601 to magnetize the ferromagnetic layer 631, and a local heating process (step S3), in which the laminated film 601 is locally heated, can be carried out next. Specifically, a magnetic field in the +Z direction (or a magnetic field in the -Z direction) can be applied to the laminated film 601 to form a first magnetically fixed layer 63 from the ferromagnetic layer 631, which has a magnetically fixed direction relative to the external magnetic field, after which the application of the magnetic field can be stopped (step S2). The laminated film 601 can then be heated (annealed) to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer 66 to form a magnetic laminated body 6 (step S3).The blocking temperature can be determined by the material of the antiferromagnetic layer 66. By heating the antiferromagnetic layer 66 to a temperature equal to or higher than its blocking temperature, an exchange coupling can occur between the antiferromagnetic layer 66 and the first magnetically fixed layer 63. The magnetization process (step S2) and the local heating process (step S3) should not be carried out simultaneously or at overlapping times, but rather at completely separate times. The magnetization direction of the magnetically free layer 61 is temporarily tilted in the Z-direction in step S2, but since no magnetic field is applied in step S3, the magnetization direction reverses to the X-direction, which is the direction of slight magnetization.

[0018] Fig. Figure 3 shows the schematic structure of the magnetizing and heating device 100 used in this embodiment. The magnetizing and heating device 100 can be part of the device for manufacturing the magnetic laminated body 6.

[0019] The magnetizing and heating device 100 can comprise a magnetic field application device 101, a heating device 102, and a transfer device 103. The magnetic field application device 101 can apply a magnetic field in the Z-direction to the laminated film 601 (ferromagnetic layer 631) to form a first magnetically fixed layer 63 from the ferromagnetic layer 631, which has a fixed magnetization direction with respect to the external magnetic field. The magnetic field application device 101 can comprise a pair of magnets 104 for applying a magnetic field to the wafer 8 and a holding device for the wafer 8 (not shown). The pair of magnets 104 can comprise electromagnets or permanent magnets. Fig. 3. The wafer 8 is held vertically between the pair of magnets 104, but the orientations of the pair of magnets 104 and the wafer 8 are not limited to the example shown in the drawing. For example, the pair of magnets 104 can be arranged in an upper position and a lower position, and the wafer 8 can be held horizontally between the pair of magnets 104.

[0020] The heating device 102 can heat the laminated film 601 to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer 66. The heating device 102 can be capable of locally heating the laminated film 601. For example, the heating device 102 can include a laser irradiation device 105 for heating the laminated film 601 with a laser beam. The heating device 102 can include a table 106 that holds the wafer 8 horizontally, a laser irradiation device 105, a reflection mirror 107 for deflecting the path of the laser beam, and an objective lens 108. The table 106 can be driven in two mutually orthogonal directions parallel to the wafer holding surface of the table 106 by a linear guide (not shown) driven by a motor 109.

[0021] The transfer device 103 can transfer the wafer 8 (laminated film 601) between the magnetic field application device 101 and the heating device 102. The transfer device 103 can comprise a base 110, a pivot axis 111 supported by the base 110, an arm 112 connected at approximately a right angle to the pivot axis 111, and a wafer holding section 113 connected to the arm 112. The arm 112 can be rotatable about the pivot axis 111 and extendable and retractable in the direction of the long axis 114 of the arm 112 itself. The wafer holding section 113 can be rotatable about the long axis 114 of the arm 112. This rotation can enable the transfer device 103 to remove the vertically oriented wafer 8 from the magnetic field application device 101, change the orientation of the wafer 8 and place the wafer 8 horizontally on the table 106 of the heating device 102.The structure of the transfer device 103 is not limited to this configuration, and the transfer device 103 can, for example, be used in combination with a conveyor to transport the wafer 8.

[0022] In the Fig. In Comparative Example 1 shown in Figure 2B, the magnetic laminated body 601 can be formed by heating (annealing) the laminated body 601 at a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer 66 while a magnetic field is applied to the laminated body 601 in the +Z direction (step S12). A first magnetically fixed layer 63 with a fixed magnetization direction relative to the external magnetic field can be formed, and simultaneously, exchange coupling can occur between the antiferromagnetic layer 66 and the first magnetically fixed layer 63. The number of steps in Comparative Example 1 can be fewer than in this embodiment, and the time required in Comparative Example 1 can also be shorter than in this embodiment.In comparative example 1, however, one of the magnets 104 may tend to interfere with the beam path 115 of the laser beam irradiation, since the direction of the applied magnetic field and the direction of heating (laser beam irradiation direction) may be aligned in the same direction (the Z-direction). In particular, step S12 of comparative example 1 can be performed if the pair of magnets 104 is attached to the magnets shown in the diagram. Fig. The positions shown by the three dashed lines are arranged, but one magnet 104 may need to be positioned further away from the table 106 than elements of the optical system such as the reflecting mirror 107 and the objective lens 108, and the distance between the two magnets 104 will increase. Applying a magnetic field of at least several thousand Oe (several hundred thousand A / m) can magnetize the ferromagnetic layer 631, but increasing the distance between the two magnets 104 may result in an increase in the size of the magnets 104, and in the case of electromagnets, increasing the size of components such as coils and the like will increase both their size and power consumption.

[0023] In comparative example 1, the motor 109 for position control of the table 106 is likely to be exposed to a relatively strong magnetic field. Since commercially available motors typically use iron (a ferromagnetic material), a strong magnetic field can exert an attractive force on the motor, and this force can affect the positional accuracy of the laser beam irradiation. A motor that does not use iron is not practical. One could consider placing a magnet with a hole between the reflecting mirror 107 or the objective lens 108 and the table 106, and then using the hole in the magnet as a beam path for the laser beam, but motor 109 would still be similarly exposed to the magnetic field.

[0024] As previously described, the magnetization process and the local heating process are carried out at different times in this embodiment, and the magnetic field application device 101 for the magnetization process and the heating device 102 for the local heating process can therefore be installed as separate devices. Since, in this case, interference between the laser beam irradiation optics path 115 and the magnet 104 is fundamentally impossible, and furthermore, interference between the magnetic field application device 101 and the heating device 102 is also rather unlikely, the respective structures of the magnetic field application device 101 and the heating device 102 are simplified.Since the magnetic field application device 101 and the heating device 102 can be positioned far apart, it is also unlikely that the magnetic field of the magnetic field application device 101 will affect the heating device 102.

[0025] Since the ferromagnetic layer 631 can be magnetized in the Z-direction in this embodiment, the magnetization process (step S2) and the local heating process (step S3) can easily be carried out separately. When a magnetic field is applied to the ferromagnetic layer 631 in the Z-direction, the layer is magnetized in the Z-direction and remains magnetized in the Z-direction even after the magnetic field application is discontinued. This property results from the fact that the ferromagnetic layer 631 exhibits a large magnetic anisotropy in the direction of the film thickness (Z-direction), which makes the magnetization in the Z-direction stable and resistant to fluctuations. Consequently, the first magnetically fixed layer 63, which is magnetized in the Z-direction, is obtained in this state by performing the local heating process.

[0026] In contrast, the magnetization direction of a ferromagnetic layer magnetized in the plane (X-direction) tends to vary within the plane when the application of a magnetic field is stopped after magnetization in the plane. This is because the magnetization in the plane of a plane-magnetized film can generally be relatively unstable and prone to fluctuations compared to the magnetization in the thickness direction of a perpendicularly magnetized film. If a local heating process is performed in this state, a condition in which the magnetization direction varies will be fixed.To avoid this, the application of a magnetic field to the ferromagnetic layer can continue and the local heating process can be carried out while maintaining the magnetization state in which the ferromagnetic layer is magnetized in the X-direction. In other words, the method of this embodiment, in which the magnetization process and the local heating process are carried out separately, is not very suitable for a magnetic sensor in which the first magnetically fixed layer 63 is magnetized in the plane, but is suitable for a magnetic sensor 1 in which the first magnetically fixed layer 63 is magnetized in the film thickness direction. Second embodiment

[0027] Fig. Figure 4A shows the schematic structure of the magnetic sensor 1 according to the second embodiment. The explanation of the structure and the effects, which are identical to those of the first embodiment, is omitted from the description. The magnetic laminated body 6 can comprise a magnetically free layer 61, a non-magnetic layer 62, a first magnetically fixed layer 63, an intermediate layer 64, a second magnetically fixed layer 65, and an antiferromagnetic layer 66. The magnetically free layer 61, the non-magnetic layer 62, the first magnetically fixed layer 63, and the antiferromagnetic layer 66 can be configured as in the first embodiment. The antiferromagnetic layer 66 can have the same effect as in the first embodiment.These layers can also be arranged in the following order in the -Z direction from the upper electrode layer 5 to the lower electrode layer 7: magnetically free layer 61, non-magnetic layer 62, first magnetically fixed layer 63, intermediate layer 64, second magnetically fixed layer 65, and antiferromagnetic layer 66, and adjacent layers can be in contact with each other. In other words, in this embodiment, the second magnetically fixed layer 65 can be a magnetically fixed layer in contact with the antiferromagnetic layer 66, and the first magnetically fixed layer 63 can be a ferromagnetic intermediate layer. These layers can also be stacked in reverse order.In particular, they can be arranged in the sequence antiferromagnetic layer 66, second magnetically fixed layer 65, intermediate layer 64, first magnetically fixed layer 63, non-magnetic layer 62 and magnetically free layer 61 in the -Z direction from the upper electrode layer 5 to the lower electrode layer 7.

[0028] The first magnetically fixed layer 63 can be magnetically coupled to the second magnetically fixed layer 65 via the intermediate layer 64 by synthetic antiferromagnetic coupling. The magnetization direction of the first magnetically fixed layer 63 is fixed in the opposite direction to the magnetization direction of the second magnetically fixed layer 65. The first magnetically fixed layer 63 and the second magnetically fixed layer 65 can be formed from multilayer films of Co and Pt films or from materials with large perpendicular magnetic anisotropy, such as multilayer films of Co and Pd films, Co and Ni films, or the like. The intermediate layer 64 can be formed from a non-magnetic metal that generates RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling, such as ruthenium or the like.The multilayer film, comprising the first magnetically bonded layer 63, the intermediate layer 64, and the second magnetically bonded layer 65, can also be referred to as a synthetic antiferromagnetic (SAF) structure. Since the magnetization directions of the first magnetically bonded layer 63 and the second magnetically bonded layer 65 can be oriented in opposite directions, the stray field exerted by the first magnetically bonded layer 63 on the magnetically free layer 61 can be suppressed. The magnitude of the magnetic moment of the first magnetically bonded layer 63 and that of the second magnetically bonded layer 65 can be made nearly equal. Fig. 4A and Fig. 4B the first magnetically fixed layer 63 can be magnetized in the -Z direction and the second magnetically fixed layer 65 can be magnetized in the +Z direction, but the first magnetically fixed layer 63 can also be magnetized in the +Z direction and the second magnetically fixed layer 65 can be magnetized in the -Z direction.

[0029] Fig. Figure 4B shows the schematic structure of a variant of the magnetic sensor 1 according to the second embodiment. In the zero-magnetic-field state, the magnetization direction of the magnetically free layer 61 can exhibit a vortex shape in the plane perpendicular to the Z-direction. Details can be found in the description of the first embodiment. Method for manufacturing magnetic sensor 1

[0030] The magnetic sensor 1 of this embodiment can be manufactured using the same manufacturing process as in the first embodiment. To manufacture the magnetic sensor 1, the lower electrode layer 7, the laminated film 601, and the upper electrode layer 5 can first be successively formed on the wafer 8, which is a substrate (step S1). Fig. Figure 5 shows the structure of the laminated film 601 in this embodiment. The laminated film 601 in this embodiment can be produced by successively forming an antiferromagnetic layer 66, a ferromagnetic layer 651, an intermediate layer 64, a ferromagnetic layer 631, a non-magnetic layer 62, and a magnetically free layer 61 in the +Z direction on the lower electrode layer 7. Next, the magnetization process (step S2) can be carried out as in the first embodiment. The ferromagnetic layer 651, which is in contact with the antiferromagnetic layer 66, can be magnetized to become the second magnetically fixed layer 65, and the ferromagnetic layer 631 can be magnetized to become the first magnetically fixed layer 63.Next, a local heating process (step S3) can be performed to firmly fix the magnetization direction of the second magnetically fixed layer 65 in the Z-direction. The devices used in the magnetization process and in the local heating process are the same as in the first embodiment. Details can be found in the description of the first embodiment.

[0031] In this embodiment, the ferromagnetic layer 651 and the ferromagnetic layer 631 can be magnetized in the same direction (the +Z direction) when a magnetic field is applied during the magnetization process (step S2) (e.g., in the +Z direction). When the application of a magnetic field is discontinued, the magnetization directions of the ferromagnetic layer 651 and the ferromagnetic layer 631 may be oriented in opposite directions due to the SAF structure. In other words, either the magnetization direction of the ferromagnetic layer 651 or that of the ferromagnetic layer 631 may be reversed (the magnetization direction may be oriented in the -Z direction). Next, the local heating process (step S3) can be performed to fix the magnetization directions of the ferromagnetic layer 651 and the ferromagnetic layer 631.Therefore, either the magnetization direction of the first magnetically fixed layer 63 or the magnetization direction of the second magnetically fixed layer 65 can be opposite to the direction in which the magnetic field is applied during magnetization. There is no functional problem even if the magnetization direction of one of the two ferromagnetic layers is reversed. However, since the magnetic sensor 1 is typically manufactured in large quantities in wafer or batch units, a deviation in the magnetization direction of the first magnetically fixed layer 63 and the second magnetically fixed layer 65 on the same wafer or in the same batch leads to a deviation in the output on the same wafer or in the same batch and is therefore undesirable.

[0032] Which of the ferromagnetic layers 651 or 631 experiences a reversal of magnetization direction when the application of a magnetic field is discontinued depends on the magnetic properties of the ferromagnetic layer 651 and the ferromagnetic layer 631. For example, the magnetization direction of a ferromagnetic layer with a small magnetic moment is more likely to reverse than that of a ferromagnetic layer with a large magnetic moment. To suppress fluctuations in the magnetization direction, the magnetic moments of the ferromagnetic layer 651 and the ferromagnetic layer 631 can therefore differ to some extent. For example, if the ferromagnetic layer 651 and the ferromagnetic layer 631 are formed from the same material, the film thickness or volume can differ.The ferromagnetic layer with a greater film thickness or volume also has a greater magnetic moment. If the film thicknesses or volumes of the ferromagnetic layer 651 and the ferromagnetic layer 631 are nearly equal, materials with different magnetic moments per unit volume can be used. However, if the difference in magnetic moment between the ferromagnetic layer 651 and the ferromagnetic layer 631 is too large, the stray field of the ferromagnetic layer 631 has a greater influence on the magnetically free layer 61. Therefore, if the magnetic moment of the first magnetically fixed layer 63 is M1 and the magnetic moment of the second magnetically fixed layer 65 is M2, then... |M2−M1| / M1 between 3% and 20%.

[0033] Since a ferromagnetic layer exhibiting low perpendicular magnetic anisotropy tends to undergo a reversal of magnetization direction more readily than a ferromagnetic layer exhibiting high perpendicular magnetic anisotropy, a difference in the magnitude of the perpendicular magnetic anisotropy can be provided between the first magnetically fixed layer 63 and the second magnetically fixed layer 65. For example, if the first magnetically fixed layer 63 and the second magnetically fixed layer 65 are formed by multilayer films (e.g., Co and Pt films), a difference in the magnitude of the perpendicular magnetic anisotropy can be provided by changing the thickness ratio of the films comprising the multilayer film (e.g., Co and Pt films).This method can be used to suppress the influence of stray magnetic fields, since the magnetic moments of the first magnetically fixed layer 63 and the second magnetically fixed layer 65 can be the same. Third example

[0034] Fig. Figure 6 shows the schematic structure of the magnetic sensor 1 according to a third embodiment. The magnetic sensor 1 of this embodiment can comprise the magnetic field sensor elements 2 of the first and second embodiments mentioned above, combined as a half-bridge. The magnetic sensor 1 can comprise a first and a second element unit 11 and 12, each comprising at least one magnetic field sensor element 2. In one example, each of the first and second element units 11 and 12 can comprise an arrangement of a plurality of magnetic field sensor elements 2 connected in series. The first and second element units 11 and 12 can be connected in series to form the group 15. One end of the group 15 can be connected to the power supply VDD and the other end can be grounded (GND).The voltage drops across the first and second element units 11 and 12 can be approximately proportional to their electrical resistances. Therefore, if the electrical resistances of the first and second element units 11 and 12 are R1 and R2 respectively, the midpoint voltage V1 can satisfy the following equation: V1 = R2 / (R1 + R2) x VDD. The magnetic sensor 1 can include an output section 17 positioned between the first and second element units 11 and 12, and the output section 17 can output the midpoint voltage V1.

[0035] The magnetization direction of the magnetically fixed layer in contact with the antiferromagnetic layer 66 of the first element unit 11 and the magnetization direction of the magnetically fixed layer in contact with the antiferromagnetic layer 66 of the second element unit 12 are opposite to each other. In the first embodiment, the magnetically fixed layer in contact with the antiferromagnetic layer 66 is the first magnetically fixed layer 63, and in the second embodiment, it is the second magnetically fixed layer 65. Method for manufacturing a magnetic sensor 1

[0036] The magnetic sensor 1 according to a third embodiment can be a combination of several magnetic field sensor elements 2, and individual magnetic field sensor elements 2 can be manufactured by the manufacturing processes of each embodiment described above. The explanation here focuses on the magnetization process and the local heating process of each of the element units 11 and 12 with reference to the Fig. 7A to 7D. The magnetic field sensor element 2 can comprise the magnetic laminated body 6 of the first embodiment, but the magnetic field sensor element 2 comprising the magnetic laminated body 6 of the second embodiment can also be manufactured in the same way. The symbols used in the Fig. 7A to 7D specify the +Z direction and the -Z direction, and can indicate the magnetization direction of the ferromagnetic layer 631 or the first magnetically fixed layer 63 in the Fig. 2A and Fig. Specify 2B.

[0037] First, as in Fig. As shown in Figure 7A, a first magnetic field H1 is applied in the -Z direction to the first and second element units 11 and 12, whereupon the application of the first magnetic field H1 is discontinued. The ferromagnetic layer 631 of the first element unit 11 can be magnetized in the -Z direction to become the first magnetically fixed layer 63. At this point, the ferromagnetic layer 631 of the second element unit 12 can also be magnetized in the -Z direction. Next, as shown in Fig. As shown in Figure 7B, the first element unit 11 is irradiated with a laser beam to heat it to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer 66 of the first element unit 11, in order to fix the magnetization direction of the first magnetically fixed layer 63 by exchange coupling with the antiferromagnetic layer 66. The heating of the second element unit 12 can be kept at a sufficiently low level to allow for local heating by the laser beam.

[0038] Next, as in Fig. Figure 7C shows that a second magnetic field H2 is applied in the +Z direction to the first and second element units 11 and 12, whereupon the application of the second magnetic field H2 is discontinued. The second magnetic field H2 can be in the opposite direction to the first magnetic field H1 (the directions differ by 180°). The second magnetic field H2 should have at least one component in the opposite direction to the first magnetic field H1. The ferromagnetic layer 631 of the second element unit 12 is already magnetized in the -Z direction, but when a magnetic field is applied in the +Z direction, the ferromagnetic layer 631 is magnetized in the +Z direction and becomes the first magnetically fixed layer 63.At this point, the magnetization direction of the first magnetically fixed layer 63 of the first element unit 11 may temporarily reverse, but when the application of the magnetic field is discontinued, the magnetization direction returns to the -Z direction through exchange coupling with the antiferromagnetic layer 66. Next, as in . Fig. Figure 7D shows the second element unit 12 being irradiated with a laser beam and heated to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer 66 of the second element unit 12 in order to fix the magnetization direction of the first magnetically fixed layer 63 by exchange coupling with the antiferromagnetic layer 66. The laser beams are irradiated at several positions. Taking into account the shape accuracy of the element unit and other factors, the distances between the laser beam irradiation positions can be approximately 5 µm or more and 10 µm or more.

[0039] In this embodiment, the first or second element unit 11 and 12 can be heated locally by laser annealing, but the heating method is not limited to laser light as long as the first element unit 11 or the second element unit 12 can be heated locally. For example, wiring can be provided near the first element unit 11 and the second element unit 12, and the first element unit 11 and the second element unit 12 can be selectively heated by supplying energy to the wiring and generating heat in the wiring. Fourth embodiment

[0040] Fig. Figure 8 shows the schematic structure of the magnetic sensor 1 according to the fourth embodiment. The magnetic sensor 1 of this embodiment can comprise the magnetic field sensor elements 2 of the first and second embodiments mentioned above, combined as a full bridge. The magnetic sensor 1 can comprise a first to fourth element unit 11-14, each comprising at least one magnetic field sensor element 2. In one example, each of the first to fourth element units 11-14 can comprise an arrangement of a plurality of magnetic field sensor elements 2 connected in series. The first and second element units 11 and 12 can be connected in series to form a first group 16A. The third and fourth element units 13 and 14 can be connected in series to form a second group 16B.One end of each of the first and second groups 16A and 16B can be connected to the power supply VDD, and the other ends of each of the first and second groups 16A and 16B can be grounded (GND). The first element unit 11 and the fourth element unit 14 can be positioned on the power supply VDD side, and the second element unit 12 and the third element unit 13 can be positioned on the ground (GND) side. The magnetic sensor 1 can include a differentiator 18 to determine the difference between the output V1, located between the first element unit 11 and the second element unit 12, and the output V2, located between the third element unit 13 and the fourth element unit 14.

[0041] The magnetization directions of the magnetically fixed layers in contact with the antiferromagnetic layer 66 of the first and third element units 11 and 13 are aligned. The magnetization directions of the magnetically fixed layers in contact with the antiferromagnetic layers 66 of the second and fourth element units 12 and 14 are opposite to the magnetization direction of the magnetically fixed layers in contact with the antiferromagnetic layer 66 of the first and third element units 11 and 13. In the first embodiment, the magnetically fixed layers in contact with the antiferromagnetic layers 66 can be the first magnetically fixed layers 63, and in the second embodiment, they can be the second magnetically fixed layers 65.

[0042] The voltage drops in each of the element units 11-14 can be approximately proportional to the electrical resistances of the first to fourth element units 11-14. Therefore, if the electrical resistances of the first to fourth element units 11-14 are R1-R4 respectively, the mean voltage V1 can satisfy the equation V1 = R2 / (R1 + R2) x VDD, and the mean voltage V2 can satisfy the equation V2 = R3 / (R3 + R4) x VDD. By determining the difference V1 - V2 between the mean voltages V1 and V2 using the differentiator 18, the sensitivity is twice as high as when detecting the mean voltages V1 and V2 alone. Even if the mean voltages V1 and V2 are offset, the effect of the offset can be eliminated by detecting the difference. Method for manufacturing a magnetic sensor 1

[0043] The magnetic sensor 1 according to the fourth embodiment can be a combination of several magnetic field sensor elements 2, and individual magnetic field sensor elements 2 can be manufactured by the manufacturing process of each embodiment mentioned above. The following explanation focuses on the magnetization process and the local heating process of each of the element units 11-14 with reference to the Fig. 9A to 9D. These processes can be essentially the same as those in the third embodiment. Magnetic field sensor elements 2 can comprise magnetic laminated bodies 6 of the first embodiment, but magnetic field sensor elements 2 comprising magnetic laminated bodies 6 of the second embodiment can also be manufactured in the same way. The symbols indicating the +Z direction and the -Z direction in the Fig. 9A-9D can indicate the magnetization directions of the ferromagnetic layers 631 or the first magnetically fixed layers 63 in the Fig. 2A and Fig. Show 2B.

[0044] First, as in Fig. As shown in Figure 9A, a first magnetic field H1 is applied in the -Z direction to the first to fourth element units 11-14, after which the application of the first magnetic field H1 is discontinued. The ferromagnetic layers 631 of the first and third element units 11 and 13 can be magnetized to become the first magnetically fixed layers 63. Next, as shown in Fig. As shown in Figure 9B, the first and third element units 11 and 13 are irradiated with a laser beam to heat them to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layers 66 of the first and third element units 11 and 13, in order to fix the magnetization directions of the first magnetically fixed layers 63 by exchange coupling with the antiferromagnetic layers 66. Next, as shown in Fig. As shown in Figure 9C, a second magnetic field H2 is applied in the +Z direction to the first to fourth element units 11-14, after which the application of the second magnetic field H2 is discontinued. Ferromagnetic layers 631 of the second and fourth element units 12 and 14 can be magnetized in the +Z direction to become the first magnetically fixed layers 63. Next, as shown in Fig. Figure 9D shows that the second and fourth element units 12 and 14 are irradiated with a laser beam to heat them to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layers 66 of the second and fourth element units 12 and 14, in order to fix the magnetization direction of the first magnetically fixed layers 63 by exchange coupling with the antiferromagnetic layers 66. In this embodiment, the distances between the irradiation positions of the laser beam can be approximately 5 µm or more and approximately 10 µm or more. Example

[0045] Samples comprising stacked antiferromagnetic and ferromagnetic layers were prepared, and magnetization curves were obtained. In this example, a magnetic field perpendicular to the film surface of a ferromagnetic layer was applied to the prepared samples, and the samples were heated after the magnetic field application was complete. In Comparative Example 2, a magnetic field perpendicular to the film surface of a ferromagnetic layer was applied to the prepared samples while the samples were simultaneously heated. The present example corresponds to embodiments 1 to 4, and Comparative Example 2 corresponds to Comparative Example 1. Fig. Figure 10A shows the magnetization curve of the example and the Fig. Figure 10B shows the magnetization curve of comparison example 2. The horizontal axis of the magnetization curves indicates the strength of the external magnetic field, and the vertical axis indicates the magnetic moment. The ranges of the horizontal and vertical axes are shown in the Fig. 10A and Fig.10B identical. The magnetization curves in the present example and the comparison example have almost the same shape, and the centers of the magnetization curves are located at almost the same position on the horizontal axis. This correspondence shows that there is almost no difference in the exchange coupling strength between annealing under the application of a magnetic field, as in the conventional technology, and annealing after the application of a magnetic field, as in the present example. In other words, it was found that the exchange coupling strength in the present example was sufficiently large to fix the magnetization direction of magnetically fixed layers in contact with antiferromagnetic layers.

[0046] According to the present disclosure, a method for producing a magnetic laminated body can be provided which can simplify a device for magnetizing a magnetically fixed layer and for heating an antiferromagnetic layer. REFERENCE MARK 1 magnetic sensor 2 Magnetic field sensor element 6 magnetic laminated bodies 7 lower electrode layer 11-14 first to fourth element unit 61 magnetically free layer 62 first non-magnetic layer 63 first magnetically fixed layer 64 Intermediate shift 65 second magnetically fixed layer 66 antiferromagnetic layer 100 Magnetizing and heating device 101 Magnetic field application device 102 Heating device 103 Transmission device QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] JP 2018-6598A [0002, 0005] JP 2015-207625A

[0002]

Claims

[1] Method for producing a magnetic laminated body (6) comprising the following steps: Forming a laminated film (601) comprising a ferromagnetic layer (631) and an antiferromagnetic layer (66), wherein the ferromagnetic layer (631) and the antiferromagnetic layer (66) are in contact with each other in a first direction; Forming a magnetically fixed layer (63) from the ferromagnetic layer (631) having a fixed magnetization direction with respect to an external magnetic field by applying a magnetic field in the first direction to the laminated film (601); and After the magnetic field has been applied, the laminated film (601) is heated to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer (66) to form the magnetic laminated body (6). [2] Manufacturing method of a magnetic laminated body (6) according to claim 1, wherein the laminated film (601) is heated by a laser beam. [3] Method for producing a magnetic laminated body (6) according to claim 1 or 2, wherein after the application of the magnetic field is discontinued, the laminated film (601) is transferred to heat the laminated film (601). [4] Method for producing a magnetic laminated body (6) according to any one of claims 1 to 3, wherein the laminated film (601) comprises a magnetically free layer (61) whose magnetization direction changes with respect to an external magnetic field, and a non-magnetic layer (62), and the ferromagnetic layer (631), the antiferromagnetic layer (66), the magnetically free layer (61) and the non-magnetic layer (62) are arranged in the first direction in the order of the magnetically free layer (61), the non-magnetic layer (62), the ferromagnetic layer (631) and the antiferromagnetic layer (66). [5] Method for producing a magnetic laminated body (6) according to any one of claims 1 to 3, wherein the laminated film (601) comprises a magnetically free layer (61) whose magnetization direction changes with respect to an external magnetic field, a non-magnetic layer (62), an intermediate ferromagnetic layer (63) and an intermediate layer (64) formed of a non-magnetic metal, and the ferromagnetic layer (631), the antiferromagnetic layer (66), the magnetically free layer (61), the non-magnetic layer (62), the ferromagnetic intermediate layer (63) and the intermediate layer (64) are arranged in the order of the magnetically free layer (61), the non-magnetic layer (62), the ferromagnetic intermediate layer (63), the intermediate layer (64), the ferromagnetic layer (631) and the antiferromagnetic layer (66) in the first direction. [6] Method for producing a magnetic laminated body (6) according to claim 5, wherein, when the magnetic moment of the ferromagnetic intermediate layer (63) is M1 and the magnetic moment of the ferromagnetic layer (631) is M2, |M2 - M1| / M1 is between 3% and 20%. [7] Method for producing a magnetic laminated body (6) according to claim 5, wherein the magnitudes of the perpendicular magnetic anisotropy of the ferromagnetic intermediate layer (63) and the ferromagnetic layer (631) are different from each other. [8] Method for producing a magnetic laminated body (6) according to any one of claims 4 to 7, wherein the magnetization direction of the magnetically free layer (61) in a plane perpendicular to the first direction has a vortex shape in a state in which no external magnetic field is applied. [9] Method for producing a magnetic laminated body (6) according to any one of claims 4 to 8, wherein the non-magnetic layer (62) comprises an insulating layer. [10] Method for manufacturing a magnetic sensor (1) comprising the following steps: Arranging a ferromagnetic layer (631), a magnetically free layer (61) whose magnetization direction changes with respect to an external magnetic field, a non-magnetic layer (62) and an antiferromagnetic layer (66) in the order of the magnetically free layer (61), the non-magnetic layer (62), the ferromagnetic layer (631) and the antiferromagnetic layer (66) in a first direction; Forming a group consisting of a first element unit (11) and a second element unit (12) in which the first element unit (11) and the second element unit (12) are connected in series, each of the first and second element units (11, 12) comprising a laminated film (601) in which the ferromagnetic layer (631) and the antiferromagnetic layer (66) are in contact with each other, and wherein one end of the group is connected to a power supply and the other end is grounded; Providing an output section between the first element unit (11) and the second element unit (12); Forming a magnetically fixed layer (63) from the ferromagnetic layer (631) of the first element unit (11), which has a fixed magnetization direction with respect to an external magnetic field, by applying a first magnetic field in the first direction to the first element unit (11); After the first magnetic field has been applied, the first element unit (11) is heated to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer (66) of the first element unit (11); Forming a magnetically fixed layer (63) from the ferromagnetic layer (631) of the second element unit (12), which has a fixed magnetization direction with respect to an external magnetic field, by applying a second magnetic field, which encloses a component in a direction opposite to the first direction, to the second element unit (12); and After the application of the second magnetic field has ended, the second element unit (12) is heated to a temperature equal to or higher than a blocking temperature of the antiferromagnetic layer (66) of the second element unit (12). [11] Method for manufacturing a magnetic sensor (1) comprising the following steps: Arranging a ferromagnetic layer (631), a magnetically free layer (61) whose magnetization direction changes with respect to an external magnetic field, a non-magnetic layer (62) and an antiferromagnetic layer (66) in the order of the magnetically free layer (61), the non-magnetic layer (62), the ferromagnetic layer (631) and the antiferromagnetic layer (66) in a first direction; Forming a first group consisting of a first element unit (11) and a second element unit (12) in which the first element unit (11) and the second element unit (12) are connected in series, and forming a second group consisting of a third element unit (13) and a fourth element unit (14) in which the third element unit (13) and the fourth element unit (14) are connected in series, wherein each of the first to fourth element units (11, 12, 13, 14) comprises a laminated film (601) in which the ferromagnetic layer (631) and the antiferromagnetic layer (66) are in contact with each other, and one end of each of the first and second groups is connected to a power supply and the other ends are grounded, and wherein the first element unit (11) and the fourth element unit (14) are arranged on the power supply side and the second element unit (12) and the third element unit (13) are arranged on the grounding side; Providing a differentiator (18) for determining a difference between an output that lies between the first element unit (11) and the second element unit (12) and an output that lies between the third element unit (13) and the fourth element unit (14); Forming magnetically fixed layers (63) from the ferromagnetic layers (631) of the first and third element units (11, 13), each of which has a fixed magnetization direction with respect to an external magnetic field, by applying a first magnetic field in the first direction to the first and third element units (11, 13); After the first magnetic field has been applied, the first and third element units (11, 13) are heated to a temperature equal to or higher than the blocking temperatures of the antiferromagnetic layers (66) of the first and third element units (11, 13); Forming magnetically fixed layers (63) from the ferromagnetic layers (631) of the second and fourth element units (12, 14), each of which has a fixed magnetization direction with respect to an external magnetic field, by applying a second magnetic field, enclosing a component in a direction opposite to the first direction, to the second and fourth element units (12, 14); and After the application of the second magnetic field has ended, the second and fourth element units (12, 14) are heated to a temperature equal to or higher than the blocking temperatures of the antiferromagnetic layers (66) of the second and fourth element units (12, 14). [12] Method for manufacturing a magnetic sensor (1) according to claim 10 or 11, wherein the second magnetic field extends in a direction opposite to the first direction. [13] Device for producing a magnetic laminated body (6), comprising: a magnetic field application device (101) which applies a magnetic field in a first direction to a laminated film (601) of a wafer, the laminated film (601) comprising a ferromagnetic layer (631) and an antiferromagnetic layer (66) in contact with each other in the first direction to form a magnetically fixed layer (63) from the ferromagnetic layer (631), wherein a magnetization direction of the magnetically fixed layer (63) is fixed with respect to an external magnetic field; a heating device (102) that heats the laminated film (601) to a temperature higher than a barrier temperature of the antiferromagnetic layer (66); and a transfer device (103) that transfers the wafer between the magnetic field application device (101) and the heating device (102). [14] Device for producing a magnetic laminated body (6) according to claim 13, wherein the heating device (102) comprises a laser beam irradiation device for heating the laminated film (601) with a laser beam.

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