CN116718963A - Method and system for manufacturing linear GMR magnetic sensor based on current annealing - Google Patents
Method and system for manufacturing linear GMR magnetic sensor based on current annealing Download PDFInfo
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Abstract
A method and system for manufacturing a linear GMR magnetic sensor based on current annealing includes: depositing a GMR multilayer film structure on a substrate: magnetizing the pinning layer of the multilayer film structure under a first condition, wherein the current annealing direction is along the short direction of the magnetic resistance strip; magnetizing the free layer of the multilayer film structure under a second condition, wherein the current annealing direction is along the length direction of the magnetic resistance strip; in the GMR Wheatstone full-bridge structure, the four groups of GMR multilayer film structures are respectively subjected to the current annealing treatment, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained. The invention can realize the linear voltage output of a single magnetic resistance strip. Further, the local current magnetic annealing is respectively carried out on the structures in different areas on the same substrate so as to realize the two opposite directions of the response of the four groups of magneto resistances of the Wheatstone bridge structure to the external magnetic field, and finally, the linear voltage output of the full bridge structure is realized.
Description
Technical Field
The invention belongs to the technical field of sensor manufacturing, and particularly relates to a method and a system for manufacturing a linear GMR magnetic sensor based on current annealing.
Background
The magnetic field sensor is widely applied to modern measurement systems due to the characteristics of high sensitivity, high stability and the like, and is used for detecting physical parameters including magnetic field intensity, direction, displacement and the like. The magnetic sensor designed and manufactured based on the Giant Magnetoresistance (GMR) effect is widely applied to the magnetic sensing market due to the advantages of high magnetoresistance change rate, high sensitivity, good stability and the like, and particularly the fields of magnetic storage probes and biomedical detection.
GMR magnetic sensors mainly have different structures such as single magneto-resistance, reference resistance half-bridge, wheatstone full-bridge, etc. Among them, the wheatstone full bridge structure is one of the most well-performing and most applicable structures. For the magnetic sensor, the magnetic resistor needs to have the characteristics of linear change along with an external magnetic field, no hysteresis and the like in order to realize linear voltage output. Currently, three general processing methods exist for realizing linear output without hysteresis of a GMR magnetic sensor: rotating the direction of the magnetic field in the growth process to enable the two ferromagnetic layers to be coupled at 90 degrees; the thickness of each layer is regulated and controlled by a special structure (artificial antiferromagnetic) to realize 90-degree coupling; the pinned and free layers are coupled at 90 degrees by different temperature/magnetic field magnetic anneals, respectively.
At present, the production and manufacture of the linear GMR single magnetic resistance structure mostly adopts physical deposition modes such as magnetron sputtering, so that if magnetic fields with different angles are respectively applied in the growth process, specific modification is needed to be carried out on production equipment, the production cost is high, and the production efficiency is low. If the linear output of the GMR device is realized by means of interlayer coupling regulation and control of a special structure (artificial antiferromagnetic), the requirements on the accuracy of the instrument and the thickness between layers are increased, interlayer diffusion and other phenomena of the GMR structure are easier to occur at high temperature, and the device has poor stability, high cost and high technical requirements. The former approach generally requires higher production costs, and the latter approach is more widely used. However, the annealing mode in the prior art generally determines the magnetization directions of all the magnetoresistive strips to the same angle, and linear output cannot be realized for the individual GMR magnetoresistive structures. And if the linear output of the Wheatstone bridge structure is to be realized, an assembly mode is needed to ensure that the four groups of magnetic resistances respond to the external magnetic field in a pairwise reverse manner, so that the sensing precision is reduced and the production cost is increased.
Disclosure of Invention
The invention aims to provide a method and a system for manufacturing a linear GMR magnetic sensor based on current annealing, which are used for solving the problems that the response of four groups of magnetic resistances to external magnetic fields is reversed every two by two in an assembly mode, so that the sensing precision is reduced and the production cost is increased.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a method of fabricating a linear GMR magnetic sensor based on current annealing comprising:
depositing a GMR multilayer film structure on the substrate, the GMR multilayer film structure comprising a pinned layer, a nonmagnetic metal layer and a free layer:
magnetizing the pinning layer of the multilayer film structure under a first condition, wherein the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The magnitude of the annealing magnetic field is greater than or equal to that of the magnetic field when the pinning layer is completely turned over, and can be about 1200Oe (the specific magnitude is determined according to the selected antiferromagnetic material);
magnetizing the free layer of the multilayer film structure under a second condition, wherein the current annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The annealing magnetic field is smaller than the magnetic field when the pinning layer is completely turned over, and can be about 200Oe (the specific value is determined according to the selected free layer material);
forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
in the GMR Wheatstone full-bridge structure, the four groups of GMR multilayer film structures are respectively subjected to the current annealing treatment, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
Furthermore, in the Wheatstone full bridge structure, after the four groups of GMR multilayer film structures are deposited and grown on the same substrate, current annealing treatment is performed respectively, so that the magnetic annealing directions of the first group of GMR structures R1 and the third group of GMR structures R3 are the same, the magnetic annealing directions of the second group of GMR structures R2 and the fourth group of GMR structures R4 are the same, and the directions are opposite to the first two groups.
Further, the free layer is a bilayer structure formed by CoFe/NiFe.
Further, the pinning layer includes a metal inducing layer, an antiferromagnetic layer, and a ferromagnetic layer, the ferromagnetic layer being a CoFe layer.
Further, the GMR multilayer film structure further comprises an adhesion layer and a protective layer, wherein the adhesion layer, the pinning layer, the nonmagnetic metal layer, the free layer and the protective layer are sequentially grown on the substrate.
Further, the order of the pinned layer and the free layer can be interchanged to correspond to the bottom pinning and the top pinning of the GMR multilayer film structure.
Further, the protective layer is made of insulating materials and oxidation-resistant metal materials, and the thickness is 2-20 nm; the adhesive layer is a Ta/Ru adjacent metal film with the thickness of 2-20 nm.
Further, the antiferromagnetic layer is made of IrMn and PtMn materials, and the thickness is 5-10 nm; the non-magnetic metal layer is made of metal material and has a thickness of 1.8-5 nm.
Further, the substrate material is a silicon wafer, a glass sheet, a Kapton or PET substrate.
Further, a current annealing based linear GMR magnetic sensor manufacturing system comprising:
a deposition module for depositing a GMR multilayer film structure on a substrate, the GMR multilayer film structure comprising a pinned layer, a non-magnetic metal layer and a free layer:
the first annealing treatment module is used for magnetizing the pinning layer of the multilayer film structure under a first condition, and the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The magnitude of the annealing magnetic field is greater than or equal to that of the magnetic field when the pinning layer is completely turned over, and can be about 1200Oe (the specific magnitude is determined according to the selected antiferromagnetic material);
second annealing treatmentThe module is used for magnetizing the free layer of the multilayer film structure under the second condition, and the current annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The annealing magnetic field is smaller than the magnetic field when the pinning layer is completely turned over, and can be about 200Oe (the specific value is determined according to the selected free layer material); forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
and the GMR magnetic sensor generating module is used for respectively carrying out the current annealing treatment on the four groups of GMR multilayer film structures in the GMR Wheatstone full-bridge structure, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
Compared with the prior art, the invention has the following technical effects:
according to the invention, through the current annealing effect under the action of currents of different magnitudes and magnetic fields of different magnitudes, the single GMR magnetic resistance structure deposited and grown on the same substrate is subjected to current magnetic annealing treatment in different directions respectively; by magnetizing the pinned layer of the multilayer film structure under the condition of large magnetic field and large current and magnetizing the free layer of the multilayer film structure under the condition of small magnetic field and small current, the linear voltage output of the single magnetic resistance strip can be realized. Further, the local current magnetic annealing is respectively carried out on the structures in different areas on the same substrate so as to realize the two opposite directions of the response of the four groups of magneto resistances of the Wheatstone bridge structure to the external magnetic field, and finally, the linear voltage output of the full bridge structure is realized.
Drawings
FIG. 1 illustrates a schematic diagram of current annealing of individual GMR structures.
FIG. 2 illustrates a schematic diagram of a GMR Wheatstone bridge configuration current anneal.
FIG. 3 illustrates a schematic structure of a top pinned GMR magnetoresistive cell.
FIG. 4 is a graph showing the response of the magnetoresistance to an external magnetic field of a conventional GMR magnetoresistive element with the magnetization direction of the pinned layer pointing in the negative H direction.
Fig. 5a and b are schematic diagrams showing the response curves of the magnetoresistance to an external magnetic field of a GMR magnetoresistive element using the patent for current magnetic annealing, in which the magnetization direction of the pinned layer is directed in the negative H direction.
Fig. 6a and b illustrate output voltage graphs for the partial half-bridge structure and the wheatstone full-bridge structure shown in fig. 2.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
referring to fig. 1-6, the present invention provides a method and system for fabricating a linear GMR magnetic sensor based on current annealing.
Depositing a GMR multilayer film structure on a substrate, the GMR magnetoresistive cell comprising at least a pinned layer, a nonmagnetic metal layer and a free layer:
the current annealing pinning layer is used for magnetizing the pinning layer of the multilayer film structure under the condition of large magnetic field and large current, and the current annealing direction is along the short direction of the magnetic resistance strip;
the free layer is subjected to current annealing, and the free layer of the multilayer film structure is magnetized under the condition of small magnetic field and small current, and the current annealing direction is along the length direction of the magnetic resistance strip;
for a GMR single magnetic resistance structure, forming a linear GMR magnetic resistance chip with low magnetic hysteresis after current annealing;
in the GMR Wheatstone full-bridge structure, current annealing treatment is respectively carried out on the four groups of magneto-resistance structures, so that magneto-resistance on two adjacent bridge arms is opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
Example 1:
a method of fabricating a linear GMR magnetic sensor based on current annealing comprising:
depositing a GMR multilayer film structure on the substrate, the GMR multilayer film structure comprising a pinned layer, a nonmagnetic metal layer and a free layer:
magnetizing the pinning layer of the multilayer film structure under a first condition, wherein the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The annealing magnetic field is larger than or equal to the magnetic field when the pinning layer is completely turned overThe field size, which may be around 1200Oe (the specific size being determined by the antiferromagnetic material chosen);
magnetizing the free layer of the multilayer film structure under a second condition, wherein the current annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The annealing magnetic field is smaller than the magnetic field when the pinning layer is completely turned over, and can be about 200Oe (the specific value is determined according to the selected free layer material);
forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
in the GMR Wheatstone full-bridge structure, the four groups of GMR multilayer film structures are respectively subjected to the current annealing treatment, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
Example 2:
a current annealing based linear GMR magnetic sensor manufacturing system comprising:
a deposition module for depositing a GMR multilayer film structure on a substrate, the GMR multilayer film structure comprising a pinned layer, a non-magnetic metal layer and a free layer:
the first annealing treatment module is used for magnetizing the pinning layer of the multilayer film structure under a first condition, and the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The magnitude of the annealing magnetic field is greater than or equal to that of the magnetic field when the pinning layer is completely turned over, and can be about 1200Oe (the specific magnitude is determined according to the selected antiferromagnetic material);
the second annealing treatment module is used for magnetizing the free layer of the multilayer film structure under a second condition, and the current annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The annealing magnetic field is smaller than the magnetic field when the pinning layer is completely turned, and can be 20Around 0Oe (specific values are determined according to the selected free layer material);
forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
and the GMR magnetic sensor generating module is used for respectively carrying out the current annealing treatment on the four groups of GMR multilayer film structures in the GMR Wheatstone full-bridge structure, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
The division of the modules in the embodiments of the present invention is schematically only one logic function division, and there may be another division manner in actual implementation, and in addition, each functional module in each embodiment of the present invention may be integrated in one processor, or may exist separately and physically, or two or more modules may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules.
As shown in fig. 1, the magnetization directions of the pinned layer and the free layer of the GMR structure can be respectively determined by performing current annealing on the individual GMR structure, so that the pinned layer and the free layer have an included angle of 90 degrees, and the linear output of the response of the magnetic resistance of the GMR structure to the external magnetic field can be realized and can be used as an individual linear magnetic sensor device. And applying current to two ends of the GMR strip structure through a direct current or alternating current power supply, simultaneously applying magnetic fields in different directions and sizes, and performing current annealing for 3-5 minutes to reconstruct the magnetization direction of the GMR structure. When the pinning layer of the multilayer film structure is magnetized under the condition of large magnetic field and large current, and the current annealing direction is along the short direction of the magnetic resistance strip, the current annealing can reconstruct the magnetization direction of the pinning layer; when the free layer of the multilayer film structure is magnetized under the condition of small magnetic field and small current, and the current annealing direction is along the length direction of the magnetic resistance strip, the current annealing can reconstruct the magnetization direction of the free layer. In the current annealed pinned layer, an annealing current density of about 1.85MA/cm at an ambient temperature of 25℃ 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The above specific current density magnitudes are related to ambient temperature conditions; in the current annealing pinning layer, an annealing magnetic field is larger than or equal to the pinning layer and is completely turned overThe magnitude of the magnetic field at this time may be around 1200Oe (the specific magnitude being determined by the antiferromagnetic material chosen). In the current annealing free layer, the annealing current is smaller than that of the pinning layer, and the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The specific current density magnitudes above are related to ambient temperature conditions; in the current annealed free layer, the annealing field is much smaller than the field magnitude when the pinned layer is fully flipped, which can be around 200Oe (the specific value is determined by the selected free layer material).
The invention can be applied to the sensor current annealing manufacture of an independent GMR structure, and can be applied to the GMR sensor linearization manufacture of a Wheatstone bridge structure. As shown in fig. 2, after four separate GMR structures (R1, R2, R3, R4) of the wheatstone bridge structure are grown on the same substrate at the same time, they are subjected to a current annealing operation as shown in the drawing, so that the magnetic annealing directions of the first group of GMR structures (R1) and the third group of GMR structures (R3) are the same, and the magnetic annealing directions of the second group of GMR structures (R2) and the fourth group of GMR structures (R4) are the same, which are opposite to those of the first two groups (R1, R3). In the process, the nodes a, b and c can be communicated before the magnetic annealing, and the nodes d and e are communicated after the magnetic annealing step is finished, so that the influence on the current annealing effect caused by the serial-parallel connection in the current annealing process of four independent GMR structures is avoided. Two groups of corresponding driving power supplies are connected in the node a, b, c, d (e), and the other two groups are used as output signal ends, so that the full-bridge structure magnetic sensor working mode is obtained. Meanwhile, in fig. 2, if two sets of opposite GMR structures are separately selected to be connected, the two sets of GMR structures may be used as a single-bridge sensor structure, and taking R1 and R2 as examples, the voltage output between the driving power connection nodes b and d, ad or ab is the output signal of the half-bridge sensor structure.
As shown in fig. 3, the GMR magnetoresistive cell is a multilayer film structure (here, a top-pinned GMR structure is exemplified), which sequentially includes: a protective layer, a pinning layer, a nonmagnetic metal layer, a free layer, and an adhesion layer. Wherein, the protective layer can adopt SiO 2 The thickness of the insulating material, the oxidation-resistant metal material such as Ta and the like is 2-20 nm. When the thickness of the protective layer is less than 2nm, the oxidation preventing effect is poorThe thickness of the protective layer should therefore be greater than 2nm. When the thickness of the metal material protection layer is too thick, the shunt effect exists for the magnetic material functional layer, which can lead to the sensitivity of the sensor to be reduced, so that the thickness of the metal material protection layer is less than 20nm. The pinning layer is a double-layer structure that includes a ferromagnetic layer and an antiferromagnetic layer in this order from bottom to top. The ferromagnetic layer is made of CoFe and has a thickness of 2-8 nm. The antiferromagnetic layer can be made of IrMn, ptMn and other materials, and the thickness is 5-10 nm. The non-magnetic metal layer can be made of metal materials such as Cu and the like, and the thickness is 1.8-5 nm. The free layer is a double-layer structure formed by CoFe/NiFe, and the thickness is 5-20 nm. The adhesion layer is usually a metal layer structure, so that the influence of the lattice parameter of the substrate on the upper magnetic material can be reduced, and the thickness of the adjacent Ta/Ru metal film is 2-20 nm. The thickness of each layer structure in the GMR magnetoresistive unit can influence the resistance value and the magnetic resistance change rate of the GMR magnetoresistive unit, when the thickness of each layer structure is thicker, the resistance is smaller, and the inflow of current in a nonmagnetic layer (Cu and the like) is smaller, so that the magnetic resistance change rate of the GMR magnetoresistive unit is reduced, and in addition, the power consumption under the same bias voltage can be improved due to the reduction of the resistance of the GMR magnetoresistive unit, so that the thickness of each layer structure in the GMR magnetoresistive unit can be reasonably set according to actual needs.
The method for preparing the GMR sensor of the present invention is further described below, and comprises the steps of:
providing a substrate including, but not limited to, a flexible substrate such as a silicon wafer, glass sheet, kapton, or PET;
sequentially depositing an adhesion layer, a free layer, a non-magnetic metal layer, a pinning layer and a protective layer on a substrate by adopting a physical sputtering method, such as a magnetron sputtering method, to form a GMR (GMR) magnetoresistive unit with a multilayer film structure;
carrying out photoetching operation on the substrate deposited with the GMR film material, uniformly photoresist and developing a desired structure through a mask and a photoetching technology to form mutually independent GMR magnetoresistive chips;
and growing electrodes after photoetching the substrate according to the device requirement to form a magnetic sensor with an independent GMR magnetoresistive strip structure or a Wheatstone bridge structure.
The invention changes the traditional linear treatment process step in the conventional linear GMR magnetic field sensor preparation process into a specific local current annealing step, adopts a current annealing mode, can respectively realize the magnetic annealing treatment requirements of different magnetization directions of the GMR structure on the same substrate through current driving, and is different from the traditional mode magnetic annealing mode, the mode does not need to apply a magnetic field in the GMR film material deposition process, and the requirements on a film growth instrument are greatly reduced; the local annealing characteristic of the mode can meet the magnetic annealing treatment requirements of GMR structures on the same substrate in different magnetization directions, and compared with the traditional post assembly mode, the mode has the characteristics of high manufacturing precision, simple process, low cost, low technical barrier, low instrument requirement and low production cost.
FIG. 4 is a graph of the magnetoresistive output characteristics of an individual GMR magnetoresistive element prepared by a conventional fabrication process and not subjected to linearization, showing a relatively large hysteresis of the GMR magnetoresistive element, a sensor curve that is not symmetric about the origin of H=0, and a bias magnetic field H 0 Is not suitable for linear magnetic field test.
Fig. 5a and 5b are graphs of magnetoresistive output characteristics of individual GMR magnetoresistive cells manufactured using the manufacturing method of the present invention. As shown in FIGS. 5a and 5b, after the low-temperature magnetic annealing step, the linear change range of the resistance change curve increases, that is, the saturation magnetic field H in FIGS. 5a and 5b s Greater than the saturation magnetic field H in FIG. 4 1 The hysteresis factor is sharply reduced, and a linear change interval exists in the change curve of the resistance along with the magnetic field, which is caused by the fact that the magnetic moments of the free layer and the pinning layer are mutually perpendicular due to two times of annealing in the current annealing treatment process. The output curve is still generally not symmetrical about the origin of h=0, the saturation magnetic field H s Usually there is a bias magnetic field, H, relative to the origin 0 Is typically 2 to 25Oe in size. The saturation field is related to the roughness of the ferromagnetic film in the GMR structure and depends on the material and manufacturing process, the saturation field H s And bias magnetic field H 0 The relation between them satisfies: h 0 <H s . The magnetoresistive unit with low hysteresis and high linearity can be obtained by the current annealing technology.
Fig. 6a and 6b are graphs of the output voltages of the partial half-bridge structure and the wheatstone full-bridge structure shown in fig. 2, in which the GMR magnetoresistive cell is linearized by the present invention. As shown in FIG. 6a, ideally, the two GMR magnetoresistive elements of the half-bridge structure have the same resistance, and the output voltage is equal to V in the zero-field condition bias Half of (a) is provided. Whereas the full bridge output response is bipolar, so that in zero field, V + ＝V - ＝V bias Output voltage V/2 out Zero and the sensitivity to the response of the magnetic field H should be twice that of the half bridge. As shown in fig. 6b, the sensor output curve of the full bridge structure is ideally symmetrical about the origin center. The sensitivity of the half-bridge and full-bridge structures is improved along with the improvement of the magnetic resistance change rate, and the sensitivity is improved along with H s Is decreased by an increase in (a).
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (10)
1. A method of fabricating a linear GMR magnetic sensor based on current annealing comprising:
depositing a GMR multilayer film structure on the substrate, the GMR multilayer film structure comprising a pinned layer, a nonmagnetic metal layer and a free layer:
magnetizing the pinning layer of the multilayer film structure under a first condition, wherein the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The annealing magnetic field is larger than or equal to the magnetic field when the pinning layer is completely turned over;
magnetizing the free layer of the multilayer film structure under a second condition, and applying a currentThe annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 The annealing current density at 10℃ambient temperature was 2.59MA/cm 2 The magnitude of the magnetic field is smaller than that when the pinning layer is completely overturned;
forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
in the GMR Wheatstone full-bridge structure, the four groups of GMR multilayer film structures are respectively subjected to the current annealing treatment, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
2. The method of manufacturing a linear GMR magnetic sensor based on current annealing defined in claim 1, wherein in the wheatstone full bridge structure, four GMR multilayer film structures are deposited and grown simultaneously on the same substrate and then subjected to current annealing treatment respectively, so that the first GMR structure R1 and the third GMR structure R3 are annealed in the same direction, and the second GMR structure R2 and the fourth GMR structure R4 are annealed in the same direction, opposite to the first two groups.
3. The method of fabricating a linear GMR magnetic sensor based on current annealing defined in claim 1, wherein the free layer has a double layer structure of CoFe/NiFe.
4. The method of fabricating a linear GMR magnetic sensor based on current annealing defined in claim 1, wherein the pinning layer comprises a metal inducing layer, an antiferromagnetic layer and a ferromagnetic layer, the ferromagnetic layer being a CoFe layer.
5. The method of fabricating a linear GMR magnetic sensor based on current annealing defined in claim 1, wherein the GMR multilayer film structure further comprises an adhesion layer and a protective layer, the adhesion layer, the pinning layer, the nonmagnetic metal layer, the free layer and the protective layer being sequentially grown on the substrate.
6. The method of fabricating a linear GMR magnetic sensor based on current annealing defined in claim 5, wherein the order of the pinned layer and the free layer is interchangeable to correspond to the bottom-pinned and top-pinned structures in the GMR multilayer film structure.
7. The method for manufacturing a linear GMR magnetic sensor based on current annealing defined in claim 5, wherein the protective layer is made of insulating material and oxidation-preventing metal material and has a thickness of 2-20 nm; the adhesive layer is a Ta/Ru adjacent metal film with the thickness of 2-20 nm.
8. The method for manufacturing a linear GMR magnetic sensor based on current annealing defined in claim 5, wherein the antiferromagnetic layer is made of IrMn, ptMn material and has a thickness of 5-10 nm; the non-magnetic metal layer is made of metal material and has a thickness of 1.8-5 nm.
9. The method of fabricating a linear GMR magnetic sensor based on current annealing defined in claim 1, wherein the substrate material is a silicon wafer, a glass sheet, kapton or PET substrate.
10. A current annealing based linear GMR magnetic sensor manufacturing system comprising:
a deposition module for depositing a GMR multilayer film structure on a substrate, the GMR multilayer film structure comprising a pinned layer, a non-magnetic metal layer and a free layer:
the first annealing treatment module is used for magnetizing the pinning layer of the multilayer film structure under a first condition, and the current annealing direction is along the short direction of the magnetic resistance strip; the first condition is an annealing current density of about 1.85MA/cm at an ambient temperature of 25 DEG C 2 The annealing current density is about 2.59MA/cm at 10 DEG C 2 The annealing magnetic field is larger than or equal to the magnetic field when the pinning layer is completely turned over;
the second annealing treatment module is used for magnetizing the free layer of the multilayer film structure under a second condition, and the current annealing direction is along the length direction of the magnetic resistance strip; the second condition is that the annealing current density is 1.85MA/cm at 25 ℃ ambient temperature 2 Below, in an environment of 10 DEG CAnnealing current density at temperature of 2.59MA/cm 2 The annealing magnetic field is smaller than the magnetic field when the pinning layer is completely turned over; forming a linear GMR magnetoresistive chip with low hysteresis after current annealing;
and the GMR magnetic sensor generating module is used for respectively carrying out the current annealing treatment on the four groups of GMR multilayer film structures in the GMR Wheatstone full-bridge structure, so that the magnetic resistances on two adjacent bridge arms are opposite along with the change of an external magnetic field, and the GMR magnetic sensor with the full-bridge structure is obtained.
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