CN112945292A - Gear position/speed sensor - Google Patents
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- CN112945292A CN112945292A CN201911265609.0A CN201911265609A CN112945292A CN 112945292 A CN112945292 A CN 112945292A CN 201911265609 A CN201911265609 A CN 201911265609A CN 112945292 A CN112945292 A CN 112945292A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Abstract
The invention discloses a gear position/speed sensor which comprises a sensing circuit, a signal processing chip, a back magnet, a magnetic shielding layer and a substrate, wherein the sensing circuit comprises two magnetic tunnel junction magnetic resistance components with opposite connecting directions. The low resistance and the high resistance generated when the gear passes through the magnetic tunnel junction reluctance component are changed, and the corresponding voltage or signal is subjected to differential processing and output, so that a signal with high signal-to-noise ratio can be output, and the interference of an external magnetic field can be greatly reduced.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a gear sensor combined with a magnetic tunnel structure.
Background
In the prior art, a gear position/speed sensor (hereinafter referred to as a gear sensor) generally requires high sensitivity, low power consumption, interference resistance, integration and wide application temperature. The high sensitivity is because the strength of the detected signal is weaker and weaker, which requires the sensitivity of the sensor to be greatly improved. The low power consumption is of great help to extend the useful life of the sensor. The anti-interference performance means that the sensor needs to have certain resistance to changes of external electromagnetism, temperature, humidity and the like. Integration refers to the development of miniaturization, integration and intellectualization of the sensor. The wide applicable temperature means that the working environment of the sensor is more and more severe, and the sensor needs to be adapted to more temperature ranges as much as possible.
At present, the traditional gear sensor mainly uses a Hall sensor based on Hall effect and a magneto-resistance sensor based on giant magneto-resistance effect (GMR). The integrated gear has the defects of low sensitivity, low integration degree and poor anti-interference performance, and is difficult to meet the requirements of accurate monitoring of the rotating speed, tooth position positioning and moving direction of the existing gear.
Disclosure of Invention
In order to solve the above technical problem, an object of the present invention is to provide a tooth sensor having a high signal-to-noise ratio and a high interference immunity in combination with a magnetic tunnel junction.
The purpose of the application and the technical problem to be solved are realized by adopting the following technical scheme.
According to the first gear sensor that this application provided, including signal processing chip, sensing circuit, back of the body magnet, magnetic shielding layer and base plate, the magnetic shielding layer with the base plate forms the accommodation space, the signal processing chip sensing circuit with back of the body magnet is located the accommodation space just sets up one side of base plate, the base plate has been seted up the opening in order to show sensing circuit, just sensing circuit and gear are the corresponding setting in position, the signal processing chip is connected sensing circuit, in order to control sensing circuit's signal output input, and control back of the body magnet produces the drive the magnetic field of gear. The sensing circuit comprises a Wheatstone bridge, the input end and the output end of the Wheatstone bridge are connected with the signal processing chip, each bridge of the Wheatstone bridge is connected with two magnetic tunnel junction magnetic resistance components in opposite directions, and the two magnetic tunnel junction magnetic resistance components are adjacent to teeth of the gear.
The second embodiment of the invention comprises a sensing circuit, a back magnet, a magnetic shielding layer and a substrate, a signal processing chip is eliminated, and an output end is directly connected with an external circuit. The magnetic tunnel junction magnetic resistance device is characterized in that the sensing circuit comprises a Wheatstone bridge, the output end of the Wheatstone bridge is connected with the external circuit, each bridge of the Wheatstone bridge is connected with two magnetic tunnel junction magnetic resistance components in opposite directions, and the two magnetic tunnel junction magnetic resistance components are adjacent to the teeth of the gear.
The third embodiment of the invention comprises a sensing circuit, a back magnet, a magnetic shielding layer and a substrate, wherein the sensing circuit of a Wheatstone bridge is eliminated, and two magnetic tunnel junction magnetoresistive components with opposite extension and retraction are directly adopted. The magnetic tunnel junction magnetic field sensing device is characterized in that the sensing circuit comprises two magnetic tunnel junction magnetic resistance assemblies which are opposite in connection direction, and the two magnetic tunnel junction magnetic resistance assemblies are adjacent to teeth of the gear.
In the above three embodiments, the magnetic shielding layer can shield the external magnetic field, and the substrate serves the purpose of protecting the circuit.
The technical problem solved by the application can be further realized by adopting the following technical measures.
In an embodiment of the present application, each of the magnetic tunnel junction magnetoresistive components has a structure including a top electrode, a free layer, a barrier layer, a pinned layer, a bottom electrode, and a silicon substrate.
In an embodiment of the present application, the top electrode is formed of Ti, TiN, Ta, TaN, W, WN, or a combination thereof; the thickness of the top electrode is 50-100 nm. The top electrode is formed by physical vapor deposition.
In one embodiment of the present application, the free layer is formed of a ferromagnetic material, which is Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni/Ir)/Co/(CoFeB, or FeB)/Co/(Pt, Co, pd, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the content of B is 15-40%, in the FeCoB material, the proportion of Fe and Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm. Wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os etc., and the thickness is 0.2-0.5 nm.
In an embodiment of the present application, the barrier layer is formed of an insulating non-magnetic metal oxide material that is MgO, MgZnO, MgBO, or MgAlO; preferably MgO; the barrier layer has a thickness of 2-5 nm.
In an embodiment of the present application, the pinning layer is formed of a ferromagnetic material and an antiparallel ferromagnetic superlattice layer; the ferromagnetic material includes Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB or FeB)/X/Co/(CoFeB, CoB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB/Co/X/Co/(CoFeB, CoB or FeB), (CoFeB, Pt, Ni, or Ir, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the content of B is 15-40%, and in the FeCoB material, the proportion of Fe to Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm; the antiparallel ferromagnetic superlattice layer is [ Co/Pt ]]nCo/(Ru、Ir、Rh)，[Co/Pt]nCo/(Ru、Ir、Rh)/Co[Pt/Co]m，[Co/Pd]nCo/(Ru、Ir、Rh)，[Co/Pd]nCo/(Ru、Ir、Rh)/Co[Pd/Co]m，[Co/Ni]nCo/(Ru, Ir, Rh) or [ Co/Ni ]]nCo/(Ru、Ir、Rh)/Co[Ni/Co]mA superlattice structure, wherein n is more than or equal to 1, and m is more than or equal to 0.
In an embodiment of the present application, the material of the bottom electrode includes Cu, Al, W, Ti, or a combination thereof, and the thickness of the bottom electrode is 50-100 nm.
In an embodiment of the present application, the silicon substrate is a single crystal silicon material.
In an embodiment of the present application, the magnetic field generated by the back magnet is correspondingly changed according to whether the tooth passes through or not, so as to change the magnetization direction of the free layer of the two mtj magnetoresistive elements. When the teeth pass through a magnetic field generated by the back magnet, the magnetization directions of the free layers of the two magnetic tunnel junction magnetoresistive components are changed from a plane to be vertical so as to be in a high resistance state or a low resistance state respectively. When the teeth do not pass through a magnetic field generated by the back magnet, the magnetization directions of the free layers of the two magnetic tunnel junction magnetoresistive components are planes, and the resistance values of the two magnetic tunnel junction magnetoresistive components are equal or close.
In an embodiment of the present application, the signal processing chip includes a differential amplifier and a smith trigger, the differential amplifier differentially outputs the voltages of the two mtj magnetoresistive elements, and the output signal is a sine wave output signal or a similar sine wave output signal, and the smith trigger performs a sine wave processing on the output signal to form a square wave which can be processed by a digital circuit.
This application combines wheatstone bridge magnetic tunnel junction magnetic resistance subassembly through the sensor, when the gear through two magnetic tunnel junction magnetic resistance subassemblies that connect opposite direction, two subassemblies are in parallel and anti-parallel state respectively, low resistance and high resistance state promptly. By using the differential amplifier, the voltages of the two magnetic tunnel junction magnetoresistive components are differentially output, so that a signal with high signal-to-noise ratio can be output, and the interference of an external magnetic field can be greatly reduced.
Drawings
FIG. 1 is a basic structure diagram of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a connection circuit of an embodiment of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a second connection circuit of an embodiment of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a third connection circuit of an embodiment of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIGS. 5-1 and 5-2 illustrate a schematic view of a magnetic moment direction of an embodiment of a magnetic tunnel junction gear sensor in accordance with an embodiment of the present application;
FIGS. 6-1 and 6-2 are schematic diagrams illustrating a magnetic moment direction of an embodiment of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIGS. 7-1 and 7-2 are schematic diagrams of three magnetic moment directions of an embodiment of a magnetic tunnel junction gear sensor according to an embodiment of the present application;
FIG. 8 is a schematic diagram of a MTJ magnetoresistive element according to an embodiment of the present application
Detailed Description
Refer to the drawings wherein like reference numbers refer to like elements throughout. The following description is based on illustrated embodiments of the application and should not be taken as limiting the application with respect to other embodiments that are not detailed herein.
The following description of the various embodiments refers to the accompanying drawings, which illustrate specific embodiments that can be used to practice the present application. In the present application, directional terms such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", and the like are merely referring to the directions of the attached drawings. Accordingly, the directional terminology is used for purposes of illustration and understanding, and is in no way limiting.
The terms "first," "second," "third," and the like in the description and in the claims of the present application and in the above-described drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the objects so described are interchangeable under appropriate circumstances. Furthermore, the terms "include" and "have," as well as other similar variations of embodiments, are intended to cover non-exclusive inclusions.
The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts of the present application. Unless the context clearly dictates otherwise, expressions used in the singular form encompass expressions in the plural form. In the present specification, it will be understood that terms such as "including," "having," and "containing" are intended to specify the presence of the features, integers, steps, acts, or combinations thereof disclosed in the specification, and are not intended to preclude the presence or addition of one or more other features, integers, steps, acts, or combinations thereof. Like reference symbols in the various drawings indicate like elements.
The drawings and description are to be regarded as illustrative in nature, and not as restrictive. In the drawings, elements having similar structures are denoted by the same reference numerals. In addition, the size and thickness of each component shown in the drawings are arbitrarily illustrated for understanding and ease of description, but the present application is not limited thereto.
In the drawings, the range of configurations of devices, systems, components, circuits is exaggerated for clarity, understanding, and ease of description. It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present.
In addition, in the description, unless explicitly described to the contrary, the word "comprise" will be understood to mean that the recited components are included, but not to exclude any other components. Further, in the specification, "on.
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description of a tooth sensor according to the present invention will be given with reference to the accompanying drawings and embodiments. Please also refer to the accompanying drawings for better understanding.
In the embodiment of the present application, as shown in fig. 1, a gear sensor includes a magnetic shielding layer 101, a back magnet 102, a circuit board 103 configuring a sensing circuit, magnetic tunnel junction resistors 104 and 105, a signal processing chip 108, and a substrate 109. The back magnet 102, a circuit board 103 for configuring a sensing circuit, the magnetic tunnel junction resistors 104 and 105, a signal processing chip 108, and the like form the sensing circuit. Magnetic shielding layer 101 with base plate 109 forms the accommodation space, sensing circuit is located the accommodation space just sets up one side of base plate 109, base plate 109 has seted up the opening in order to expose sensing circuit's magnetic tunnel junction magneto resistance 104, 105, just sensing circuit and gear are the corresponding setting in position, signal processing chip 108, in order to control sensing circuit's signal output input, and control back of the body magnet 102 produces the drive the magnetic field of gear, its characterized in that, the gear is as the signal source, presses close to and adopts opposite direction's magnetic tunnel junction magneto resistance 104, 105 among the wheatstone bridge connecting circuit. The magnetic shield layer 101 functions to shield an external magnetic field, and the substrate 109 functions to protect a circuit.
In the embodiment of the present application, the sensing circuit is a wheatstone bridge connected circuit, which is composed of four magnetic tunnel junction magnetoresistances MR1a, MR2a, MR1b, and MR2b with opposite connection directions, wherein MR1a and MR1b have the same connection direction, and MR2a and MR2b have the same connection direction, as shown in fig. 2 and fig. 8. Magnetic tunnel junction magnetoresistive components (MR1a, MR2a, MR1b, MR2b) are made with tunnel magnetoresistance effect (TMR), i.e. tunneling effect of electron spins. The mtj magnetoresistive elements (MR1a, MR2a, MR1b, MR2b) mainly include a top electrode 14, a free layer 15, a barrier layer 16, a pinned layer 17, a bottom electrode 18, and a silicon substrate 19. The free layer 15 and the pinned layer 16 are made of ferromagnetic material and the barrier layer 17 is made of a very thin layer of insulating metal oxide. The pinning layer 16 is made of a material that is not easily switched by an external magnetic field so that its magnetization direction always faces one direction. The free layer 15 is made of a material susceptible to an external magnetic field, and when a signal passes through the free layer 15, the magnetization direction of the free layer 15 is changed. Since the electrons in the 3d orbit of the ferromagnetic material are not filled with orbitals, their energy bands are polarized and the electrons are separated into spin-up and spin-down energy states. When the magnetization directions of the free layer 15 and the pinned layer 16 are the same, the magnetic tunnel junction magnetoresistive element assumes a low resistance state, and when the magnetization directions of the free layer 15 and the pinned layer 16 are opposite, the magnetic tunnel junction magnetoresistive element assumes a high resistance state. Now, the two magnetic tunnel junction magnetoresistive elements are connected in opposite directions, and when a signal passes through the two magnetic tunnel junction magnetoresistive elements, one magnetic tunnel junction magnetoresistive element is in a high-resistance state, and the other magnetic tunnel junction magnetoresistive element is in a low-resistance state. When the signal does not pass through the two magnetic tunnel junction magneto-resistive elements, the two magnetic tunnel junction magneto-resistive elements are in a low-resistance state. Here, two magnetic tunnel junction magnetoresistive components close to the gear are regarded as the aforementioned magnetic tunnel junction magnetoresistors 104 and 105.
The signal processing chip 108 may be an integrated circuit chip or an embedded system integrated chip, which mainly includes a differential amplifier, a smith trigger, and the like. The differential amplifier differentially outputs the voltages of the two magnetic tunnel junction magnetoresistive components on the Wheatstone bridge to obtain a sine wave output signal or a similar sine wave output signal. The smith trigger can be used as a waveform shaping circuit and can process the sine waveform of an analog signal into a square waveform which can be processed by a digital circuit.
The back magnet 102 is located behind the circuit board 103 to generate a constant magnetic field. When the gear made of ferromagnetic material passes through the magnetic field generated by the back magnet, the size and the direction of the magnetic field are changed. The change in the magnitude and direction of the magnetic field changes the magnetization direction of the free layer 15 of the mtj magnetoresistive element, thereby causing the mtj magnetoresistive element to assume a high resistance state or a low resistance state, respectively. By recording the change of the resistance value of the magnetic resistance component of the magnetic tunnel junction and processing the change by the signal processing chip 12, the information such as the rotating speed, the moving speed, the missing tooth and the like of the gear can be obtained.
The second embodiment of the present application is shown in fig. 3. The sensing circuit adopts a Wheatstone bridge connection circuit and consists of four magnetic tunnel junction magnetoresistances MR1a, MR2a, MR1b and MR2b which are connected in opposite directions, wherein the connection directions of MR1a and MR1b are the same, and the connection directions of MR2a and MR2b are the same. In contrast to the first embodiment, the second embodiment eliminates the signal processing chip 108 and connects the output terminal directly to the external circuit. The purpose of recording the gear rotating speed, the moving speed and the missing tooth information can be achieved by processing the output signal through an external circuit.
The third embodiment of the present application is shown in fig. 4. The sensing circuit uses two magnetic tunnel junction magnetoresistances MR1a, MR2a with opposite connection directions. The output end is connected with an external circuit, and the gear rotating speed, the moving speed and the tooth missing information can be recorded. The third embodiment is adopted to achieve the purpose of saving cost on the premise of reducing certain sensitivity.
FIGS. 5-1 and 5-2, FIGS. 6-1 and 6-2, and FIGS. 7-1 and 7-2 are schematic diagrams illustrating magnetic moment directions of a MTJ MR element according to embodiments of the present invention, which correspond to embodiments I, II, and III, respectively. The magnetic field generated by the back magnet 102 is correspondingly changed according to whether the tooth passes through or not, so as to change the magnetization direction of the free layers of the two mtj magnetoresistive elements 104 and 105. When the teeth pass through the magnetic field generated by the back magnet 102, the magnetization direction of the free layer of the mtj element 104, 105 changes from planar to perpendicular to assume a high resistance state or a low resistance state, respectively. When the tooth does not pass through the magnetic field generated by the back magnet 102, the magnetization direction of the free layer of the magnetic tunnel junction magnetoresistive element 104, 105 is a plane, and the resistance values of the magnetic tunnel junction magnetoresistive element 104, 105 are equal or close.
In the first and second embodiments, the sensor uses a wheatstone bridge to connect the mtj elements, and when the gear passes through four mtj elements connected in opposite directions, the four elements are in parallel and anti-parallel states, i.e., low resistance and high resistance states, respectively. By using the differential amplifier, the voltages of the two groups of magnetic tunnel junction magnetoresistive components are differentially output, namely, a signal with high signal-to-noise ratio can be output, and the interference of an external magnetic field can be greatly reduced. The output signal may be processed by the signal processing chip 108 or an external circuit. As shown in fig. 5-1 and 5-2, and fig. 6-1 and 6-2.
In the third embodiment, the sensor uses two magnetic tunnel junction magnetoresistances with opposite connection directions, and when the gear passes through the two magnetic tunnel junction magnetoresistances with opposite connection directions, the two components are respectively in parallel and anti-parallel states, i.e. in a low resistance state and a high resistance state. When the gear does not pass through the magnetic tunnel junction reluctance component, the two components are in a parallel state, namely a low resistance state. The output signal is connected with an external circuit, so that the rotating speed, the moving speed and the tooth missing information of the gear can be recorded. As shown in fig. 7-1 and 7-2
In the first, second and third embodiments of the present application, a schematic diagram of a magnetic tunnel junction magnetoresistive device is shown in fig. 8. Mainly comprises a top electrode 14, a free layer 15, a barrier layer 16, a pinning layer 17, a bottom electrode 18 and a silicon substrate 19.
The forming material of the top electrode 14 is Ti, TiN, Ta, TaN, W, WN or the combination thereof; the top electrode 14 has a thickness of 50-100 nm. In order to ensure that the surface flatness of the magnetic tunnel junction can be achieved, Physical Vapor Deposition (PVD) is generally used.
The free layer is formed of a ferromagnetic material that is Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoFeB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or FeB)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni, or Ir)/Co/X/(CoFeB, CoFeB or FeB), (CoFeB, CoB, or FeB)/X/Co/(Pt, Pd, Ni, or Ir)/Co/X/(CoFeB, CoFeB or FeB), (CoFeB )/X/, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the content of B is 15-40%, and in the FeCoB material, the proportion of Fe to Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm. Wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os etc., and the thickness is 0.2-0.5 nm.
The barrier layer 16 is formed of a layer of an insulating non-magnetic metal oxide material, which is MgO, MgZnO, MgBO, or MgAlO; preferably MgO; the barrier layer has a thickness of 2-5 nm.
The pinned layer 17 is formed of a ferromagnetic material and an antiparallel ferromagnetic superlattice layer; the ferromagnetic material is identical to the material of the free layer 15, and includes Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoFeB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/(Pt, CoFeB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoFeB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(CoFeB, Pt, CoFeB or FeB)/X/(CoFeB, and, Pd, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the content of B is 15-40%, in the FeCoB material, the proportion of Fe and Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm; the antiparallel ferromagnetic superlattice layer is [ Co/Pt ]]nCo/(Ru、Ir、Rh)，[Co/Pt]nCo/(Ru、Ir、Rh)/Co[Pt/Co]m，[Co/Pd]nCo/(Ru、Ir、Rh)，[Co/Pd]nCo/(Ru、Ir、Rh)/Co[Pd/Co]m，[Co/Ni]nCo/(Ru, Ir, Rh) or [ Co/Ni ]]nCo/(Ru、Ir、Rh)/Co[Ni/Co]mA superlattice structure, wherein n is more than or equal to 1, and m is more than or equal to 0. The pinned layer 17 has strong perpendicular anisotropy (PMA) and requires an extremely strong external magnetic field to flip it.
The bottom electrode 18 is generally made of a material with good conductivity, such as Cu, Al, W, Ti, or a combination thereof, and has a thickness of 50-100 nm.
The silicon substrate is made of a single crystal silicon material.
The terms "in one embodiment of the present application" and "in various embodiments" are used repeatedly. This phrase generally does not refer to the same embodiment; it may also refer to the same embodiment. The terms "comprising," "having," and "including" are synonymous, unless the context dictates otherwise.
Although the present application has been described with reference to specific embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application, and all changes, substitutions and alterations that fall within the spirit and scope of the application are to be understood as being covered by the following claims.
Claims (16)
1. The utility model provides a gear position/speed sensor, includes sensing circuit, back of the body magnet, magnetic shielding layer and base plate, the magnetic shielding layer with the base plate forms the accommodation space, sensing circuit with back of the body magnet is located accommodation space and setting are in one side of base plate, the base plate has been seted up the opening in order to show sensing circuit, just sensing circuit and gear are the corresponding setting in position, through external power control sensing circuit input, transmission circuit's output voltage exports to external circuit, the mobility control of tooth back of the body magnet produces the drive the magnetic field of gear, its characterized in that, sensing circuit includes two magnetic tunnel junction magnetic resistance subassemblies that connect opposite direction, two magnetic tunnel junction magnetic resistance subassemblies are close to the tooth of the gear.
2. The gear position/speed sensor according to claim 1, wherein said sensing circuit comprises a wheatstone bridge having an output connected to an external circuit, each of said wheatstone bridge having said two magnetic tunnel junction magnetoresistive elements connected in opposite directions, said two magnetic tunnel junction magnetoresistive elements being adjacent to teeth of said gear.
3. The gear position/speed sensor according to claim 2, further comprising a signal processing chip disposed on the substrate, the signal processing chip being connected to the sensing circuit to alternatively control the signal input and output of the sensing circuit; and the output end of the Wheatstone bridge is connected with the signal processing chip.
4. The gear position/speed sensor of claim 1, wherein each of the magnetic tunnel junction magnetoresistive components has a structure comprising a top electrode, a free layer, a barrier layer, a pinned layer, a bottom electrode, and a silicon substrate.
5. The gear position/speed sensor according to claim 4, wherein the top electrode is formed of a material of Ti, TiN, Ta, TaN, W, WN or a combination thereof; the thickness of the top electrode is 50-100 nm.
6. The gear position/speed sensor of claim 4 wherein the formation of the top electrode is by physical vapor deposition.
7. The gear position/speed sensor according to claim 4, wherein the free layer is formed of a ferromagnetic material that is Co/(Pt, Pd, Ni, or Ir)/(CoFeB, CoB, or FeB), (CoFeB, CoB, or FeB)/(Pt, Pd, Ni, or Ir)/Co, (CoFeB, CoB, or FeB)/Co/(Pt, Pd, Ni, or Ir)/Co, (CoFeB, CoB, or FeB)/(Pt, Pd, Ni, or Ir)/(CoFeB, CoB, or FeB), Co/(Pt, Pd, Ni, or Ir)/Co/(CoFeB, CoB, or FeB), (CoFeB, CoB, or FeB)/Co/(Pt, Pd, Ni, or Ir)/Co/(CoFeB, or FeB), (CoFeB, CoB, CoFeB, or FeB)/X/Co/(Pt, Pd, Ni, or Ir)/Co/X/(CoFeB)/Co/(CoFeB, Pd, Ni, CoB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni or Ir), Co/(Pt, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the B content is 15% to 40%, in the FeCoB material, the ratio of Fe to Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm; wherein X is W, Mo, V, Nb, Cr, Hf, Ti, Zr, Ta, Sc, Y, Zn, Ru or Os, and the thickness is 0.2-0.5 nm.
8. The gear position/speed sensor of claim 4, wherein the barrier layer is formed of an insulating non-magnetic metal oxide material that is MgO, MgZnO, MgBO, or MgAlO; preferably MgO; the barrier layer has a thickness of 2-5 nm.
9. The gear position/speed sensor of claim 4 wherein the pinned layer is formed of a ferromagnetic material and an antiparallel ferromagnetic superlattice layer; the ferromagnetic material includes Co/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co, (CoFeB, CoB or FeB)/(Pt, Pd, Ni or Ir)/(CoFeB, CoB or FeB), Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoB or FeB), (CoFeB, CoB or FeB)/Co/(Pt, Pd, Ni or Ir)/Co/(CoFeB, CoFeB or FeB), (CoFeB, CoB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB or FeB)/X/Co/(CoFeB, CoB or FeB), (CoFeB, CoFeB or FeB)/X/Co/(Pt, Pd, Ni or Ir), (CoFeB, CoFeB/Co/X/Co/(CoFeB, CoB or FeB), (CoFeB, Pt, Ni, or Ir, Pd, Ni or Ir)/Co/X/(CoFeB, CoB or FeB), wherein in the B-containing ferromagnetic material, the content of B is 15-40%, and in the FeCoB material, the proportion of Fe to Co is 3: 1 to 1: 3; the thickness of the free layer is 1.5-2.5 nm; the antiparallel ferromagnetic superlattice layer is [ Co/Pt ]]nCo/(Ru、Ir、Rh)，[Co/Pt]nCo/(Ru、Ir、Rh)/Co[Pt/Co]m，[Co/Pd]nCo/(Ru、Ir、Rh)，[Co/Pd]nCo/(Ru、Ir、Rh)/Co[Pd/Co]m，[Co/Ni]nCo/(Ru, Ir, Rh) or [ Co/Ni ]]nCo/(Ru、Ir、Rh)/Co[Ni/Co]mA superlattice structure, wherein n is more than or equal to 1, and m is more than or equal to 0.
10. The gear position/speed sensor according to claim 4, wherein the material of the bottom electrode comprises Cu, Al, W, Ti or a combination thereof, and the thickness of the bottom electrode is 50-100 nm.
11. The gear position/speed sensor of claim 4, wherein the silicon substrate material is a single crystal silicon material.
12. The gear position/speed sensor according to claim 1, wherein the magnetic field generated by the back magnet varies correspondingly according to whether the teeth pass or not, so as to change the magnetization direction of the free layer of the two mtj magnetoresistive elements.
13. The gear position/speed sensor of claim 1, wherein the magnetization direction of the free layer of the mtj magnetoresistive element changes from planar to perpendicular to assume a high-resistance or low-resistance state, respectively, when the tooth passes through the magnetic field generated by the back magnet.
14. The gear position/speed sensor according to claim 1, wherein when the tooth is not passing through the magnetic field generated by the back magnet, the magnetization directions of the free layers of the two magnetic tunnel junction magnetoresistive elements are in a plane, and the resistance values of the two magnetic tunnel junction magnetoresistive elements are equal or close.
15. The gear position/speed sensor according to claim 3, wherein the signal processing chip comprises a differential amplifier and a Smith trigger, the differential amplifier differentially outputs the voltages of the two MTJ magnetoresistive elements, the output signal is a sine wave output signal or a similar sine wave output signal, and the Smith trigger sinusoidally processes the output signal to form a square wave waveform that can be processed by a digital circuit.
16. The gear position/speed sensor according to claim 1, wherein the magnetic shielding layer is made of FeNi alloy and functions to shield an external magnetic field.
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