Magnetic sensor bridge using double free layers

Abstract

The present invention is entitled "Magnetic Sensor Bridge Using Double Free Layer." The present disclosure as a whole relates to a sensor device, such as a magnetic sensor bridge, utilizing a double free layer (DFL) structure. The device includes a plurality of resistors, each resistor including the same DFL structure. Adjacent to the DFL structure is a magnetic structure, which may include a permanent magnet, an anti-magnetic (AFM) layer with a synthetic AFM (SAF) structure thereon, a permanent magnet with a SAF structure thereon, or an AFM layer with a ferromagnetic layer thereon. The DFL structure is aligned with different layers of the magnetic structure to distinguish the resistors. The different alignments and / or different magnetic structures reduce production time due to reduced complexity, thereby reducing costs.

Description

Background Art Technical Field

[0002] Embodiments of the present disclosure generally relate to Wheatstone bridge arrays and methods of fabricating the same.

[0003] Description of related art

[0004] A Wheatstone bridge is a circuit used to measure unknown resistance by balancing two legs of a bridge circuit, one of which contains the unknown component. Compared to a simple voltage divider, the Wheatstone circuit provides extremely accurate measurements.

[0005] A Wheatstone bridge circuit includes multiple resistors and, more recently, magnetic materials such as magnetic sensors. Magnetic sensors can include Hall effect sensors, anisotropic magnetoresistive (AMR) sensors, giant magnetoresistive (GMR) sensors, and tunnel magnetoresistive (TMR) sensors. Compared to other magnetic sensors, TMR sensors have very high sensitivity.

[0006] A Wheatstone bridge array has a linear output signal and is resistant to ambient temperature. Any temperature variations in the Wheatstone bridge array are eliminated. A Wheatstone bridge array has four resistors. Two of these resistors have the same resistance, while the remaining two resistors have the same resistance relative to each other but differ from the original two resistors.

[0007] In conventional GMR- or TMR-based Wheatstone bridge sensors, the different resistances of the resistors are achieved by having two of the resistors have opposite pinning directions relative to the other two. To achieve different pinning directions, different sensor stacks or specialized anneals can be used, but manufacturing two different sensors and performing specialized anneals increases production time, which can be expensive, complex, and time-consuming.

[0008] Therefore, there is a need in the art for an improved Wheatstone bridge array. Summary of the Invention

[0009] The present disclosure generally relates to sensor devices, such as magnetic sensor bridges, that utilize a double free layer (DFL) structure. The device includes a plurality of resistors, each including the same DFL structure. Adjacent to the DFL structure is a magnetic structure that may include a permanent magnet, an antiferromagnetic (AFM) layer with a synthetic antiferromagnetic AFM (SAF) structure thereon, a permanent magnet with a SAF structure thereon, or an AFM layer with a ferromagnetic layer thereon. The DFL structures are aligned with different layers of the magnetic structures to differentiate the resistors. Different alignments and / or different magnetic structures reduce production time due to reduced complexity, thereby reducing costs.

[0010] In one embodiment, a sensor device includes a first resistor comprising at least one first double-free layer (DFL) sensor; and at least one first magnetic structure, wherein each first magnetic structure comprises a first antiferromagnetic (AFM) layer; and a synthetic antiferromagnetic (SAF) structure disposed above the first AFM layer, wherein the at least one first DFL sensor is linearly aligned with the SAF structure when viewed in cross-section; and a second resistor comprising at least one second DFL sensor; and at least one second magnetic structure, wherein each second magnetic structure comprises a second AFM layer; and a ferromagnetic layer disposed above the second AFM layer, wherein the at least one second DFL sensor is linearly aligned with the ferromagnetic layer when viewed in cross-section.

[0011] In another embodiment, a sensor device includes: a first resistor, the first resistor including: at least one first double free layer (DFL) sensor; and at least one magnetic structure, each magnetic structure including: a first permanent magnet; and a synthetic antiferromagnetic (SAF) structure disposed above the first permanent magnet, wherein when viewed in cross section, the at least one first DFL sensor is linearly aligned with the SAF structure; and a second resistor, the second resistor including: at least one second DFL sensor; and at least one second permanent magnet, wherein when viewed in cross section, the at least one second DFL sensor is linearly aligned with the at least one second permanent magnet.

[0012] In another embodiment, a sensor device includes at least one first resistor, the at least one first resistor including at least one first double-free layer (DFL) sensor; and at least one first magnetic structure, wherein each first magnetic structure includes: a first antiferromagnetic (AFM) layer including a first material; and a first ferromagnetic layer disposed above the first AFM layer; and at least one second resistor, the at least one second resistor including: at least one second DFL sensor; and at least one second magnetic structure, wherein each second magnetic structure includes: a second AFM layer including a second material, wherein the second material is different from the first material; and a second ferromagnetic layer disposed above the second AFM layer, wherein the second ferromagnetic layer is the same as or different from the first ferromagnetic layer. When viewed in cross section, the at least one first DFL sensor is linearly aligned with the first ferromagnetic layer. When viewed in cross section, the at least one second DFL sensor is linearly aligned with the second ferromagnetic layer.

[0013] In another embodiment, a method includes: forming a plurality of double-free layer sensors for a plurality of resistors; covering at least one first resistor of the plurality of resistors, wherein at least one second resistor of the plurality of resistors remains exposed; forming a first permanent magnet or a first antiferromagnetic layer adjacent to the double-free layer sensor of the at least one second resistor; exposing the at least one first resistor; covering the at least one second resistor; forming a second permanent magnet or a second antiferromagnetic layer adjacent to the double-free layer sensor of the at least one first resistor; exposing the at least one second resistor; and performing a bridge pinning reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Thus, a detailed understanding of the manner in which the above-recited features of the present disclosure are understood, a more particular description of the disclosure, the brief summary above, and the like, may be obtained by reference to the embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0015] Figure 1 is a schematic diagram of the Wheatstone bridge array design.

[0016] Figure 2 is a schematic diagram of a Wheatstone bridge array, where each resistor has multiple TMR structures.

[0017] Figure 3 is a cross-sectional view of a single read head of a double free layer (DFL) sensor.

[0018] Figures 4A to 4F is a schematic diagram of a sensor device according to one embodiment.

[0019] Figures 5A to 5F is a schematic diagram of a sensor device according to another embodiment.

[0020] Figures 6A to 6F is a schematic diagram of a sensor device according to another embodiment.

[0021] Figure 7 is a flow chart illustrating a method of manufacturing a sensor device according to one embodiment.

[0022] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION

[0023] Hereinafter, reference is made to embodiments of the present disclosure. However, it should be understood that the present disclosure is not limited to the specifically described embodiments. On the contrary, any combination of the following features and elements (whether or not related to different embodiments) is considered to implement and practice the present disclosure. In addition, although the embodiments of the present disclosure can achieve advantages over other possible solutions and / or advantages over the prior art, whether a specific advantage is achieved by a given embodiment is not a limitation of the present disclosure. Therefore, the following aspects, features, embodiments and advantages are merely illustrative and are not considered to be elements or limitations of the appended claims unless expressly stated in the claims. Similarly, reference to "the present disclosure" should not be interpreted as a summary of any inventive subject matter disclosed herein and should not be considered to be elements or limitations of the appended claims unless expressly stated in the claims.

[0024] The present disclosure generally relates to sensor devices, such as magnetic sensor bridges, that utilize a double free layer (DFL) structure. The device includes a plurality of resistors, each including the same DFL structure. Adjacent to the DFL structure is a magnetic structure that may include a permanent magnet, an antiferromagnetic (AFM) layer with a synthetic antiferromagnetic AFM (SAF) structure thereon, a permanent magnet with a SAF structure thereon, or an AFM layer with a ferromagnetic layer thereon. The DFL structures are aligned with different layers of the magnetic structures to differentiate the resistors. Different alignments and / or different magnetic structures reduce production time due to reduced complexity, thereby reducing costs.

[0025] Figure 1 FIG2 is a schematic diagram of a Wheatstone bridge array 100 design. Array 100 includes a bias source 102, a first resistor 104, a second resistor 106, a third resistor 108, a fourth resistor 110, a first node 112 for wire connection, a second node 114 for wire connection, and a ground connection 116. A bias voltage is applied across the array from bias source 102 to ground connection 116. The output of the applied voltage is sensed at first node 112 and second node 114. Any temperature variations from resistors 104, 106, 108, and 110 are canceled out.

[0026] As discussed herein, resistors 104, 106, 108, 110 each comprise a DFL sensor. In one embodiment, resistors 104, 110 are identical to one another, and resistors 106, 108 are identical to one another but different from resistors 104, 110. For the DFL sensors in array 100, the RA of array 100 is approximately 100 ohms / square micron.

[0027] Typical magnetic field sensors use MR (magnetoresistive) devices in a Wheatstone bridge circuit. This sensor requires various modifications to the MR devices within the bridge circuit. As described in this article, a new approach to magnetic field sensors utilizes identical DFL sensors but differentiates these resistors using different adjacent magnetic structures. The reliability and performance of the DFL sensors determine the magnetoresistive response. This combination of different magnetic structures of adjacent DFL sensors creates a perfect Wheatstone bridge design for magnetic field sensing.

[0028] Figure 2 FIG2 is a schematic diagram of a Wheatstone bridge array 200, wherein each resistor R1, R2, R3, and R4 has multiple DFL sensors. R1 may correspond to resistor 104; R2 may correspond to resistor 106; R3 may correspond to resistor 110; and R4 may correspond to resistor 108. When the operating field bias is set to 0, R1 = R2 = R3 = R4. Furthermore, based on the magnetic structure adjacent to the DFL sensor, resistors R1 and R3 differ from resistors R2 and R4 to provide two different magnetoresistive responses.

[0029] In array 200, each resistor R1, R2, R3, R4 includes multiple magnetic structures adjacent to DFL sensors. More specifically, in one embodiment, resistors R1 and R3 include multiple DFL sensors with adjacent magnetic structure 204, and resistors R2 and R4 include multiple DFL sensors with adjacent magnetic structure 202.

[0030] Figure 3 is a cross-sectional view of a dual free layer (DFL) sensor 300. The DFL sensor 300 includes a bottom lead (S1) 302, a seed layer 304, a first free layer (FL) 306, a barrier layer 308, a second FL 310, a cap 312, a top lead (S2) 322, and an insulating material 324. It should be understood that other materials not listed for each of the layers described herein are contemplated, and the embodiments discussed herein are not limited to the materials listed for each of the layers of the DFL sensor.

[0031] Each of S1 302 and S2 322 comprises a conductive material selected from the group consisting of copper (Cu), tungsten (W), tantalum (Ta), aluminum (Al), and alloys thereof. Each of S1 302 and S2 322 may have a thickness between approximately 20 nm and approximately 500 nm. Furthermore, it should be understood that while Cu, W, Ta, and Al have been exemplified as materials for S1 302 and S2 322, other materials are contemplated, and the embodiments discussed herein are not limited to Cu, W, Ta, or Al for S1 302 and S2 322.

[0032] A seed layer 304 is formed on S1 302. The seed layer 304 is deposited by a well-known deposition method, such as electroplating, physical vapor deposition (PVD), atomic layer deposition (ALD), or chemical vapor deposition (CVD). The seed layer 304 comprises a material selected from tantalum (Ta), tungsten (W), ruthenium (Ru), and alloys thereof. Furthermore, it should be understood that while Ta, W, and Ru have been exemplified as seed layer 304 materials, other materials are contemplated, and the embodiments discussed herein are not limited to Ta, W, or Ru for the seed layer 304.

[0033] The first FL 306 is formed on the seed layer 304. The first FL 306 includes a CoFe / CoFeB / Ta / NiFe multilayer stack. The CoFe layer may have a thickness between about 3 angstroms and about 10 angstroms. The CoFeB layer may have a thickness between about 10 angstroms and about 20 angstroms. The Ta layer may have a thickness between about 0.5 angstroms and about 2 angstroms. The NiFe layer may have a thickness between about 3 angstroms and about 300 angstroms, such as between about 3 angstroms and about 10 angstroms or between about 10 angstroms and about 300 angstroms. The first FL 306 can be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while CoFe / CoFeB / Ta / NiFe has been exemplified as the first FL 306 material, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe / CoFeB / Ta / NiFe for the first FL 306.

[0034] A barrier layer 308 is formed on the first FL 306. The barrier layer 308 comprises a material, such as magnesium oxide (MgO), having a thickness between about 10 angstroms and about 20 angstroms. It should be understood that while MgO is illustrated as the barrier layer 308, other insulating materials are contemplated and the embodiments discussed herein are not limited to MgO for the barrier layer 308.

[0035] Second FL 310 is formed on barrier layer 308. Second FL 310 includes a CoFe / CoFeB / Ta / NiFe multilayer stack. The CoFe layer may have a thickness between about 3 angstroms and about 10 angstroms. The CoFeB layer may have a thickness between about 10 angstroms and about 20 angstroms. The Ta layer may have a thickness between about 0.5 angstroms and about 2 angstroms. The NiFe layer may have a thickness between about 3 angstroms and about 300 angstroms, such as between about 3 angstroms and about 10 angstroms or between about 10 angstroms and about 300 angstroms. Second FL 310 may be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while CoFe / CoFeB / Ta / NiFe has been exemplified as the second FL 310 material, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe / CoFeB / Ta / NiFe for the second FL 310. The magnetic moments of the first FL 306 and the second FL 310 may be antiparallel due to an antiparallel bias from a synthetic antiferromagnetic (SAF) soft bias (SB), described further below.

[0036] A cap 312 is formed on the second FL 310. The cap 312 comprises a material selected from tantalum (Ta), ruthenium (Ru), titanium (Ti), and other non-magnetic conductive materials. The cap 312 can be formed by well-known deposition methods, such as sputtering. The cap 312 can have a thickness between about 10 angstroms and about 100 angstroms. Furthermore, it should be understood that while Ta, Ru, and Ti are exemplified as cap 312 materials, other materials are contemplated, and the embodiments discussed herein are not limited to Ta, Ru, or Ti for the cap 312.

[0037] The DFL sensor 300 further includes a first synthetic antiferromagnetic (SAF) soft bias (SB) (e.g., a side shield) and a second SAF SB, the first SAF SB including a first lower SB 316 a, a first spacer 318 a, and a first upper SB 320 a, and the second SAF SB including a second lower SB 316 b, a second spacer 318 b, and a second upper SB 320 b.

[0038] The first lower portion SB 316a and the second lower portion SB 316b include a material selected from the group consisting of NiFe, CoFe, CoNi, CoFeNi, CoFeB, Co, and alloys thereof. The first lower portion SB 316a and the second lower portion SB 316b can be formed by a well-known deposition method (such as sputtering). The first lower portion SB 316a and the second lower portion SB 316b can each have a thickness between about 15 angstroms and about 340 angstroms. In addition, it should be understood that although NiFe, CoFe, CoNi, CoFeNi, CoFeB, and Co have been exemplified as materials for the cap 312, other materials are also contemplated, and the embodiments discussed herein are not limited to Ta, Ru, or Ti for the cap 312.

[0039] A first spacer 318a is formed on the first lower SB 316a, and a second spacer 318b is formed on the second lower SB 316b. Suitable materials for the first spacer 318a and the second spacer 318b include ruthenium (Ru) with a thickness between about 4 angstroms and about 10 angstroms. It should be understood that while Ru has been illustrated as a material for the first spacer 318a and the second spacer 318b, other materials are contemplated, and the embodiments discussed herein are not limited to Ru for the first spacer 318a and the second spacer 318b.

[0040] The first upper SB 320a and the second upper SB 320b include a material selected from NiFe, CoFe, CoNi, CoFeNi, CoFeB, Co, and alloys thereof. The first upper SB 320a and the second upper SB 320b can be formed by a well-known deposition method (such as sputtering). The first upper SB 320a and the second upper SB 320b can each have a thickness between about 15 angstroms and about 340 angstroms. In addition, it should be understood that although NiFe, CoFe, CoNi, CoFeNi, CoFeB, and Co have been exemplified as the first upper SB 320a and the second upper SB 320b materials, other materials are also contemplated, and the embodiments discussed herein are not limited to NiFe, CoFe, CoNi, CoFeNi, CoFeB, and Co used for the first upper SB 320a and the second upper SB 320b. In various embodiments, similar to the cap 312, a capping layer can be formed on the first upper SB 320a and the second upper SB 320b. The capping layer may have a thickness between about 10 angstroms and about 100 angstroms.

[0041] Insulating material 324 may be placed in DFL sensor 300 to prevent electrical shorting between S1 302, seed layer 304, first FL 306, barrier layer 308, second FL 310, cap 312, S2 322, first SAF SB, and second SAF SB. Suitable materials for insulating layer 324 include dielectric materials such as aluminum oxide, silicon oxide, and silicon nitride. Insulating layer 324 may be formed using well-known deposition methods, such as atomic layer deposition (ALD) or sputtering. Insulating layer 324 may have a thickness between approximately 10 angstroms and approximately 700 angstroms.

[0042] In one embodiment, the first lower portion SB 316a is identical to the second lower portion SB 318b. Furthermore, the first upper portion SB 320a is identical to the second upper portion SB 320b. Furthermore, the first spacer 318a is identical to the second spacer 318b.

[0043] Figure 4A is a schematic top view of a sensor device 400 according to one embodiment. Figure 2 Aspects of the Wheatstone bridge array 200 may be similar to Figure 4A For example, the first resistor 402 may correspond to R4, the second resistor 404 may correspond to R1, the third resistor 406 may correspond to R3, and the fourth resistor 408 may correspond to R2. In addition, based on the DFL sensor having different adjacent magnetic structures, the first resistor 402 and the fourth resistor 408 are different from the second resistor 404 and the third resistor 406, providing two different magnetoresistive responses.

[0044] The first resistor 402 and the fourth resistor 408 each include an antiferromagnetic / ferromagnetic (AFM / FM) structure 410a, 410b and a DFL sensor 412. As will be discussed below, the DFL sensor 412 is disposed adjacent to the AFM / FM structures 410a, 410b. The DFL sensor 412 may be Figure 3 The DFL sensor 300 is described. The AFM / FM structures 410a and 410b are multilayer structures, where the base layer is an AFM layer and the FM portion is a ferromagnetic structure formed on the AFM layer. The pinning direction of the FM layer is set by cooling from the AFM's blocking temperature to room temperature in a downward-pointing global magnetic field. Due to the exchange bias between the AFM and FM layers, the FM layer is aligned approximately in the same direction as the magnetic field during the annealing process. The magnetic field directions of the AFM / FM structures 410a and 410b are indicated by arrows in the AFM / FM structures 410a and 410b.

[0045] The AFM layer of the AFM / FM structures 410a, 410b can include IrMn, FeMn, NiMn, PdMn, or PtMn having a thickness between about 40 angstroms and about 500 angstroms. The AFM layer can be formed by well-known deposition methods, such as sputtering. In addition, it should be understood that while IrMn, FeMn, NiMn, PdMn, and PtMn have been exemplified as AFM layer materials, other materials are also contemplated, and the embodiments discussed herein are not limited to IrMn, FeMn, PdMn, NiMn, or PtMn for the AFM layer.

[0046] The FM layer of the AFM / FM structures 410a, 410b can comprise CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, other soft or hard ferromagnetic materials, or other Heusler alloys, with a thickness equal to or greater than the thickness of the DFL sensor, and typically having a thickness between about 100 angstroms and about 1000 angstroms. The FM layer can be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, and Heusler alloys are exemplified as FM layer materials, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, or Heusler alloys for the FM layer. Suitable materials for the spacer layer are discussed below.

[0047] The second resistor 404 and the third resistor 406 each include an AFM / SAF structure 414a, 414b and a DFL sensor 412. The DFL sensor 412 is disposed adjacent to the AFM / SAF structure 414a, 414b. The DFL sensor 412 may be Figure 3 The DFL sensor 300 .

[0048] Figure 4B and Figure 4C 4 is a schematic cross-sectional view of resistor elements 420, 430 of the TMR sensor device 400 according to various embodiments. The resistor elements 420, 430 can be any of the resistors 402, 404, 406, 408. Two of the resistors 402, 408 have the same resistor element 420, while the remaining two resistors 404, 406 have the same resistor element 430. Figure 4BA resistor element 420 is shown. The resistor element 420 includes a magnetic structure 414 adjacent to the DFL sensor 412. The magnetic structure 414 includes an AFM layer 422 having a synthetic antiferromagnetic (SAF) structure 421 thereon. The SAF structure 421 includes a first ferromagnetic (FM1) layer 424 disposed on or above the AFM layer 422, a spacer layer 426 disposed on or above the FM1 layer 424, and a second ferromagnetic (FM2) layer 428 disposed on the spacer layer 426. The spacer layer 426 is a metal layer having a specific thickness such that the FM1 layer 424 and the FM2 layer 428 are antiferromagnetically coupled to each other. In one embodiment, when viewed in cross section, the DFL 412 is linearly aligned with the FM2 layer 428, as shown in FIG. Figure 4B shown. Figure 4C A resistor element 430 is shown. Resistor element 430 includes a DFL sensor 412 adjacent to a magnetic structure 432. Magnetic structure 432 includes an AFM layer 422 with a ferromagnetic (FM) layer 434 thereon. When viewed in cross-section, DFL sensor 412 is linearly aligned with FM layer 434. The pinning direction of FM2 layer 428 is set by the same cooling process in magnetic structures 414 and 432. Due to the exchange bias between AFM layer 422 and FM1 layer 424, and between AFM layer 422 and FM layer 434, FM1 layer 424 and FM layer 434 are aligned approximately identically with the magnetic field direction during the annealing process, and FM2 layer 428 is aligned in the opposite direction to the magnetic field, or in the opposite direction to FM layer 434 in resistor element 430. The magnetic field directions of magnetic structures 414 and 432 are shown by arrows in AFM / FM structures 410a and 410b.

[0049] The different magnetic structures 414, 432 used for the resistor elements 420, 430 in the different resistors 402, 404, 406, 408 are responsible for the differences in the various resistors 402, 404, 406, 408. For example, resistors 402, 408 may include one or more resistor elements 420, while resistors 404, 406 may include one or more resistor elements 430. Alternatively, resistors 402, 408 may include one or more resistor elements 430, while resistors 404, 406 may include one or more resistor elements 420. By using the same DFL sensor 412 for resistor elements 420, 430, but using different magnetic structures adjacent thereto, the manufacture of the resistors is simplified.

[0050] The AFM layer 422 may include IrMn, FeMn, NiMn, PdMn, or PtMn having a thickness between about 40 angstroms and about 500 angstroms. The AFM layer may be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while IrMn, FeMn, NiMn, PdMn, and PtMn have been exemplified as AFM layer materials, other materials are contemplated, and the embodiments discussed herein are not limited to IrMn, FeMn, PdMn, NiMn, or PtMn for the AFM layer.

[0051] SAF structure 421 includes FM1 layer 424, spacer layer 426, and FM2 layer 428. FM1 layer 424, FM2 layer 428, and FM layer 434 may comprise CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, other soft ferromagnetic materials, or other Heusler alloys with a thickness equal to or greater than that of a DFL sensor, and typically have a thickness between about 100 angstroms and about 1000 angstroms as magnetic layers with a spacer layer therebetween. FM1 layer 424 and FM2 layer 428 may be formed by well-known deposition methods, such as sputtering. Additionally, it should be understood that while CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, and Heusler alloys have been exemplified as FM layer materials, other materials are contemplated and the embodiments discussed herein are not limited to CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, or Heusler alloys for the FM1 layer 424 and the FM2 layer 426.

[0052] Suitable materials for the spacer layer 426 include ruthenium (Ru) having a thickness between about 4 angstroms and 5 angstroms or 8 angstroms and 9 angstroms. It should be understood that while Ru has been exemplified as the spacer layer 426 material, other materials are contemplated and the embodiments discussed herein are not limited to Ru for the spacer layer 426. Due to the antiparallel coupling with the spacer layer 426, the magnetization direction of the FM1 layer 424 is opposite to the magnetization direction of the FM2 layer 428.

[0053] Figures 4D to 4F FIG. 4 is a schematic diagram of resistors 440, 450, 460 of a DFL sensor device 400 according to one embodiment. The resistors 440, 450, 460 may be Figure 4AAny of the resistors 402, 404, 406, 408. The AFM stacks (which may be referred to as magnetic structures or MS) 442a-442c, 452a-452i, 462a-462f may be AFM / FM structures 410a, 410b or AFM / SAF structures 414. The DFLs 444a-444f, 454a-454f, 464a-464f may be Figure 3 DFL sensor 300. Figures 4D to 4F The number of rows and columns of AFM stacks shown is not intended to be limiting, but rather to provide examples of possible implementations. Figures 4D to 4F The number of rows and columns of DFLs shown is not intended to be limiting, but rather to provide examples of possible implementations.

[0054] exist Figure 4D , resistor 440 includes a first magnetic structure 442a, a plurality of DFL sensors 444a-444c, a second magnetic structure 442b, a plurality of DFL sensors 444d-444f, and a third magnetic structure 442c. In one embodiment, magnetic structures 442a-442c have the same size as the three DFL sensors 444a-444c combined.

[0055] Multiple DFL sensors 444a-444f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 444a is connected to the bottom lead of the second DFL sensor 444b, the top lead of the second DFL sensor 444b is connected to the bottom lead of the third DFL sensor 444c, and so on.

[0056] Since the multiple DFL sensors 444a-444f are connected in series, a single shared bias unit may be used to bias all of the DFL sensors simultaneously. Figure 4D The biasing unit can be any of the magnetic structures 442a-442c. For example, the first magnetic structure 442a and the second magnetic structure 442b can act on the first, second, and third DFL sensors 444a-444c, wherein the magnetic field direction of the first magnetic structure 442a is applied to the first, second, and third DFL sensors 444a-444c. Due to the same global magnetic field, the fourth, fifth, and sixth DFL sensors 444d-444f are biased in the same direction as the first, second, and third DFL sensors 444a-444c by the magnetic structures 442b and 442c.

[0057] exist Figure 4E, resistor 450 includes a plurality of magnetic structures 452a-452c, a plurality of DFL sensors 454a-454c, a plurality of magnetic structures 452d-452f, a plurality of DFL sensors 454d-454f, and a plurality of magnetic structures 452g-452i. In one embodiment, the magnetic structure has the same size as each of the DFL sensors.

[0058] Multiple DFL sensors 454a-454f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 454a is connected to the bottom lead of the second DFL sensor 454b, the top lead of the second DFL sensor 454b is connected to the bottom lead of the third DFL sensor 454c, and so on.

[0059] Each of the DFL sensors 454a-454f is individually biased by each pair of magnetic structures 452a-452i above and below it. For example, the first DFL sensor 454a can be acted upon by the magnetic structure 452a above and the magnetic structure 452d below, where the magnetic field direction of the first magnetic structure 452a is applied to the first DFL sensor 454a, and the magnetic field direction of the magnetic structure 452d is applied to the first DFL sensor 454a. Due to the same global magnetic field, the second through sixth DFL sensors 454d-454f are biased in the same direction as the first DFL sensor 454a.

[0060] exist Figure 4F , resistor 460 includes a plurality of magnetic structures 462a-462c, a plurality of DFL sensors 464a-464c, a fourth magnetic structure 462d, a plurality of DFL sensors 464d-464f, and a plurality of magnetic structures 462g-462f. In one embodiment, the magnetic structures have the same dimensions as one, two, and / or three of the DFL sensors. The dimensions listed above are not intended to be limiting, but rather to provide examples of possible embodiments. For example, first magnetic structure 462a has the same dimensions as first DFL sensor 464a, fourth magnetic structure 462d has the same dimensions as the combined first, second, and third DFL sensors 464a, 464b, and 464c, and sixth magnetic structure 462f has the same dimensions as the combined fourth and fifth DFL sensors 464d and 464e.

[0061] Multiple DFL sensors 464a-464f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 464a is connected to the bottom lead of the second DFL sensor 464b, the top lead of the second DFL sensor 464b is connected to the bottom lead of the third DFL sensor 464c, and so on.

[0062] Since the multiple DFL sensors are connected in series, a single shared bias unit can be used to bias all of the DFL sensors simultaneously. Figure 4F The biasing unit can be any of the magnetic structures 462a-462f. For example, the first magnetic structure 462a can act on the first DFL sensor 454a, wherein the magnetic field direction of the first magnetic structure 462a is applied to the first DFL sensor 464a. Due to the same global magnetic field, the second to sixth DFL sensors 464d-464f are biased in the same direction as the first DFL sensor 464a.

[0063] Figure 5A is a schematic top view of a sensor device 500 according to another embodiment. Figure 2 Aspects of the Wheatstone bridge array 200 may be similar to Figure 5A For example, the first resistor 502 may correspond to R4, the second resistor 504 may correspond to R1, the third resistor 506 may correspond to R3, and the fourth resistor 508 may correspond to R2. In addition, based on the DFL sensor being adjacent to different magnetic structures, the first resistor 502 and the fourth resistor 508 are different from the second resistor 504 and the third resistor 506 to provide two different magnetoresistive responses.

[0064] The first resistor 502 and the fourth resistor 508 each include a permanent magnet 510a, 510b and a DFL sensor 512. The DFL sensor 512 is disposed adjacent to the PM 510a, 510b. The DFL sensor 512 may be Figure 3 The DFL sensor 300 is shown in FIG. 5 . The magnetic field of the PMs 510a and 510b is set by a substantially global magnetic field that is greater than the coercive force of the PMs pointing downward. The directions of the magnetic fields of the PMs 510a and 510b are shown by arrows on the PMs 510a and 510b.

[0065] The second resistor 504 and the third resistor 506 each include a PM / SAF structure 514 and a DFL sensor 512. The DFL sensor 512 is disposed adjacent to the PM / SAF structure 514. The DFL sensor 512 may be Figure 3 The DFL sensor 300 .

[0066] Figure 5B and Figure 5C 5 is a schematic diagram of resistor elements 520, 530 of resistors 502, 504, 506, 508 of sensor device 500 according to various embodiments. Resistor element 520 includes PM / SAF structure 514 and DFL 512. Resistor element 530 includes PM 532 and DFL sensor 512. PM / SAF structure 514 includes PM 522 with SAF 521 thereon. SAF 521 includes FM1 layer 524 disposed on or above PM 522, spacer layer 526 disposed on or above FM1 layer 524, and FM2 layer 528 disposed on or above spacer layer 526. In one embodiment, DFL sensor 512 is aligned with FM2 layer 528, as shown in FIG. Figure 5B As shown. The magnetic orientation of the FM2 layer is set by the same field setting process as described above. Due to the strong coupling between PM 522 and FM1 layer 524, FM1 layer 524 is aligned approximately in the same direction as the magnetic field during the field reset process, while FM2 layer 528 is aligned in the opposite direction. The magnetic field direction of FM2 layer 528 in magnetic structure 514 is shown by the arrows in PM / SAF structures 514a and 514b.

[0067] PM 522 is formed from a material having high coercivity, for example, a material including one or more of Co, Pt, and / or Cr, such as CoPt or CoPtCr. It has a thickness between about 100 angstroms and about 1000 angstroms. PM 522 can be formed by well-known deposition methods, such as physical vapor deposition (PVD), sputtering, or IBD. Furthermore, it should be understood that while CoPt or CoPtCr has been exemplified as PM materials, other materials are contemplated, and the embodiments discussed herein are not limited to CoPt or CoPtCr for PMs.

[0068] The SAF structure 521 includes an FM1 layer 524, a spacer layer 526, and an FM2 layer 528. The FM1 layer 524 and the FM2 layer 528 may comprise CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, other soft ferromagnetic materials or hard ferromagnetic materials, or other Heusler alloys having a thickness between about 100 angstroms and about 1000 angstroms. The FM layers may be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, and Heusler alloys have been exemplified as FM layer materials, other materials are contemplated, and the embodiments discussed herein are not limited to CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, or Heusler alloys for the FM layers.

[0069] Suitable materials for the spacer layer 526 include ruthenium (Ru) with a thickness between approximately 4 angstroms and 5 angstroms or 8 angstroms and 9 angstroms. It should be understood that while Ru has been exemplified as the spacer layer 526 material, other materials are contemplated, and the embodiments discussed herein are not limited to Ru for the spacer layer 526. Due to the antiparallel coupling with the spacer layer 526, the magnetization direction of the FM1 layer 524 is opposite to the magnetization direction of the FM2 layer 528. Furthermore, the PM / SAF structure 514 may be biased toward the DFL sensor 512 due to the magnetic orientation of the FM2 layer 528.

[0070] Figures 5D to 5F is a schematic diagram of resistors 540, 550, 560 of sensor device 500 according to one embodiment. Resistors 540, 550, 560 may be Figure 5A Any of the resistors 502, 504, 506, 508. The magnetic structures 542a-542c, 552a-552i, 562a-562f can be PM 510a, 510b or PM / SAF structures 514a, 514b. The DFL sensors 544a-544f, 554a-554f, 564a-564f can be Figure 3 DFL sensor 300. Figures 5D to 5F The number of rows and columns of magnetic structures shown in are not intended to be limiting, but rather to provide examples of possible implementations. Figures 5D to 5F The number of rows and columns of DFL sensors shown is not intended to be limiting, but rather to provide examples of possible implementations.

[0071] exist Figure 5D, resistor 540 includes a first magnetic structure 542a, a plurality of DFL sensors 544a-544c, a second magnetic structure 542b, a plurality of DFL sensors 544d-544f, and a third magnetic structure 542c. In one embodiment, the magnetic structure has the same size as the three DFL sensors.

[0072] Multiple DFL sensors 544a-544f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 544a is connected to the bottom lead of the second DFL sensor 544b, the top lead of the second DFL sensor 544b is connected to the bottom lead of the third DFL sensor 544c, and so on.

[0073] Since the multiple DFL sensors are connected in series, a single shared bias unit can be used to bias all of the DFL sensors simultaneously. Figure 5D The biasing unit can be any of the magnetic structures 542a-542c. For example, the first magnetic structure 542a and the second magnetic structure 542b can act on the first, second, and third DFL sensors 544a-544c, wherein the magnetic field directions of the first magnetic structure 542a and the second magnetic structure are applied to the first, second, and third DFL sensors 544a-544c. Due to the global field during the PM reset process, the fourth, fifth, and sixth DFL sensors 544d-544f are biased in the same direction as the first, second, and third DFL sensors 544a-544c.

[0074] exist Figure 5E , the resistor 550 includes a plurality of magnetic structures 552a-552c, a plurality of DFL sensors 554a-554c, a plurality of magnetic structures 552d-552f, a plurality of DFL sensors 554d-554f, and a plurality of magnetic structures 552g-552i.

[0075] Multiple DFL sensors 554a-554f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 554a is connected to the bottom lead of the second DFL sensor 554b, the top lead of the second DFL sensor 554b is connected to the bottom lead of the third DFL sensor 554c, and so on.

[0076] Each of the DFL sensors 554a-554f is individually biased by each pair of magnetic structures 552a-552i above and below it. Figure 5EThe biasing unit can be any of the magnetic structures 552a-552i. For example, the first magnetic structure 552a can act on the first DFL sensor 554a, wherein the magnetic field direction of the first magnetic structure 552a is applied to the first DFL sensor 554a. Due to the global field during the PM reset process, the second to sixth DFL sensors 554d-554f are biased in the same direction as the first DFL sensor 554a.

[0077] exist Figure 5F , resistor 560 includes a plurality of magnetic structures 562a-562c, a plurality of DFL sensors 564a-564c, a fourth magnetic structure 562d, a plurality of DFL sensors 564d-564f, and a plurality of magnetic structures 562g-562f. In one embodiment, these magnetic structures have the same dimensions as one of the DFL sensors, two of the DFL sensors, and / or three of the DFL sensors. The dimensions listed above are not intended to be limiting, but rather to provide examples of possible embodiments. For example, first magnetic structure 562a has the same dimensions as first DFL sensor 564a, fourth magnetic structure 562d has the same dimensions as the combined first, second, and third DFL sensors 564a, 564b, and 564c, and sixth magnetic structure 562f has the same dimensions as the combined fourth and fifth DFL sensors 564d and 564e.

[0078] Multiple DFL sensors 564a-564f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 564a is connected to the bottom lead of the second DFL sensor 564b, the top lead of the second DFL sensor 564b is connected to the bottom lead of the third DFL sensor 564c, and so on.

[0079] Due to the global field during the PM reset process, a single shared bias unit can be used to bias all DFL sensors simultaneously. Figure 5F The biasing unit can be any of the magnetic structures 562a-562f. For example, the first magnetic structure 562a can act on the first DFL sensor 554a, wherein the magnetic field direction of the first magnetic structure 562a is applied to the first DFL sensor 564a. Due to the global field during the PM reset process, the second to sixth DFL sensors 564d-564f are biased in the same direction as the first DFL sensor 564a.

[0080] Figure 6A is a schematic diagram of a sensor device 600 according to another embodiment. Figure 2 Aspects of the Wheatstone bridge array 200 may be similar to Figure 6A For example, the first resistor 602 may correspond to R4, the second resistor 604 may correspond to R1, the third resistor 606 may correspond to R3, and the fourth resistor 608 may correspond to R2. In addition, based on the TMR structure, the first resistor 602 and the fourth resistor 608 are different from the second resistor 604 and the third resistor 606 to provide two different magnetoresistive responses.

[0081] The first resistor 602 and the fourth resistor 608 each include a first AFM1 / FM1 structure 610a, a DFL sensor 612, and a second AFM1 / FM1 structure 610b. The DFL sensor 612 is disposed between the first AFM1 / FM1 structure 610a and the second AFM2 / FM2 structure 610b. The DFL sensor 612 may be Figure 3 The DFL sensor 300 is shown in FIG. 1 . The magnetic field of the AFM1 / FM1 structures 610a and 610b is arranged around the global magnetic field pointing downward. The direction of the magnetic field of the AFM1 / FM1 structures 610a and 610b is shown by the arrows of the AFM1 / FM1 structures 610a and 610b.

[0082] The second resistor 604 and the third resistor 606 each include a first AFM2 / FM2 structure 614a, a DFL sensor 612, and a second AFM2 / FM2 structure 614b. The DFL sensor 612 is disposed between the first AFM2 / FM2 structure 614a and the second AFM2 / FM2 structure 614b. The DFL sensor 612 may be Figure 3 The DFL sensor 300 is shown in FIG. 1 . The magnetic field direction of the AFM2 / FM2 structures 614a and 614b is shown by arrows on the AFM2 / FM2 structures 614a and 614b.

[0083] Figure 6B and Figure 6C Schematic diagrams of resistor elements 620, 630 of resistors 602, 604, 606, 608 of a TMR sensor device 600 according to various embodiments. The resistor element 620 can be used for the first resistor 602 and / or the fourth resistor 608. The resistor element 620 includes a first AFM1 / FM1 structure 610a, a second AFM1 / FM1 structure 610b, and a DFL sensor 612. The AFM1 / FM1 structures 610a, 610b each include an AFM1 layer 622 and an FM1 layer 624 disposed on the AFM1 layer 622.

[0084] The resistor element 630 can function as the second resistor 604 and / or the third resistor 606. The resistor element 630 includes a first AFM2 / FM2 structure 614a, a second AFM2 / FM2 structure 614b, and a DFL sensor 612. The AFM2 / FM2 structures 614a and 614b each include an AFM2 layer 632 and an FM2 layer 634 disposed on the AFM2 layer 632.

[0085] Regarding resistor element 620, in one embodiment, DFL sensor 612 is aligned with FM1 layer 624. Regarding resistor element 630, in one embodiment, DFL sensor 612 is aligned with FM2 layer 634. Figure 6C shown.

[0086] The AFM1 layer 622 and the AFM2 layer 632 can include IrMn, FeMn, NiMn, PdMn, or PtMn having a thickness between about 40 angstroms and about 500 angstroms. The AFM layers 622 and 632 can be formed by well-known deposition methods, such as sputtering. Furthermore, it should be understood that while IrMn, FeMn, NiMn, PdMn, and PtMn have been exemplified as AFM layer materials, other materials are contemplated, and the embodiments discussed herein are not limited to IrMn, FeMn, PdMn, NiMn, or PtMn for the AFM layer. In one embodiment, the AFM1 layer 622, 610a, 610b is different from the AFM2 layer 632, 614a, 614b, such that the AFM1 layer 622 and the AFM2 layer 632 have different blocking temperatures. Furthermore, the AFM1 layer 622 is set by cooling from a first blocking temperature toward a first bias direction in a first magnetic field. The AFM2 layer 632 is cooled in a second magnetic field from a second blocking temperature to a second bias direction, wherein the second blocking temperature is less than the first blocking temperature, the second magnetic field direction is opposite to the first magnetic field direction, and the second bias direction is opposite to the first bias direction. The magnetic field direction from the FM1 layer 624 is opposite to the magnetic field direction from the FM2 layer 634.

[0087] Figure 6B and Figure 6CThe FM1 layer 624 and the FM2 layer 634 in the embodiment of the present invention can include CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, other soft ferromagnetic materials or hard ferromagnetic materials, or other Heusler alloys with a thickness between about 100 angstroms and about 1000 angstroms. The FM layer can be formed by well-known deposition methods such as sputtering. In addition, it should be understood that while CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, and Heusler alloys have been exemplified as FM layer materials, other materials are also contemplated, and the embodiments discussed herein are not limited to CoFe, NiFe, CoFeNi, CoMnGe, NiCo, NiFeCu, CoFeMnGe, CoMnSi, CoFeSi, or Heusler alloys for the FM layer. In one embodiment, the FM1 layer 624 includes the same material as the FM2 layer 634. In another embodiment, the FM1 layer 624 does not contain the same material as the FM2 layer 634. Since the field direction is opposite during the field cooling process, the magnetization direction of the FM1 layer 624 is opposite to that of the FM2 layer 634. Figure 6C The magnetization direction of the FM2 layer 634 is opposite.

[0088] Figures 6D to 6F FIG. 6 is a schematic diagram of resistors 640, 650, 660 of a TMR sensor device 600 according to one embodiment. The resistors 640, 650, 660 may be Figure 6A Any of the resistors 602, 604, 606, 608. The AFM1 / 2 stacks 642a-642c, 652a-652i, 662a-562f can be AFM1 / FM1 layers 610a, 610b or AFM2 / FM2 structures 614a, 614b. The DFL sensors 644a-644f, 654a-654f, 664a-664f can be Figure 3 DFL sensor 300. Figures 6D to 6F The number of rows and columns of AFM stacks shown is not intended to be limiting, but rather to provide examples of possible implementations. Figures 6D to 6F The number of rows and columns of DFL sensors shown is not intended to be limiting, but rather to provide examples of possible implementations.

[0089] exist Figure 6DIn FIG. 6 , resistor 640 includes a first AFM1 / 2 stack 642a, a plurality of DFL sensors 644a-644c, a second AFM1 / 2 stack 642b, a plurality of DFL sensors 644d-644f, and a third AFM1 / 2 stack 642c. In one embodiment, the AFM1 / 2 stack has the same dimensions as the three DFL sensors. The dimensions listed above are not intended to be limiting, but rather to provide examples of possible implementations. For example, the first AFM1 / 2 stack 642a has the same dimensions as the combined first, second, and third DFL sensors 644a-644c.

[0090] Multiple DFL sensors 644a-644f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 644a is connected to the bottom lead of the second DFL sensor 644b, the top lead of the second DFL sensor 644b is connected to the bottom lead of the third DFL sensor 644c, and so on.

[0091] Due to the global field during field cooling, a single shared bias unit can be used to bias all DFL units simultaneously. Figure 6D The biasing unit can be any of the AFM1 / 2 stacks 642a-642c. For example, the first AFM1 / 2 stacks 642a and 642b can act on the first, second, and third DFL sensors 644a-644c, wherein the magnetic field direction of the first AFM1 / 2 stacks 642a and 642b is applied to the first, second, and third DFL sensors 644a-644c. Because these DFL sensors are connected in series, the fourth, fifth, and sixth DFL sensors 644d-644f are biased in the same direction as the first, second, and third DFL sensors 644a-644c.

[0092] exist Figure 6E In FIG. 1 , resistor 650 includes a plurality of AFM1 / 2 stacks 652a-652c, a plurality of DFL sensors 654a-654c, a plurality of AFM1 / 2 stacks 652d-652f, a plurality of DFL sensors 654d-654f, and a plurality of AFM1 / 2 stacks 652g-652i. In one embodiment, the AFM1 / 2 stacks have the same dimensions as each of the DFL sensors. The dimensions listed above are not intended to be limiting, but rather to provide examples of possible embodiments. For example, the first AFM1 / 2 stack 652a has the same dimensions as each of the plurality of DFL sensors 654a-654f.

[0093] Multiple DFL sensors 654a-654f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 654a is connected to the bottom lead of the second DFL sensor 654b, the top lead of the second DFL sensor 654b is connected to the bottom lead of the third DFL sensor 654c, and so on.

[0094] Each of the DFL sensors 654a-654f is individually biased by each pair of AFM1 / 2 stacks 652a-652i above and below it. For example, the first DFL sensor 654a can be acted upon by the AFM1 / 2 stack 652a above it and the AFM1 / 2 stack 652d below it, where the magnetic field direction of the first AFM1 / 2 stacks 652a and 652d is applied to the first DFL sensor 654a. Due to the same global magnetic field, the second through sixth DFL sensors 654d-654f are biased in the same direction as the first DFL sensor 654a.

[0095] exist Figure 6F , resistor 660 includes a plurality of AFM1 / 2 stacks 662a-662c, a plurality of DFL sensors 664a-664c, a fourth AFM1 / 2 stack 662d, a plurality of DFL sensors 664d-664f, and a plurality of AFM1 / 2 stacks 662g-662f. In one embodiment, the AFM1 / 2 stack has the same dimensions as one of the DFL sensors, two of the DFL sensors, and / or three of the DFL sensors. The dimensions listed above are not intended to be limiting, but rather to provide examples of possible implementations. For example, the first AFM1 / 2 stack 662a has the same size as the first DFL sensor 664a, the fourth AFM1 / 2 stack 662d has the same size as the combined first DFL sensor 664a, the second DFL sensor 664b and the third DFL sensor 664c, and the sixth AFM1 / 2 stack 662f has the same size as the combined fourth DFL sensor 664d and the fifth DFL sensor 664e.

[0096] Multiple DFL sensors 664a-664f are connected in series, with the top lead of one sensor connected to the bottom lead of an adjacent sensor. For example, the top lead of the first DFL sensor 664a is connected to the bottom lead of the second DFL sensor 664b, the top lead of the second DFL sensor 664b is connected to the bottom lead of the third DFL sensor 664c, and so on.

[0097] Due to the global field during field cooling, a single shared bias unit can be used to bias all DFL sensors simultaneously. Figure 6F The biasing unit can be any of the AFM1 / 2 stacks 662a-662f. For example, the first AFM1 / 2 stack 662a can act on the first DFL sensor 654a, wherein the magnetic field direction of the first AFM1 / 2 stack 662a is applied to the first DFL sensor 664a. Because the DFL sensors are connected in series, the second to sixth DFL sensors 664d-664f are biased in the same direction as the first DFL sensor 664a.

[0098] Figure 7 is a flow chart illustrating a method 700 for manufacturing a TMR sensor device according to one embodiment. It begins with a silicon wafer. At block 702, a DFL sensor is formed and insulated using a material such as Al2O3, Si3N4, MgO, or a combination thereof. A DFL sensor is formed for each of the resistors in the TMR sensor device. At block 704, resistors R2 and R4 are covered or masked so that processing of resistors R1 and R3 can continue. More specifically, resistors R2 and R4 are covered with a hard mask material such as DLC. Thereafter, a photoresist (such as duramide) is deposited over resistors R1-R4. The photoresist is then patterned to expose the desired areas of resistors R1 and R3 for processing. The exposed desired areas of resistors R1 and R3 are then etched using a removal process such as RIE to remove material. At block 706, a PM, AFM, or AFM1 is formed adjacent to the DFL structures of resistors R1 and R3. At block 708 , SAF is deposited on PM and AFM or FM1 is deposited on AFM1 (instead of depositing SAF on AFM1 ). After SAF deposition, a hard mask material such as DLC is deposited, followed by a CMP strip process and a RIE process.

[0099] At block 710, resistors R2 and R4 are exposed and removed. Resistors R1 and R3 are then covered or masked so that processing of resistors R2 and R4 can continue. The covering and masking includes covering resistors R1 and R3 with a hard mask material such as DLC. Thereafter, a photoresist (such as duramide) is deposited over resistors R1-R4. The photoresist is then patterned to expose the desired areas of resistors R2 and R4 for processing. The exposed desired areas of resistors R2 and R4 are then etched using a removal process such as RIE to remove material. At block 714, a PM, AFM, or AFM2 is formed adjacent to the DFL structure. At block 716, a FM is formed over the AFM, or FM2 is deposited on AFM2 (nothing is formed over the PM). After the FM or FM2 is deposited, a hard mask material such as DLC is deposited, followed by a CMP stripping process and an RIE process. At block 718, resistors R1 and R3 are exposed, and further processing of the DFL TMR sensor device continues with the top lead / contact steps for the bridge sensor. The final step before dicing and packaging is a field reset process at block 720. For bridges with PM / FM and PM / SAF, a global uniform magnetic field greater than the PM coercivity is applied to set the PM orientation. For bridges with AFM / FM and AFM / SAF, the entire wafer is cooled in a global uniform magnetic field starting from the AFM's blocking temperature. For bridges with AFM1 / FM1 and AFM2 / FM2, a two-step field cooling step is performed: the first wafer is set by cooling in a first magnetic field from the first blocking temperature of AFM1 toward the bias direction. The AFM2 layer is then set by continuously cooling in a second magnetic field from the second blocking temperature of AFM2 to room temperature, where the second blocking temperature is less than the first blocking temperature and the second magnetic field direction is opposite to the first.

[0100] By using the same DFL structure and PM or AFM structure, but aligning different FM layers of the PM or AFM structure with the DFL structure, a TMR sensor bridge device can be manufactured with reduced production time, thereby saving cost and reducing complexity. In addition, using the same DFL structure with different AFM materials in the AFM structure will also reduce production time, thereby also saving cost and reducing complexity.

[0101] In one embodiment, a TMR sensor is used in a camera operating as a single-axis sensor. However, it is contemplated that TMR sensors can be used as two- or even three-dimensional sensors. Furthermore, it is contemplated that TMR sensors can be integrated and used in inertial measurement unit technologies beyond cameras, such as wearable devices, compasses, and MEMS devices. Furthermore, TMR sensors can operate as position sensors, bridge angle sensors, magnetic switches, current sensors, or a combination thereof. TMR sensors can be used to focus cameras, such as smartphone cameras, by using the TMR sensor as a position and angle sensor. Furthermore, TMR sensors can also be used in the automotive industry as switches, current, and angle sensors, replacing current Hall, AMR, and GMR sensors. TMR sensors can also be used as position and angle sensors in drones and robotics. Medical devices can also utilize TMR sensors for flow control in infusion systems, as sensors for endoscope cameras, and more. Therefore, the TMR sensors discussed herein have applications far beyond smartphone cameras and should not be limited to use as sensors for smartphone cameras. Furthermore, TMR sensors do not need to be arranged in a Wheatstone bridge configuration but can be arranged in any number of different configurations.

[0102] In one embodiment, a sensor device includes a first resistor comprising at least one first double-free layer (DFL) sensor; and at least one first magnetic structure, wherein each first magnetic structure comprises a first antiferromagnetic (AFM) layer; and a synthetic AFM (SAF) structure disposed above the first AFM layer, wherein the at least one first DFL sensor is linearly aligned with the SAF structure when viewed in cross-section; and a second resistor comprising at least one second DFL sensor; and at least one second magnetic structure. The SAF structure comprises a first ferromagnetic layer; a spacer layer disposed above the first ferromagnetic layer; and a second ferromagnetic layer disposed above the spacer layer. The at least one first DFL sensor is linearly aligned with the second ferromagnetic layer. The at least one second magnetic structure comprises a second AFM layer; and a ferromagnetic layer disposed above the second AFM layer. When viewed in cross-section, the at least one second DFL sensor is linearly aligned with the ferromagnetic layer. The at least one first DFL sensor comprises a plurality of first DFL sensors, wherein the at least one first magnetic structure comprises a plurality of first magnetic structures, and wherein the number of the plurality of first DFL sensors is greater than the number of the plurality of first magnetic structures. The at least one second DFL sensor includes a plurality of second DFL sensors, wherein the at least one second magnetic structure includes a plurality of second magnetic structures, and wherein the number of the plurality of second DFL sensors is greater than the number of the plurality of second magnetic structures. The sensor device also includes a third resistor, wherein the third resistor is substantially the same as the first resistor; and a fourth resistor, wherein the fourth resistor is substantially the same as the second resistor. The sensor device is a Wheatstone bridge array.

[0103] In another embodiment, a sensor device includes a first resistor comprising at least one first double-free layer (DFL) sensor; and at least one magnetic structure, wherein each magnetic structure comprises a first permanent magnet; and a synthetic antiferromagnetic (SAF) structure disposed above the first permanent magnet, wherein the at least one first DFL sensor is linearly aligned with the SAF structure when viewed in cross-section; and a second resistor comprising at least one second DFL sensor; and at least one second permanent magnet, wherein the at least one second DFL sensor is linearly aligned with the at least one second permanent magnet when viewed in cross-section. The at least one first DFL sensor is a plurality of first DFL sensors connected in series. The at least one second DFL sensor is a plurality of second DFL sensors connected in series. The SAF structure comprises a first ferromagnetic layer; a spacer layer disposed above the first ferromagnetic layer; and a second ferromagnetic layer disposed above the spacer layer, wherein the at least one first DFL sensor is linearly aligned with the second ferromagnetic layer. The at least one magnetic structure comprises a plurality of magnetic structures, wherein the at least one second permanent magnet comprises a plurality of second permanent magnets, and wherein the number of the plurality of magnetic structures is equal to the number of the plurality of second permanent magnets. The sensor device is a Wheatstone bridge array.

[0104] In another embodiment, a sensor device includes at least one first resistor, the at least one first resistor including at least one first double-free layer (DFL) sensor; and at least one first magnetic structure, wherein each first magnetic structure includes: a first antiferromagnetic (AFM) layer including a first material; and a first ferromagnetic layer disposed above the first AFM layer; and at least one second resistor, the at least one second resistor including: at least one second DFL sensor; and at least one second magnetic structure, wherein each second magnetic structure includes: a second AFM layer including a second material, wherein the second material is different from the first material; and a second ferromagnetic layer disposed above the second AFM layer, wherein the second ferromagnetic layer is the same as or different from the first ferromagnetic layer. When viewed in cross section, the at least one first DFL sensor is linearly aligned with the first ferromagnetic layer. When viewed in cross section, the at least one second DFL sensor is linearly aligned with the second ferromagnetic layer. The at least one first resistor includes a plurality of first resistors, and the at least one second resistor includes a plurality of second resistors. The sensor device is a Wheatstone bridge array.

[0105] In another embodiment, a method includes forming a plurality of dual-free layer sensors for a plurality of resistors; covering at least one first resistor of the plurality of resistors, wherein at least one second resistor of the plurality of resistors remains exposed; forming a first permanent magnet or a first antiferromagnetic layer adjacent to the dual-free layer sensor of the at least one second resistor; exposing the at least one first resistor; covering the at least one second resistor; forming a second permanent magnet or a second antiferromagnetic layer adjacent to the dual-free layer sensor of the at least one first resistor; exposing the at least one second resistor; and performing a bridge pinning reset. The method further includes forming both a first permanent magnet and a second permanent magnet. The method further includes forming a synthetic antiferromagnetic structure above the first permanent magnet. The method further includes forming both a first antiferromagnetic layer and a second antiferromagnetic layer. The first antiferromagnetic layer and the second antiferromagnetic layer comprise different materials. The method further includes forming a ferromagnetic layer above the first antiferromagnetic layer and the second antiferromagnetic layer. The first antiferromagnetic layer and the second antiferromagnetic layer comprise the same material. The method further includes forming a synthetic antiferromagnetic structure above the first antiferromagnetic layer. The method further includes forming a ferromagnetic layer above the second antiferromagnetic layer.

[0106] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be envisaged without departing from the basic scope thereof, and the scope of the disclosure is determined by the claims that follow.

Claims

1. A sensor device comprising: A first resistor, the first resistor comprising: at least one first dual free layer sensor, i.e., a first DFL sensor, each first DFL sensor comprising a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer disposed between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield comprises a first lower soft bias, a first spacer disposed on the first lower soft bias, and a first upper soft bias disposed on the first spacer, and wherein the second SAF soft bias side shield comprises a second lower soft bias, a second spacer disposed on the second lower soft bias, and a second upper soft bias disposed on the second spacer; and at least one first magnetic structure, wherein each first magnetic structure comprises: a first antiferromagnetic (AFM) layer, namely a first AFM layer; and a synthetic antiferromagnetic (SAF) structure disposed above the first AFM layer, wherein the at least one first DFL sensor is linearly aligned with the SAF structure when viewed in cross-section; and a second resistor, the second resistor comprising: at least one second DFL sensor; and At least one second magnetic structure.

2. The sensor device according to claim 1, wherein the SAF structure comprises: a first ferromagnetic layer; a spacer layer disposed above the first ferromagnetic layer; and A second ferromagnetic layer is disposed over the spacer layer. 3 . The sensor device of claim 2 , wherein the at least one first DFL sensor is linearly aligned with the second ferromagnetic layer.

4. The sensor device of claim 1 , wherein the at least one second magnetic structure comprises: Second AFM layer; and A ferromagnetic layer is disposed above the second AFM layer. 5 . The sensor device of claim 4 , wherein the at least one second DFL sensor is linearly aligned with the ferromagnetic layer when viewed in cross-section. 6 . The sensor device of claim 1 , wherein the at least one first DFL sensor is a plurality of first DFL sensors, wherein the at least one first magnetic structure is a plurality of first magnetic structures, and wherein the number of the plurality of first DFL sensors is greater than the number of the plurality of first magnetic structures. 7 . The sensor device of claim 6 , wherein the at least one second DFL sensor is a plurality of second DFL sensors, wherein the at least one second magnetic structure is a plurality of second magnetic structures, and wherein the number of the plurality of second DFL sensors is greater than the number of the plurality of second magnetic structures.

8. The sensor device according to claim 1, further comprising: a third resistor, wherein the third resistor is the same as the first resistor; and a fourth resistor, wherein the fourth resistor is the same as the second resistor.

9. The sensor device of claim 1, wherein the sensor device is a Wheatstone bridge array.

10. The sensor device according to claim 1, wherein each second DFL sensor includes a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer arranged between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield includes a first lower soft bias, a first spacer arranged on the first lower soft bias, and a first upper soft bias arranged on the first spacer, and wherein the second SAF soft bias side shield includes a second lower soft bias, a second spacer arranged on the second lower soft bias, and a second upper soft bias arranged on the second spacer.

11. A sensor device comprising: A first resistor, the first resistor comprising: at least one first dual free layer sensor, i.e., a first DFL sensor, each first DFL sensor comprising a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer disposed between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield comprises a first lower soft bias, a first spacer disposed on the first lower soft bias, and a first upper soft bias disposed on the first spacer, and wherein the second SAF soft bias side shield comprises a second lower soft bias, a second spacer disposed on the second lower soft bias, and a second upper soft bias disposed on the second spacer; and at least one magnetic structure, wherein each magnetic structure comprises: a first permanent magnet; and a synthetic antiferromagnetic (SAF) structure disposed above the first permanent magnet, wherein the at least one first DFL sensor is linearly aligned with the SAF structure when viewed in cross-section; and a second resistor, the second resistor comprising: at least one second DFL sensor; and At least one second permanent magnet, wherein the at least one second DFL sensor is linearly aligned with the at least one second permanent magnet when viewed in cross-section. 12 . The sensor device according to claim 11 , wherein the at least one first DFL sensor is a plurality of first DFL sensors, each of the plurality of first DFL sensors being connected in series. 13 . The sensor device according to claim 11 , wherein the at least one second DFL sensor is a plurality of second DFL sensors, each of the plurality of second DFL sensors being connected in series.

14. The sensor device according to claim 11, wherein the SAF structure comprises: a first ferromagnetic layer; a spacer layer disposed above the first ferromagnetic layer; and A second ferromagnetic layer is disposed over the spacer layer, wherein the at least one first DFL sensor is linearly aligned with the second ferromagnetic layer. 15 . The sensor device of claim 11 , wherein the at least one magnetic structure is a plurality of magnetic structures, wherein the at least one second permanent magnet is a plurality of second permanent magnets, wherein the number of the plurality of magnetic structures is equal to the number of the plurality of second permanent magnets. The sensor device of claim 11 , wherein the sensor device is a Wheatstone bridge array.

17. The sensor device according to claim 11, wherein each second DFL sensor includes a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer arranged between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield includes a first lower soft bias, a first spacer arranged on the first lower soft bias, and a first upper soft bias arranged on the first spacer, and wherein the second SAF soft bias side shield includes a second lower soft bias, a second spacer arranged on the second lower soft bias, and a second upper soft bias arranged on the second spacer.

18. A sensor device comprising: at least one first resistor, the at least one first resistor comprising: at least one first dual free layer sensor, i.e., a first DFL sensor, each first DFL sensor comprising a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer disposed between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield comprises a first lower soft bias, a first spacer disposed on the first lower soft bias, and a first upper soft bias disposed on the first spacer, and wherein the second SAF soft bias side shield comprises a second lower soft bias, a second spacer disposed on the second lower soft bias, and a second upper soft bias disposed on the second spacer; and at least one first magnetic structure, wherein each first magnetic structure comprises: a first antiferromagnetic layer, ie, a first AFM layer, comprising a first material; and a first ferromagnetic layer disposed over the first AFM layer; and at least one second resistor, the at least one second resistor comprising: at least one second DFL sensor; and at least one second magnetic structure, wherein each second magnetic structure comprises: a second AFM layer comprising a second material, wherein the second material is different from the first material; and A second ferromagnetic layer is disposed over the second AFM layer.

19. The sensor device of claim 18, wherein the at least one first DFL sensor is linearly aligned with the first ferromagnetic layer when viewed in cross-section.

20. The sensor device of claim 19, wherein the at least one second DFL sensor is linearly aligned with the second ferromagnetic layer when viewed in cross-section. 21 . The sensor device of claim 18 , wherein the at least one first resistor comprises a plurality of first resistors, and wherein the at least one second resistor comprises a plurality of second resistors.

22. The sensor device of claim 18, wherein the sensor device is a Wheatstone bridge array.

23. The sensor device according to claim 18, wherein each second DFL sensor includes a first synthetic antiferromagnetic soft bias side shield, i.e., a first SAF soft bias side shield, a second SAF soft bias side shield, and a first free layer and a second free layer arranged between the first and second SAF soft bias side shields, wherein the first SAF soft bias side shield includes a first lower soft bias, a first spacer arranged on the first lower soft bias, and a first upper soft bias arranged on the first spacer, and wherein the second SAF soft bias side shield includes a second lower soft bias, a second spacer arranged on the second lower soft bias, and a second upper soft bias arranged on the second spacer.

24. A method for use with the sensor device of claim 1, 11 or 18, comprising: forming a plurality of double free layer sensors for the plurality of resistors; covering at least one first resistor of the plurality of resistors, wherein at least one second resistor of the plurality of resistors remains exposed; forming a first permanent magnet or a first antiferromagnetic layer adjacent to the dual free layer sensor of the at least one second resistor; exposing the at least one first resistor; covering the at least one second resistor; forming a second permanent magnet or a second antiferromagnetic layer adjacent to the dual free layer sensor of the at least one first resistor; exposing the at least one second resistor; as well as Perform a bridge pinning reset.

25. The method of claim 24, wherein both a first permanent magnet and a second permanent magnet are formed.

26. The method of claim 25, further comprising forming a synthetic antiferromagnetic structure over the first permanent magnet.

27. The method of claim 24, wherein both the first antiferromagnetic layer and the second antiferromagnetic layer are formed.

28. The method of claim 27, wherein the first antiferromagnetic layer and the second antiferromagnetic layer comprise different materials.

29. The method of claim 28, further comprising forming a ferromagnetic layer over the first and second antiferromagnetic layers.

30. The method of claim 27, wherein the first antiferromagnetic layer and the second antiferromagnetic layer comprise the same material.

31. The method of claim 30, further comprising forming a synthetic antiferromagnetic structure over the first antiferromagnetic layer.

32. The method of claim 31, further comprising forming a ferromagnetic layer over the second antiferromagnetic layer.

Images