Magnetic sensor with magnetoresistance element and system for programming such a magnetic sensor - Patents.com

Abstract

The present disclosure relates to a magnetic sensor (10) comprising a plurality of magnetoresistive elements (1). Each magnetoresistive element comprises a ferromagnetic layer (21) having a magnetization (210) oriented above a threshold temperature. The magnetic sensor further comprises a plasmonic structure (5) illuminated by electromagnetic radiation (70), comprising a spatially periodic plasmonic array (50) of metallic structures (51). The period of the plasmonic array and the lateral dimensions of the metallic structures are adjusted to obtain plasmon resonance of the plasmonic structure for a given wavelength of the electromagnetic radiation (70). The plasmonic array is disposed in the magnetic sensor such that it heats the first ferromagnetic layer above a threshold temperature, enhancing absorption of the electromagnetic radiation by plasmon resonance. The disclosure further relates to a system comprising a sensor and an emission device (7) configured to emit electromagnetic radiation.

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor comprising a magnetoresistive element and to a system for programming such a magnetic sensor. [Background technology]

[0002] Magnetic sensors based on magnetic tunnel junction (MTJ) technology outperform GMR, AMR, and Hall effect sensors in several essential variables such as sensitivity, die size, etc. The perfect performance of TMR sensors can be achieved in a Wheatstone bridge configuration where the diagonal branches are programmed in the same direction and the diagonal branches that make up each half bridge are programmed in opposite directions. Therefore, the Wheatstone bridge configuration requires sequential programming of different sensor branches under different magnetic field directions.

[0003] Among other techniques, laser programming is an effective tool to deliver high energy densities to spots of micrometer size. Another advantage is that an entire wafer can be programmed in a few tens of minutes. All this directly impacts the cost of the final product and therefore at least partially determines its success on the market.

[0004] However, the effectiveness of laser programming strongly depends on the complete sensor layout design. A typical tunneling magnetoresistance (TMR) sensor comprises a stacked array of MTJs connected in a specific series-to-parallel ratio. Metal layers act as interconnects within the MTJ array as well as electrical leads to the periphery, thus partially or completely hiding the MTJ stacks from direct exposure to the laser beam. Metals also have low absorption in the visible and near-infrared regions, so all metal layers act as mirrors that reflect rather than absorb the laser energy. This makes the absorption of energy non-uniform over the sensor area (to a first approximation it depends on the surface density of the metal) and very inefficient.

[0005] Patent document 1 (US2011111133) discloses a method in which portions of a wafer-level fabrication can be selectively heated by forming a plasmon generating layer of a particular size, shape, orientation, and material on the fabrication, and then irradiating the fabrication with electromagnetic radiation of a wavelength and polarization that is optimally absorbed by the plasmon generating layer to generate plasmons therein. As a result, the generated plasmons generate thermal energy which is transferred to the part of the workpiece with which the plasmon generating layer has thermal contact.

[0006] US2015132503 discloses a method for forming a near-field transducer, comprising depositing a plasmonic material and laser annealing the plasmonic material. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US Patent Application Publication No. 2011 / 111133 [Patent Document 2] US Patent Application Publication No. 2015 / 132503 Summary of the Invention [Problem to be solved by the invention]

[0008] Plasmon resonance is a well-known and established effect that has been developed and occurs in metallic structures with micrometer to sub-micrometer textures (surface states), which has overcome laboratory conditions and been adopted for real-life applications, i.e., thermally assisted programming of high-coercivity recording media, absolute or selective absorbing layers for optical sensing, laser color printing on metals, etc. The resonant absorption in plasmonic structures may be tuned to the laser beam polarization and its wavelength by engineering the characteristic dimensions of the surface states, such as the size of the elements, their shapes, and their relative distances.

[0009] The present disclosure relates to a magnetic sensor including a plurality of magnetoresistive elements. Each magnetoresistive element comprises a MTJ comprising a first ferromagnetic layer having a first magnetization switchable according to an external magnetic field above a threshold temperature.

[0010] The magnetic sensor further comprises a plasmonic structure adapted to be illuminated by electromagnetic radiation. The plasmonic structure comprises a spatially periodic plasmonic array of metallic structures, the period of the plasmonic array and the lateral dimensions of the metallic structures being tailored to obtain plasmon resonance of the plasmonic structure for a given wavelength of electromagnetic radiation. The plasmonic array is disposed within the magnetic sensor to heat the first ferromagnetic layer at a threshold temperature from enhanced absorption of the electromagnetic radiation due to the plasmon resonance.

[0011] The magnetic sensor comprises an array of sensor locations, each sensor location comprising a plurality of magnetoresistive elements, and the plasmonic structure comprises a plurality of plasmonic sub-arrays, each plasmonic sub-array comprising a periodic array of metallic structures interleaved with the sensor locations.

[0012] The plasmonic structure comprises at least a first plasmonic sub-array and a second plasmonic sub-array having a different resonant response with respect to polarization and wavelength than the first plasmonic sub-array.

[0013] The present disclosure further relates to a system comprising a magnetic sensor and an electromagnetic radiation emitting device configured to emit electromagnetic radiation having a wavelength adapted to illuminate an illumination area of ​​the magnetic sensor and generate plasmon resonance of the plasmonic structure. Effect of the Invention

[0014] The magnetic sensor disclosed herein can be programmed by using electromagnetic radiation to provide efficient absorption of optical energy in the MTJ. Different metal layers can be used for absorbing optical energy, and the absorption of optical energy is also more uniform.

[0015] The invention will be better understood with the aid of the description of embodiments given by way of example and illustrated by the drawings, in which: [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of a magnetic sensor comprising multiple magnetoresistance elements and a plasmonic structure according to one embodiment. [Diagram 2] FIG. 2 illustrates a side view of an isolated magnetoresistive element according to one embodiment. [Diagram 3] FIG. 3 represents the topology of the magnetic sensor showing one MTJ on a silicon-based CMOS front-end circuit. [Figure 4] FIG. 4a shows a rectangular shaped metal structure (FIG. 4a) according to one embodiment. [Figure 4b] FIG. 4b shows a disk-shaped metal structure (FIG. 4b) according to one embodiment. [Figure 4c] FIG. 4c shows a periodic plasmonic array comprising elliptical shaped metallic structures (FIG. 4c) according to one embodiment. [Diagram 5] FIG. 5 shows a plasmonic structure located on top of a magnetoresistive element and on top of a top metal connecting layer, according to one embodiment. [Figure 6] FIG. 6 shows a top view of a magnetic sensor arrangement comprising a plasmonic structure located at the level of the upper metal connection layer according to one embodiment. [Figure 7] FIG. 7 is a diagram illustrating a plasmonic structure comprising a plasmonic array and an auxiliary plasmonic structure, according to one embodiment. [Figure 8] FIG. 8 illustrates a magnetic sensor in which the plasmonic structure comprises a first plasmonic sub-array and a second plasmonic sub-array, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Fig. 1 shows a side view of a magnetic sensor 10 comprising multiple magnetoresistance elements 1 according to one embodiment. Fig. 2 shows a side view of an isolated magnetoresistance element 1 according to one embodiment.

[0018] As shown in FIG. 2, the magnetoresistance element 1 may comprise a magnetic tunnel junction (MTJ) 2 comprising a first ferromagnetic layer 21 having a first magnetization 210 and a second ferromagnetic layer 23 having a second magnetization 230 that can be switched with respect to the first magnetization 210. A tunnel barrier layer 22 is provided between the first ferromagnetic layer 21 and the second ferromagnetic layer 23. The first magnetization 210 may be switchable according to an external magnetic field when the MTJ 2 is heated to a temperature equal to or greater than a threshold temperature, such as a blocking temperature, a Neel temperature, or another threshold temperature. The first magnetization 210 is fixed at a temperature below the threshold temperature. The threshold temperature may be greater than 150° C. or 200° C., or at least greater than the temperature of the normal use condition of the magnetoresistance element 1. Below the threshold temperature, the first magnetization 210 is fixed and its direction remains stable with respect to the temperature and the external magnetic field corresponding to the normal use condition of the magnetoresistance element 1.

[0019] The MTJ 2 may further comprise a pinning layer 24, such as an antiferromagnetic layer, adjacent to the first ferromagnetic layer 21. The pinning layer 24 pins the first magnetization 210 along a pinning direction by exchange coupling below a threshold temperature, which may correspond to a temperature close to the Néel temperature and at the same time above the blocking temperature of the antiferromagnetic material of the antiferromagnetic layer 24.

[0020] As shown in FIG. 1, the magnetoresistive element 1 may be embedded in a dielectric layer 27 .

[0021] FIG. 3 illustrates the topology of the magnetic sensor 10 showing the top surface 28, the upper metal contact layer MCT, the first current line 3, the MTJ 2, the second current line 4, and a silicon-based complementary metal oxide semiconductor (CMOS) front-end circuit 80.

[0022] The magnetoresistive element 1 may further comprise metal conductors to provide write and read functionality. In the example of Figure 3, a first current line 3 may be electrically coupled to the magnetoresistive element 1. The second current line 4 may extend substantially perpendicular (or parallel) to the first current line 3 and be magnetically coupled to the magnetoresistance element 1. The magnetoresistance element 1 may further comprise a selection transistor (not shown) electrically connected to the magnetoresistance element 1. The magnetoresistance element 1 may further comprise an upper metal connection layer MCT above the MTJ2 and a lower metal connection layer MCB below the MTJ2, connected to the MTJ2 by ​​a metal via VM. The upper metal connection layer MCT electrically connects the lower metal connection layer MCB, and the lower metal connection layer MCB may be used as a field line.

[0023] The magnetoresistance element 1 further comprises a plasmonic structure 5 configured to enhance and localize energy absorption of electromagnetic radiation 70 emitted from an electromagnetic radiation emitting device 7 .

[0024] In one embodiment, the plasmonic structure 5 comprises a spatially periodic plasmonic array 50 of metallic structures 51. As shown in Figures 4a-4c, the periodic plasmonic array 50 may comprise a spatially periodic arrangement of rectangular shaped metallic structures 51 (Figure 4a), disk shaped metallic structures 51 (Figure 4b), or elliptical shaped metallic structures 51 (Figure 4c). Other shapes of metallic structures 51 may also be contemplated.

[0025] The metal structures 51 in a plasmonic array 50 may all have substantially the same shape, although a plasmonic array 50 may also include metal structures 51 having different shapes. Principles of Plasmonic Structures

[0026] During a programming operation of the magnetic sensor 10, the first magnetization 210 is switched from an initial orientation to a programmed orientation. The programmed orientation can be any direction according to the direction of an external magnetic field. The programming operation can be performed for all magnetoresistance elements 1 in the magnetic sensor 10 or for a selected subensemble of magnetoresistance elements 1.

[0027] During a programming operation, electromagnetic radiation 70 emitted by the electromagnetic radiation emitting device 7 illuminates an illumination area 71 of the magnetic sensor 10. As shown in Fig. 1, the illumination area 71 may cover a surface area surrounding two adjacent magnetoresistance elements 1. However, the illumination area 71 may cover a surface area surrounding a single magnetoresistance element 1, a subensemble of magnetoresistance elements 1, or all magnetoresistance elements 1 within the magnetic sensor 10.

[0028] At the condition of plasmon resonance of the plasmonic structure 5 at the wavelength of the electromagnetic radiation 70, the plasmonic structure 5 provides enhanced absorption of the electromagnetic radiation 70. As a result, in the illuminated region 71, the plasmonic structure 5 provides enhanced heat generation. The enhanced heat is transferred to the selected magnetoresistance element 1 in the illuminated region 71, allowing the first ferromagnetic layer 21 of the selected magnetoresistance element 1 to be heated above a threshold temperature. Since the enhanced heating occurs only in the illuminated region 71, selective and mask-free programming of the magnetic sensor 10 is achievable.

[0029] The plasmonic structure 5 can further provide uniform heat generation within the illumination area 71.

[0030] The radiation emitting device 7 may comprise a laser emitting device which directs a focused laser beam 70 onto an illumination area 71 of the magnetic sensor 10 (see FIG. 1). Focusing of the laser beam 70 may be achieved by using a near-field optical element such as a solid immersion lens. Arrangement of an array of metal structures

[0031] The arrangement of the metallic structures 51 in the periodic plasmonic array 50 can be optimized to obtain plasmon resonance at the wavelength of the electromagnetic radiation 70. This can be achieved by varying the lateral dimension d of the metallic structures 51 and the periodic arrangement of the metallic structures 51. The plasmonic array 50 may comprise a two-dimensional lattice with a substantially equal distance L between two adjacent metallic structures 51. The plasmonic array 50 may comprise any one of a square lattice (as shown in FIG. 4), a rectangular lattice, a hexagonal lattice, or a diamond lattice, or any other type of lattice of metallic structures 51.

[0032] For example, the distance L between two adjacent metallic structures 51 in the periodic plasmonic array 50 should be less than or equal to the wavelength of the electromagnetic radiation 70 (the sub-wavelength plasmonic array 50). The lateral dimension d of the metallic structure 51 must be smaller than the wavelength of the electromagnetic radiation 70 (sub-wavelength metallic structure 51).

[0033] Under resonance conditions, ie when the wavelength of the electromagnetic radiation 70 coincides with the plasmon resonance of the metallic structure 51, the power absorption in the metallic structure 51 can be increased by at least one order of magnitude. Under resonance conditions, the heat generation in the illuminated region 71 can reach up to nine times the heat generation without plasmon resonance. Location of plasmonic structures

[0034] The plasmonic structure 5 should be positioned in the magnetic sensor 10 so that heat absorbed by the plasmonic structure 5 in the irradiated region 71 can be transferred to the MTJ 2, thereby making the reference magnetization at the high temperature threshold. Here, close to the magnetoresistance element 1 may comprise a distance of 50 nm to 5000 nm.

[0035] The plasmonic structure 5 should further be positioned within the magnetic sensor 10 such that it is easily illuminated by the radiation-emitting device 7. Ideally, the plasmonic structure 5 should not be masked from the radiation-emitting device 7 by metal connecting layers or other structures that do not participate in the plasmon resonance.

[0036] In one embodiment, the plasmonic structure 5 is provided between the top surface 28 of the magnetic sensor 10 and at least one of the MTJs 2.

[0037] Figure 5 shows a partial view of the topological representation of Figure 4. In the example shown in Figure 5, the plasmonic structure 5 is provided between the top surface 28 and the upper metal contact layer MCT. The plasmonic structure 5 may be embedded in a dielectric layer 27. The dielectric layer 27 should be optically transparent to electromagnetic radiation 70. The dielectric layer 27 is made of silicon dioxide SiO 2 , silicon nitride, SiN, or other dielectric materials.

[0038] An advantage of the configuration of FIG. 5, in which the plasmonic structure 5 is disposed above the magnetoresistive element, is that the plasmonic structure 5 is not shadowed by a higher level metal layer.

[0039] The lateral dimensions of the metal structure 51 may correspond approximately to the ratio between the wavelength of the electromagnetic radiation 70 and the refractive index of the dielectric layer 27, ie the wavelength λ of the electromagnetic radiation 70 in the dielectric layer 27, or a fraction of this ratio.

[0040] For example, if the dielectric layer 27 comprises silicon nitride (SiN), the incident wavelength λ of the emitted electromagnetic radiation 70 at 1064 nm i decreases in the dielectric layer 27, and SiNλ i The wave in is the incident wave λ i is the refractive index of SiN i Therefore, the lateral dimension of the metal structure 50 is equal to SiNλ divided by 1.885=564 nm. i The spacing L between two adjacent metal structures 50 may be substantially equal to a half wavelength, i.e., SiNλ i The wavelength may be substantially equal to half a wavelength of the

[0041] In another embodiment, the plasmonic structure 5 is arranged at the level of the top metal contact layer MCT (at the same height in the sensor height direction).

[0042] 6 shows a top view of a configuration of a magnetic sensor 10 comprising a plasmonic structure 5 located at the level of the upper metal connection layer MCT, i.e. in the plane of the upper metal connection layer MCT. The magnetic sensor 10 comprises an array of sensor branches 40, each sensor branch 40 comprising a plurality of interconnected magnetoresistance elements 1. The plasmonic structure 5 may comprise a plurality of plasmonic sub-arrays 52, each plasmonic sub-array 52 comprising a periodic array of metallic structures 51. Each plasmonic sub-array 52 may be interleaved with a sensor branch 40.

[0043] In one embodiment, the plasmonic subarray 52 is sized to have a width W of the sensor region 40. S Twice the width W P In other words, the surface area occupied by the plasmonic sub-array 52 corresponds to the surface area of ​​the two sensor sub-arrays 40. The plasmon resonance of each plasmonic sub-array 52 depends on the periodicity of the array of metallic structures 51 and the lateral dimension d of the metallic structures 51.

[0044] In one example, the width of the plasmonic sub-array 52 is about 5.0 μm and the lateral dimension d of the metallic structure 51 is about 0.4 μm. However, other arrangements of the plasmonic sub-array 52 relative to the sensor region 40 are contemplated.

[0045] Other arrangements of the plasmonic structures 5 are possible, for example the plasmonic structures 5 can be arranged at any one (in a plane) level of the metal layer, such as at the level of the second current lines 4 or the metal connection layer MCB. Such an arrangement may comprise a number of plasmonic sub-arrays 52 interleaved with the sensor branches 40, as described above.

[0046] A configuration of the magnetic sensor 10 in which the plasmonic structures 5 are provided in the plane of the top metal connection layer MCT, the bottom metal connection layer MCB, or other metal connection layers or metal vias may result in a low density of the magnetoresistance elements 1 per area in the magnetic sensor 10. In fact, the available surface area of ​​the magnetic sensor 10 must be shared between the surface area occupied by the plasmonic structures 5 and the surface area occupied by the magnetoresistance elements 1.

[0047] The resonance frequencies were modeled for plasmonic structures 5 located at the level of the upper metal connection layer MCT and arranged according to the configuration shown in Fig. 6. The resonance frequencies were modeled for a spatially periodic arrangement of metal structures 51 having a rectangular shape (see Fig. 4a), a disk shape (see Fig. 4b). The resonance frequencies were modeled for multiple lateral dimensions d of the metal structures 51 and multiple distances L between two adjacent metal structures 51.

[0048] Table 1 reports the plasmonic resonance values ​​obtained from the modeling of plasmonic structures 5 located at the level of the upper metal connection layer MCT. The modeling was performed for plasmonic arrays 50 with rectangular (sq) and disk-shaped (circ) metal structures 51 spaced apart by a distance L between 500 nm and 700 nm and with lateral dimensions d between 200 nm and 300 nm. [Table 1]

[0049] Table 2 reports the plasmonic resonance values ​​obtained from modeling of plasmonic structures 5 located at the level of the bottom metal connection layer MCB. The modeling was performed for plasmonic arrays 50 with rectangular (sq) and disk-shaped (circ) metal structures 51 separated by a distance L between 500 nm and 880 nm and with lateral dimensions d between 200 nm and 400 nm.

[0050] Simulations show that resonant absorption can occur in both the metal structure 51 and the metal layer below it, for example, in both the metal structure 51 and the upper metal contact layer MCT, or in both the metal structure 51 and the lower metal contact layer MCB.

[0051] Depending on the configuration and position of the plasmonic structure 5 within the magnetic sensor 10, the refractive index of the electromagnetic radiation 70 emitted by the emission device 7 may be reduced to less than 20%. The frequency corresponds to a laser wavelength of 1064 nm. [Table 2]

[0052] Other configurations of the plasmonic structures 5 may be considered. For example, the plasmonic structures 5 may be arranged at the level of the upper metal contact layer MCT, and the metal structures 51 may be separated by a distance L between 400 nm and 700 nm and may have a lateral dimension d between 200 nm and 300 nm.

[0053] In another configuration, the plasmonic structures 5 may be located at the level of the bottom metal contact layer MCB, and the metal structures 51 may be separated by a distance L between 500 nm and 900 nm and may have a lateral dimension d between 200 nm and 400 nm.

[0054] In yet another configuration, the plasmonic structure 5 is located at the level of the second current line 4 below the MTJ2, and the metal structures 51 may be separated by a distance L between 450 nm and 850 nm and have a lateral dimension d between 200 nm and 450 nm.

[0055] For plasmonic arrays 50 with rectangular and disk-shaped metallic structures 51 , simulations showed that the resonant frequency is determined by the lateral dimension d and the distance L between adjacent metallic structures 51 .

[0056] In yet another configuration, the metallic structure 51 may be elliptical in shape ( FIG. 4 c). For a plasmonic structure 5 comprising an elliptical metallic structure 51, simulations have shown that the resonant frequency is determined by the major (a) and minor (b) axes of the elliptical metallic structure 51. The elliptical metallic structure 51 may have a major axis between 230 nm and 470 nm and a minor axis between 470 nm and 230 nm, respectively.

[0057] Other configurations of the plasmonic structure 5 may be considered. In the embodiment shown in FIG. 7, the plasmonic structure 5 comprises a plasmonic array 50 and an auxiliary plasmonic structure 53 configured to tune the absorption of electromagnetic radiation energy. In other words, under resonance conditions, the plasmonic array 50 and the auxiliary plasmonic structure 53 resonate simultaneously due to the electromagnetic coupling between them. The auxiliary plasmonic structure 53 may provide an amplification of power absorption by a factor of three or more. The plasmonic array 50 may be provided between the auxiliary plasmonic structure 53 and the electromagnetic radiation emitting device 7. The auxiliary plasmonic structure 55 may comprise a spatially periodic arrangement of metal structures or a continuous metal layer.

[0058] In yet another embodiment shown in Fig. 8, the plasmonic structure 5 comprises at least a first plasmonic sub-array 52a and a second plasmonic sub-array 52b. The first plasmonic sub-array 52a is configured to transfer heat generated by plasmonic resonance to a first subset of magnetoresistance elements 1 of the magnetic sensor 10, and the second plasmonic sub-array 52b is configured to transfer heat generated by plasmonic resonance to a second subset of magnetoresistance elements 1. In Fig. 8, the first subset is represented as two sensor branches 40 comprising magnetoresistance elements 1, and the second subset comprises one such branch 40. Other configurations of subsets, as well as the number of plasmonic sub-arrays and subsets, should also be considered.

[0059] The plasmonic sub-arrays 52a, 52b can be located on top of the magnetoresistive element 1 and on top of the top metal contact layer MCT.

[0060] At least the first plasmonic sub-array 52a has a different resonant response with respect to the polarization or wavelength λ of the electromagnetic radiation 70 than the second plasmonic sub-array 52b.

[0061] At least one of the wavelength and polarization of the electromagnetic radiation 70 emitted by the electromagnetic radiation emitting device 7 can be tuned to correspond to a resonant condition of one of the first plasmonic sub-array 52a or the second plasmonic sub-array 52b such that plasmon resonance occurs only for one of the first or second plasmonic sub-arrays 52a, 52b. Thus, only the sensor branch 40 corresponding to the resonating plasmonic sub-array 52a or 52b is heated at the high temperature threshold.

[0062] This latter configuration allows selective programming of sensor regions 40 when the entire magnetic sensor 10 is fully illuminated, without the need for a mask for windowing the illumination beam. Positioning constraints are also reduced since an electromagnetic radiation emitting device 7 (such as a laser) can be moved over the upper surface 28 of the magnetic sensor 10 so as to selectively heat one or several magnetoresistance elements 1 surrounded by the irradiation area (71). The present application provides, for example, the following aspects: [Point 1] A magnetic sensor (10) comprising a plurality of magnetoresistance elements (1), Each of the magnetoresistance elements (1) comprises an MTJ (2) including a first ferromagnetic layer (21) having a first magnetization (210) that is fixed below a threshold temperature and free above a threshold temperature such that the first magnetization (210) is switchable when the first ferromagnetic layer (21) is at a high temperature threshold temperature during a programming operation; The magnetic sensor (10) further comprises a plasmonic structure (5) adapted to be illuminated by electromagnetic radiation (70); The plasmonic structure (5) comprises a spatially periodic plasmonic array (50) of metallic structures (51); The period of the plasmonic array (50) and the lateral dimension (d) of the metallic structure (51) are adjusted to obtain a plasmon resonance of the plasmonic structure (5) for a given wavelength (λ) of the electromagnetic radiation (70), wherein: the plasmonic array (50) is disposed within the magnetic sensor (10) to heat the first ferromagnetic layer (21) above the threshold temperature from enhanced absorption of the electromagnetic radiation (70) due to plasmon resonance. A magnetic sensor (10) including a plurality of magnetoresistance elements (1), The magnetic sensor (10) comprises an array of a plurality of sensor locations (40), each sensor location comprising a plurality of magnetoresistance elements (1); The plasmonic structure (5) comprises a plurality of plasmonic sub-arrays (52), each of which comprises a periodic array of metal structures (51) interleaved with the sensor sub-arrays (40). A magnetic sensor comprising: [Point 2] The magnetic sensor of aspect 1, wherein the period of the plasmonic array (50) and the lateral dimension (d) of the metal structure (51) are adjusted to obtain plasmon resonance of the plasmonic structure (5) for a given wave (λ) of the electromagnetic radiation (70). [Point 3] the MTJ (2) is between a front-end circuit (80) and a top surface (28) of the magnetic sensor (10); and The plasmonic structure (5) is disposed between the top surface (28) and the front-end circuit (80). A magnetic sensor according to aspect 1 or 2. [Point 4] The magnetoresistive element (1) comprises a top metal contact layer (MCT) between the MTJ (2) and the top surface (28); and A magnetic sensor according to aspect 3, wherein the plasmonic structure (5) is provided in the plane of the top metal contact layer (MCT). [Point 5] The magnetoresistive element (1) includes a lower metal contact layer (MCB) between the MTJ (2) and the front-end circuit (80); The magnetic sensor according to aspect 3, wherein the plasmonic structure (5) is provided in the plane of the bottom metal contact layer (MCB). [Point 6] The plasmonic structure (5) is embedded in a dielectric layer (27); A magnetic sensor as described in any one of aspects 1 to 5, wherein the period of the plasmonic array (50) and the lateral dimension (d) of the metal structure (51) are adjusted to obtain plasmon resonance of the plasmonic structure (5) for a given ratio between the wavelength (λ) of the electromagnetic radiation (70) and the refractive index of the dielectric layer (27). [Point 7] 7. The magnetic sensor according to any one of the preceding aspects, wherein the plasmonic structure (5) comprises at least a first plasmonic sub-array (52a) and a second plasmonic sub-array (52b) having a different resonant response with respect to polarization or wavelength (λ) of the electromagnetic radiation (70) than the first plasmonic sub-array (52a). [Point 8] A magnetic sensor according to any one of the preceding aspects, wherein the plasmonic structure (5) further comprises an auxiliary plasmonic structure (53) configured to adjust absorption of the electromagnetic radiation (70). [Point 9] A magnetic sensor according to aspect 8, wherein the auxiliary plasmonic structure (53) comprises a spatially periodic arrangement of metal structures or a continuous metal layer. [Point 10] A magnetic sensor according to any one of aspects 3, 8 and 9, wherein the auxiliary plasmonic structure (53) and the plasmonic array (50) are between the magnetoresistance element (1) and the upper surface (28). [Point 11] A magnetic sensor according to any one of Aspects 1 to 10; and an electromagnetic radiation emitting device (7) configured to emit electromagnetic radiation (70) having a wavelength (λ) adapted to illuminate an illumination area (71) of the magnetic sensor (10) and generate plasmon resonance of the plasmonic structure (5). [Point 12] The system of aspect 11, wherein the illumination area (71) surrounds at least one magnetoresistance element (1). [Point 13] The system according to aspect 11 or 12, wherein the electromagnetic radiation emitting device (7) comprises a laser emitting device which directs focused electromagnetic radiation (70) towards the illumination area (71) of the magnetic sensor (10). [Point 14] The system described in any one of aspects 11 to 13, wherein the electromagnetic radiation emitting device (7) is movable over the surface (28) of the magnetic sensor (10) so as to selectively heat the one or more magnetoresistance elements (1) surrounded by the irradiation area (71). [Point 15] the plasmonic structure (5) comprises at least a first plasmonic sub-array (52a) and a second plasmonic sub-array (52b) having a different resonant response with respect to polarization or wavelength (λ) of the electromagnetic radiation (70) than the first plasmonic sub-array (52a); and 15. The system of any one of aspects 11 to 14, wherein at least one of the wavelength and the polarization of the electromagnetic radiation (70) is tunable to correspond to a resonance condition of one of the first plasmonic sub-array or the second plasmonic sub-array (52a, 52b). [Point 16] The system described in any one of aspects 1 to 15, wherein the plasmonic array (50) has a two-dimensional lattice in which the distance (L) between two adjacent metal structures (51) is substantially equal, and the plasmonic array (50) has any one of a square lattice, a rectangular lattice, a hexagonal lattice, or a rhombic lattice. [Explanation of symbols]

[0063] 1. Magnetoresistance effect element 10 MRAM-based sensors 2. Magnetic tunnel junction 21 Reference layer 210 Reference magnetization 22 Tunnel Barrier Layer 23 Sense Layer 230 Sense Magnetization 24 Pinning Layer 27 Dielectric Layer 28 Top 3 1st current line 4 2nd current line 40 Sensa Branch 5 Plasmonic Structures 50 Plasmonic Array 51 Metal structure 52 Plasmonic Sub-Array 53 Auxiliary Plasmonic Structures 7. Electromagnetic Radiation Emitting Devices 70 Electromagnetic Radiation 71 Irradiation area 80 Front-end circuit λ wavelength d Horizontal dimension L distance MCB bottom metal connection layer, field lines MCT top metal connection layer VM Metal Via W P Width of the plasmonic substructure W S Sensor base width

Claims

1. A magnetic sensor including a plurality of magnetoresistance elements, each said magnetoresistive element comprises a MTJ comprising a first ferromagnetic layer having a first magnetization that is fixed below a threshold temperature and free above a threshold temperature such that the first magnetization is switchable when the first ferromagnetic layer is at a high temperature threshold temperature during a programming operation; the magnetic sensor further comprising a plasmonic structure adapted to be illuminated by electromagnetic radiation; the plasmonic structure comprises a spatially periodic plasmonic array of metallic structures; a period of the plasmonic array and a lateral dimension of the metallic structure are adjusted to obtain a plasmon resonance of the plasmonic structure for a given wave of the electromagnetic radiation, wherein: the plasmonic array is disposed within the magnetic sensor to heat the first ferromagnetic layer above the threshold temperature from enhanced absorption of the electromagnetic radiation due to plasmon resonance. In a magnetic sensor having a plurality of magnetoresistance elements, the magnetic sensor comprises an array of sensor locations, each sensor location comprising a plurality of magnetoresistive elements; the plasmonic structure comprises a plurality of plasmonic sub-arrays, each plasmonic sub-array comprising a periodic array of metallic structures interleaved with the sensor sub-arrays, the plasmonic structure comprising at least a first plasmonic sub-array and a second plasmonic sub-array having a different resonant response with respect to polarization or wavelength of the electromagnetic radiation than the first plasmonic sub-array.

2. The magnetic sensor of claim 1 , wherein the period of the plasmonic array and the lateral dimensions of the metallic structures are tailored to obtain plasmon resonance of the plasmonic structures for a given wave of the electromagnetic radiation.

3. the MTJ is between a front-end circuit of the magnetic sensor and a top surface; and The plasmonic structure is disposed between the top surface and the front-end circuitry. The magnetic sensor according to claim 1 .

4. the magnetoresistive element comprises a top metal contact layer between the MTJ and the top surface; and The magnetic sensor of claim 3 , wherein the plasmonic structure is disposed in the plane of the top metal interconnect layer.

5. the magnetoresistive element includes a lower metal connection layer between the MTJ and the front-end circuitry; The magnetic sensor of claim 3 , wherein the plasmonic structure is disposed in the plane of the bottom metal interconnect layer.

6. the plasmonic structure is embedded in a dielectric layer; 2. The magnetic sensor of claim 1, wherein a period of the plasmonic array and a lateral dimension of the metallic structure are tailored to obtain plasmon resonance of the plasmonic structure for a given ratio of a wavelength of the electromagnetic radiation and a refractive index of the dielectric layer.

7. The magnetic sensor of claim 1 , wherein the plasmonic structure further comprises an auxiliary plasmonic structure configured to tune the absorption of the electromagnetic radiation.

8. The magnetic sensor of claim 7 , wherein the auxiliary plasmonic structure comprises a spatially periodic arrangement of metallic structures or a continuous metallic layer.

9. The MTJ is between a front-end circuit and an upper surface of the magnetic sensor, and the plasmonic structure is provided between the upper surface and the front-end circuit, The magnetic sensor of claim 7 , wherein the auxiliary plasmonic structure and the plasmonic array are between the magnetoresistive element and the top surface.

10. The magnetic sensor according to claim 1 ; and an electromagnetic radiation emitting device configured to emit electromagnetic radiation having a wavelength adapted to illuminate an illumination area of ​​the magnetic sensor and generate plasmon resonance of the plasmonic structure.

11. The system of claim 10 , wherein the illuminated region surrounds at least one magnetoresistive element.

12. The system of claim 10 , wherein the electromagnetic radiation emitting device comprises a laser emitting device that directs focused electromagnetic radiation toward the illumination area of ​​the magnetic sensor.

13. The system of claim 10 , wherein the electromagnetic radiation emitting device is movable over a top surface of the magnetic sensor to selectively heat the one or more magnetoresistance elements surrounded by the illumination area.

14. the plasmonic structure comprises at least a first plasmonic sub-array and a second plasmonic sub-array having a different resonant response with respect to polarization or wavelength of the electromagnetic radiation than the first plasmonic sub-array; and 11. The system of claim 10, wherein at least one of the wavelength and the polarization of the electromagnetic radiation is tunable to correspond to a resonance condition of one of the first plasmonic sub-array or the second plasmonic sub-array.

15. 11. The system of claim 10, wherein the plasmonic array comprises a two-dimensional lattice in which a distance between two adjacent metallic structures is substantially equal, and the plasmonic array comprises any one of a square lattice, a rectangular lattice, a hexagonal lattice, or a diamond lattice.

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