Magnetic sensor and method for manufacturing the same

Abstract

To provide a magnetic sensor and a method for manufacturing the magnetic sensor with which it is possible to improve the sensitivity of detecting a magnetic field.SOLUTION: A sensor unit 12 comprises a magnetism detection layer 21 which is provided so that the direction of magnetization is changeable, a barrier layer 22 that includes a nonmagnetic substance and that is disposed on one surface side of the magnetism detection layer 21, and a reference layer 23 the magnetization direction of which is fixed and which is disposed on the side of the barrier layer 22 that is reverse from the magnetism detection layer 21. A magnetism convergence layer 13 is formed from the same material as the magnetism detection layer 21 and is disposed to the side of the magnetism detection layer 21 by being spaced apart from the side face of the magnetism detection layer 21. After a layer constituting the magnetism detection layer 21 and the magnetism convergence layer 13 is formed, a groove 15 is formed that penetrate the layer in the thickness direction, thereby separating between the magnetism detection layer 21 and the magnetism convergence layer 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic sensor and a method for manufacturing the magnetic sensor. [Background technology]

[0002] Conventionally, magnetic sensors utilizing the magnetoresistance effect include, for example, MR sensors (magnetoresistive sensors) that utilize the TMR effect of a tunnel magnetoresistance (TMR) element. In this magnetic sensor, an element for detecting a magnetic field has a magnetic detection layer whose magnetization direction is variable, a barrier layer containing a nonmagnetic material and disposed on one surface side of the magnetic detection layer, and a reference layer whose magnetization direction is fixed and disposed on the surface of the barrier layer opposite to the magnetic detection layer (see, for example, Patent Document 1).

[0003] Furthermore, in order to improve the magnetic flux collection efficiency and increase the sensitivity of detecting a magnetic field, magnetic sensors equipped with magnetic flux concentrators near the element are widely used. For example, as shown in Fig. 5, a magnetic sensor equipped with magnetic flux concentrators has an interlayer insulating film provided so as to cover the entire side and top surfaces of the element to insulate the element formed on a substrate such as a silicon wafer, and a pair of magnetic flux concentrators provided on a protective layer so as to sandwich the element (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-52050 [Patent Document 2] Japanese Patent Application Publication No. 2018-194534 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional magnetic sensor having a magnetic concentrator such as that shown in Fig. 5 or Patent Document 2, it is necessary to control the positional relationship between the element and the magnetic concentrator with high precision in order to improve the sensitivity of detecting a magnetic field. However, because each layer of the element and the magnetic concentrator are formed separately, variations in the accuracy of masking, patterning, etc. in the manufacturing process can cause the position of the magnetic concentrator to shift relative to the element, which poses a problem in that the sensitivity of detecting a magnetic field cannot be improved as expected.

[0006] The present invention has been made in light of the above-mentioned problems, and has an object to provide a magnetic sensor and a method for manufacturing the magnetic sensor that can improve the detection sensitivity of a magnetic field. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the magnetic sensor according to the present invention is characterized by having a sensor section including a magnetic detection layer whose magnetization direction is variable, a barrier layer containing a non-magnetic material and arranged on one surface side of the magnetic detection layer, and a reference layer whose magnetization direction is fixed and arranged on the surface of the barrier layer opposite the magnetic detection layer, and a magnetic converging layer made of the same material as the magnetic detection layer and arranged on the side of the magnetic detection layer with a gap between it and the side of the magnetic detection layer.

[0008] The method for manufacturing a magnetic sensor according to the present invention is a method for manufacturing a magnetic sensor for manufacturing a magnetic sensor according to the present invention, and is characterized in that after depositing layers constituting the magnetic detection layer and the magnetic convergence layer, a groove is formed that penetrates the layer in the thickness direction, thereby dividing the layer into the magnetic detection layer and the magnetic convergence layer.

[0009] The method for manufacturing a magnetic sensor according to the present invention can suitably manufacture the magnetic sensor according to the present invention. The method for manufacturing a magnetic sensor according to the present invention can form a magnetic detection layer and a magnetic converging layer by dividing a deposited layer by forming a groove penetrating the layer in the thickness direction. Because the magnetic detection layer and the magnetic converging layer can be formed simultaneously by simply forming the groove, the positional accuracy of the magnetic converging layer relative to the magnetic detection layer can be improved. Furthermore, the distance between the magnetic detection layer and the magnetic converging layer can be easily adjusted by adjusting the width of the groove. Thus, the magnetic sensor and the method for manufacturing a magnetic sensor according to the present invention can improve the positional accuracy of the magnetic converging layer relative to a sensor section including the magnetic detection layer, thereby improving magnetic field detection sensitivity.

[0010] In the magnetic sensor and the method for manufacturing the magnetic sensor according to the present invention, the surfaces of the magnetic detection layer and the magnetic concentrating layer are located on the same plane, so that, for example, when processing the sensor portion by etching or the like, the processing accuracy can be improved by monitoring the position of the surface of the magnetic concentrating layer. In particular, when etching the sensor portion through the barrier layer to the surface of the magnetic detection layer, etching can be stopped at the same height as the surface of the magnetic concentrating layer, and high-precision processing is possible even when the barrier layer is very thin, on the order of several nanometers.

[0011] In the magnetic sensor and method for manufacturing the magnetic sensor according to the present invention, the magnetic detection layer, reference layer, and magnetic flux concentrating layer preferably contain a ferromagnetic material. The barrier layer preferably comprises an insulating non-magnetic material. In the magnetic sensor and method for manufacturing the magnetic sensor according to the present invention, other layers may be provided on the surface of the sensor portion facing the magnetic detection layer and the surface facing the reference layer. Other layers may be inserted between the magnetic detection layer and the barrier layer, and between the barrier layer and the reference layer. In the method for manufacturing the magnetic sensor according to the present invention, the barrier layer and the reference layer may be formed before forming the groove separating the magnetic detection layer and the magnetic flux concentrating layer, or the barrier layer and the reference layer may be formed after forming the groove. In addition, the magnetic sensor according to the present invention may be any type of sensor portion, such as a TMR sensor, an AMR sensor, a GMR sensor, an MI sensor, or a fluxgate sensor.

[0012] In the magnetic sensor according to the present invention, the magnetic concentrating layers preferably comprise a pair and are arranged to sandwich the magnetic sensing layer from the sides. In the method for manufacturing the magnetic sensor according to the present invention, the grooves are preferably formed on both sides of the magnetic sensing layer, and a pair of magnetic concentrating layers are preferably formed to sandwich the magnetic sensing layer from the sides. In these cases, the magnetic collection efficiency can be further improved, and the magnetic field detection sensitivity can be further improved. Furthermore, during manufacturing, the magnetic concentrating layers can be efficiently arranged on a substrate such as a silicon wafer, thereby improving manufacturing efficiency.

[0013] In the magnetic sensor according to the present invention, the magnetic detection layer is preferably electrically insulated from the magnetic concentrating layer. In the method for manufacturing the magnetic sensor according to the present invention, an insulating film is preferably provided in the groove formed between the magnetic detection layer and the magnetic concentrating layer. In these cases, noise can be blocked, thereby improving the detection sensitivity of the magnetic field.

[0014] The magnetic sensor according to the present invention preferably includes a substrate having the sensor unit and the magnetic concentrating layer formed on one surface thereof, and the sensor unit is formed on the substrate so that the magnetic detection layer faces the substrate. The method for manufacturing the magnetic sensor according to the present invention preferably includes forming the magnetic detection layer and the magnetic concentrating layer on one surface of the substrate, and then forming the barrier layer and the reference layer on the surface of the magnetic detection layer opposite the substrate. In these cases, it is easy to form the magnetic concentrating layer.

[0015] The magnetic sensor according to the present invention may include a magnetic concentrator plate disposed parallel to the surface of the magnetic concentrator layer at a distance from the magnetic concentrator layer along the stacking direction from the magnetic detection layer toward the reference layer, and provided inside a range projected of the magnetic concentrator layer in the stacking direction. The method for manufacturing a magnetic sensor according to the present invention may also include forming a magnetic concentrator plate parallel to the surface of the magnetic concentrator layer at a distance from the magnetic concentrator layer along the stacking direction from the magnetic detection layer toward the reference layer, and inside a range projected of the magnetic concentrator layer in the stacking direction. In these cases, the magnetic concentrator plate can further increase the magnetic flux collection efficiency and further improve the magnetic field detection sensitivity. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a magnetic sensor and a method for manufacturing the magnetic sensor that can improve the detection sensitivity of a magnetic field. [Brief explanation of the drawings]

[0017] [Figure 1] 1A is a plan view of a magnetic sensor according to an embodiment of the present invention seen through an insulating film, and FIG. 1B is a cross-sectional view thereof. [Figure 2] 1A and 1B are a plan view and a cross-sectional view showing a modified example of the magnetic sensor according to the embodiment of the present invention, seen through an insulating film. [Figure 3] 1A shows a design pattern of a magnetic detection layer of a comparative example, and FIG. 1B shows design patterns of a magnetic detection layer and a magnetic concentrator layer of a magnetic sensor and a method of manufacturing the magnetic sensor according to an embodiment of the present invention. [Figure 4] 3(a) shows the magnetoresistance curve of the comparative example shown in FIG. 3(a), and FIG. 3(b) shows the magnetoresistance curve of the magnetic sensor according to the embodiment of the present invention shown in FIG. 3(b). [Figure 5] 1A is a plan view of a conventional magnetic sensor seen through an interlayer insulating film, and FIG. 1B is a cross-sectional view thereof. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 4 show a magnetic sensor and a method for manufacturing the magnetic sensor according to an embodiment of the present invention. As shown in FIG. 1, the magnetic sensor 10 includes a substrate 11, a sensor portion 12, a magnetic flux concentrating layer 13, and an insulating film 14.

[0019] The substrate 11 is made of a commercially available silicon wafer. The sensor section 12 is provided on one surface of the substrate 11 and includes a magnetic detection layer 21, a barrier layer 22, and a reference layer 23. The magnetic detection layer 21 is made of a ferromagnetic material and is formed on the substrate 11. The magnetic detection layer 21 is provided so that the magnetization direction can change in a direction parallel to the surface of the layer under the influence of external magnetic flux. The magnetic detection layer 21 is made of a soft magnetic material such as CoFeSiB, FeCuNbSiB, or NiFe, and has a layer thickness of approximately 10 nm to 200 nm.

[0020] The barrier layer 22 is made of an insulating non-magnetic material and is formed on the surface of the magnetic detection layer 21 opposite to the substrate 11. The barrier layer 22 is made of, for example, MgO, Mg-Al-O, AlOx, etc., and has a layer thickness of about 1 nm to 10 nm. The reference layer 23 is made of a ferromagnetic material and is formed on the surface of the barrier layer 22 opposite to the magnetic detection layer 21. The magnetization direction of the reference layer 23 is fixed in a direction parallel to the surface of the layer. The reference layer 23 is made of, for example, CoFeB, and has a layer thickness of about 2 nm to 10 nm.

[0021] The sensor unit 12 may have each layer stacked such that the reference layer 23 faces the substrate 11. The magnetic detection layer 21 and the reference layer 23 may each be composed of multiple layers, for example, multiple magnetic layers with an insertion layer sandwiched between them. In this case, it is preferable that the magnetic layers are magnetostatically coupled with each other via the insertion layer. The insertion layer is preferably made of, for example, Ru, Ta, TaB, or the like, and has a thickness of 2 nm or more. The sensor unit 12 may have other layers inserted between the magnetic detection layer 21 and the barrier layer 22, and between the barrier layer 22 and the reference layer 23.

[0022] The magnetic concentrating layer 13 is made of the same ferromagnetic material as the magnetic sensing layer 21 and has the same thickness as the magnetic sensing layer 21. The magnetic concentrating layer 13 is formed on the substrate 11 on the side of the magnetic sensing layer 21 with a gap between it and the side surface of the magnetic sensing layer 21. The magnetic concentrating layer 13 is arranged with a groove 15 between it and the magnetic sensing layer 21. In the specific example shown in FIG. 1 , the magnetic concentrating layer 13 consists of a pair and is arranged on the sides of the magnetic sensing layer 21 to sandwich the magnetic sensing layer 21.

[0023] The insulating film 14 is provided on the surfaces of the substrate 11, the sensor unit 12, and the magnetic converging layer 13 so as to cover the sensor unit 12 and the magnetic converging layer 13. The insulating film 14 is formed so as to have a flat surface. The insulating film 14 also extends between the magnetic sensing layer 21 and the magnetic converging layer 13, and electrically insulates the magnetic sensing layer 21 from the magnetic converging layer 13. The insulating film 14 may be made of any material that can insulate the sensor unit 12, such as silicon oxide, silicon nitride, or aluminum oxide.

[0024] 1 , the surfaces of barrier layer 22 and reference layer 23 have the same size and are smaller than the surface of magnetic detection layer 21. A pair of barrier layer 22 and reference layer 23 are arranged in parallel with a predetermined gap on one magnetic detection layer 21. The pair of barrier layer 22 and reference layer 23 is aligned perpendicular to the direction of alignment of magnetic detection layer 21 and the pair of magnetic concentrating layers 13.

[0025] The magnetic sensor 10 may also have another layer between the reference layer 23 and the insulating film 14 of the sensor section 12. In the specific example shown in Fig. 1, the magnetic sensor 10 is made up of a TMR sensor, but is not limited to a TMR sensor and may also be made up of, for example, an AMR sensor, a GMR sensor, an MI sensor, a fluxgate sensor, or the like.

[0026] The magnetic sensor 10 is preferably manufactured by a method for manufacturing a magnetic sensor according to an embodiment of the present invention. In the method for manufacturing a magnetic sensor according to an embodiment of the present invention, first, layers constituting the magnetic detection layer 21 and the magnetic converging layer 13 are formed on one surface of the substrate 11, and then a groove 15 is formed through the layer in the thickness direction to the substrate 11 to divide the layer into the magnetic detection layer 21 and the magnetic converging layer 13. Then, a barrier layer 22 and a reference layer 23 are formed on the magnetic detection layer 21, i.e., on the surface of the magnetic detection layer 21 opposite the substrate 11. In this manner, the sensor section 12 and the magnetic converging layer 13 are formed. Note that the groove 15 dividing the magnetic detection layer 21 and the magnetic converging layer 13 may be formed by any processing method, such as etching. Alternatively, before forming the groove 15, the barrier layer 22 and the reference layer 23 may be formed on the portion that will become the magnetic detection layer 21, and then the groove 15 may be formed to divide the layer into the magnetic detection layer 21 and the magnetic converging layer 13.

[0027] After forming the sensor section 12 and the magnetic converging layer 13, the insulating film 14 is formed on the surfaces of the substrate 11, the sensor section 12, and the magnetic converging layer 13 so as to cover the sensor section 12 and the magnetic converging layer 13. At this time, the insulating film 14 is also formed in the groove 15 formed between the magnetic detection layer 21 and the magnetic converging layer 13. In this manner, the magnetic sensor 10 can be manufactured. Note that the method for forming each layer may be any method that allows film formation, such as sputtering or vapor deposition.

[0028] The method for manufacturing the magnetic sensor according to the embodiment of the present invention can simultaneously form the magnetic detection layer 21 and the magnetic concentrating layer 13 simply by forming the grooves 15, thereby improving the positional accuracy of the magnetic concentrating layer 13 relative to the magnetic detection layer 21. Furthermore, the distance between the magnetic detection layer 21 and the magnetic concentrating layer 13 can be easily adjusted by changing the width of the grooves 15. In this way, the magnetic sensor 10 and the method for manufacturing the magnetic sensor according to the embodiment of the present invention can improve the positional accuracy of the magnetic concentrating layer 13 relative to the sensor unit 12 including the magnetic detection layer 21, thereby improving the sensitivity to detect a magnetic field.

[0029] In the magnetic sensor 10 and the method for manufacturing the magnetic sensor according to the embodiment of the present invention, the surfaces of the magnetic detection layer 21 and the magnetic concentrating layer 13 are located on the same plane, so that when processing the sensor unit 12 by etching or the like, for example, the processing can be performed while monitoring the position of the surface of the magnetic concentrating layer 13, thereby improving processing accuracy. In particular, when etching the sensor unit 12 through the barrier layer 22 to the surface of the magnetic detection layer 21, etching can be stopped at the same height as the surface of the magnetic concentrating layer 13, and high-precision processing is possible even when the barrier layer 22 is very thin, on the order of several nanometers.

[0030] In the magnetic sensor 10 and the method for manufacturing the magnetic sensor according to the embodiment of the present invention, the pair of magnetic concentrating layers 13 are arranged to sandwich the magnetic sensing layer 21 from the sides of the magnetic sensing layer 21, thereby further increasing the magnetic flux collection efficiency and further improving the magnetic field detection sensitivity. Furthermore, during manufacturing, the magnetic sensor 10 can be efficiently arranged on the substrate 11, such as a silicon wafer, thereby improving manufacturing efficiency.

[0031] Furthermore, in the magnetic sensor 10 and the method for manufacturing the magnetic sensor according to the embodiment of the present invention, the insulating film 14 is also formed in the groove 15 between the magnetic detection layer 21 and the magnetic converging layer 13, and the magnetic detection layer 21 and the magnetic converging layer 13 are electrically insulated from each other, thereby blocking noise and improving the detection sensitivity of the magnetic field.

[0032] 2, the magnetic sensor 10 may have a magnetic concentrator plate 31 disposed on the surface of the insulating film 14 opposite to the magnetic concentrator layer 13, with a gap between the magnetic concentrator plate 31 and the magnetic concentrator layer 13, and parallel to the surface of the magnetic concentrator layer 13. The magnetic concentrator plate 31 is provided inside the range of the magnetic concentrator layer 13 projected in the stacking direction from the magnetic detection layer 21 toward the reference layer 23. In this case, the magnetic concentrator plate 31 can further increase the magnetic flux collection efficiency and further improve the magnetic field detection sensitivity. [Example]

[0033] The magnetic sensor 10 shown in FIG. 1 was manufactured, and its magnetoresistance curve was measured. In the manufactured magnetic sensor 10, the magnetic sensing layer 21 and magnetic converging layer 13 were made of CoFeSiB amorphous and had a thickness of 140 nm, the barrier layer 22 was made of MgO and had a thickness of 2 nm, and the reference layer 23 was made of CoFeB and had a thickness of 3 nm. The insulating film 14 had a thickness of 200 nm from the surface of the magnetic sensing layer 21 and magnetic converging layer 13. The distance between the magnetic sensing layer 21 and the magnetic converging layer 13 was 5000 nm. As a comparative example, a sensor without a magnetic converging layer 13 was also manufactured. The design patterns of the magnetic sensing layer 21 of the manufactured comparative example and the magnetic sensing layer 21 and magnetic converging layer 13 of the magnetic sensor 10 are shown in FIGS. 3(a) and 3(b), respectively.

[0034] The magnetoresistance curves of the comparative example and magnetic sensor 10 are shown in Figures 4(a) and (b), respectively. Comparing Figures 4(a) and (b), it is confirmed that the magnetoresistance curve of magnetic sensor 10 in Figure 4(b) has a smaller anisotropy magnetic field Hk than that of the comparative example in Figure 4(a). From this result, it can be said that magnetic concentrating layer 13 reduces magnetic anisotropy and significantly increases the magnetic field detection sensitivity.

[0035] Furthermore, in the magnetic sensor 10, when the sensor portion 12 and the like are etched, the magnetic flux concentrating layer 13 is also etched at the same time, so the end point of etching can be detected using a large signal from a wide area. The end point of etching can be detected, for example, by plasma spectroscopy or secondary ion mass spectrometry. For example, the magnetic sensor 10 with the design pattern of FIG. 3(b) has an opening area 141 times larger during etching than the comparative example with the design pattern of FIG. 3(a). This allows the end point of etching to be detected with high accuracy, thereby improving the processing accuracy of the etching process. [Explanation of symbols]

[0036] 10 Magnetic Sensor 11 Circuit Board 12 Sensor section 21 Magnetic detection layer 22 Barrier Layer 23 Reference layer 13 Magnetic Concentration Layer 14 insulating film 15 groove 31 Magnetic concentrator

Claims

1. a sensor unit including a magnetic detection layer whose magnetization direction is variable, a barrier layer containing a non-magnetic material and disposed on one surface side of the magnetic detection layer, and a reference layer whose magnetization direction is fixed and disposed on the surface side of the barrier layer opposite to the magnetic detection layer; a magnetic concentrator layer made of the same material as the magnetic sensing layer and disposed laterally of the magnetic sensing layer with a gap between the magnetic concentrator layer and the side surface of the magnetic sensing layer; a magnetic concentrator plate disposed parallel to a surface of the magnetic concentrator layer along a stacking direction from the magnetic detection layer toward the reference layer, with a gap between the magnetic concentrator plate and the magnetic concentrator layer, and provided inside a range obtained by projecting the magnetic concentrator layer in the stacking direction; A magnetic sensor comprising:

2. 2. The magnetic sensor according to claim 1, wherein the magnetic flux concentrating layers are a pair and are arranged on either side of the magnetic sensing layer to sandwich the magnetic sensing layer.

3. 3. The magnetic sensor according to claim 1, wherein the magnetic detection layer is electrically insulated from the magnetic flux concentrating layer.

4. a substrate on one surface of which the sensor unit and the magnetic concentrating layer are formed; The sensor unit is formed on the substrate so that the magnetic detection layer faces the substrate.

4. The magnetic sensor according to claim 1, wherein the magnetic field is a magnetic field.

5. A method for manufacturing the magnetic sensor according to any one of claims 1 to 4, comprising the steps of: After depositing the layers constituting the magnetic detection layer and the magnetic concentrating layer, a groove is formed through the layers in the thickness direction to divide the layers into the magnetic detection layer and the magnetic concentrating layer. A method for manufacturing a magnetic sensor.

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