JP2020161604A - Magnetic sensor and manufacturing method thereof - Google Patents

Abstract

To provide a magnetic sensor capable of improving detection sensitivity.SOLUTION: The magnetic sensor includes a magnetization intensity fixed-bed 60 where the magnetization direction is fixed, a magnetic field detection layer 80 where the magnetization direction changes by an external magnetic field, a tunnel layer 70 placed between the magnetization intensity fixed-bed 60 and the magnetic field detection layer 70, and having a value of resistance changing by the angle formed between the magnetization direction of the magnetization intensity fixed-bed 60 and the magnetization direction of the magnetic field detection layer 80, and a board 10 on which the magnetization intensity fixed-bed 60, the tunnel layer 70 and the magnetic field detection layer 80 are placed while being laminated. On the board 10, a planarization layer 40 composed of an amorphous layer or a microcrystal layer where one face 41 on the opposite side to the board 10 side is a flat surface is placed, and the magnetization intensity fixed-bed 60, the tunnel layer 70 and the magnetic field detection layer 80 are placed on the planarization layer 40 while being laminated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic sensor that measures an external magnetic field and a method for manufacturing the same.

Conventionally, a magnetic sensor including a free layer whose magnetization direction is changed by an external magnetic field, a pin layer whose magnetization direction is fixed, and a tunnel layer arranged between the free layer and the pin layer has been proposed ( For example, see Patent Document 1).

In such a magnetic sensor, the magnetization direction of the free layer changes depending on the external magnetic field. Then, in the magnetic sensor, the resistance value of the tunnel layer changes depending on the angle formed between the magnetization direction of the free layer and the magnetization direction of the pin layer. That is, in the magnetic sensor, the resistance value of the tunnel layer changes depending on the spin state of the free layer and the spin state of the pin layer. Therefore, in the magnetic sensor, an external magnetic field is detected based on a change in the resistance value of the tunnel layer or the like.

Japanese Unexamined Patent Publication No. 2015-162515

By the way, in the above-mentioned magnetic sensor, it is known that the detection sensitivity is improved by increasing the crystallinity of the tunnel layer. For example, it is known that the detection sensitivity of a magnetic sensor is improved by increasing the crystallinity of the tunnel layer by performing a heat treatment at 350 ° C. or higher. However, in recent years, it has been desired to further improve the detection sensitivity of the magnetic sensor.

In view of the above points, an object of the present invention is to provide a magnetic sensor capable of improving the detection sensitivity and a method for manufacturing the same.

The first aspect of claim 1 for achieving the above object is a magnetic sensor in which a tunnel layer (70) is arranged between a magnetization fixing layer (60) and a magnetic field detection layer (80), and the magnetization direction is fixed. It is arranged between the magnetization fixed layer, the magnetic field detection layer whose magnetization direction changes depending on the external magnetic field, and the magnetization fixed layer and the magnetic field detection layer, and is between the magnetization direction of the magnetization fixed layer and the magnetization direction of the magnetic field detection layer. It includes a tunnel layer whose resistance value changes depending on the angle formed, and a substrate (10) on which a magnetization fixing layer, a tunnel layer, and a magnetic field detection layer are laminated and arranged. A flattening layer (40) composed of an amorphous layer or a microcrystal layer and having one surface (41) opposite to the substrate side as a flat surface is arranged on the substrate, and a magnetization fixing layer and a tunnel are arranged. The layer and the magnetic field detection layer are laminated and arranged on the flattening layer.

According to this, it is possible to improve the flatness of the tunnel layer on one surface on the substrate side and the other surface on the substrate side as compared with the case where the flattening layer is not arranged. Therefore, the detection sensitivity of the magnetic sensor can be improved.

Further, claim 6 is a method for manufacturing a magnetic sensor in which a tunnel layer (70) is arranged between a magnetization fixing layer (60) and a magnetic field detection layer (80), and a substrate (10) is prepared. The lower electrode film (30a) forming the lower electrode (30) is formed on the substrate, and the magnetization fixing film (60a) and the tunnel layer (70) forming the magnetization fixing layer are formed on the lower electrode film. A laminated film (S) formed by forming a tunnel film (70a) and a magnetic field detection film (80a) constituting a magnetic field detection layer is arranged, and an upper electrode (100) is formed on the laminated film. The upper electrode film (100a) to be formed is formed, the lower electrode, the magnetization fixing layer, the tunnel layer, the magnetic field detection layer, and the upper electrode are formed by patterning, and the tunnel layer is heat-treated. .. Then, before arranging the laminated film, the flattening film (40a) composed of the amorphous layer or the microcrystal layer is arranged on the lower electrode, and the portion arranged between the laminated film and the substrate. The surface opposite to the substrate is flattened.

According to this, since the tunnel film is arranged on the flattened portion, the flatness on one surface of the tunnel film on the substrate side and the other surface on the substrate side is improved as compared with the case where the flattening film is not arranged. Can be made to. Therefore, it is possible to improve the flatness of the tunnel layer formed by patterning the tunnel film on one surface on the substrate side and the other surface on the substrate side. Therefore, a magnetic sensor with improved detection sensitivity can be manufactured.

The reference reference numerals in parentheses attached to each component or the like indicate an example of the correspondence between the component or the like and the specific component or the like described in the embodiment described later.

It is sectional drawing of the magnetic sensor in 1st Embodiment. It is sectional drawing which shows the manufacturing process of the magnetic sensor in 1st Embodiment. It is sectional drawing which shows the manufacturing process of the magnetic sensor which follows FIG. 2A. It is sectional drawing which shows the manufacturing process of the magnetic sensor which follows FIG. 2B. It is sectional drawing which shows the manufacturing process of the magnetic sensor following FIG. 2C. It is a figure for demonstrating flatness. It is a figure which shows the relationship between the change rate of the ideal conductance of the magnetic sensor shown in FIG. 1 and the strength of an external magnetic field. It is a schematic diagram which shows the magnetization direction at the arrow VA point in FIG. It is a schematic diagram which shows the magnetization direction at the arrow VB point in FIG. It is a schematic diagram which shows the magnetization direction at the arrow VC point in FIG. It is a figure which shows the experimental result about the relationship between the change rate of conductance and the strength of an external magnetic field. It is a figure which shows the experimental result about the relationship between the usable magnetic field range and the heat treatment temperature. It is a figure which shows the relationship between the flatness at the interface of a tunnel layer, and the usable magnetic field range. It is sectional drawing of the magnetic sensor in 3rd Embodiment. It is sectional drawing of the magnetic sensor in 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, parts that are the same or equal to each other will be described with the same reference numerals.

(First Embodiment)
The first embodiment will be described with reference to the drawings. The magnetic sensor of the present embodiment is preferably mounted on a vehicle and is preferably used to form a current detection device for detecting a current or a rotation angle detection device for detecting a rotation angle. At this time, the magnetic sensor is formed and used so as to form a bridge circuit, for example.

As shown in FIG. 1, the magnetic sensor of the present embodiment has a substrate 10, an insulating film 20, a lower electrode 30, a flattening layer 40, a base layer 50, a pin layer 60, a tunnel layer 70, a free layer 80, and a protective layer. 90, the upper electrode 100 is laminated.

The substrate 10 is made of, for example, a silicon substrate or the like. The insulating film 20 is made of, for example, an oxide film or the like. The lower electrode 30 is made of Cu (copper) or an alloy containing Cu as a main component.

The flattening layer 40 is composed of an amorphous layer or a microcrystal layer of a non-magnetic layer, and is formed in a thin film shape on one surface 31 of the lower electrode 30 opposite to the substrate 10 side. In the present embodiment, the flattening layer 40 is, for example, Ta-B (boron tantalum mixture), Ta (tantalum), TaN (tantalum nitride), TaO ₂ (tantalum oxide), W (tungsten), Mo-B (boron). Molybdenum mixture), Nb-B (boron niobium mixture), WB (boron-tungsten mixture) and the like. Further, as the flattening layer 40, as will be described in detail later, one surface 41a on the side opposite to the substrate 10 side is a flat surface. In the present embodiment, one surface 41a of the flattening layer 40 is a flat surface that has been flattened. The microcrystal layer is a layer having an amorphous layer in the crystal layer, and is a layer in which a crystalline portion and an amorphous portion are mixed.

The base layer 50 is composed of Ta, Ru (ruthenium), etc., and is formed in a thin film shape on the lower electrode 30. In this embodiment, Ta and Ru are laminated in this order from the substrate 10 side. The base layer 50 is provided to improve the crystallinity of the pin layer 60 and the like.

The pin layer 60 is a layer in which the magnetization direction is fixed in a predetermined direction. In the present embodiment, the pin layer 60 is configured by laminating an antiferromagnetic layer 61, a first ferromagnetic layer 62, a non-magnetic layer 63, and a second ferromagnetic layer 64.

The antiferromagnetic layer 61 is made of a material containing Mn (manganese) and is formed in a thin film on the base layer 50. In the present embodiment, the antiferromagnetic layer 61 is composed of IrMn (iridium manganese), PtMn (platinum manganese), and the like. The magnetization direction of the pin layer 60 is fixed in a predetermined direction by fixing the magnetization direction of the antiferromagnetic layer 61 in a predetermined direction. In the present embodiment, the magnetization direction of the antiferromagnetic layer 61 is parallel to the plane direction of the antiferromagnetic layer 61 as shown by the arrow A in FIG.

It should be noted that IrMn and PtMn, which are materials containing Mn, are materials having a high nail point. Therefore, by constructing the antiferromagnetic layer 61 using these materials, the magnetization direction of the pin layer 60 can be stably maintained up to a temperature sufficiently higher than the operating temperature. Further, the plane direction of the antiferromagnetic layer 61 is, in other words, the plane direction of the substrate 10. Then, in the present embodiment, the pin layer 60 corresponds to the magnetization fixing layer.

The first ferromagnetic layer 62 is made of an alloy such as a CoFe film containing Co (cobalt) and Fe (iron), and is formed in a thin film on the antiferromagnetic layer 61. The non-magnetic layer 63 is made of Ru or the like, and is formed in a thin film on the first ferromagnetic layer 62. The second ferromagnetic layer 64 is made of an alloy such as a CoFe film or a CoFeB film containing Co, Fe, Ni, and B (boron), and is formed in a thin film on the non-magnetic layer 63. The first ferromagnetic layer 62, the non-magnetic layer 63, and the second ferromagnetic layer 64 suppress the magnetic field from the antiferromagnetic layer 61 side from leaking to the free layer 80 side.

The tunnel layer 70 is formed in a thin film on the second ferromagnetic layer 64. In the present embodiment, the tunnel layer 70 is made of MgO (magnesium oxide) or the like.

The free layer 80 is a layer whose magnetization direction changes depending on an external magnetic field, and is formed in a thin film on the tunnel layer 70. The free layer 80 of the present embodiment is composed of an alloy such as a CoFeB film containing Co, Fe, B and the like. In this embodiment, the free layer 80 corresponds to the magnetic field detection layer.

Here, the pin layer 60, the tunnel layer 70, and the free layer 80 are formed on the flattened film 40a that has been flattened. Therefore, one surface 611 to 641, 71, 81 on the side opposite to the substrate 10 side in each layer 60 to 80 and the other surfaces 612 to 642, 72, 82 on the substrate 10 side are different from the case where the flattening layer 40 is not formed. In comparison, the flatness is improved with less unevenness.

The protective layer 90 protects the free layer 80, is composed of Ta, Ru, W, and the like, and is formed in a thin film on the free layer 80.

Like the lower electrode 30, the upper electrode 100 is made of Cu or an alloy containing Cu as a main component.

The above is the configuration of the magnetic sensor in this embodiment. Next, a method of manufacturing the magnetic sensor will be described.

First, as shown in FIG. 2A, the substrate 10 is prepared, and the insulating film 20 is formed on the substrate 10. The insulating film 20 is formed by, for example, thermal oxidation.

Next, as shown in FIG. 2B, the one subjected to the step of FIG. 2A is arranged in the chamber, and the lower electrode film 30a constituting the lower electrode 30 is formed by sputtering or the like. Then, a flattening film 40a constituting the flattening layer 40 is formed on one surface 31a of the lower electrode film 30a. The flattening film 40a is composed of an amorphous layer or a microcrystal layer of a non-magnetic layer as described above. Then, by performing a flattening treatment on one surface 41a of the flattening film 40a, one surface 41a of the flattening film 40a is flattened. In this embodiment, dry etching is performed as a flattening process.

Subsequently, as shown in FIG. 2C, the antiferromagnetic film 61a forming the antiferromagnetic layer 61 in the pin layer 60, the first ferromagnetic film 62a forming the first ferromagnetic layer 62, and the non-ferromagnetic film 62a forming the first ferromagnetic layer 62 by sputtering or the like. The non-magnetic film 63a constituting the magnetic layer 63 and the second ferromagnetic film 64a constituting the second ferromagnetic layer 64 are formed in this order. That is, the pin film 60a constituting the pin layer 60 is formed. Further, the tunnel film 70a forming the tunnel layer 70 and the free film 80a forming the free layer 80 are formed in order by sputtering or the like. That is, the laminated film S having the pin film 60a, the tunnel film 70a, and the free film 80a is arranged on the substrate 10. Then, the protective film 90a constituting the protective layer 90 and the upper electrode film 100a constituting the upper electrode 100 are formed in this order by sputtering or the like.

At this time, one surface 41 of the flattening film 40a is flattened. Therefore, as compared with the case where the flattening film 40a is not formed, the pin film 60a, the tunnel film 70a, and the free film 80a laminated on the flattening film 40a have one surface 611a to 641a on the opposite side of the substrate 10. , 71a, 81a and the other surfaces 612a to 642a, 72a, 82a on the substrate 10 side are formed in a state where the flatness is improved.

Here, the flatness of the surface indicates a state based on the length between the maximum position and the minimum position in the unevenness of the surface. For example, as shown in FIG. 3, the flatness of the one surface 71a of the tunnel film 70a is the tip position of the convex portion 701 farthest from the substrate 10 of the one surface 71a of the tunnel film 70a and the most flatness on the substrate 10 side. It shows a state based on the length L between the bottom surface position and the close recess 702. In other words, the flatness on one surface 71a of the tunnel film 70a indicates a state based on the length L, which is the difference in unevenness at the interface with the free film 80a. The flatness becomes higher as the length L becomes shorter.

Further, the pin layer 60, the tunnel layer 70, and the free layer 80 are formed by patterning the pin film 60a, the tunnel film 70a, and the free film 80a, as will be described later. Therefore, the flatness of one surface 71 of the tunnel layer 70 shows a state based on the length L, which is the difference in unevenness at the interface with the free layer 80, and the shorter the length L, the higher the flatness. Further, the flatness of the other surface 72 of the tunnel layer 70 indicates a state based on the length L, which is the difference in unevenness at the interface with the pin layer 60, and the shorter the length L, the higher the flatness.

Then, in this step, as will be described in detail later, the length L of the difference between the unevenness on one surface 71a and the other surface 72a of the tunnel film 70a is set to 1.8 nm or less. That is, in the step of flattening the flattening film 40a, the length L of the difference between the unevenness on one surface 71a and the other surface 72a of the tunnel film 70a is 1 in consideration of the thickness of each of the laminated films 50a to 70a. The conditions for the flattening process are set so as to be 0.8 nm or less.

Subsequently, as shown in FIG. 2D, the films 30a to 100a are appropriately patterned by etching or the like. Then, the shape of the magnetic sensor shown in FIG. 1 is formed by forming the lower electrode 30, the flattening layer 40, the base layer 50, the pin layer 60, the tunnel layer 70, and the free layer 80. In the present embodiment, the pin film 60a corresponds to the magnetization fixing film, and the free film 80a corresponds to the magnetic field detection film.

Then, in order to promote crystallization while crystallizing MgO constituting the tunnel layer 70, heat treatment is performed at a temperature of 350 ° C. or higher. As a result, the magnetic sensor shown in FIG. 1 is manufactured.

Subsequently, the ideal operation of the magnetic sensor will be described with reference to FIGS. 4 and 5A to 5C. In addition, in FIGS. 5A to 5C, the pin layer 60 is schematically shown. Further, in FIGS. 5A to 5C, the arrow A indicates the magnetization direction of the pin layer 60, the arrow B indicates the magnetization direction of the free layer 80, and the arrow C indicates the direction of the external magnetic field. Further, the rate of change of conductance in FIG. 4 is based on the state in which no external magnetic field is applied (that is, the state in FIG. 5A).

In the magnetic sensor, the magnetization direction of the free layer 80 changes due to an external magnetic field, and the conductance of the tunnel layer 70 changes depending on the angle formed between the magnetization direction of the free layer 80 and the magnetization direction of the pin layer 60. That is, in the magnetic sensor, the conductance of the tunnel layer 70 changes depending on the spin state of the free layer 80 and the spin state of the pin layer 60.

Specifically, as shown in FIG. 5A, when the strength of the external magnetic field is 0, the magnetization direction of the free layer 80 is a vertical direction orthogonal to the plane direction of the free layer 80.

Then, as shown in FIGS. 4 and 5B, when the direction of the external magnetic field is the same as the magnetization direction of the pin layer 60, the greater the strength of the external magnetic field, the more the magnetization direction of the free layer 80 and the pin layer. The angle formed with the magnetization direction of 60 becomes smaller. Then, in the magnetic sensor, the resistance value of the tunnel layer 70 decreases and the conductance increases as the strength of the external magnetic field increases.

On the contrary, as shown in FIGS. 4 and 5C, when the direction of the external magnetic field is opposite to the magnetization direction of the pin layer 60, the greater the strength of the external magnetic field, the more the magnetization direction of the free layer 80 and the pins. The angle formed by the layer 60 with the magnetization direction becomes large. Then, in the magnetic sensor, the resistance value of the tunnel layer 70 increases and the conductance decreases as the strength of the external magnetic field increases.

Next, the result of comparing the magnetic sensor of the present embodiment with the magnetic sensor not provided with the flattening layer 40 will be described with reference to FIG. The usable magnetic field range in FIG. 6 is a range in which the rate of change of conductance changes linearly with a change in the external magnetic field and is substantially symmetric with respect to the case where the external magnetic field is 0. is there. Further, FIG. 6 is a diagram showing the experimental results of a magnetic sensor manufactured by using Ta-B as the flattening layer 40 and performing heat treatment at 360 ° C.

As shown in FIG. 6, it is confirmed that the magnetic sensor of the present embodiment has a larger inclination regarding the rate of change of conductance than the conventional magnetic sensor. Although the reason for this phenomenon is not clear, the flatness of one surface 71 and the other surface 72 of the tunnel layer 70 is improved by forming the flattening layer 40, and the tunnel layer 70 is a pin layer 60 and a free layer. It is presumed that this is because it is easily affected by the spin state of 80. Therefore, in the magnetic sensor of the present embodiment, the detection sensitivity can be improved.

Further, it is confirmed that the magnetic sensor of the present embodiment has a wider usable magnetic field range than the conventional magnetic sensor. The reason for this event is not clear, but it is presumed to be due to the following reasons.

That is, by performing the heat treatment, the crystallization of the tunnel layer 70 can be promoted as described above to improve the detection sensitivity. However, when a material containing Mn is used as the antiferromagnetic layer 61 constituting the pin layer 60, Mn is easily diffused, so that Mn diffuses when heat-treated. Therefore, the characteristics of the antiferromagnetic layer 61 are deteriorated.

However, in this embodiment, the antiferromagnetic layer 61 is formed on the flattened layer 40 that has been flattened. Therefore, the antiferromagnetic layer 61 is in a state where the flatness of the other surface 612 on the base layer 50 side and the flatness of one surface 611 on the first ferromagnetic layer 62 layer side is improved. Therefore, it is presumed that the magnetic sensor of the present embodiment can suppress the diffusion of Mn as compared with the conventional magnetic sensor, and can also suppress the deterioration of the characteristics of the antiferromagnetic layer 61. As a result, it is estimated that the magnetic field range of the magnetic field of the present embodiment can be widened.

Such an event related to the usable magnetic field range is clear from the result of FIG. 7, and as shown in FIG. 7, when the heat treatment of 350 ° C. or higher is performed, the magnetic sensor of the present embodiment has the conventional magnetic sensor. It is confirmed that the usable magnetic field range is wider than that of the magnetic sensor. The magnetic sensor of the first embodiment in FIG. 7 shows the result of using Ta-B as the flattening layer 40.

It is not clear why the conventional magnetic sensor has a higher usable magnetic field range than the magnetic sensor of the present embodiment when the heat treatment is performed in a range of less than 350 ° C. When Ta-B is used as the flattening layer 40, it is presumed that the diffusion of B has an effect. However, in the present embodiment, the usable magnetic field range can be widened while improving the detection sensitivity by performing the heat treatment in the range of 350 ° C. or higher.

Further, when the magnetic sensor is mounted on a vehicle and used, at present, a magnetic sensor having a usable magnetic field range of 70 mT or more is required. Then, as shown in FIG. 8, the flatness of the tunnel layer 70 is such that the usable magnetic field range is 70 mT or more when it is 1.8 nm or less. That is, when the length L, which is the difference between the unevenness on one surface 71 and the other surface 72 of the tunnel layer 70, is 1.8 nm or less, the usable magnetic field range is 70 mT or more. Therefore, in the present embodiment, the flatness of the one surface 71 and the other surface 72 of the tunnel layer 70 is set to 1.8 nm or less. FIG. 8 is a diagram showing the experimental results of a magnetic sensor manufactured by using Ta-B as the flattening layer 40 and performing heat treatment at 360 ° C.

As described above, in the present embodiment, the flattening layer 40 having the flattened flat surface is arranged between the tunnel layer 70 and the lower electrode 30. Therefore, the flatness on one surface 71 and the other surface 72 of the tunnel layer 70 can be improved as compared with the case where the flattening layer 40 is not arranged. Therefore, the detection sensitivity of the magnetic sensor can be improved.

Further, by arranging the flattening layer 40, the flatness on one surface 611 and the other surface 612 of the antiferromagnetic layer 61 can be improved. Therefore, even if the antiferromagnetic layer 61 is made of a material containing Mn, it is possible to suppress the diffusion of Mn during heat treatment, and it is possible to suppress the narrowing of the usable magnetic field range.

Further, in the present embodiment, the flattening layer 40 is composed of an amorphous layer or a microcrystal layer. Therefore, as compared with the case where the flattening layer 40 is composed of a crystal layer, when the flattening film 40a constituting the flattening layer 40 is formed, one surface 41a side can be easily flattened. Therefore, the flatness of one surface 41a can be improved as compared with the case where the flattening layer 40 is composed of a crystal layer. In particular, Ta-B has a higher degree of amorphousness than materials such as Ta, TaN, TaO ₂ , W, Mo-B, Nb-B, and WB, so that the flatness can be further improved.

The flattening layer 40 is composed of a non-magnetic layer. Therefore, the flattening layer 40 does not have internal magnetization and is not affected by the magnetic fields of other layers. Therefore, the other layer can receive only the magnetic field to be detected, and the detection accuracy can be improved.

Further, in the present embodiment, the flatness of the one surface 71 and the other surface 72 of the tunnel layer 70 is set to 1.8 nm or less. Therefore, the usable magnetic field range can be set to 70 mT or more, and the conditions required when mounted on a vehicle can be satisfied.

(Second Embodiment)
The second embodiment will be described. This embodiment is a modification of the first embodiment in a manufacturing process. Others are the same as those in the first embodiment, and thus the description thereof will be omitted here.

In the present embodiment, after the lower electrode film 30a is formed by performing the step of FIG. 2A, the formed lower electrode film 30a is once taken out of the chamber. Next, one surface 31a of the lower electrode film 30a is flattened by a chemical mechanical polishing (CMP: abbreviation) method as a flattening treatment. After that, it is placed in the chamber again, and the steps after FIG. 2B are performed.

As described above, in the present embodiment, the lower electrode film 30a is flattened, and then the flattening film 40a is formed. Therefore, the flatness of one surface 41 of the flattening film 40a can be further improved, and the flatness of the antiferromagnetic layer 61 and the tunnel layer 70 can be further improved. Therefore, the usable magnetic field range can be further widened while further improving the detection sensitivity of the magnetic sensor.

(Modified example of the second embodiment)
A modified example of the second embodiment will be described. In the present embodiment, since the flattening step is performed on the lower electrode film 30a, the flattening step may not be performed on the flattening film 40a. As a method for manufacturing such a magnetic sensor, the same effect as that of the first embodiment can be obtained by performing the flattening step on the lower electrode film 30a. Even if the flattening film 40a is not subjected to the flattening treatment, it is compared with the case where the flattening film 40a is composed of a crystal film by forming the flattening film 40a with an amorphous layer or a microcrystal layer. As a result, the crystal grain boundaries are reduced, so that one surface 41a of the flattening film 40a becomes a flat surface because it is easy to flatten. That is, when manufacturing a magnetic sensor, the surface of the portion arranged between the substrate 10 and the laminated film S on the opposite side of the substrate 10 is flattened to make the tunnel layer 70 or the like flat. Can be improved.

(Third Embodiment)
A third embodiment will be described. In this embodiment, the positional relationship between the pin layer 60 and the free layer 80 is changed from that of the first embodiment. Others are the same as those in the first embodiment, and thus the description thereof will be omitted here.

In the present embodiment, as shown in FIG. 9, the free layer 80, the tunnel layer 70, and the pin layer 60 are laminated in this order on the base layer 50 from the base layer 50 side. That is, in the present embodiment, the positional relationship between the free layer 80 and the pin layer 60 is opposite to that of the first embodiment with the tunnel layer 70 as a reference. In the present embodiment, the pin layer 60 has a configuration in which the second ferromagnetic layer 64, the non-magnetic layer 63, the first ferromagnetic layer 62, and the antiferromagnetic layer 61 are laminated in this order from the substrate 10 side. .. It should be noted that such a magnetic sensor is manufactured by changing the order of the films to be laminated in the manufacturing method of the first embodiment.

In this way, even if the positional relationship between the free layer 80 and the pin layer 60 is changed, the same effect as that of the first embodiment can be obtained.

(Fourth Embodiment)
A fourth embodiment will be described. In this embodiment, the magnetization direction of the pin layer 60 is changed with respect to the first embodiment. Others are the same as those in the first embodiment, and thus the description thereof will be omitted here.

In the present embodiment, as shown in FIG. 10, the pin layer 60 is composed of a first ferromagnetic layer 62, a non-magnetic layer 63, and a second ferromagnetic layer 64 in that order. In the present embodiment, the first ferromagnetic layer 62 and the second ferromagnetic layer 64 are configured by alternately stacking Co and Pt a plurality of times in order. Further, the non-magnetic layer 63 is made of Ru or the like. As a result, the magnetization direction of the pin layer 60 becomes a vertical direction orthogonal to the plane direction of the pin layer 60, as shown by the arrow A in FIG. In the case of such a configuration, when the external magnetic field is 0, the magnetization direction of the free layer 80 is the plane direction of the free layer 80 as shown by the arrow B in FIG. .. It should be noted that such a magnetic sensor is formed by omitting the step of forming the antiferromagnetic film 61a in the manufacturing method of the first embodiment.

As described above, even if the magnetization direction of the pin layer 60 is set to the vertical direction, the same effect as that of the first embodiment can be obtained.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the claims.

For example, in the present embodiment, the example in which the free layer 80 is composed of the CoFeB film has been described, but other materials may be used. Similarly, the materials constituting the pin layer 60, the tunnel layer 70, and the like can be appropriately changed.

Further, in each of the above embodiments, the flatness of the tunnel layer 70 may be made larger than 1.8 nm. Even in such a configuration, since the flattening layer 40 is arranged, the flatness of the tunnel layer 70 is improved as compared with the case where the flattening layer 40 is not arranged. A similar effect can be obtained.

10 Substrate 40 Flattening layer 41 One side 60 pin layer (magnetization fixed layer)
70 Tunnel layer 80 Free layer (magnetic field detection layer)

Claims (8)

A magnetic sensor in which a tunnel layer (70) is arranged between a magnetization fixing layer (60) and a magnetic field detection layer (80).
With the magnetization fixed layer whose magnetization direction is fixed,
The magnetic field detection layer whose magnetization direction changes with an external magnetic field,
The tunnel layer, which is arranged between the magnetization fixing layer and the magnetic field detection layer, and whose resistance value changes depending on the angle formed between the magnetization direction of the magnetization fixing layer and the magnetization direction of the magnetic field detection layer.
A substrate (10) on which the magnetization fixing layer, the tunnel layer, and the magnetic field detection layer are laminated and arranged is provided.
A flattening layer (40) composed of an amorphous layer or a microcrystal layer and having one surface (41) opposite to the substrate side as a flat surface is arranged on the substrate.
A magnetic sensor in which the magnetization fixing layer, the tunnel layer, and the magnetic field detection layer are laminated and arranged on the flattening layer. The magnetic sensor according to claim 1, wherein the flattening layer is a non-magnetic layer. The magnetic sensor according to claim 2, wherein the flattening layer is composed of any one of a tantalum nitride mixture, tantalum, tantalum nitride, tantalum oxide, tungsten, a boron molybdenum mixture, a boron niobium mixture, and a boron tungsten mixture. The magnetic sensor according to any one of claims 1 to 3, wherein the magnetization fixing layer has an antiferromagnetic layer (61) made of a material containing manganese. The length (L) of the tunnel layer, which is the difference between the unevenness on one surface (71) opposite to the substrate and the other surface (72) on the substrate side, is 1.8 nm or less. The magnetic sensor according to any one of claims 1 to 4. A method for manufacturing a magnetic sensor in which a tunnel layer (70) is arranged between a magnetization fixing layer (60) and a magnetic field detection layer (80).
Preparing the board (10) and
By forming the lower electrode film (30a) constituting the lower electrode (30) on the substrate,
On the lower electrode film, a magnetization fixing film (60a) constituting the magnetization fixing layer, a tunnel film (70a) constituting the tunnel layer (70), and a magnetic field detection film (80a) constituting the magnetic field detection layer are formed. Arranging the laminated film (S) formed by film formation and
Forming the upper electrode film (100a) constituting the upper electrode (100) on the laminated film and
By patterning, the lower electrode, the magnetization fixing layer, the tunnel layer, the magnetic field detection layer, and the upper electrode are formed.
The tunnel layer is heat-treated and
Prior to arranging the laminated film, a flattening film (40a) composed of an amorphous layer or a microcrystal layer is arranged on the lower electrode, and the laminated film is arranged between the laminated film and the substrate. A method for manufacturing a magnetic sensor, in which the surface of the portion opposite to the substrate is flattened. In claim 6, in forming the flattening film, after arranging the flattening film, one surface (41a) of the flattening film opposite to the substrate side is dry-etched as the flattening treatment. The method for manufacturing a magnetic sensor according to. In forming the lower electrode, after forming the lower electrode film and before arranging the flattening film, as the flattening treatment, one surface of the lower electrode film on the opposite side to the substrate side ( The method for manufacturing a magnetic sensor according to claim 6 or 7, wherein 31a) is chemically mechanically polished.

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