JP3882895B2 - Crossed MI element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crossed MI element used for a magnetic detection element or a magnetic head of a magnetic sensor.
[0002]
[Prior art]
The MI element is a magnetically sensitive element that utilizes a phenomenon (MI effect) in which the impedance significantly changes due to an external magnetic field due to the skin effect when a high-frequency current is passed through a magnetic material.
[0003]
FIG. 5 shows a configuration example of the crossed MI element 10.
In the MI element 10, a first magnetic body 12 is formed on a plate surface of a substrate (for example, a glass substrate) 11 by sputtering in a magnetic field, and a second magnetic body is formed on the upper surface of the first magnetic body 12. After thin film 13 is formed, it is patterned by a photolithographic method to form an elongated shape.
The first and second magnetic bodies 12 and 13 are made of a soft magnetic material (conductive material) such as an amorphous magnetic material, permalloy, or microcrystalline material.
[0004]
Further, the MI device 10, with respect to the reference line 0o serving as a current path direction, the axis of easy magnetization Jm ₁ of the first magnetic body 12 at an angle of alpha °, the easy magnetization axis Jm ₂ of the second magnetic member 13 Is provided at an angle of −α °, and the easy magnetization axes Jm ₁ and Jm ₂ are provided so as to intersect with each other.
[0005]
The MI element 10 configured as described above senses the external magnetic field Hex applied in the direction of the reference line 0o (the longitudinal direction of the element) of the MI element 10 by flowing a high-frequency current Iac.
That is, since the permeability in the direction of inclination of the magnetization vector changes due to the external magnetic field Hex, the impedance changes.
[0006]
More specifically, as shown in FIG. 6, when a high-frequency current Iac is passed through the MI element 10, the magnetization formed into a flat spiral shape by the easy magnetization axes Jm ₁ and Jm _{2 is} caused in the longitudinal direction of the element. Since the magnetization vector of this magnetization is changed by the external magnetic field Hex, the impedance of the MI element 10 is changed.
[0007]
FIG. 7 is a characteristic diagram showing the relationship between the voltage (measured value of the voltage between the end portions of the element) generated by the impedance change in the crossed MI element 10 and the external magnetic field Hex.
As shown in the figure, the MI element 10 exhibits an asymmetric impedance characteristic (MI characteristic) with respect to a positive and negative external magnetic field Hex.
[0008]
In this characteristic diagram, the characteristic curve indicated by the solid line is the MI characteristic when the external magnetic field Hex is changed from the negative side to the positive side, and the characteristic curve indicated by the dotted line is the change of the external magnetic field Hex from the positive side to the negative side. This is the MI characteristic when
[0009]
FIG. 8 is a block diagram of a magnetic field sensor circuit including two MI elements 30a and 30b similar to the MI element 10 described above.
This magnetic field sensor circuit outputs a high-frequency pulse current Ipc from the high-frequency pulse power supply 31, and this high-frequency pulse current Ipc flows in one direction to the MI element 30a and flows in the other direction in the MI element 30b. Supply.
[0010]
The high frequency pulse voltage is detected by the detector 32a from the one end P of the MI element 30a whose impedance is changed according to the external magnetic field Hex, and similarly, the high frequency pulse voltage is detected from the other end Q of the MI element 30b. Detection is performed by 32b, and impedance change components of the MI elements 30a and 30b are detected.
[0011]
Further, the detection voltage of the detector 32a is integrated and input to the differential amplifier 33 as the integration voltage Va. Similarly, the detection voltage of the detector 32b is also integrated and input to the differential amplifier 33 as the integration voltage Vb.
[0012]
Therefore, the differential voltage between the integrated voltages Va and Vb is amplified and output as the magnetic field detection voltage PO.
This magnetic field sensor circuit is configured to obtain a linear magnetic field detection characteristic by feeding back a part of the magnetic field detection voltage PO to the negative feedback coil 34.
[0013]
[Problems to be solved by the invention]
In the crossed MI element 10 described above, the first and second magnetic bodies 12 and 13 are formed in a thin film on the substrate 11 by using sputtering in a magnetic field.
[0014]
Specifically, a magnetic material was sputtered while applying a magnetic field for magnetization from the angle direction of the easy axis Jm ₁ (α °) to the substrate 11 to form a thin film of the first magnetic body 12 on the surface of the substrate 11. Thereafter, the direction in which the magnetic field for magnetization is applied is changed, the magnetic material is sputtered while applying the magnetic field for magnetization from the angle direction of the easy magnetization axis Jm ₂ (−α °), and the _second magnetic material 12 is formed on the surface of the first magnetic body 12. The magnetic body 13 is formed as a thin film.
Then, the elongated cross-shaped MI element 10 is manufactured by patterning by photolithography.
[0015]
Such a crossed MI element 10 can obtain an asymmetric impedance characteristic with respect to a positive and negative external magnetic field Hex without providing a permanent magnet or a coil for biasing, and has a linear magnetic field detection characteristic. Since it can be obtained, it becomes an extremely small and highly sensitive magnetic sensitive element.
[0016]
However, since the magnetization direction of the crossed MI element 10 changes abruptly at the layer interface between the first and second magnetic bodies 12 and 13, hysteresis may occur in the MI characteristics.
[0017]
Further, the MI characteristics of the MI elements vary depending on the manufacturing conditions.
Specifically, since it is difficult to produce a uniform and unidirectional magnetic field as a large area because it is manufactured by sputtering in a magnetic field, element characteristics greatly vary depending on points on the substrate.
[0018]
In view of the above circumstances, an object of the present invention is to provide a highly accurate cross-type MI element with improved characteristic variation and hysteresis.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the first magnetic body and the second magnetic body are formed on the substrate surface, and the easy axis of magnetization of the first magnetic body and the second magnetic body are formed. In the crossed MI element configured to intersect the easy magnetization axis, the anisotropy of the easy magnetization axis provided on the magnetic material is formed between the first magnetic material and the second magnetic material. A cross-type MI element is proposed, which is characterized in that a supporting film is formed.
[0020]
[Action]
The magnetization assistant provided between the first magnetic body and the second magnetic body in a film-forming layer prevents the change of the easy axis due to the magnetization that suddenly changes at the interface between the first and second magnetic layers. Subsidize.
[0021]
As a result, since the easy magnetization axes of the first and second magnetic bodies are reliably held without being disturbed, a cross-type MI element with extremely little hysteresis and characteristic variation is obtained.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially cutaway perspective view of a cross-type MI element, and FIG. 2 is an enlarged partial cross-sectional view of the cross-type MI element cut along the longitudinal direction.
[0023]
In this figure, 50 is a crossed MI element, 51 is a substrate (for example, a glass substrate), 52 is a first magnetic body, 53 is a magnetization assistant, and 54 is a second magnetic body.
In the crossed MI element 50, a magnetic material is sputtered on the surface of the substrate 51 to form a first magnetic body 52 in a thin film, and then the magnetic material is sputtered on the surface of the first magnetic body 52 to assist magnetization. The body 53 is formed into a thin film, and a second magnetic body 54 is formed into a thin film by sputtering a magnetic material on the surface of the magnetization auxiliary body 53.
In addition, the 1st, 2nd magnetic bodies 52 and 54 and the magnetization auxiliary body 53 can be comprised with soft magnetic materials (conductive material), such as an amorphous magnetic material, a permalloy, and a microcrystal material.
[0024]
The thin film is formed by sputtering in a magnetic field.
That is, the first magnetic body 52 is sputtered while applying a magnetic field for magnetization from the direction of the angle α ° as in the conventional example to form the easy magnetization axis Jm ₁ .
Similarly, the second magnetic body 54 is sputtered while applying a magnetic field for magnetization from the direction of the angle −α ° to form the easy magnetization axis Jm ₂ .
[0025]
The magnetization assistant 53 is formed as shown in FIG.
Specifically, the magnetization auxiliary body 53 of the present embodiment has a three-layer configuration of magnetic layers 53a, 53b, and 53c. The magnetization layers 53a, 53b, and 53c are changed in a range of α ° to −α °. Magnetization axes Jma, Jmb, and Jmc are formed.
[0026]
That is, the magnetization layer 53a is α ° −A ° (α °> A °> 0 °), the magnetization layer 53b is 0 °, and the magnetization layer 53c is −α ° + C ° (−α ° <C ° <0 °). Sputtering is performed while applying a magnetic field for magnetization from the direction, and magnetization axes Jma, Jmb, and Jmc provided at respective inclination angles are formed.
[0027]
In the crossed MI element 50 configured as described above, when the second magnetic body 54 is formed after the first magnetic body 52 is formed, the easy magnetization axis Jm ₁ becomes the easy magnetization axis Jm ₂ . Since it is not affected by the magnetic field for magnetization for setting, the angle setting of the easy magnetization axes Jm ₁ and Jm ₂ becomes accurate.
[0028]
As a result, crossover MI element 50 described above, the magnetization easy axis _Jm 1, Jm high _second setting accuracy, also, since the easy axis of magnetization _Jm 1, Jm ₂ do not interfere directly, no hysteresis In addition, the characteristic variation is extremely small.
[0029]
Specifically, after the first magnetic body 52 is deposited by 3 μm by sputtering in a magnetic field, the magnetization auxiliary body 53 having a thickness of 0.1 to 0.2 μm is deposited by changing the direction of the magnetic field for magnetization. Furthermore, it was confirmed that the cross-type MI element in which the second magnetic body 54 is deposited by 3 μm is an MI element with little hysteresis and no variation in characteristics.
[0030]
FIG. 4 is a cross-sectional view similar to FIG. 2 showing a crossed MI element 60 of another embodiment.
In the crossed MI element 60, a nonmagnetic layer (conductive material) 61 is provided between the first and second magnetic bodies 52, 54 and the magnetization auxiliary body 53 and between the magnetization layers of the magnetization auxiliary body 53. The other features are the same as those of the crossed MI element 50 described above.
The cross-type MI element 60 configured as described above can obtain the same effect as the cross-type MI element 50 described above, and is advantageous in reducing triangular magnetic domains that cause hysteresis and uniform formation of each magnetic layer. .
[0031]
Although the embodiment of the present invention has been described above, the number of layers of the magnetization auxiliary body 53 can be arbitrarily determined as necessary.
[0032]
In practicing the present invention, the first magnetic body 52, the magnetization auxiliary body 53, and the second magnetic body 54 may be formed separately, but the first magnetic body 52, the magnetization The auxiliary body 53 and the second magnetic body 54 can be continuously deposited to form a crossed MI element having an integral structure.
[0033]
【The invention's effect】
As described above, in the present invention, since the magnetization assisting body for assisting the anisotropy of the easy axis of magnetization is provided between the film formation layers of the first magnetic body and the second magnetic body, the first and second magnetic bodies are provided. In the body, there is little interference of the easy magnetization axis, and the cross-type MI element has very little variation in characteristics and hysteresis due to disturbance of the easy magnetization axis.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view of a cross-type MI element shown as a first embodiment.
FIG. 2 is an enlarged partial cross-sectional view of the crossed MI element cut along the longitudinal direction.
FIG. 3 is an explanatory diagram of a layer film forming a magnetization assistant provided in the crossed MI element.
FIG. 4 is a cross-sectional view similar to FIG. 2 of the crossed MI element shown as the second embodiment.
FIG. 5 is a partially cutaway perspective view showing a conventional crossed MI element.
FIG. 6 is an explanatory diagram showing spiral magnetization generated in a crossed MI element by supplying a high-frequency current.
7 is a diagram showing MI characteristics of the crossed MI element shown in FIG. 5; FIG.
FIG. 8 is a block diagram of a magnetic field sensor-circuit comprising two crossed MI elements.
[Explanation of symbols]
50 Crossed MI element 51 Substrate 52 First magnetic body 53 Magnetization aids 53a, 53b, 53c Magnetization layer 54 Second magnetic body

Claims (1)

A cross type having a configuration in which the first magnetic body and the second magnetic body are formed on the substrate surface and the easy axis of magnetization of the first magnetic body intersects the easy axis of magnetization of the second magnetic body. In the MI element, a magnetization assistant that assists the anisotropy of the easy axis of magnetization provided in the magnetic material is formed between the first magnetic material and the second magnetic material. Characteristic cross-type MI element.

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