JP3182858B2 - Ferromagnetic magnetoresistive element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic magnetoresistive element for detecting a magnetic field by utilizing a magnetoresistance effect of a ferromagnetic material.

[0002]

2. Description of the Related Art Generally, a ferromagnetic magnetoresistive element is formed by forming a thin film of a Ni-based alloy having a ferromagnetic magnetoresistive effect in which the resistivity changes depending on the angle between a magnetization direction and a current direction on an insulating substrate, A magnetic field sensing part is provided by lithography, an extraction electrode part is formed as necessary, and a protective film is formed on the surface. The ferromagnetic magnetoresistive layer is given a uniaxial anisotropy as required, and has a meandering line shape in order to improve sensitivity and reduce power consumption by the device. Further, if necessary, element portions made of a ferromagnetic magnetoresistive pattern are formed on the same substrate at an appropriate angle to each other.

FIGS. 3 and 4 show the structure and characteristics of a conventional ferromagnetic magnetoresistive element. FIG. 3A is a plan view of the ferromagnetic magnetoresistive element. In FIG. 3A, reference numeral 1 denotes an insulating glass substrate, and 2 denotes a ferromagnetic magnetoresistive film pattern. Specifically, a Ni-25% Co alloy is deposited on the surface of the insulating glass substrate 1 by a vapor deposition method in a magnetic field to form a film having a thickness of 400Å, and then, by photolithography, the line width is set to 10 μm with the magnetic easy axis as the longitudinal direction. 300μm strip pattern
Ten pieces are arranged so that the gap s is 5 μm, and the respective ends are alternately connected in series to form a meander line shape. FIG. 3B shows the signal magnetic field strength when a signal magnetic field is applied in the hard magnetic axis direction (perpendicular to the magnetic easy axis) of the ferromagnetic magnetoresistive film pattern 2 in FIG. 7 shows a change in resistance value of a ferromagnetic magnetoresistive film pattern.

FIG. 4A is a plan view of another ferromagnetic magnetoresistive element. In FIG. 4A, 1 is an insulating glass substrate, 2 is a ferromagnetic magnetoresistive film pattern, and 3 is an electrode.
A ferromagnetic magnetoresistive element having such a structure is manufactured as follows. First, a Ni-19% Fe alloy having a film thickness of 300 was formed on the insulating surface of the thermally oxidized silicon substrate 1 by a magnetic field evaporation method.
Å Film formation, and then, by photolithography, ten strip-shaped patterns having a line width of 30 μm and a length of 500 μm are arranged so that the gap s is 10 μm, with the hard magnetic axis as the longitudinal direction, and the respective ends are alternately arranged. Connect in series and form a meander line. Next, a thin film of 3000% of Au and 17% of a Co-17% Ni alloy is formed, and then the electrode 3 having the same width as the width of the ferromagnetic magnetoresistive film pattern 2 is formed by photolithography. , And the electrodes 3 are magnetized in the magnetic easy axis direction of the ferromagnetic magnetoresistive film pattern 2. FIG.
FIG. 4B shows a change in the resistance value of the element with respect to the signal magnetic field intensity when a signal magnetic field is applied in the direction of the hard magnetic axis of the ferromagnetic magnetoresistive film pattern 2 in FIG.

[0005]

However, in the conventional ferromagnetic magnetoresistive element shown in FIG.
Is 400 °, the gap s of the pattern is 5
Since it is μm, the ratio of the gap to the film thickness is as large as 125 times. Therefore, the adjacent ferromagnetic magnetoresistive film patterns are magnetically separated from each other, and the change in the resistance value of the element due to the rotation of the magnetization according to the strength of the signal magnetic field becomes relatively gradual, and the resistance value increases. The width of the curve showing the maximum is wide,
The sensitivity as a magnetic field detecting element is low.

On the other hand, in the conventional ferromagnetic magnetoresistive element shown in FIG. 4, since the ferromagnetic magnetoresistive film pattern 2 is long in the direction of the hard magnetic axis, return magnetic domains are easily generated. Hysteresis characteristics occur as shown. For this reason, it has been difficult to reliably detect the presence or absence or strength of a signal magnetic field that changes only in one direction (the same polarity).

In order to improve the magnetic field detection sensitivity of the ferromagnetic magnetoresistive element, it is necessary to increase the pattern width of the ferromagnetic magnetoresistive film pattern or reduce its thickness. However, if the pattern width is increased, the impedance of the element is reduced, so that the power consumption by the element is increased, and the area of the magnetically sensitive portion is increased, which causes a problem in detecting a magnetic field having a small area. In addition, when the thickness of the ferromagnetic magnetoresistive film pattern is reduced, there arises a problem that the resistivity increases due to the size effect, the sensitivity decreases, and the manufacturing difficulty increases.

An object of the present invention is to provide a ferromagnetic magnetoresistive element in which the change in the resistance of the element with respect to the change in the intensity of the signal magnetic field is sharpened and the sensitivity as a magnetic field detecting element is enhanced.

Another object of the present invention is to provide a ferromagnetic magnetoresistive element which suppresses generation of a return magnetic domain in a ferromagnetic magnetoresistive film pattern and has no hysteresis characteristics.

[0010]

A ferromagnetic magnetoresistive element according to the present invention is a ferromagnetic magnetoresistive element formed by forming a ferromagnetic magnetoresistive film pattern on a substrate in a meander line shape. The film thickness t is set to 500 ° or less, and the gap s between adjacent patterns is set to t <s <38t.

[0011]

According to the ferromagnetic magnetoresistive element of the present invention, the thickness t of the ferromagnetic magnetoresistive film is 500 ° or less, and the gap s between adjacent patterns is t <s <38t. Are formed in a meander line shape. As described above, since the thickness of the ferromagnetic magnetoresistive film pattern is sufficiently smaller than the normal pattern width, there is no decrease in the magnetoresistance effect (difference between the lateral effect and the longitudinal effect of resistivity) due to the large film thickness. . Further, by setting the gap s between the adjacent patterns to the above condition, as the direction of magnetization of the ferromagnetic magnetoresistive film pattern is oriented in a direction perpendicular to the longitudinal direction of the pattern,
Interaction with the magnetization of the adjacent pattern increases apparent permeability and sensitivity. Further, the return magnetic domain is reduced or lost due to the interaction of the magnetizations of the adjacent patterns of the ferromagnetic magnetoresistive film pattern, so that the hysteresis characteristic is reduced or lost. Therefore, the presence / absence or strength of the signal magnetic field in one direction (the same polarity) can be accurately detected.

FIG. 6 schematically shows the rotation of the magnetization direction when a signal magnetic field is applied in a direction perpendicular to the longitudinal direction of the ferromagnetic magnetoresistive film pattern as a magnetic easy axis. FIG. 3B shows a conventional case, in which the magnetization direction of each ferromagnetic magnetoresistive film pattern 2 rotates according to the strength of a signal magnetic field applied from the outside. (A) is the case of the present invention, and since the gap s between the ferromagnetic magnetoresistive film patterns 2 is small, the sense of the ferromagnetic magnetoresistive film patterns arranged in a meander line shape due to the interaction of magnetization between adjacent patterns. The apparent magnetic permeability of the entire magnetic part increases, and the rotation angle of the magnetization direction of each ferromagnetic magnetoresistive film pattern 2 increases.

FIG. 7 shows an example in which a signal magnetic field is applied to a ferromagnetic magnetoresistive element whose magnetic easy axis is set in a direction perpendicular to the longitudinal direction of the ferromagnetic magnetoresistive film pattern.
(B) is a conventional example, in which a ferromagnetic magnetoresistive film pattern 2 is used.
Is a hard magnetic axis in the longitudinal direction, and thus a return magnetic domain is easily generated as shown in the figure, and when the strength of the signal magnetic field changes, the hysteresis characteristic occurs due to the movement of the domain wall. On the other hand, (A) is an example of the present invention, and since the gap s between the ferromagnetic magnetoresistive film patterns 2 is small, the return magnetic domain is reduced or reduced due to the interaction of magnetization between the adjacent ferromagnetic magnetoresistive film patterns. Disappear. Therefore, even when the intensity of the signal magnetic field changes, the domain wall does not move, and the hysteresis characteristic does not appear. Therefore, even if the signal magnetic field strength changes with the same polarity, the signal strength can be detected with high accuracy.

[0014]

FIG. 1 shows the structure and characteristics of a ferromagnetic magnetoresistive element according to a first embodiment of the present invention. FIG. 1A is a plan view of the ferromagnetic magnetoresistive element. In FIG. 1A, reference numeral 1 denotes an insulating glass substrate, and 2 denotes a ferromagnetic magnetoresistive film pattern. Specifically, the surface of the insulating glass substrate 1 is coated with Ni.
A −25% Co alloy is deposited in a thickness of 400 ° by a magnetic field evaporation method, and then a strip pattern having a line width of 10 μm and a length of 300 μm with a magnetic easy axis as a longitudinal direction is formed by photolithography so that a gap s is 1 μm. , And each end is alternately connected in series to form a meander line. FIG. 1B shows the ferromagnetic properties with respect to the signal magnetic field intensity when a signal magnetic field is applied in the direction of the hard magnetic axis (perpendicular to the easy magnetic axis) of the ferromagnetic magnetoresistive film pattern 2 in FIG. 4 shows a resistance value change characteristic of a magnetoresistive film pattern.

As described above, when the thickness of the ferromagnetic magnetoresistive film pattern 2 is 400 °, the gap s between the patterns is 1 μm.
As the signal magnetic field strength increases and the magnetization direction of the ferromagnetic magnetoresistive film pattern rotates from the easy axis direction, the apparent magnetic permeability increases due to the interaction with the magnetization of the adjacent pattern. , The resistance value drops sharply. As shown in FIG. 3B, the width of the curve showing the maximum of the resistance value becomes narrow, and the sensitivity as the magnetic field detecting element increases.

Next, FIG. 2 shows the structure and characteristics of a ferromagnetic magnetoresistive element according to a second embodiment of the present invention. FIG.
(A) is a plan view of a ferromagnetic magnetoresistive element. In (A), 1 is an insulating glass substrate, 2 is a ferromagnetic magnetoresistive film pattern, and 3 is an electrode. In order to produce a ferromagnetic magnetoresistive element having such a structure, first, a Ni-19% Fe alloy is formed on an insulating surface of a thermally oxidized silicon substrate 1 by a vapor deposition method in a magnetic field to a thickness of 300.degree. The line width is 30 μm and the length is 5 with the hard magnetic axis as the longitudinal direction.
Ten 100 μm strip-shaped patterns are arranged so that the gap s is 1 μm, and their ends are alternately connected in series to form a meander line shape. Then, Co-17
% Ni alloy, a thin film made of 3000% and Au1000% is formed, and then electrodes 3 having the same width as the ferromagnetic magnetoresistive film pattern 2 are formed at both ends of the ferromagnetic magnetoresistive film pattern 2 by photolithography. Further, the electrode 3 is magnetized in the magnetic easy axis direction of the ferromagnetic magnetoresistive film pattern 2. FIG. 2B shows a change in the resistance value of the element with respect to the signal magnetic field intensity when a signal magnetic field is applied in the direction of the hard magnetic axis of the ferromagnetic magnetoresistive film pattern 2 in FIG.

When the ferromagnetic magnetoresistive film pattern 2 is long in the direction of the hard magnetic axis as described above, a return domain is apt to be generated. Is as small as 1 μm, so that the return magnetic domain is reduced or disappears due to the interaction between the magnetizations of the adjacent patterns. As a result, characteristics without hysteresis are obtained as shown in FIG.

FIG. 5 shows a change in the coercive force Hc when the gap s between the patterns is changed in the ferromagnetic magnetoresistive element having the structure shown in FIG. 2A or 4A. Here, as shown in FIG. 4B, the coercive force Hc is the magnetic field strength at which the resistance takes a minimum value. The gap s between the patterns is 0.5 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm
m, 10 μm, 12 μm, 14 μm and 15 μm
Zero samples were prepared and the coercive force Hc was measured. Since the ferromagnetic magnetoresistive film pattern has a film thickness of 300 °, the gap A between the patterns is in the range A of 300 ° to 1.1 μm, and the coercive force is extremely small as shown in FIG. It can be seen that almost no hysteresis occurs in the change in the resistance value with respect to the change in.

[0019]

According to the present invention, when the longitudinal direction of the ferromagnetic magnetoresistive film pattern is defined as the magnetic easy axis, as the magnetization direction of the ferromagnetic magnetoresistive film pattern rotates from the direction of the easy axis, it becomes adjacent. Due to the interaction with the magnetization of the pattern, the apparent magnetic permeability increases, so that the impedance does not decrease or the area of the magnetic sensing portion does not increase,
The sensitivity as a magnetic sensor can be increased. Also,
When the longitudinal direction of the ferromagnetic magnetoresistive film pattern is set as the hard magnetic axis, the magnetization domains of adjacent patterns reduce or eliminate the return magnetic domain due to the interaction of magnetization, so that the hysteresis characteristic does not appear and the polarity of the signal magnetic field is one. Even in the case of only the direction, the presence or absence of the magnetic field or the strength thereof can be detected with high accuracy.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing the structure and characteristics of a ferromagnetic magnetoresistive element according to a first embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B shows a change characteristic of a resistance value with respect to a signal magnetic field. FIG.

FIGS. 2A and 2B are diagrams showing a structure and characteristics of a ferromagnetic magnetoresistive element according to a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B shows a change characteristic of a resistance value with respect to a signal magnetic field. FIG.

3A and 3B are diagrams showing the structure and characteristics of a conventional ferromagnetic magnetoresistive element, in which FIG. 3A is a plan view and FIG. 3B is a diagram showing a change characteristic of a resistance value with respect to a signal magnetic field.

4A and 4B are diagrams illustrating the structure and characteristics of a conventional ferromagnetic magnetoresistive element, wherein FIG. 4A is a plan view and FIG. 4B is a diagram illustrating a change characteristic of a resistance value with respect to a signal magnetic field.

FIG. 5 is a diagram showing a change in coercive force when a gap s between patterns is changed in the ferromagnetic magnetoresistive element having the structure shown in FIG. 2A or 4A.

6A and 6B are explanatory diagrams of an operation of an element having a longitudinal direction of a ferromagnetic magnetoresistive film pattern as an easy axis of magnetic field, wherein FIG. 6A is a diagram according to the present invention and FIG. 6B is a diagram according to a conventional example.

7A and 7B are diagrams illustrating the operation of an element having a hard magnetic axis in the longitudinal direction of a ferromagnetic magnetoresistive film pattern, wherein FIG. 7A is a diagram according to the present invention and FIG. 7B is a diagram according to a conventional example.

[Explanation of symbols]

 1-substrate 2-ferromagnetic magnetoresistive film pattern 3-electrode gap between s-ferromagnetic magnetoresistive film pattern

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takuji Nakagawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Co., Ltd. Inside Murata Manufacturing Co., Ltd. (72) Mibun Ogiso 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan (56) References JP-A-2-161784 (JP, A) JP-A-2-66479 (JP, A) JP-A-2-229479 (JP, A) (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 43/08 H01F 10/08 G11B 5/39 G01R 33/09 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A ferromagnetic magnetoresistive element in which a ferromagnetic magnetoresistive film pattern is formed in a meandering line pattern on a substrate, wherein the thickness t of the ferromagnetic magnetoresistive film is 500 ° or less, and a gap between adjacent patterns is provided. A ferromagnetic magnetoresistive element, wherein s is set to t <s <38t.