JPH06268281A - Magneto resistive element - Google Patents

Abstract

(57) [Abstract] [Purpose] A linear output type magnetoresistive element that detects changes in an external magnetic field does not require a magnet for generating a bias magnetic field or for stabilizing a bias magnetic field. [Structure] A first magnetic material pattern 2 for magnetoelectrically converting an external magnetic field is formed on a surface of a substrate 1 made of silicon or the like,
On the insulating layer 3 on the magnetic material pattern 2, the 2nd magnetic material pattern 4 which carries out magnetoelectric conversion of the external magnetic field is provided. Since a bias magnetic field is applied to the magnetic material patterns 2 and 4 without using a magnet, currents in opposite directions are applied to the magnetic material patterns 2 and 4. The magnetic material patterns 2 and 4 are connected at the same side ends thereof so that the currents in the opposite directions can flow to the magnetic material patterns 2 and 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element which utilizes the magnetoresistive effect of a ferromagnetic film to magnetoelectrically convert an external magnetic field to detect fluctuations in the external magnetic field.

A magnetoresistive element utilizing a ferromagnetic pattern is used in a position sensor, an angle sensor, a rotary encoder, etc. because it has a higher sensitivity to a minute magnetic field and an excellent resolution as compared with a Hall element or a magnetic semiconductor element. .
Especially in applications requiring analog output,
Output characteristic linearity is required.

[0003]

2. Description of the Related Art Conventionally, a magnetoresistive element having a linear output characteristic is one which applies a bias magnetic field to a magnetic material pattern by using a permanent magnet, and a large number of conductor layers inclined in the length direction of the magnetic material pattern. There is known a barber pole type which is formed into a striped pattern.

FIG. 6 is an explanatory view of a conventional magnetoresistive element having a linear output. (A) is an external view of a full-bridge type magnetoresistive element using a magnet, and (b) and (c) are barber poles. 3A and 3B are a plan view and a cross-sectional view of a magnetic detection pattern called a mold.

In FIG. 6 (a), the full-bridge type magnetoresistive element has a magnetic material pattern 22 and an external connection pad 23 formed on the surface of a substrate 21 made of silicon or the like, and a magnetic material pattern on the back surface of the substrate 21. A permanent magnet 24 for applying a bias magnetic field is attached to the body pattern 22.

The magnetic material pattern 22 is formed by removing unnecessary portions of a ferromagnetic thin film such as permalloy, and connects a pair of group A whose inclination direction is clockwise and a pair of group B counterclockwise. The permanent magnet 24 applies a bias magnetic field from the upper side to the lower side in the figure, and detects the fluctuation of the external magnetic field orthogonal to the bias magnetic field.

In FIGS. 6B and 6C, a substrate made of silicon or the like is used.
Barber pole-shaped magnetic detection pattern formed on 25
Is a striped pattern 27 made of a ferromagnetic material such as permalloy, and a large number of conductor layers 28 made of gold, for example, in stripes inclined at 45 degrees.
Are formed and configured.

The magnetic pattern 27 is subjected to an initialization process for aligning the direction of internal magnetization in the lengthwise direction, and the applied current i is applied in a direction perpendicular to the conductor layer 27 during the formation of the conductor layer 27. Accordingly, the fluctuation of the external magnetic field applied in the width direction of the magnetic material pattern 27 is detected.

Unlike the magnetic pattern 22, the magnetic detection pattern 26 does not require a permanent magnet.

[0010]

A conventional magnetoresistive element using a magnetic material pattern 22 formed of a magnetic thin film requires a magnet 24 for applying a bias magnetic field.
However, there is a problem that the step of accurately aligning and attaching the element to the element substrate 25 is required, and the output characteristics vary depending on the magnetic force of the magnet and the alignment accuracy of the magnet.

A conventional barber pole type magnetoresistive element in which a conductor layer 28 is formed in stripes on a magnetic material pattern 27 formed of a magnetic thin film requires an initializing step for aligning the directions of internal magnetization of the magnetic material pattern 27. However, since it is necessary to apply a magnetic field in a fixed direction by using a magnet or a coil before use, it is troublesome to use.

Moreover, there is a problem that the output is inverted when a magnetic field in the direction opposite to the initializing direction is applied to the element during magnetic field detection. In order to avoid such output reversal, conventionally, a magnet that applies a bias magnetic field in the initializing direction is arranged, but in the arrangement of the magnet, like the magnetic resistance element that obtains a linear output by the bias magnet, The manufacturing process (sticking of the permanent magnet) becomes complicated, and the accuracy of detecting the external magnetic field is poor.

[0013]

FIG. 1 is a plan view (a) and a side view (b) of a basic structure of a magnetoresistive element according to the present invention, and FIG. 2 shows a relationship between an output of a magnetic material pattern and a bias magnetic field. FIG.

In FIG. 1, a first magnetic material pattern 2 for magnetoelectrically converting an external magnetic field is formed on the surface of a substrate 1 made of silicon (Si) or glass, and an insulating layer on the magnetic material pattern 2 is formed. A second magnetic material pattern 4 that magnetoelectrically converts an external magnetic field is provided on (eg, silicon nitride; SiN) 3.

The magnetic material patterns 2 and 4 facing each other in the thickness direction of the insulating layer 3 are strips of the same width, and the magnetic material patterns 2 and 4 are connected at the right end in the length direction, and at the left end of the magnetic material pattern 2. When the conductor pad 5 is connected and the conductor pad 6 is connected to the left end of the magnetic material pattern 4, the current i flowing in from the conductor pad 5 and flowing out from the conductor pad 6 is
The flow directions are opposite between # 4 and # 4. Therefore, as shown by the white arrow in the figure, the bias magnetic field is applied in the width direction of the magnetic material patterns 2 and 4.

Such a bias magnetic field has an effect of improving linearity as in the case of applying the bias magnetic field by a magnet. That is, when no bias magnetic field is applied to one magnetic material pattern 2'as shown in FIG. 2A, the magnetic resistance change ΔR with respect to the external magnetic field Hex in the width direction (magnetic field sensitive direction) of the magnetic material pattern 2'is: As shown in FIG. 2B, the magnetic field is applied in the width direction to the magnetic pattern 2'while the external magnetic field H in the direction opposite to the bias magnetic field H is applied to the magnetic pattern 2 '.
The magnetic resistance change ΔR with respect to ex comes to change linearly as shown in FIG.

[0017]

As described in the above means, in a magnetoresistive element in which a pair of magnetic material patterns are opposed to each other and a current in the opposite direction is passed, a bias magnetic field in the width direction of the magnetic material pattern is generated by the driving current. Occurs, and by utilizing that bias magnetic field, a linear output can be obtained without a magnet.

[0018]

FIG. 3 is a plan view (a) showing the magnetic material pattern of a magnetoresistive element according to an embodiment of the present invention and its equivalent circuit diagram (b).
Is.

In FIG. 3 (a), an input pad (first terminal) 11 for applying a drive current and a ground pad connected to the ground are provided on an insulating surface of a substrate made of silicon (Si), glass or the like. (Second terminal) 12, output pad (third terminal) 13 for outputting a fluctuation signal of the external magnetic field, and a plurality of first magnets formed on the substrate surface and aligned in the front-back direction (vertical direction in the figure). A body pattern 2, an insulating film (not shown) exposing a predetermined portion of the magnetic body pattern 2, and a plurality of second magnetic body patterns 4 facing the magnetic body pattern 2 via the insulating film. , And conductor patterns 14, 15, 16 and 17 for connecting the magnetic material patterns 2 and 4.

The input pad 11 is at the frontmost position (the highest position in the figure)
To the left end of the magnetic material pattern 2. The ground pad 12 is connected to the right end of the second magnetic body pattern 4 from the frontmost position.

The output pad 13 is at the last position (at the bottom of the figure)
To the right end of the magnetic material pattern 2 and the left end of the second magnetic material pattern 4 from the last position. Conductor pattern
Reference numeral 14 connects the right end of the magnetic material pattern 2 and the right end of the magnetic material pattern 4.

The conductor pattern 15 connects the left end of the magnetic material pattern 2 and the left end of the magnetic material pattern 4. The conductor pattern 16 connects the left end portion of the magnetic material pattern 4 and the left end portion of the magnetic material pattern 2 which is one distance away from the magnetic material pattern 4.

The conductor pattern 17 connects the right end portion of the magnetic material pattern 2 and the right end portion of the magnetic material pattern 4 which is one distance away from it. However, the conductor patterns 14 and 15 are alternately formed in the arrangement direction of the magnetic material patterns 2 and 4.

Therefore, when a predetermined drive current i is input from the input pad 11 to the frontmost (first) magnetic material pattern 2, the current i is the first magnetic material pattern 4 → the third magnetic material pattern 2 → Third magnetic material pattern 4 → ...
-> The second magnetic material pattern 2 from the last position (last) → the second magnetic material pattern 4 from the last → the output pad 13
→ Last magnetic material pattern 2 → Last magnetic material pattern 4 →
---> It leads to the second magnetic material pattern 4-> ground pad 12.

When such a current i is passed, the input pad
In the magnetic material patterns 2 and 4 connected between the output pad 13 and the output pad 13, a bias magnetic field Hb ₁ directed in the width direction and downward in the drawing is generated, so that the output pad 13 and the ground pad 12 are connected to each other. A bias magnetic field Hb ₂ is generated in the connected magnetic patterns 2 and 4 in the width direction thereof and in the upward direction of the drawing.

Therefore, when the magnetic material patterns 2 and 4 which generate the bias magnetic field Hb ₁ are group A and the magnetic material patterns 2 and 4 which generate the bias magnetic field Hb ₂ are group B, the input pad 11 and the output pad 13 are used. The magnetic patterns 2 and 4 connected between the output pad 13 and the ground pad 12 are group A.
The magnetic material patterns 2 and 4 connected between and form the B group.

Therefore, the equivalent circuit of the magnetoresistive element of FIG. 3A has a half-bridge structure in which the magnetic substance pattern group A and the magnetic substance pattern group B are connected as shown in FIG. 3B. By matching the direction of the bias magnetic field Hb ₁ or Hb _{2 with} the direction of the external magnetic field to be detected, the fluctuation of the external magnetic field can be detected.

FIG. 4 is a plan view (a) showing the magnetic pattern of a magnetoresistive element according to another embodiment of the present invention and its equivalent circuit diagram (b). In FIG. 4 (a), an input pad (first terminal) 11 for applying a driving current and a ground pad (second terminal) for applying a driving current are formed on the insulating surface of a substrate made of silicon (Si) or glass. Terminal) 12 and an output pad (third and fourth terminals) 1 for outputting a fluctuation signal of the external magnetic field
3 _-1 , 13 _-2 , a plurality of first magnetic material patterns 2 formed on the surface of the substrate and aligned in the front-back direction (vertical direction in the figure), and an insulating film exposing a predetermined portion of the magnetic material pattern 2 ( (Not shown)
And a plurality of second magnetic material patterns 4 facing each of the magnetic material patterns 2 through the insulating film, and conductor patterns 14, 15, 16, 17 connecting the magnetic material patterns 2 and 4 to each other. .

The input pad 11 is at the frontmost position (the highest position in the figure)
To the left end of the magnetic material pattern 2. The ground pad 12 is connected to the left end of the magnetic material pattern 2 at the last position (the lowest in the figure) and the right end of the second magnetic material pattern 4 from the last position.

The output pad 13 _-1 is connected to the right ends of the pair of magnetic material patterns 2 adjacent to the center of the alignment. The output pad 13 _-2 is connected to the left end portion of the pair of magnetic material patterns 4 located before and after the magnetic material pattern 2 to which the output pad 13 _-1 is connected.

The conductor pattern 14 connects the right end of the magnetic material pattern 2 and the right end of the magnetic material pattern 4. The conductor pattern 15 connects the left end of the magnetic material pattern 2 and the left end of the magnetic material pattern 4.

The conductor pattern 16 connects the left end portion of the magnetic material pattern 4 and the left end portion of the magnetic material pattern 2 which is one distance away from the magnetic material pattern 4. The conductor pattern 17 connects the right end portion of the magnetic material pattern 2 and the right end portion of the magnetic material pattern 4 which is one distance away from the right end portion.

The conductor patterns 14 and 15 are alternately formed in the arrangement direction of the magnetic material patterns 2 and 4. However, since the same ends of the magnetic material patterns 2 and 4 are connected at the central portion in the alignment direction, the conductor patterns 14 (or
15) is continuously formed.

Therefore, a predetermined drive current i is input from the input pad 11 to the frontmost (first) magnetic material pattern 2 and the second magnetic material pattern 4 from the front. Then, one of the currents i is the first magnetic material pattern 4 → the third magnetic material pattern 2 → the third magnetic material pattern 4 →
・ → Output pad 13 _-2 → ・ ・ ・ ・ ・ ・ → Last position (Last)
Magnetic material pattern 4 → the last magnetic material pattern 2 → the ground pad 12, and the other side of the current i is the second magnetic material pattern 2 → the fourth magnetic material pattern 4 → the fourth magnetic material pattern 2 → ・ ・ ・ ・ ・ ・ → Output pad 13 _-1
→ ・ ・ ・ ・ ・ ・ → The second-to-last magnetic material pattern 2 →
The penultimate magnetic material pattern 4 → ground pad 12
Lead to.

When such a current i is passed, the input pad
In the magnetic material patterns 2 and 4 connected between the output pad 13 _-2 and the output pad 13 _-2 , a bias magnetic field Hb ₁ directed in the width direction and downward in the figure is generated, and the output pad 13 _-2 and the ground pad 12 are connected.
A bias magnetic field Hb ₂ directed in the width direction and upward in the drawing is generated in the magnetic patterns 2 and 4 connected between
In the magnetic material patterns 2 and 4 connected between the input pad 11 and the output pad 13 _-1 , a bias magnetic field Hb ₂ is generated in the width direction and upward in the figure, and the output pad 13 _-1 and the ground are provided. The magnetic patterns 2 and 4 connected between the pad 12 and the pad 12 have a bias magnetic field Hb ₁ directed in the width direction and downward in the drawing.
Will occur.

Therefore, when the magnetic material patterns 2 and 4 which generate the bias magnetic field Hb ₁ are group A and the magnetic material patterns 2 and 4 which generate the bias magnetic field Hb ₂ are group B, the input pad 11 and the output pad 13 are used. magnetic pattern 2 and 4 connected between _-2 becomes group a, magnetic pattern 2 and 4 which are connected between the output pad 13 _-2 and the ground pad 12 becomes group B, the input pad 11 The magnetic material patterns 2 and 4 connected between the output pad 13 _-1 and the output pad 13 _-1 are group B, and the output pad 13 _-1
The magnetic material patterns 2 and 4 connected between the ground pad 12 and the ground pad 12 are classified into the A group.

Therefore, the magnetoresistive element of FIG. 4 (a) has a full bridge structure in which a pair of A pattern group and B pattern group are connected, and its equivalent circuit is shown in FIG. 4 (b). In the above embodiment, the magnetic patterns 2, 4
Is formed by a photolithography method from a thin film made of a ferromagnetic material such as permalloy and having a thickness of 500 to 1000Å. The insulating film is made of silicon oxide or polyimide resin to have a thickness of several thousand Å to 1 μm, Gold and aluminum were used for the conductor pattern.

FIG. 5 is an explanatory diagram (a) of the magnetoresistance change of the magnetic material pattern of the magnetoresistive element according to the embodiment of the present invention and an explanatory diagram (b) of the output characteristic of the magnetoresistive element. In FIG. 5A, the magnetic resistance change ΔR _{−1 of} the magnetic material pattern A and the magnetic resistance change ΔR ₋₂ of the magnetic material pattern B corresponding to the change of the external magnetic field Hex are reversed in the tilt direction as shown in the figure. Three
(B), The output of the magnetoresistive element in which the magnetic material patterns A and B are connected to the half bridge or the full bridge as shown in FIG. 4 (b) is as shown in FIG. 5 (b) without using a magnet. A linear output can be obtained similarly to the conventional barber pole type element.

[0039]

As described above, according to the present invention, the bias magnetic field is generated by the driving current, and the linear output can be obtained by the bias magnetic field.

Therefore, the step of attaching the bias magnetic field applying magnet, the bias magnetic field stabilizing magnet, and the bias magnet to the element substrate becomes unnecessary, and the conventional magnetoresistive element using the magnet for applying the bias magnetic field and Compared to the conventional barber pole type magnetoresistive element that requires a magnet for the initialization process and bias magnetic field stabilization, the output characteristics are not only stable and highly sensitive, but also provided at a low cost. There is.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of a magnetoresistive element according to the present invention.

FIG. 2 is an explanatory diagram of a relationship between an output of a magnetic material pattern and a bias magnetic field.

FIG. 3 is an explanatory diagram of a magnetoresistive element according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a magnetoresistive element according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram of magnetoresistance change and output characteristics of a magnetoresistive element according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional magnetoresistive element.

[Explanation of symbols]

1 is an element substrate 2, 4 is a magnetic material pattern 3 is an insulating film 11 is a first terminal (input pad) 12 is a second terminal (ground pad) 13, 13 _-1 is a third terminal (output pad) 13 _-2 is the fourth terminal (output pad) 14 is the conductor pattern for connecting one end of the opposing magnetic material pattern 16, 17 is the conductor pattern i is the drive current

Claims (4)

[Claims] 1. A first magnetic material pattern (2) for magnetoelectrically converting an external magnetic field through a current (i) in a predetermined direction, an insulating film (3) laminated on the first magnetic material pattern, and the insulation. A second magnetic material pattern (4) which opposes the first magnetic material pattern in the thickness direction through the film and which magnetoelectrically converts an external magnetic field through a current in a direction opposite to the first magnetic material pattern. A magnetoresistive element characterized by being provided. 2. The first magnetic material pattern according to claim 1.
The one end in the length direction of (2) and the one end in the length direction of the second magnetic material pattern (4) according to claim 1 are connected, and the first magnetic material pattern and the second magnetic material are connected. 2. The current (i) in the opposite direction to the pattern is made to flow to the pattern.
The magnetoresistive element described. 3. A plurality of the first and second magnetic material patterns (2, 4) connected at one end are aligned in the width direction, and the second magnetic material pattern is arranged every other in the alignment direction. And the other end of the first magnetic material pattern are connected by a conductor pattern (16, 17), and the other ends of the first magnetic material pattern which is the first in the alignment direction are connected to the first and second The first terminal (11) for passing an electric current is connected to the magnetic material pattern of the second magnetic material pattern, and the second terminal of the second magnetic material pattern which is second in the alignment direction is connected to the first and second terminals.
Second terminal (12) for passing current through the magnetic material pattern of
Are connected to the other end of the last first magnetic material pattern in the alignment direction and the other end of the penultimate second magnetic material pattern in the alignment direction. A magnetoresistive element, characterized in that a third terminal (13) for outputting a magnetoelectrically converted signal of the body pattern is connected. 4. A plurality of the first and second magnetic material patterns (2, 4) connected at one end are aligned in the width direction, and the second magnetic material pattern is arranged every other in the alignment direction. And the other end of the first magnetic material pattern are connected by a conductor pattern (16, 17), and the other end of the first magnetic material pattern which is the first in the alignment direction and the second end of the first magnetic material pattern in the alignment direction. A first terminal (11) for passing a current through the first and second magnetic material patterns is connected to the other end of the second magnetic material pattern, and is the last first magnetic material in the alignment direction. The other end of the pattern and the other end of the penultimate second magnetic material pattern in the alignment direction are provided with a second terminal (12) for passing a current through the first and second magnetic material patterns. They are connected to each other, and the magnetoelectric conversion signals of the first and second magnetic material patterns are output to the other ends of the pair of first magnetic material patterns at the center in the alignment direction. Third terminal (13 _-1) is connected, the first first them to a pair of second magnetic pattern before and after magnetic pattern, a second magnetic pattern to the terminal of the third is connected A magnetoresistive element characterized by being connected to a fourth terminal (13 _-2 ) for outputting the magnetoelectrically converted signal of.