JPH04303979A - Magnetoresistance element - Google Patents

Abstract

PURPOSE:To provide a magnetoresistance element with an improved magnetoresistance effect, a high sensitivity, and a high output. CONSTITUTION:A title item is provided with a base 9 consisting of an insulation material, a pattern 8 consisting of a magnetoresistance film 81 which is formed on the base 9, and an electrode 7 which is electrically connected to the pattern 8. Then an auxiliary magnetic pole 10 consisting of a thin-film high permeability film 1 is formed on the entire surface of the base 9 and the pattern 8, thus enabling a diamagnetic field coefficient to be reduced and a sensitivity in a low magnetic field also to be improved.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has excellent magnetoresistive effect and
The present invention relates to highly sensitive and high output magnetoresistive elements.

0002

2. Description of the Related Art Magnetoresistive elements utilize the anisotropic magnetic effect, that is, the development in which the electrical resistance of a ferromagnetic metal changes anisotropically depending on the angle formed between the magnetization direction and the current direction. As shown in FIG. 8, the magnetoresistive element includes a substrate 9 made of an insulating material such as quartz, and an I layer formed on the substrate 9.
It consists of a comb-shaped pattern 8 made of a magnetoresistive film 81 having a large magnetoresistive effect, such as nSb or Ni-Co, and an electrode 7 electrically connected to the pattern 8. The above-mentioned magnetoresistive effect is the resistance generated in the magnetoresistive film 81 through which current flows due to the application of a magnetic field.

Furthermore, since the magnetoresistive element is a magnetic sensor that utilizes the magnetoresistive effect, it also has a magnetic anisotropy effect in which the resistance value changes in the direction of the magnetic field. By the way, the relationship between the magnetic field and the rate of change in resistance of the magnetoresistive element is such that when a magnetic field parallel to the magnetoresistive element acts, the rate of change in resistance is maximum, while when a magnetic field perpendicular to the element acts, the rate of change in resistance is the minimum. becomes. Therefore, magnetoresistive elements are used in combination with magnetic rotors to utilize this property, and are used in vehicle speed sensors for speedometers and VTRs (VTRs) to detect the rotational speed as an electrical signal.
It is used as a rotation sensor for video).

0004

[Problem to be Solved] However, the above-mentioned conventional technology has the following problems. That is, as shown in FIG. 8, the pattern 8 made of the magnetoresistive film 81 has a comb shape, and the stripe width W between each row is extremely narrow. Therefore,
Magnetoresistive elements have a large demagnetizing field coefficient. The magnetoresistive effect and sensitivity of the magnetoresistive element decrease in low magnetic fields, making it impossible to obtain high sensitivity and high output. The above-mentioned demagnetizing field coefficient is a coefficient that gives the relationship between the strength of magnetization of a magnetic body and the strength of the demagnetizing field. The present invention has been made in view of the above-mentioned conventional problems, and aims to provide a magnetoresistive element with excellent magnetoresistive effect, high sensitivity, and high output.

[0005]

[Means for Solving the Problems] The present invention includes a substrate made of an insulating material, a pattern made of a magnetoresistive film formed on the substrate,
A magnetoresistive element having an electrode connected to the pattern, characterized in that an auxiliary magnetic pole made of a thin film-like high magnetic permeability film is formed on the entire surface of one of the magnetoresistive films. . The most noteworthy feature of the present invention is that an auxiliary magnetic pole made of a thin film-like high magnetic permeability film is formed on one of the surfaces of the magnetoresistive film, that is, the entire front side or the entire back side. be. The thin film-like high magnetic permeability film has a film thickness of, for example, 0.02 to 0.
There is a film with a large magnetic induction capacity that is 10 μm thick and has a flat plate shape. The material for the high magnetic permeability film is CoFe2
O4, Li0.5 Fe2.5 O4, ZnFe2
O4, FeSi, FeAl, FeAlSi, MnF
e2 O4, permalloy (78.5% Ni-Fe) alloy, etc.

[0006] Furthermore, as the substrate, for example, quartz (S
There are insulating materials made of iO2), glass, alumina, etc. Further, as the above-mentioned magnetoresistive film, there are metal films such as NiCo, NiFe, and InSn, which have large anisotropy and magnetoresistive effect. Further, as the above-mentioned electrode, for example, FeNi, F
There are metal films such as e, Ni, and Al. In manufacturing the magnetoresistive element, a magnetoresistive film, a high magnetic permeability film, an insulating film, and an electrode film are formed on the substrate. Therefore, thin film formation techniques such as vacuum evaporation and sputtering are used to
First, either the above magnetoresistive film or high magnetic permeability film is formed. That is, for the above magnetoresistive film, after forming a solid thin film using the above thin film forming technique, forming a resist film,
For example, a comb-shaped pattern is formed using a series of pattern forming techniques including exposure, development, etching, and film peeling.

On the other hand, regarding the above-mentioned high magnetic permeability film, unlike the above-mentioned magnetoresistive film, a flat plate (
It is formed into a solid thin film. Further, the insulating film is formed on the high magnetic permeability film by the thin film forming technique described above. Then, a pattern made of the magnetoresistive film is formed on the insulating film. Further, a protective film is formed on the pattern as necessary. Then, electrode films are formed on both ends of the pattern made of the magnetoresistive film using the thin film forming technique described above. The electrode film is electrically connected to the magnetoresistive film. Furthermore, the substrate can be placed obliquely to the evaporation source and sputtering target when performing vacuum evaporation or sputtering. Further, it is preferable that the film is formed with a magnetic pole placed behind the substrate, and that the substrate is placed so that the longitudinal direction forms the axis of easy magnetization.

[0008]

[Operations and Effects] In the magnetoresistive element according to the present invention, an auxiliary magnetic pole made of a thin film with high magnetic permeability is formed on the surface of either the substrate or the magnetoresistive film. The auxiliary magnetic pole is made of a high magnetic permeability film so as to enhance the magnetic induction effect and the magnetoresistive effect. Therefore, the auxiliary magnetic pole acts to lower the demagnetizing field coefficient with respect to the pattern made of the magnetoresistive film. Thereby, the auxiliary magnetic pole increases the magnetoresistive effect and sensitivity of the magnetoresistive element even in a low magnetic field. Therefore, the above auxiliary magnetic pole is
In a low magnetic field, even if the pattern has a comb shape with a narrow stripe width, it works to increase the rate of change in resistance, increase sensitivity, and produce high output. As described above, according to the present invention, it is possible to provide a magnetoresistive element with excellent magnetoresistive effect, high sensitivity, and high output.

[0009]

[Example] Example 1 Regarding the magnetoresistive element according to Example 1 of the present invention, FIGS.
This will be explained using FIG. 4. That is, the magnetoresistive element of this example is
As shown in FIGS. 1 and 2, a substrate 9 made of an insulating material,
It has a comb-shaped pattern 8 made of a magnetoresistive film 81 formed on the substrate 9, and an electrode 7 connected to the pattern 8. As shown in FIG. 1, a thin high magnetic permeability film 1 is formed on the surfaces of the substrate 9 and the pattern 8. A quartz substrate is used as the substrate 9 made of the above-mentioned insulating material. Further, the magnetoresistive film 81 has a thickness of 100 mm.
It consists of a μm Ni-Co film.

The high magnetic permeability film 1 is a film having a thickness of 60 nm. Further, the electrode 7 is made of Ni with a thickness of 200 nm.
It consists of a double layer film of and Fe. Next, a method for manufacturing the above magnetoresistive element will be explained using FIG. 3. FIG. 3 is a process explanatory diagram showing the manufacturing procedure of the magnetoresistive element. first,
A solid thin film of Ni-Co with a thickness of about 100 nm is deposited on a substrate 9 made of quartz (SiO2) by vacuum evaporation.
A magnetoresistive film 81 is formed. At this time, the evaporation source (
(not shown), the substrate 9 is placed diagonally. As a result, as shown in FIG. 2, an axis of easy magnetization is formed in the longitudinal direction B of the comb-shaped pattern 8.

Next, a photoresist solution (not shown) consisting of a dry film is applied onto the magnetoresistive film 81.
Let it harden. Next, as shown in FIG. 2, in order to form a comb-shaped pattern 8, the resist film is exposed and developed. Then, a comb-shaped pattern 8 is selectively etched using an etching liquid gas. Thereafter, the resist film is peeled off to complete pattern formation. Note that the pattern 8 has a stripe width W of approximately 20 μm. Next, as shown in Figure 1,
The portion where the electrode 7 will be formed is masked with a thin SUS plate 71. Then, the board 9 other than the masked part is
CoF, a soft ferrite with high resistivity, is deposited on the surface of
A high magnetic permeability film 1 of e2O4 is formed into a thin film. The high magnetic permeability film 1 is formed in a solid manner over the comb-shaped pattern 8 and the other surface of the substrate 9.

Next, parts other than the electrode 7 are masked using a thin SUS plate. Then, an electrode 7 made of a double layer film of Ni and Fe is formed in the masked part, that is, in the electrode forming part. Thereby, the electrode 7 is electrically connected to both ends of the pattern 8. Furthermore, since the electrode 7 is made of a double layer of Ni and Fe, solder does not penetrate therethrough. Next, using FIGS. 9 and 10, Comparative Example 1
, 2 will be explained. First, as shown in FIG. 9, a magnetoresistive element as Comparative Example 1 has a comb-shaped high magnetic permeability film 51 formed between the magnetoresistive films 81.

However, since the high magnetic permeability film 51 is formed adjacent to the comb-shaped magnetoresistive film 81, it is difficult to form a uniform film. This is done by first forming a comb-shaped pattern on either the magnetoresistive film 81 or the high magnetic permeability film 51, and then uniformly applying photoresist to form the other pattern in the meantime. This is because it is difficult. The rest is the same as in the first embodiment. Next, Figure 10
As shown in FIG. 8, the material and manufacturing method of the magnetoresistive element as Comparative Example 2 are the same as those shown in the conventional example (FIG. 8).

For each magnetoresistive element of Example 1 of the present invention, the relationship between the magnetic field (H) and the resistance value (R) was measured in order to evaluate the effective magnetoresistive effect. Moreover, this result is shown in the graph of FIG. As shown in Figure 5, Example 1 has a high Rmax (sensitivity) in a low magnetic field,
The magnetoresistive effect curve is sharp. As is clear from the above results, the magnetoresistive element of Example 1 has significantly improved magnetoresistive effect. This is because the demagnetizing field coefficient becomes smaller.

That is, in the magnetoresistive element of this example, an auxiliary magnetic pole made of a solid, thin film-like high magnetic permeability film 1 is formed on the entire surface of the magnetoresistive film 81. The auxiliary magnetic pole is constituted by a high magnetic permeability film 1 so as to enhance the magnetic induction effect and the magnetoresistive effect. Therefore, the above auxiliary magnetic pole is
The pattern 8 made of the magnetoresistive film 8 acts to lower the demagnetizing field coefficient. As a result, the auxiliary magnetic pole increases the magnetoresistive effect and sensitivity of the magnetoresistive element even in a low magnetic field. Therefore, in a low magnetic field, even if the pattern has a comb shape with a narrow stripe width, the auxiliary magnetic pole increases the rate of resistance change, increases the sensitivity, and works to output high output.

Next, FIG. 4 shows the magnitude of the magnetic field H and the resistance value R.
This is a graph that has a relationship with . In this graph,
A state in which the magnetic field H=0 and the resistance value R=0 (Ro) is shown. Then, when the magnetic field H is gradually increased, the resistance value R increases once and eventually reaches the maximum value Rmax. Here, in view of the characteristics of the magnetoresistive element, it is ideal that H=0 and Rmax. However, in reality, Rmax is not achieved when H=0 due to the spin pinning effect of the magnetoresistive element. However, in the magnetoresistive element of Example 1, H=
0 is Rmax. This is due to the magnetoresistive effect produced by forming the solid, thin, high magnetic permeability film 1 on the magnetoresistive film 81.

In other words, the high magnetic permeability film 1 having high specific resistivity
The formation of , increases the effective magnetic field change when changing the magnetic field. Due to this, the demagnetizing field coefficient decreases. Therefore, Rmax (sensitivity) in a low magnetic field increases. Therefore, as shown in FIG. 4, it is known that in Example 1, the demagnetizing field coefficient is reduced and the sensitivity in low magnetic fields is increased.

That is, in the magnetoresistive element of Example 1, as shown in FIG. 1, the pattern 8 has a comb shape with a narrow stripe width W. Therefore, the demagnetizing field coefficient generally becomes large. However, in the magnetoresistive element of Example 1, as shown in FIG. A high magnetic permeability film 11 is formed. Therefore, this makes it possible to reduce the demagnetizing field coefficient of the entire magnetoresistive element. Also, hysteresis is reduced. Therefore, the magnetoresistive element of Example 1 has a small resistance change rate in a low magnetic field, and has high sensitivity and high output. Further, the high magnetic permeability film 1 has a function as a protective film for the pattern 8 made of the magnetoresistive film 81. Furthermore, since the high magnetic permeability film 1 is not patterned into a comb shape, manufacturing is easier than in Comparative Example 1 described above. In addition, as in Comparative Example 2 above, in a low magnetic field, Rmax (sensitivity)
never becomes low.

Embodiment 2 As shown in FIG. 6, the magnetoresistive element of this embodiment includes a solid thin high magnetic permeability film 1 formed on the surface of a substrate 9, an insulating film 2 formed on the surface, Comb-shaped pattern 8 on its surface
was formed. Further, a protective film 4 is formed on the pattern 8. The rest is the same as the magnetoresistive element of Example 1 above. The above magnetoresistive element is manufactured as follows. That is, as shown in FIGS. 6 and 7, a ferrite film (Li0.5 Fe2.5
A solid, thin, high magnetic permeability film 12 made of O4) is formed.

Next, as shown in FIG. 6, an insulating film 2 is formed on the high magnetic permeability film 12. Next, a solid thin magnetoresistive film 81 is formed on the insulating film 2 in a vacuum. This prevents pinholes from forming in the magnetoresistive film 81. As shown in FIG. 7, the above Example 1
Similarly, a resist film made of ultraviolet curing resin is then formed on the magnetoresistive film to form a pattern, and the resist film is exposed and developed. Next, the resist film is selectively etched with an etching solution (ferric chloride aqueous solution) to form a pattern 8 as shown in FIG. 6, and then the film is peeled off. As a result, a magnetoresistive film 81 having a comb-shaped pattern is formed. Note that the etching solution used is one that does not react with the insulating film 2.

Next, on the pattern 81, Al2
A protective film 4 made of O3 is formed by sputtering. At both ends of the pattern 8, Ni and F
An electrode 7 consisting of a double layer with e is formed. As a result,
Solder will no longer penetrate into the electrode 7. In this example, an insulating film 2 is placed between the pattern 8 and the high permeability film 12.
is formed. Therefore, no leakage occurs between the two. Further, a protective film 4 is formed on the pattern 81. Therefore, the pattern 8 has excellent durability. Other effects similar to those of the first embodiment can be obtained.

[Brief explanation of drawings]

FIG. 1 A- of the magnetoresistive element (FIG. 2) according to Example 1
A sectional view taken along arrow A.

FIG. 2 is a plan view of the magnetoresistive element according to Example 1.

FIG. 3 is a process explanatory diagram showing the manufacturing procedure of the magnetoresistive element of Example 1.

FIG. 4 is a graph showing the relationship between magnetic field strength and resistance value in Example 1.

FIG. 5 is a graph showing the relationship between magnetic field strength and resistance value in Example 1.

FIG. 6 is a cross-sectional view of a magnetoresistive element according to Example 2.

FIG. 7 is a process explanatory diagram showing the manufacturing procedure of the magnetoresistive element of Example 2.

FIG. 8 is a plan view of a conventional magnetoresistive element.

FIG. 9 is a cross-sectional view of a magnetoresistive element as Comparative Example 1.

FIG. 10 is a cross-sectional view of a magnetoresistive element as Comparative Example 2.

[Explanation of symbols]

1,12. ．． ．． High permeability film, 10. ．． ．． Auxiliary pole, 2. ．． ．． Insulating film, 4. ．． ．． Protective film, 7. ．． ．． electrode, 8. ．． ．． pattern, 81. ．． ．． magnetoresistive film, 9. ．． ．． substrate, W. ．． ．． stripe width,

Claims (1)

[Claims] Claim 1: A magnetoresistive element comprising a substrate made of an insulating material, a pattern made of a magnetoresistive film formed on the substrate, and an electrode connected to the pattern, wherein either surface of the magnetoresistive film is A magnetoresistive element characterized by having an auxiliary magnetic pole formed entirely of a thin film with high magnetic permeability.