JPH03219682A - Magnetoresistance element - Google Patents

Abstract

PURPOSE:To prevent a magnetic film from being damaged in a film-formation process and enable characteristics of a magnetoresistance element to be improved and stabilized by protecting the magnetic film at a part to be etched with an intermediate layer and at the same time by protecting the magnetic film at a part to be left without etching by coating a photoresist when patterning an adhesive layer or a conductive film by ion etching. CONSTITUTION:An intermediate layer 3 is clad on a magnetic film 2, a barber pole type detection hole 3a is provided at this intermediate layer 3, and a lead hole 3b is provided at the middle layer of a lead region 9c. Then, after cladding an adhesive layer 4 and a conductive film 5 onto the front of the element, the detection hole and the lead hole parts are coated with photoresist. Ion etching is performed in this state for eliminating the adhesive layer and conductive film coating the intermediate layer other than the detection hole and lead hole. Finally, the photoresist is released and a protection film is provided over the entire surface. Then, the adhesive layer and conductive film which are adhered to the magnetic film through the detection hole and the lead hole so that they can conduct current can be protected by photoresist when performing ion etching, are not affected by etching, and the magnetic film cannot be damaged at all.

Description

[Detailed Description of the Invention] [Summary] Regarding a magnetoresistive element, the purpose is to prevent the magnetic film from being damaged when patterning a conductive film, and the present invention includes a substrate, a magnetic film, an intermediate layer, an adhesive layer, The substrate has a conductive film and a protective film, and the substrate supports an element,
The magnetic film has insulating properties, the magnetic film is adhered to the substrate in the shape of an element pattern, and the intermediate layer is ferromagnetic, and the intermediate layer is adhered to the magnetic film. The intermediate layer has an insulating property, and the intermediate layer has a detection hole in which a magnetic film is exposed in a barber-pole pattern shape in the detection region of the element, and a magnetic film in the lead region. It has a lead hole that exposes
The adhesive layer maintains adhesion between the magnetic film and the conductive film and is electrically conductive, and the conductive film is adhered to the adhesive layer and has an adhesive property. It is applied to the magnetic film in a conductive manner through the layer and through the detection hole and the lead hole, and when the conductor film is patterned together with the adhesive layer, the detection hole and the lead hole are covered with photoresist. The protective film is applied to the intermediate layer other than the terminal and the conductor film after the photoresist is peeled off, and is likely to have insulating properties. Configure.

(Industrial Field of Application) The present invention relates to a magnetoresistive element, and particularly to a structure that does not damage a magnetic film when a conductive film is provided in a barber-pole magnetoresistive element.

A magnetoresistive element is a type of sensor that utilizes the magnetoresistive effect of a ferromagnetic material, such as permalloy (trade name for each fiFe alloy with high magnetic permeability, mainly composed of Ni), and has high sensitivity and temperature stability. good.

Therefore, for example, various sensors such as magnetic pattern reading sensors, position sensors, power sensors, etc.
Recently, they have attracted attention in the field of car electronics such as vehicle height sensors and acceleration sensors, but in all applications, it is a prerequisite that a linear output can be obtained with respect to an external magnetic field.

To this end, in the manufacturing process of the magnetoresistive element, it is especially important to have a film forming technique that does not damage the magnetic film.

[Conventional technology]

FIG. 8 is a partially enlarged plan view of FIG. 7, FIG. 9 is a partially enlarged sectional view of section 7, and FIG. 10 is a diagram showing an example of the structure of the magnetoresistive element shown in FIG. A film forming process diagram, FIG. 11, shows an example of characteristics of a magnetoresistive element.

In the figure, 1 is a substrate, 2 is a magnetic film, 4 is an adhesive layer, 5 is a conductor film, 6 is a protective film, 8 is a terminal, 9 is a magnetoresistive element, and 10 is an ion flow.

In FIGS. 7 to 9, the substrate 1 is, for example, a glass substrate with a thickness of several hundred μm or a silicon wafer whose surface is coated with SiOz, SiN, or the like.

On the substrate 1, a magnetic film 2 made of a ferromagnetic material such as permalloy and having a thickness of several tens to hundreds of nanometers is provided by vapor deposition or the like. This magnetic film 2 is generally etched into the pattern shape of the element 9a by photolithography.

Next, on the magnetic film 2, for example, a Tt film having a thickness of several tens of nanometers is applied.
An adhesive layer 4 such as or Cr is provided, and the adhesive layer 4
For example, a conductor If! such as Au with a film thickness of several hundred nm is placed on top of the conductor If!
J5 is provided by vapor deposition, sputtering, or the like.

The adhesive layer 4 and the conductor film 5 are finished into a so-called barber pole type element 9a resembling a herringbone pattern by, for example, ion etching using Ar gas.

Finally, except for the terminal 8 part, the whole
Made of materials with excellent corrosion resistance such as SiN and SiN, the film thickness is 1 μm.
The magnetoresistive element 9 is completed by covering with a protective film 6 having a thickness of about m.

The knee has a half-bridge circuit configuration with two terminals 8a and one common terminal 8b, and is connected to a differential amplifier circuit (not shown) and used as a sensor.

In order to use this magnetoresistive element 9 as a sensor, initial magnetization 9d is first performed in the longitudinal direction of the magnetoresistive element 9. When detecting the external magnetic field, an external field 9e in a direction perpendicular to the longitudinal direction of the magnetoresistive element 9 is detected.

By the way, in FIG. 1O, it is difficult to perform patterning by wet etching without damaging the magnetic film 2. Therefore, in the conventional film forming process of the magnetoresistive element 9, the adhesive layer 4 and the conductor film 5 are patterned by ion etching using Ar gas.

The ion flow 10 first etches the conductive film 5 one after another,
After etching of the conductor film 5 is completed, the adhesive layer 4 is then etched.

However, the adhesive N4 is a layer for gluing and is very thin. Moreover, this ion etching lacks controllability and has poor reproducibility. Therefore, it is extremely difficult to stop the etching exactly at the interface between the magnetic film 2 and the adhesive layer 4.

On the other hand, since not only the conductor film 5 but also the adhesive layer 4 has conductivity, it cannot be left on the magnetic film 2.

Therefore, if an attempt is made to completely remove the adhesive layer 4 and the conductive film 5, over-etching tends to occur.

As a result, a metallic magnetic layer 1 of the same quality as the adhesive layer 4 and the conductive film 5 is formed.
M! 2 is damaged, the linearity of the magnetoresistive element 9 deteriorates, and as shown in FIG. 11, it often happens that, for example, a hysteresis phenomenon appears in the output characteristics.

[Problems to be Solved by the Invention] As mentioned above, conventional magnetoresistive elements that use a ferromagnetic material with high magnetic permeability, such as permalloy, as a magnetic film have problems with adhesive provided on the magnetic film. When patterning the layer and conductor film, ion etching using Ar gas, for example, is used since chemical etching is difficult.

However, since this ion etching lacks controllability, there is a problem in that the magnetic film is damaged due to overetching.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetoresistive element in which ion etching is performed without forming a magnetic film when patterning the adhesive layer and the conductor film.

(Means for Solving the Problems) The problems described above include a substrate, a magnetic film, an intermediate layer, an adhesive layer, a conductive film, and a protective film, and the substrate supports an element. The magnetic film is adhered to the substrate in the shape of an element pattern and has ferromagnetism; The intermediate layer is adhered to the magnetic film. The intermediate layer is a sensing hole in which the magnetic film is exposed in a barber-pole pattern shape in the sensing region of the element, and a sensing hole in the lead region of the element. The adhesive layer has a lead hole through which the magnetic film is exposed, the adhesive layer maintains adhesion between the magnetic film and the conductive film, and has electrical conductivity, and the conductive film includes: The conductor film is attached to the adhesive layer so as to be electrically conductive to the magnetic film through the adhesive layer and through the detection hole and the lead hole, and the conductor film is patterned together with the adhesive layer. During the process, the detection hole and the lead hole are covered with photoresist and ion-etched, and after the photoresist is peeled off, the protective film is applied to the intermediate layer other than the terminal and the conductor film. The problem is solved by a magnetoresistive element configured to have an insulating property.

(Function) As mentioned above, conventionally, buttering of the adhesive layer and conductive film has been done by ion etching since chemical etching cannot be performed because the magnetic film has no resistance, but ion etching has poor controllability. In contrast, in the present invention, the magnetic film is prevented from being damaged even when ion etching is performed.

That is, an intermediate layer is deposited on the magnetic film, barber pole type detection holes are provided in the intermediate layer in the sensing region of the element, and lead holes are provided in the intermediate layer in the lead region.

After applying an adhesive layer and a conductive film to the entire surface of the element, the detection hole and lead hole are covered with photoresist.

In this state, ion etching is performed to remove the adhesive layer and conductor film covering the intermediate layer other than the detection hole and lead hole.

Finally, the photoresist is peeled off to provide a protective film over the entire surface.

In this case, the adhesive layer and the conductor film, which are in close contact with the magnetic film through the detection hole and the lead hole, are protected by the photoresist during ion etching, so they are not affected by etching, and therefore the magnetic film is also etched. It will not be damaged at all.

On the other hand, the adhesive layer and conductive film covering the intermediate layer are over-etched to completely remove them, and there is no problem even if the intermediate layer is etched to some extent.

Thus, according to the present invention, a magnetoresistive element can be obtained without damaging a magnetic film that does not have good resistance to etching during the film forming process.

[Example] Fig. 1 is a partially cutaway perspective view explaining the present invention in detail, Fig. 2 is a partially enlarged sectional view of Fig. 1, Fig. 3 is a perspective view of the magnetic film of Fig. 1, 4 is a perspective view of the intermediate layer shown in FIG. 1, FIG. 5 is a film forming process diagram of the adhesive layer and conductor film shown in FIG. 1, and FIG. 6 is a characteristic diagram of the magnetoresistive element.

In the figure, ■ is a substrate, 2 is a magnetic film, 3 is an intermediate layer, 3a is a detection hole, 3b is a lead hole, 4 is an adhesive layer, 5 is a conductor film, 6 is a protective film, 7 is a photoresist, 8 is a terminal, 9 is a magnetoresistive element, 9a is an element, 9b is a detection area, 9C is a lead area 9C
It is.

In FIGS. 1 to 3, the substrate 1 has a thickness of 1, for example.
mm glass substrate or 700 μm surface is thermally oxidized
A silicon wafer coated with iOt is used.

On the substrate l, a magnetic film 2 made of a ferromagnetic material such as permalloy and having a thickness of, for example, 100 nm is provided by vapor deposition or the like. This magnetic film 2 is etched into the pattern shape of the element 9a by, for example, photolithography.

Next, in FIGS. 1 to 4, a film of Sin! having a thickness of 400 nm, for example, is placed on the magnetic film 2. An intermediate layer 3 made of SiN or the like is provided by plasma CVD or the like.

Detection holes 3a arranged in a barber pole shape are arranged in the detection region 9b of the element 9a, and lead holes 3 are arranged in the lead region 9C.
b is provided by, for example, ion etching of a gas such as CF.

Since the intermediate layer 3 is made of a completely different material from the magnetic film 2, CF
Damage to the magnetic film 2 due to the ion etching using the four gases can be avoided.

Then 1. 1 to 5, an adhesive layer 4 and a conductive film 5 are provided. The adhesive layer 4 and the conductive film 5 are deposited on the intermediate layer 3 and in the detection holes 3a and lead holes 3b from which the intermediate layer 3 has been removed by vapor deposition, sputtering, etc., as shown in FIG. It is provided on the entire surface of the element 9a.

The adhesive layer 4 is made of, for example, Ti, Cr, or Ta with a film thickness of 50 nm.
It consists of Mo etc.

Further, the conductor film 5 is made of, for example, Au with a film thickness of 400 nm.

Then, the detection hole 3a and lead hole 3b of the intermediate Ji 3 are coated with a photoresist by photolithography, as shown in FIG. 5 is etched.

After that, when the photoresist is peeled off, as shown in FIG. A conductive film 5 having a similar structure is obtained.

Finally, on the intermediate layer 3 and the conductor film 5 excluding the terminals 8, a protective film 6 such as 5iCh or StN with a film thickness of 1 μm is formed by plasma CVD, etc., and a magnetoresistive film as shown in FIG. 1 is formed. Element 9 is completed.

The characteristics of the magnetoresistive element 9 made in this way are particularly
During the film formation process of patterning the conductor film 5, the magnetic film 2
As shown in FIG. 6, the linearity of the output with respect to the external magnetic field is good, as shown in FIG.

The present invention relates to a magnetoresistive element characterized by a film structure and a film forming process for obtaining the film structure. Various modifications can be made to the film forming method, etc.

(Effects of the Invention) As stated above, conventionally, the three films of the magnetic film, the conductor film provided thereon, and the adhesive layer interposed between them are all metallic films, so the magnetic It has been difficult to pattern the adhesive layer and conductive film without causing any damage to the film.

On the other hand, in the magnetoresistive element according to the present invention,
When the adhesive layer or conductive film is patterned by ion etching, the magnetic film in the portion where the adhesive layer or conductive film is exposed to ion plasma and is etched is protected by an intermediate layer. On the other hand, the portion of the magnetic film that is left without etching the adhesive layer or conductor film is protected by coating the adhesive layer or conductor film with photoresist.

Therefore, according to the present invention, there is no damage to the magnetic film during a series of film forming steps, which greatly contributes to improving and stabilizing the characteristics of the magnetoresistive element.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view explaining the present invention in detail, Fig. 2 is a partially enlarged sectional view of Fig. 1, Fig. 3 is a perspective view of the magnetic film in Fig. 1, and Fig. 4 is Figure 1 is a perspective view of the intermediate layer; Figures 5 (A), (B), and (C) are film formation process diagrams for the adhesive layer and conductor film in Figure 1; Figure 6 is a characteristic diagram of the magnetoresistive element. , FIG. 8 is a partially enlarged plan view of FIG. 7, FIG. 9 is a partially enlarged sectional view of FIG. 7, and FIG. 10 is a diagram showing a configuration example of the magnetoresistive element shown in FIG. 7. Figure 11 shows an example of the characteristics of a magnetoresistive element. 9 Magnetic Resistance Element ＼ In the figure, 1 is the substrate, 3 is the intermediate layer, 3b is the lead hole, 4 is the adhesive layer, 6 is the protective film, 8 is the terminal, 9 is the +i magnetoresistive element 9b is the detection area, . 2 is a magnetic film, 3a is a detection hole, 5 is a conductive film, 7 is a photoresist, 9a is an element, 9c is a lead area,
1 Chapter 11, Ikkaku Shin Omachi fD, Chapter 2, 1000-layer film strabismus, Chapter 13, (8) Photoresist moxibustion, etching (c>Photoresist 1ll-! Broom 5, (I/72) (A) Hiromi Risnoring Fa/1m'! JllD/) Hiroshi Ui and secret IP, n1rJtl Station 5
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Claims (1)

[Scope of Claims] A substrate (1), a magnetic film (2), an intermediate layer (3), an adhesive layer (4), a conductor film (5), and a protective film (6), The substrate (1) supports the element (9a) and has insulating properties, and the magnetic film (2) is coated on the substrate (1) in the pattern shape of the element (9a). The intermediate layer (3) is attached to the magnetic film (2) and has insulating properties, and the intermediate layer (3) is attached to the magnetic film (2) and has insulating properties. layer(
3) is a detection hole (3a) in which the magnetic film (2) is exposed in a barber pole pattern shape in the detection region (9b) of the element (9a) and a lead region (9b). The adhesive layer (4) has a lead hole (3b) through which the magnetic film (2) is exposed, and the adhesive layer (4) has a lead hole (3b) through which the magnetic film (2) is exposed.
5), and is electrically conductive, and the conductive film (5) is adhered to the adhesive layer (4), and the conductive film (5) is adhered to the adhesive layer (4), and via the layer (4) and the detection hole (
3a) and the lead hole (3b).
2), and the conductive film (
5) is that when patterning together with the adhesive layer (4), the detection hole (3a) and the lead hole (3b) are covered with a photoresist (7) and ion-etched, and the protection The film (6) is applied to the intermediate layer (3) other than the terminal (8) and the conductor film (5) after the photoresist (7) is peeled off, and has an insulating property. A magnetoresistive element characterized by having: