JPS62142380A - Magnetoresistance effect element - Google Patents

Abstract

PURPOSE:To facilitate formation and to simplify the structure of a thin film magnetic head and the like, by reducing the effect of the roughness of the surface of a basis on the characteristics of a thin film MR element. CONSTITUTION:Especially, a sputtering method, by which a target voltage and a target current are independently controlled, is used. In such a sputtering method, there are more controllable parameters in comparison with an ordinary RF two-pole sputtering method, and the optimum conditions are obtained. Since a substrate does not become an electrode, the element is not exposed to plasma. The element is less restricted by the configuration of a substrate holder. It is especially desirable to use a DC three-pole sputtering method. It is desirable to apply a magnetic field in the desired direction during the sputtering method is carried out. It is desirable that the direction of the magnetic field is perpendicular to the direction of the detected magnetic field of the MR element to be formed. When the magnetic field is applied, uniaxial anisotropy can be induced in the desired direction.

Description

Detailed Description of the Invention (Field of application) The present invention relates to a thin film magnetic head for reproduction that detects signals recorded on a magnetic recording medium using the magnetoresistive effect of a metal ferromagnetic thin film or The present invention relates to a thin film magnetoresistive element (hereinafter referred to as a thin film MR element) used in magnetic rotary encoders and the like that detect changes in magnetic field strength.

(Prior art) In a thin film MR element, the direction of magnetization inside the thin film MR element changes due to a signal magnetic field from the outside, and the change in electrical resistance of the thin film MR element corresponding to the change in the magnetization direction is extracted as an external output. . If this thin-film MR element is used in a reproducing magnetic head, it will be possible to easily achieve high integration and multi-element technology using semiconductor microfabrication technology, and to create a magnetic flux-responsive head that does not depend on the moving speed of the magnetic recording medium. Let it go. This head is seen as a promising magnetic head for reproduction in multi-channel fixed head type PCM recorders. Moreover, it has already been put into practical use as an element for detecting rotation angle in a magnetic rotary encoder.

This thin film MR element is electrically powered by a metal ferromagnetic -5V film made of NiFe alloy or the like and a current terminal for signal detection.The metal ferromagnetic thin film is processed into a predetermined shape by etching, etc. The front 32 current terminals are formed by coating and etching a conductive layer such as 〇 on the portion.

By the way, the thin film Mr (metal ferromagnetic thin film used in devices has conventionally been formed by evaporation in a magnetic field), but since the film thickness is very thin (300 to 500 mm), the surface roughness of the underlying layer may be affected. Therefore, in order to obtain the original magnetic properties of the NiFe film, it is necessary to reduce the surface roughness to 5 Å or less. However, it is extremely difficult to polish the substrate surface to a roughness of 5 Å or less. Furthermore, when various layers are laminated as in a thin-film magnetic head, it becomes difficult to maintain the surface roughness below 5 Å.For this reason, conventionally, Ni
As a base for the Fe film, a coated S r 02 film or the like with a surface roughness of 5 Å or less was used. However, such a coating method complicates the process and causes various problems such as cracks during processing.

(Purpose) The present invention has been made in view of the above problems, and aims to reduce the influence of the surface roughness of the underlying layer on the magnetic properties of thin film MR elements used in thin film magnetic heads, magnetic rotary encoders, etc. An object of the present invention is to obtain a thin film MR element that is easy to control (structure of the invention). Provide an element.

The sputtering method is generally performed under a dilute inert gas atmosphere.
This is a technique in which the positive ions generated by the glow discharge are accelerated and collided with the target, thereby repelling atoms or molecules of the target material and depositing them on the substrate. In this case, examples of the inert gas include neon, argon, krypton, xenon, etc., but argon is preferable.

Glow discharge is normally performed in a dilute atmosphere of 10-2 to 1 O-' Torr by applying a voltage of 1000 to 2000V.

In the present invention, in particular, a sputtering method in which target voltage and target current can be independently controlled is used. This type of sputtering method has more controllable parameters than the normal RF bipolar sputtering method, and more optimal conditions can be obtained, and since the substrate does not serve as an electrode, it is not exposed to plasma. This has the advantage that there are fewer restrictions on the shape of the holder.

In the present invention, it is particularly preferable to use the DC three-pole sputtering method.

It is preferable to apply a magnetic field in a desired direction during implementation of the above-mentioned Sufu-5 Tuttering method. The direction of the magnetic field is preferably perpendicular to the direction of the detected magnetic field of the formed MR element. Uniaxial anisotropy can be induced in a desired direction by applying a magnetic field.

The formed magnetoresistive element is made of NiFe alloy, NiCo
alloy, NiFeCo alloy, etc., but preferably NiF
It is an e-alloy.

The substrate on which the magnetoresistive element of the present invention is sputtered may be of various types depending on various purposes. For example, Si on a glass substrate, ferrite substrate, or various substrates.
A material having an insulating layer formed of Ox, SiN, AQ, O2, etc. is generally used.

The present invention will be explained in more detail with reference to Examples.

(Example) Example I A DC three-electrode sputtering method was used as a sputtering method in which the target voltage and target current could be controlled independently, and argon gas was flowed as an inert gas to maintain a gas pressure of 4 to 5 mT. orr.

A NiFe film was formed on a glass substrate by setting the target voltage to 300V and the target current to 0.5V. Table-1
is obtained using a sputtering method in which target voltage and target current can be controlled independently.
Figure 2 shows changes in the magnetic properties of the Fe film depending on the surface usage.

Table - ■ As is clear from Table - ■, the surface temperature of the base is 100 to 1
It can be seen that the influence on the magnetic properties of the N1ce film is very small. In addition, when a Nil'''e film is formed by Ike's spattering method such as RF bipolar sputtering method, the resistivity increases considerably compared to the magnetic field deposition method, so the rate of change in resistance due to the magnetoresistive effect decreases. However, according to the present invention, it is possible to obtain a specific resistance almost equivalent to that of the magnetic field evaporation method, so the rate of change in resistance does not decrease.Furthermore, like the magnetic field evaporation method, a magnetic field is applied to the substrate when forming the NiFe film. It is possible to induce anisotropy in the desired direction by applying .

Comparative Example 1 350 NiFe films were formed on substrates with various surface roughnesses by conventional magnetic field deposition. The deposition conditions were as follows: Weir plate temperature was 250°C, composition was 82.5Ni-17,5
Fe (wt%), vacuum degree during evaporation was 1.5×10-'T
The strength of the applied magnetic field was 800 e and the resistance heating method was used.

Table 2 below shows changes in magnetic properties depending on the surface roughness of the obtained NiFe film.

As is clear from Table 2, when the surface roughness exceeds 5, the magnetic properties deteriorate significantly.

(Effects of the Invention) According to the present invention, the influence of the characteristics of the thin film MR element on the surface roughness of the underlying layer can be reduced, which facilitates formation and simplifies the structure of thin film magnetic heads and the like.

Claims (1)

[Claims] 1. A magnetoresistive element formed by a sputtering method in which target voltage and target current can be independently controlled in an inert gas atmosphere. 2. The magnetoresistive element according to item 1, wherein the inert gas is argon gas. 3. The first device in which the magnetoresistive element is a nickel-iron alloy film
The magnetoresistance effect element described in . 4. The magnetoresistive element according to item 1, wherein a magnetic field is applied during film formation.