JPH02126410A - Thin film magnetic head structure - Google Patents

Abstract

PURPOSE:To obtain a magnetic head for high recording density by forming a lower magnetic layer of amorphous material and an upper magnetic layer of crystalline material and using the material whose saturation magnetic flux density is higher than that of 'Permalloy(R)'. CONSTITUTION:The lower magnetic layer 2 is formed by using quarter target of 43Co-23Ni-13Fe-21Pd in a sputtering method. In the sputtering stage, orthogonally crossed magnetic field is horizontally impressed on the surface of a substrate 1 in order to reduce anisotropic magnetic field. Then, patterning is performed on the substrate to obtain a magnetic core pattern in desired shape and dimension in an ion milling method and a conductive coil 5 is formed through a photoresist 4 and the upper magnetic layer 6 is formed on the coil 5. The curing temperature of the photoresist 4 is set at 250 deg.C at such a time and the upper magnetic film is sputtered at low temperature to prevent the photoresist from being damaged. It is assumed that film thickness is 2mum. As to the magnetic characteristic, coercive force in a direction of the axis hard to be magnetized is 1.2 oersted, anisotropic magnetic field is 6.5 oersted, magnetostriction constant is -0.5X10<-6> and the saturation magnetic flux density is 1.5 stera and the photoresist is not damaged by sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head, and more particularly to a thin film magnetic head that is compatible with high recording density and easy to manufacture.

[Conventional technology]

Conventionally, the magnetic core for thin film magnetic heads has a power of about 80vt/%.
A permalloy thin film, which is a binary alloy consisting of Ni and about 20 wt% Fe, is used. This material has low coercive force and high magnetic permeability due to its small magnetocrystalline anisotropy and magnetostriction constant, so it is widely used as a magnetic core for thin-film magnetic heads because it shows excellent read performance. It is used.

However, since permalloy has a low saturation magnetic flux density of approximately 1 Tesla, thin-film magnetic heads using permalloy films have poor writing performance and are insufficient for high coercive force media compatible with high recording densities or narrow track width magnetic heads. The disadvantage is that it does not allow accurate recording.

Therefore, it is conceivable to increase the thickness of the permalloy film to prevent magnetic saturation, but this is undesirable because it leads to a decrease in the resolution of the thin-film magnetic head. Therefore, the development of CO-based amorphous materials, Fe-based crystalline materials, and Fa-8i-AQ-based (Sendust) materials is underway as materials with higher saturation magnetic flux density than permalloy.

On the other hand, magnetic field application for writing or reading and detection of induced voltage are performed by a conductor coil made of Cu or the like with an organic insulating layer interposed between the upper and lower magnetic layers. Conventionally, a thermosetting resin such as prQ (polyimide resin), which has excellent heat resistance, has been used for the organic insulating layer. However, P.I.Q.

Since it is not a photosensitive resin, it is finished in a shape with a high level difference and a constant taper angle using a wet etching method. Therefore, due to slight differences in the thickness of the mask material, etching time, etc., subtle differences occur in the shape and dimensions of the PIQ, which poses a bottleneck in the process.

Therefore, photosensitive resin photoresists, which are inferior in heat resistance to PIQ but are advantageous in terms of processing, have come to be widely used. However, photoresist has a drawback in heat resistance, so after curing at 250°C to 300°C,
Since weight loss, deformation, etc. occur when exposed to temperatures above this temperature, the upper magnetic film formed thereon is widely used in plating methods that do not cause temperature rise. The plating method has problems such as the difficulty in controlling the composition of the film compared to the sputtering method and the limitations on the magnetic films that can be plated, which have been obstacles to the development of thin-film magnetic heads compatible with high recording densities.

[Problem to be solved by the invention]

Co-based amorphous materials are generally known as thin film materials having a higher saturation magnetic flux density than permalloy.

However, since amorphous materials are generally sputtered while cooling the substrate with water, the temperature rise in the film is smaller than when sputtering ordinary crystalline materials.

After sputtering, unless heat treatment is performed in a rotating magnetic field at a temperature of about 300° C., the anisotropic magnetic field will be large and high magnetic permeability will not be achieved. Therefore, on top of the photoresist.

That is, it is difficult to use an amorphous material for the upper magnetic film because the upper magnetic film has a heat resistance temperature higher than that of the photoresist.

On the other hand, a crystalline material with a higher saturation magnetic flux density than permalloy and a thin film material with high magnetic permeability is an Fe-based crystalline material with a saturation magnetic flux density of approximately 2 Tesla, which is significantly higher than that of permalloy, and a saturation magnetic flux density of approximately 1.1.
The Fe-8i-AQ-based viscocrystalline material (Sendust) which exhibits Tesla is known, but these materials have the disadvantage that they do not exhibit high magnetic permeability unless they are heat-treated at a temperature of 400 to 600°C after sputtering. It cannot be applied to an upper magnetic layer formed on a photoresist. Therefore, in the thin-film magnetic head process using photoresist, it is impossible to use these magnetic films as the lower and upper magnetic films, and this has become a bottleneck in the development of magnetic disk devices with increasing recording density.

(Means for solving the problem) Therefore, the inventors discovered (25-6゜wt%)
Co-(14-50 wt,%) Ni-(10-2
4wt%) Fe-(5-30wt%)Pd quaternary crystalline material has a high saturation magnetic flux density of 185 Tesla;
By changing the substrate temperature during sputtering, the magnetostriction constant can be changed without damaging other magnetic properties, and by adjusting the amount of Pd within the composition range, even at low substrate temperatures without damaging other magnetic properties. We discovered that it is possible to bring the magnetostriction constant to near zero. Therefore, by appropriately selecting the composition of the lower and upper magnetic films and the substrate temperature, it has become possible to realize a magnetic core for a thin film magnetic head with high magnetic permeability and high saturation magnetic flux density.

In addition, although there are some drawbacks in heat resistance, the saturation magnetic flux density is 1.6
It was found that a Co--Ni--Fe ternary crystalline plating film as high as ~1.7 Tesla is effective as an upper magnetic film on a resist.

In this way, we took into consideration the characteristics of the photoresist formed between the lower and upper magnetic layers, and took into consideration the thermal history caused by the process, in order to maximize the magnetic properties of both the lower and upper magnetic films. It is important to select suitable materials in order to develop thin-film magnetic heads compatible with higher recording densities.

In other words, the lower magnetic film (1) has excellent magnetic properties even when sputtered at a high substrate temperature from the viewpoint of adhesion, and (2) has a low coercive force by further heat treatment at a high temperature after sputtering. (3) Heating to the curing temperature of the photoresist (250~300℃)
For example, there is no deterioration in magnetic properties even if the temperature is increased to 0°C.

On the other hand, the upper magnetic film.

(1) Exhibits excellent magnetic properties even when sputtered at low substrate temperatures without damaging the photoresist; (2) Exhibits low coercive force and high magnetic permeability even after heat treatment at low temperatures after sputtering; ( 3) Even a plated magnetic film exhibits excellent magnetic properties.

Therefore, it is important to select materials taking these conditions into consideration.

[Effect]

Therefore, the curing temperature of the photoresist is 250 to 300℃,
The manufacturing conditions of the lower and upper magnetic films were studied taking into account the heat resistance temperature of about 250°C. That is, even if the lower magnetic film is exposed to a temperature of 300° C., which is the upper limit of the photoresist curing temperature, after sputtering.

The deterioration of magnetic properties is small, the upper magnetic film does not exceed 250°C even if the temperature rises during sputtering, and the magnetic properties are excellent even without the need for heat treatment above 250"C. etc. are necessary.

FIG. 1 is a sectional view of one element of a thin film magnetic head according to the present invention. 1 is a ceramic substrate, 2 is a lower magnetic layer made of Co-
It is a Ni-Fe-Pd quaternary crystalline magnetic thin film. 3 is a nonmagnetic gap material, 4 is a photoresist as an organic insulating layer, 5 is a conductor coil, and 6 is Co-N, which is the same as the lower magnetic layer.
It is an i-Fe-Pd quaternary crystalline magnetic thin film.

7 is AQtos as a protective film. FIG. 2 shows the experimental results of a Co--Ni--Fe--Pd quaternary crystalline sputtering film applied to the upper and lower magnetic layers of the thin-film magnetic head shown in FIG. It can be seen that by slightly changing the Pd content, the substrate temperatures at which the magnetostriction constant is suppressed within the range of ±0.5×10″B without substantially changing the coercive force exist on the low and high temperature sides. At this time, the anisotropic magnetic field showed an excellent value of 5 to 60 e. From this, the composition of the lower magnetic film is selected such that the magnetostriction constant is almost zero at high substrate temperatures, and the composition of the upper magnetic film is selected such that the magnetostriction constant is approximately zero at low substrate temperatures. Both magnetic films can be made of a material with a higher saturation magnetic flux density than permalloy, and are suitable as a thin film magnetic head compatible with high recording density magnetic disk devices. Also,
For the upper magnetic film formed on the resist, it is necessary to allow for a temperature rise due to sputtering in order to avoid damage to the resist. Figure 3 shows the film thickness 1 required for the core of a thin film magnetic head.
．． These are the results of measuring the substrate temperature after sputtering when sputtering was performed to a thickness of 5 to 2.0 μm. If the upper limit of the heat resistance temperature of photoresist is expected to be 250°C, the upper limit of the substrate temperature before sputtering will be about 120°C.

Therefore, with a film having the composition indicated by the broken line shown in FIG.
At 0'C, the magnetostriction constant of the film is almost zero, indicating that it can be used satisfactorily as a magnetic layer on photoresist. On the other hand, it is important that the amorphous material undergoes little deterioration in magnetic properties due to crystallization during curing of the photoresist. FIG. 4 shows an investigation of the relationship between heating temperature and magnetic properties by selecting a C0-Hf-Ta-Pd quaternary system as the amorphous material. The coercive force in the hard axis direction increases rapidly when the heating temperature exceeds 380'C, indicating crystallization. Therefore, it can be seen that at the upper limit of the photoresist curing temperature of 300'C, the magnetic properties do not deteriorate at all and it can be used as a lower magnetic layer.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

<Example 1> FIG. 1 shows a cross section of a thin film magnetic head formed by a combination of magnetic layers according to the present invention.

The lower magnetic layer 2 is 43Co-23Ni-13Fe-21
It was formed by sputtering using a Pd quaternary target. The sputtering method is RF magnetron sputtering, with an RF output of 1.5 KW and a substrate temperature of 280°C. The coercive force of the obtained film in the hard axis direction was 1.5 Oersteds, the anisotropic magnetic field was 6 Oersteds,
The magnetostriction constant was -0, I This is patterned into a magnetic core pattern of desired shape and dimensions by ion milling, and then a conductor coil 5 is formed through a photoresist 4 (OFPR-800), and an upper magnetic layer 6 is formed thereon. .

At this time, the curing temperature of the photoresist was 250°C.

The upper magnetic film was sputtered at low temperature to prevent damage to the photoresist. That is, in the same manner as the lower magnetic film,
Target composition is 43Co-25Ni-14Fe-18
Sputtering was performed using Pd at a substrate temperature of 100°C. The film thickness is 2.0 μm. Its magnetic properties were a coercive force in the hard axis direction of 1.2 Oersteds, an anisotropic magnetic field of 6.5 Oersteds, a magnetostriction constant of -0, 5 x 10''''8, and a saturation magnetic flux density of 1.5 Tesla. No damage to the photoresist due to sputtering was observed.

Similar to the lower magnetic layer, the upper magnetic layer 6 was patterned into a magnetic core of desired size and shape by ion milling, and then a protective film 7 was formed to form a thin film magnetic head.

They were processed into a single thin film magnetic head element and their electrical characteristics were evaluated. FIG. 5 shows the result at 111. Electrical characteristics of thin film magnetic heads using conventional permalloy 121
compared with. The reproduction output characteristics show almost the same tendency as the magnetic permeability is not much different from that of conventional permalloy, but even when the recording current increases, there is no decrease in the reproduction output, and the effect of the increased saturation magnetic flux density appears. There is. The effect of this increased saturation magnetic flux density is noticeable in the override characteristics,
The thin film magnetic head 111 according to the present invention has an improvement of about 30 to 40% compared to the conventional thin film magnetic head 121 using permalloy.

<Example 2> In FIG. 1, a thin film magnetic head was fabricated using an amorphous magnetic thin film only for the lower magnetic layer 2. That is, the substrate 1 is placed in a water-cooled substrate holder, and C0111 is used as a target.
Sputtering was performed using -Hf+-Taa-Pdz (at, %). The film thickness is 1.5 μm. After that, 3
Heat treatment was performed in a rotating magnetic field at a temperature of 50"C for one hour to reduce the anisotropic magnetic field and increase the magnetic permeability. The magnetic properties of the film were as follows: coercive force in the difficult axis direction 0.4 oersted, anisotropic. Magnetic field 2.6 oersted, magnetostriction constant -〇, 3 x 10-
8, and the saturation magnetic flux density was 1.3 Tesla. The subsequent steps were performed in the same manner as in Example-1, and the upper magnetic layer was made of 43Co-25Ni-14Fe-18Pd (wt%) similar to Example-1, which can be sputtered at a low substrate temperature.
A magnetic thin film was formed. The electrical characteristics of the thin film magnetic head thus produced are similar to those of Example 1 shown in FIG. 5, and the overwrite performance is improved compared to the conventional magnetic head using a permalloy thin film.

<Example 3> In FIG. 1, a substrate 1, a lower magnetic layer 2, a gap material 3
, photoresist 4, and conductor coil 5 were formed in exactly the same manner as in Example-1. The upper magnetic layer was formed using a plating method that causes the least damage to the photoresist. First, the photoresist is patterned into a desired shape by exposure and development.

As a base film for plating, 0.02 μm permalloy was formed on the entire surface of the substrate by vapor deposition, and then CoSO4.7H
zO: 45g/Q, N1CQ2・6H20: 60g
/Q, N15Oi・6HzO: 25g/Q
, F e S 04 ・7 H2O: 20 g
/ Q, boric acid: 25g/Q, saccharin sodium: L
Co--Ni--Fe ternary plating was performed by immersing the sample in a plating solution containing 5 g/Q of sodium lauryl sulfate and 0.15 g/Q of sodium lauryl sulfate. PH:3. Plating was performed by adjusting the bath temperature to 30° C. and applying a plating current density of 17 mA/af. During the plating, a magnetic field perpendicular to the plane of the substrate was applied in the same manner as in the sputtering method. Film thickness is 2.0μm
It is. The composition of the film at that time was 78Co-16Ni-6F
e (wt%), coercive force in difficult direction 1.0 Oe, anisotropic magnetic field 6.0 Oe, magnetostriction constant 0.8
X10'''B, and the saturation magnetic flux density was 1.6 Tesla. Thereafter, it was patterned into a magnetic core shape by the same method as in Example 1 to form a protection [7]. As shown by 112 in FIG. 5, the electrical characteristics of the device exhibit excellent override performance.

<Example 4> In FIG. 1, a sendust sputtered thin film was used as the lower magnetic layer on the substrate 1.

That is, 5.5AQ, -9,5Si-85Fe (wt%
) A thin 1.5 μm lower magnetic film was formed by sputtering using a target, and then heat treated at 600° C. for a processing time to achieve low coercive force and high magnetic permeability. The magnetic properties of the obtained film were a coercive force of 0.6 Oe, an anisotropic magnetic field of 3 Oe, and a magnetostriction constant of 2XIO-B. Moreover, the saturation magnetic flux density was 1.1 Tesla. On this lower magnetic layer, a photoresist 4, a conductive coil 6, and an upper magnetic layer 6 made of Co-Ni-Fe-Pd quaternary crystal material are formed by sputtering in the same manner as in Example-1, and furthermore, a protective A film 7 of Al2zOa was formed. The electrical characteristics of one cut out film magnetic head element were evaluated. The results showed almost the same performance as the results shown in Figure 5, but the override characteristics were slightly lower because the saturation magnetic flux density of the lower magnetic layer was slightly lower than that of other crystalline or amorphous materials. Ta. However, since the lower magnetic layer generally has a larger magnetic core area than the upper magnetic layer, it is considered that even if the saturation magnetic flux density is slightly lower, it will have little effect on the electrical characteristics of the magnetic head. Furthermore, it is expected that the performance of the magnetic head will be further improved by using a Fe-8i-based or Fe-based crystalline material with a high saturation magnetic flux density for the lower magnetic layer.

Note that when permalloy is used for the lower magnetic layer, it is thought that increasing the film thickness will reduce the resolution but improve the override performance.

<Example-5> FIG. 6 shows an example in which the upper and lower magnetic layers have a multilayer structure. In terms of electrical properties, the coercive force can be reduced by having a multilayer structure.

Playback output has improved slightly.

〔Effect of the invention〕

According to the present invention, it is possible to form a high saturation magnetic flux density material not only by plating a magnetic film on photoresist with high process precision and low cost, but also by a sputtering method that allows easy composition control, and is compatible with high recording density. This has a great effect on the production of thin-film magnetic heads.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thin film magnetic head according to an embodiment of the present invention.
Figures 2 to 4 are explanatory diagrams of experimental results that led to the present invention;
FIG. 5 is a characteristic diagram of the thin film magnetic head of the present invention, and FIG. 6 is a sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Lower magnetic layer, 3... Gap material, 4... Photoresist, 5... Conductor coil, 6... Upper magnetic layer, 7... Protective film. Figure 1. Temperature (0C) Figure Substrate temperature

Claims (1)

[Claims] 1. A thin film comprising a magnetic circuit consisting of a lower magnetic layer and an upper magnetic layer on a non-magnetic ceramic substrate, and a conductor coil with an organic insulating layer sandwiched between the upper magnetic layer and the lower magnetic layer. 1. A thin film magnetic head structure in a magnetic head, wherein the lower magnetic layer is made of an amorphous material, the upper magnetic layer is made of a crystalline material, and the material has a higher saturation magnetic flux density than permalloy. 2. The thin film magnetic layer according to claim 1, wherein the upper magnetic layer is made of a Co-Ni-Fe-Pd quaternary system or a Co-Ni-Fe ternary system crystalline material. head structure. 3. Claim 2, wherein the lower magnetic layer is made of Co-Hf-Ta-Pd quaternary amorphous material, and the upper magnetic layer is made of Co-Ni-Fe-P.
A thin film magnetic head structure characterized by being made of a quaternary system or a Co-Ni-Fe ternary system crystalline material. 4. In claim 1, the lower magnetic layer is made of a Sendust thin film, and the upper magnetic layer is made of a Co-Ni-Fe-Pd quaternary system or a Co-N
A thin film magnetic head structure comprising an i-Fe ternary crystalline material. 5. A thin film magnetic head structure according to claim 1 or 2, wherein the lower magnetic layer and the upper magnetic layer have a multilayer structure. 6. A thin film magnetic head structure according to claim 1, 2 or 5 is mounted and the track density is 2000.
Equipped with multiple magnetic disks with tracks/inch or more and linear recording density of 30 kilobits/inch or more on one rotating shaft,
A magnetic disk device further comprising: a means for rotating the magnetic disk at a speed of 26 m/s or more.