JPS61248214A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To make possible the good magnetic characteristics of an MR element by forming a thin ferromagnetic film on an SiO2 film formed by a coating stage on an insulating layer. CONSTITUTION:A conductor layer 4 is formed via the insulating layer on a substrate 1 and the MR element 7 is formed via the insulating layer 5 and the coating type SiO2 film 6 on the conductor layer 4. An upper yoke 11 if formed on the element 7 via an insulating layer 9. The ruggedness on the surface of the insulating layer 5 is flattened by the SiO2 film 6 and since the SiO2 has the excellent film quality as a substrate, the vapor deposited 'Permalloy(R)' film forming the MR element 7 has the good magnetic characteristic.

Description

[Detailed Description of the Invention] Technical Field> The present invention detects changes in a signal magnetic field applied in the direction of the hard axis of magnetization of a ferromagnetic thin film having uniaxial magnetic anisotropy as changes in electrical resistance in the direction of the easy axis of magnetization. Magnetoresistive element (hereinafter referred to as
A thin film magnetic head (hereinafter referred to as Thin III!) equipped with a thin film magnetic head (hereinafter referred to as MR element) for detecting signals recorded on a magnetic recording medium.
(referred to as MR head).

<Prior Art> Conventionally, thin film MR heads are known to have many advantages over wire-wound magnetic heads.

In this thin-film MR head, the magnetization direction inside the MR element changes by receiving a signal magnetic field written on a magnetic recording medium such as a magnetic tape, and the M
The change in internal resistance of the R element is extracted as an external output. Therefore, the thin film MR head is a magnetic flux responsive head and can reproduce a signal magnetic field without depending on the transport speed of the magnetic recording medium. Since this thin film MR head can easily be highly integrated and multi-elemented using semiconductor microfabrication technology, it is seen as a promising magnetic head for reproduction in fixed head type PCM recorders that perform high-density recording.

Originally, an MR element has a sensitivity characteristic that shows a square change in response to an external magnetic field. Therefore, when configuring an MR element as a read head, the element shape is made into a stripe shape and a linear response characteristic is obtained. It is necessary to provide a configuration for applying a predetermined bias magnetic field to the magnetic field. Known methods for applying this bias magnetic field include a method of inducing a bias magnetic field by flowing a direct current through a conductor, and a method of applying a bias magnetic field using a high coercive force thin film such as a Co-P layer. (Refer to Japanese Patent Application No. 55-126255, 4th Japanese Society of Applied Magnetics, Abstracts of Academic Lectures (1980) 5PA-4r Multi-Trunk Thin Ill! MR Head). In actual use, in a thin film MR head, an MR element is formed on the conductor or high coercive force thin film with an insulating layer interposed therebetween.

On the other hand, compared to a thin film MR head composed of a single MR element,
A normal yoke-type MR head (hereinafter referred to as a YMR head) has a structure as shown in Figure 4, in which a magnetic flux introducing path (hereinafter referred to as yoke) is arranged to separate the MR element from the tip of the head and guide the magnetic flux generated in the magnetic recording medium to the MR element. It is known that a thin-film magnetic head called MR head is more effective in improving the resolution of signals and the durability of MR elements. (Summary of the 8th Japanese Society of Applied Magnetics Academic Lectures (1984) 14
(Refer to "Reproduction characteristics of PB-11r Yoke type MR head").

FIG. 4 shows a cross-sectional structure of a conventional YMR head in a direction perpendicular to the track width direction. The upper yoke 11 is usually made of a permalloy (Ni-Fe alloy) film with a film thickness of about 0.5 to 1.0 pm, and converts the magnetic field generated by the magnetic recording medium 2 into MR.
This becomes a magnetic path for guiding to the element 7. The MR element 7 is made of a permalloy (N i -Fe alloy) vapor-deposited film, has a film thickness of 200 to 500 μm, and has a trunk width of about 50 to 200 μm since it has a multi-track configuration. Furthermore, in order to apply a bias magnetic field, Al, Cu or A1-
A conductor 4 made of a film of Cu alloy or the like is provided.

Since the recording wavelength actually used is about 0.5 μm, the head gap portion 12 has a wavelength of 0.2 to 0.5 μm. The thickness is set to about 3 μm. The substrate 1 forming the lower yoke is made of a high permeability magnetic material, and is made of Ni-Zn ferrite or Mn-
Zn ferrite is used. Conductor 4 above. The MR element 7 and the upper yoke 11 are provided on the substrate 1 with insulating layers 3, 5, .
Formed via 9.

The insulating layer 5 interposed between the conductor 4 and the MR element 7 is formed on the conductor 4 by an RF sputtering method or a plasma CVD method, which provides good step coverage. However, this insulating layer 5
In order to obtain good film quality, it is necessary to raise the temperature of the substrate 1 to at least about 200''C.
The surface of the conductor 4 already formed on the substrate 1 via the insulating layer 3 becomes rough due to the temperature rise of the substrate 1. The surface roughness of the insulating layer 5 formed on the conductor 4 with this surface roughness increases as it reflects the surface roughness of the conductor 4. In the MR element 7 made of a permalloy (Ni--Fe alloy) vapor-deposited film, the surface roughness of the insulating layer 5 is large, so the crystal orientation is disturbed and good magnetic properties cannot be obtained.

Table 1 shows that the magnetic properties of the MR element 7 deteriorate as the surface roughness of the conductor 4 and the insulating layer 5 increases. In addition,
In order to measure the characteristics, the above-mentioned N i -Z was used as the substrate 1.
A glass (#0211) substrate is used instead of the n-ferrite or Mn-Zn ferrite 6. Therefore, the insulating layer 3 is eliminated, the conductor 4 is formed directly on the glass (#0211) substrate, and the insulating layer is formed on the conductor 4. An MR element 7 made of a permalloy (Ni--Fe alloy) vapor-deposited film is formed on the layer 5 and the insulating layer 5. For comparison, Table 1 shows permalloy (N) directly on a glass (#0211) substrate.
i-Fe alloy) is formed, and glass (i-Fe alloy) is formed.
#0211) 5i02 on the substrate by RF sputtering method
A film is formed and permalloy (Ni-
The magnetic properties of each Permalloy (Ni-Fe alloy) deposited film are shown below.

As is clear from Table 1, when the conductor 4 is formed on a glass substrate, the surface roughness of the conductor 4 is ~10 Å or less, but an insulating layer made of Si 02 is formed on the conductor 4. 5, the surface roughness of this insulating layer 5 is 20~
Increases to 100 people.

As a result, the magnetic properties of permalloy (Ni-Fe alloy) deposited films on glass (#0211) substrates and glass (#0211)
0211) Compared to a permalloy (Ni-Fe alloy) vapor deposited film formed on a substrate via a 5i02 film, the coercive force Hc in the easy axis direction and the reluctance Hch in the hard axis direction
Both become larger.

As described above, in conventional YMR heads, the S/N of the reproduced waveform due to the noise peculiar to ferromagnetic materials and the distortion of the signal waveform due to the deterioration of the magnetic properties of the permalloy (Ni-Fe alloy) vapor deposited film that forms the MR element. This is a problem that has a large impact on the ratio.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a thin-film magnetic head in which good magnetic properties of an MR element can be obtained even when a conductor layer is present. purpose.

<Configuration of the Invention> The present invention provides a thin film magnetic head that detects changes in a signal magnetic field applied in the direction of the hard axis of magnetization of a ferromagnetic thin film having uniaxial magnetic anisotropy as changes in electrical resistance. It is characterized in that the above-mentioned ferromagnetic thin film is formed on an S L'oz film formed through a process.

<Example> An embodiment of the present invention will be described below.

FIG. 1 shows the cross-sectional structure of the YMR head of this embodiment in a direction perpendicular to the track width direction of the magnetic recording medium, and FIG. 2 shows the planar structure of this YMR head.

FIG. 1 shows the structure of the YMR head shown in FIG. 2 taken along the line AA'.

The upper yoke 11 is made of a high permeability magnetic film such as permalloy (Ni-Fe alloy) with a film thickness of approximately 0.5 to 1.0 μm. It becomes a magnetic path to lead to 7. MR element 7
It is made of a permalloy (N i -Fe alloy) vapor-deposited film, the thickness of which is 200 to 500, and the track width is set to about 50 to 200 μm since it has a multi-trunk configuration. The MR element 7 has a coating type 5i formed on the insulating layer 5.
02 film 6. The bias magnetic field is transferred to the MR element.
The conductor layer 4 for applying voltage to the voltage 7 is made of a film such as MOSCu or AJ2-Cu alloy. The substrate 1 forming the lower yoke is made of Ni--Zn ferrite or Mn--Zn ferrite. A conductor layer 4 is formed on this substrate 1 via an insulating layer 3, and an insulating layer 5 and a coating mold 5i are formed on the conductor layer 4.
MR element 7 is formed via 0211111i5, and M
Upper yoke 11 is formed on R element 7 with insulating layer 9 interposed therebetween.

First, on the substrate 1 (7) Ni s i 02 , S ia
The insulation N3 made of N4, Al2O3, etc. is formed by RF sputtering, P-CVD, or the like. Next, on this insulating layer 3, M o + Cu + A 12-
A conductor layer 4 made of a Cu alloy or the like is formed by a resistance heating method, an RF sputtering method, an electron beam evaporation method, or the like. In order to process this conductor layer 4 into a desired shape, a chemical etching method, a sputter etching method, or an ion milling method is used. To explain with an example, in the case of the chemical etching method, the Cu film is etched using nitric acid (HNOa).
Ammonium tenpersulfate ((NH3)2320B) raw water (
H20), AJ-Cu film is made of potassium hydroxide (KO
H) Ammonium tenpersulfate ((NHa) 2320B
) Raw water (H20) or phosphoric acid (H3PO4) deca-nitric acid (HNO3) + acetic acid (CHa C00H) raw water (H20
) may be used. In the case of sputter etching method or ion milling method, M o .

Films such as Cu and Al-Cu can be processed by introducing Ar gas.

P-CVD is applied on the conductor layer 4 formed as described above.
5i02°S i3N by method or RF sputtering method
4. An insulating layer 5 made of Al120a or the like is formed. During the formation of this insulating layer 5, the temperature of the substrate 1 reaches around 200"C, so the surface roughness of the conductor layer 40 occurs, and this surface roughness of the conductor layer 4 is directly reflected, and the surface roughness of the insulating layer 5 increases to 20"C. ~lo.

Become a person.

Next, a coated 5i02 film 6 is formed on the insulating layer 5. This coating type 5i02 film 6 is obtained by applying a solution of a silicon compound or the like in an organic solvent or the like onto the insulating layer 5 using a spinner, and then baking it. This application type 5
The thickness of the iQ2 film 6 can be controlled by the rotational speed of the spin code and the concentration of silicon compound in the solvent, and the thickness of the insulating layer 5 can be controlled by the coating type 5i02 film in the same way as when an organic material such as PIQ is used. Surface irregularities are flattened. 5i when this coated SiO2 film 6 is formed on the insulating layer 5
The surface roughness of the Q2 film 6 is such that the surface roughness of the insulating layer 5 is 20 to 1.
00 people, it is ~10 Å or less.

Permalloy (Ni-F
An MR element 7 made of a vapor-deposited film (alloy) is formed. In this case, the unevenness on the surface of the insulating layer 5 is flattened by the coated 5i02 film 6, and the coated 5iQ2 film has excellent film quality (film density, film composition, etc.) as a base layer, so the MR element 7
The permalloy (Nt-Fe alloy) vapor-deposited film that forms this has good magnetic properties.

The MR element 7 has a film thickness of 200 to 500 mm, and is etched by chemical etching or sputter etching.
It is processed into stripes of 20×50 to 100 μm.

Thereafter, the lead portion 8 is formed by a resistance heating method, an electron beam evaporation method, or an RF buffing method. Furthermore, M.R.
P-CVD method or RF
An insulating layer 9 is deposited by sputtering, and finally an upper yoke 11 made of a high permeability magnetic film is formed.

Table 2 shows the MR element 7 of the thin film magnetic head in this embodiment.
This figure shows the magnetic properties of a permalloy (Ni-Fe alloy) vapor-deposited film. Note that for the same reason as mentioned above, the substrate 1
as N i −Z n ferrite or M n −
A glass (#0211) substrate is used instead of Z n ferrite, the insulating layer 3 is eliminated, a conductor layer 4 is formed on the glass (#0211) substrate, and Si
An insulating layer 5 consisting of 02, a coating mold 5i on this insulating layer 5
02 film 6, and an MR element 7 made of a permalloy (Ni--Fe alloy) vapor-deposited film is formed on the coated Si02 film 6.

For comparison, Table 2 shows the magnetic properties of a permalloy (Ni--Fe alloy) deposited film directly formed on a glass (#0211) substrate.

As is clear from Table 2, the surface roughness of the insulating layer 50 is 20 to 100, while the coating type 5i02 film 6
The surface roughness after firing is ~1oÅ or less, and as a result,
The magnetic properties of Permalloy (Ni-Fe alloy) deposited film are similar to those of Permalloy (Ni-Fe alloy) deposited directly on a glass (#0211) substrate.
Ni-Fe alloy) deposited film and coercive force Hc in the direction of easy magnetization axis
, the coercive force Hch and the anisotropic magnetic field Hk in the direction of the hard magnetization axis both have approximately the same value.

Permalloy (Ni-Fe alloy) forming the MR element 7
In order for the deposited film to have good magnetic properties, in addition to the surface roughness of the 5i02 film forming the lower insulating layer of the MR element 7, S
The impurities contained in the i 02 film, the composition and density of the Si 02 film, and other film quality have a great influence. That is, as shown in Table 3, even if the 5i02 film has a surface roughness of ~10 Å or less, it lacks density.
CVD method, etching speed 150-200 people/min, HF
5% aqueous solution.

(liquid temperature 45-50°C), permalloy (Ni-
The deposited film (Fe alloy) does not have good magnetic properties, and it is difficult to obtain good magnetic properties when deposited on a glass (#0211) substrate or on a dense 5i02 film (RF
Sputtering method, etching speed 40-50 people/min, HF5
% aqueous solution, liquid temperature 45-50°C)
The coercive force Hc in the direction of the easy axis of magnetization and the coercive force Hch in the direction of the hard axis of magnetization both exhibit large values. However, even if the Si Q2 film lacks the above-mentioned density, a coating type 5
By forming the i02 film, the quality of the film as a base can be improved.
0211) Permalloy (Ni-
The magnetic properties are almost as good as those of the Fe alloy (Fe alloy) vapor-deposited film.

FIG. 3 shows a cross-sectional configuration of a magnetic recording medium of a YMR head in another embodiment in a direction perpendicular to the track width direction. Sendust (
Fe-AI! -3i alloy) membrane.

A high permeability magnetic film 14 made of a permalloy (Ni--Fe alloy) film or the like is formed by electron beam evaporation or sputtering. On this high permeability magnetic film 14, a conductive layer 4. MR element7. Upper yoke 11. An insulating layer 3.5.9 and a coated 5i02 film 6 are formed. In this case, the surface roughness of the high permeability magnetic film 14 is also superimposed, but the surface roughness of the coating type 5i02 film 6 is ~10
Å or less, the permalloy forming the MR element 7
(Ni-Fe alloy) The deposited film has good magnetic properties.

In addition, although the above embodiment describes the case where the present invention is applied to a YMR head, the present invention is not limited to this YMR head, and can be applied to a double-sided shield type MR head, a single-sided shield type MR head, a non-shield type MR head, etc. Permalloy (Ni-Fe alloy) 1lii with good magnetic properties can also be obtained by using a coating type 5i02 film.

<Effects of the Invention> As described in detail above, in the present invention, an M made of a ferromagnetic thin film is formed on a coated 5i02 film formed on an insulating layer.
Since the R element is formed, the MR has good magnetic properties that are not affected by the surface roughness and film quality of the underlying insulating layer.
The element is obtained, and therefore the MR characteristics (Δρ/ρ characteristics)
Therefore, a thin film MR head having a good S/N ratio can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a plan view of an embodiment of the present invention, FIG. 3 is a cross-sectional view of another embodiment of the present invention, and FIG.
The figure is a sectional view of a conventional example.

Claims (1)

[Claims] (1) In a thin film magnetic head that detects changes in the signal magnetic field applied in the direction of the hard axis of magnetization of a ferromagnetic thin film with uniaxial magnetic anisotropy as changes in electrical resistance, a thin film is formed on an insulating layer through a coating process. A thin film magnetic head characterized in that the above ferromagnetic thin film is formed on a SiO_2 film.