JPS60191418A - Manufacture of magnetic head - Google Patents

Abstract

PURPOSE:To decide whether the film formation in the process of MR head manufacture is normal or not at the end of the process by forming a magneto-resistance element thin film with necessary width and respective layers on a nonmagnetic substrate except a shield magnetic layer in the same process with the manufacture of a magnetic head, and thus forming a dummy head. CONSTITUTION:Various current are flowed to a dummy element 13 and the value at the intersection HK* of a tangent from the flection point of a characteristic curve and an axis H and the current dependency of the current bias value delta at the peak point of a resistance rate rho of the characteristic curve generated by a shunt current on a dummy element current I1 are measured. The current bias value delta is converted into an angle theta according to a mathematical expression to obtain data, and MR elements 2 having positive and negative magnetostrictive characteristics lambda are measured respectively. Consequently, the MR element with the negative characteristics tends to increase in value HK* with the dummy element current I1, but the element with positive characteristics does not vary, so the bias theta increases normally. Consequently, a shunt bias type MR head having positive magnetostrictive characteristics lambda is manufactured on the basis of said result to realize normal bias application and excellent reproduction characteristics.

Description

Detailed Description of the Invention (a) Technical Field of @Ming The present invention relates to a method of manufacturing a magnetoresistive magnetic head,
In particular, the present invention relates to a method for reducing variations in characteristics of manufactured balls.

(b) @Ming's technical field A conventional example will be explained according to the diagram. FIG. 1 is an explanatory diagram of the mutual bias system of a conventional magnetoresistive magnetic head (hereinafter simply referred to as MR head), in which (a) is a cross-sectional view of the main part;
(b) shows a perspective view and a block diagram.

In the figure, 1 r[, NiZn 7 elite, MnZ
l)-C A magnetic substrate made of light or the like is shown. actual MR
In the head, the substrate may be formed of another non-magnetic material (not shown), and the magnetic substrate 1 may be formed to the north of the substrate by thin film deposition. 2 and 2' are magnetoresistive elements (hereinafter referred to as MR elements) made of N:lF6 permalloy. 3 is a nonmagnetic insulating layer made of Sing, AhOa, etc., 4 is N1. A high magnetic permeability member such as F6 permalloy, 5 a cover plate, 6 a magnetic recording medium such as a magnetic tape, and a magnetic substrate 1 and a high magnetic permeability member 4 are arranged in the middle thereof, with a two-layer MR element 2 facing each other with a required spacing. . (4) Magnetic 1/CMR element 2. l is sensitive.

In addition, in general, in order to linearize the operation of the MR elements 2, 2,
Means such as applying a bias magnetic field to the MR element 2.2' or tilting the direction of magnetization and current are used, but in the example of Fig. 1, as shown in Fig. 1 (b) A power supply 7.7 is provided, and a so-called mutual bias system is formed in which the current flowing through each MR element 2, 2 mutually strikes a bias magnetic field f T:lJ, and a differential amplifier 8 outputs the MR element 2.2. Outputs differentially. 9ba MR element 2
．． A drawing layer for flowing 2Krt flow, made of A4 or Cu.
Formed with a thin film.

FIG. 2 is an explanatory diagram of the shunt bias method in a conventional MR head, in which FIG. 2(a) is a sectional view of the main part;
Figure (b) shows a perspective view and a block diagram.
Portions corresponding to those in the figures are given the same reference numerals and redundant explanation thereof will be omitted.

In the figure, 9e is made of titanium film and is formed by vapor deposition or sputtering before the MR element 2 is vapor deposited.
and 10 to shunt the current flowing to the MR element 2 at a predetermined ratio, and a bias magnetic field is applied to or pulled from the MR element 2 by the four shunt currents.

FIG. 3 is an explanatory diagram of the manufacturing process of a multi-element MR head for magnetic tape, and ta) is a high magnetic permeability member corresponding to FIGS. 1 and 2 on the magnetic substrate 1 or a non-magnetic substrate (not shown). 4 shows the process formed by vacuum film forming technology,
+b) is the cover plate 5 when all film formation is completed.
This shows the process of gluing.

(Q) is a cutting process in which each MR heno-F is cut individually, and the frame 11 shown in (i) is cut through the ωf polishing process.
is glued to. Furthermore, the MR head is completed by connecting the flat cape Jv12 and the head terminals by all wire bonding.

By the way, conventionally completed MP heso-l'' VCri characteristics are often accompanied by variations, and it is said that the main factor controlling this variation in properties is the magnetic anisotropy dispersion of the MR element. The magnetic anisotropic dispersion is the actual MR
Because there was no way to determine the degree of change during the head manufacturing process, the characteristics of the MR head were tested only after the actual head had gone through the manufacturing process described above and became a finished product. The only way to do so was to determine the authenticity of the production lot.

Therefore, when disqualification occurs! ! ! ! The large amount of man-hours consumed in the manufacturing process resulted in a shortage that hindered mass production.

(C) @Mei's purpose The present invention is based on the MR head manufacturing process Vc in view of the deficiencies of the conventional method.
It is an object of the present invention to provide a means for determining the quality of an MR head during failure of film formation.

(d) Structure and object of the invention According to the present invention, four magnetoresistive elements, a bias conductor layer for linearizing the operation of the magnetoresistive element, and one
In the manufacturing process of a shunt bias type magnetoresistive magnetic head, in which a non-magnetic insulating layer enveloping both of the above and a shielding magnetic layer for magnetic shielding are formed on a substrate t by vacuum film-forming technology. , At the same time as the manufacturing process of the magnetic head, a magnetoresistive thin film and each layer other than the shield magnetic layer are applied to a non-magnetic insulating layer serving as a dummy substrate having the same or similar coefficient of thermal expansion and thermal conductivity as the substrate. A dummy head is formed by depositing a film in the same process, and the current flowing through the 111 magnetoresistive element of the dummy head is used as a parameter to calculate the tilt angle of the operating part of the characteristic curve and the current bias magnetic field amount. This can be achieved by a magnetic head manufacturing method characterized by measuring the change, confirming that the measured results are as desired, and then performing the next processing step.

In the case of a mutual bias type magnetoresistive magnetic head, manufacturing of the magnetic head includes a magnetoresistive element thin film of a given width and each layer except for the shield magnetic layer and one magnetoresistive element thin film on the nonmagnetic substrate. A dummy head is formed by forming a film in the same process at the same time as the process, and the change in the slope of the operating part in the characteristic curve is measured using the current flowing through the magnetoresistive element thin film of the dummy head as a parameter (resistivity/magnetic field strength). Measure it, confirm that the measurement result is the desired value, and then proceed to the next process.

In these cases, the nonmagnetic substrate that will become the dummy substrate is formed integrally with the head pattern substrate used to manufacture the actual magnetic head, and after film formation, the dummy substrate is left in the substrate state before being separated. If the characteristics mentioned above are measured, it will be possible to judge whether the product is good or bad even more accurately.

(θ) Embodiments of the Invention An embodiment of the present invention will be described in detail with reference to FIG. 4 and subsequent drawings. In these figures, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 4 shows dummy element test data of the shunt bias method.

A dummy element (element width W=50 μIn) was fabricated on a non-magnetic crystal substrate by removing the magnetic shield layers 1 and 4 shown in FIG. 2(b) in the same manufacturing process as that shown in FIG. 8.

MR element current/f77 DC = l/. , 7).

The illustrated dummy element 13 is composed of a crystal substrate and a non-magnetic insulator.
The ``l'' is omitted. A current of 13 VC is passed through this dummy element to measure its characteristic curve (resistivity ρ/magnetic field strength H), and a tangent line is drawn from the curve of the characteristic curve to find its intersection with the H axis as shown in the figure. The deviation of the characteristic curve in the H-axis direction to the peak of the resistivity ρ caused by the shunt current, that is, the current dependence of the current bias value δ on the corresponding dummy element flow filter 1 was measured. .

Further, the current bias amount δ was converted into an angle θ using a mathematical formula to obtain data, and measurements were made for the MR element 2 with positive and negative magnetostriction characteristics λ. As a result, for the MR element 2 with a negative magnetostriction characteristic λ, the 1 shift of Hkf has an upward trend (see curve ■) with respect to the increase in the dummy element 1, so the effective bias θ changes. It turned out to be difficult to do so (see curve ■). The 1(kO) arrow shown on the vertical axis in FIG.
The ratio H to Kaoru shows the change in [k−x].

- For those with a positive universal strain characteristic λ, the curve of Hk* does not change with an increase in the dummy element current 1 (see curve ■), so the bias θ increases normally (see curve ■), that is, the shift It turns out that it does.

Based on the results described above, we manufactured so-called Shan F bias type MR heads with two types of positive and negative magnetostrictive characteristics λ, and as with the results shown in , the bias was applied more normally with the positive magnetostrictive characteristics λ, and the reproduction characteristics were better. was also good. In other words, from these measurements, it can be predicted that an MR crystal with a large current dependence of L'(k yellow) will also have a large magnetic anisotropy dispersion.

Next, a method for predicting MR-S rad using the mutual bias method shown in FIG. 1 will be described.

FIG. 5 shows dummy element test data of the mutual bias method.

At the same time as the manufacturing process shown in Fig. 3, magnetic shields 11 and 4 shown in Fig.
and MR element 2' except for the dummy element (element width W-5
0 μm). In the illustrated dummy element 14, the description of the crystal substrate and nonmagnetic insulator is omitted. Various currents were shunted through this dummy element 14 and its (resistivity ρ/magnetic field strength H) characteristic curve was measured.
The current dependence of the timmy element on the current 2 was measured at dawn. Regarding the MR element 2, measurements were taken for those with positive and negative magnetostriction characteristics λ. As a result, when the magnetostrictive characteristic λ of the MR element 2 is negative, the value of Hkf tends to increase as the dummy element 2 increases (see curve ■).
- It was found that for those with a positive universal strain characteristic λ, the peaks and peaks do not change with respect to the increase in yc of the dummy cumulonite current 2 (see curve ①). When two MR heads with two types of MR elements, one with a positive magnetostriction characteristic λ and one with a negative magnetostriction characteristic λ, were arranged in the mutual bias method described in E, the results shown in L show that the current dependence of H, -+ was When the magnetostrictive property λ is positive,
It was found that the RAD bias was applied normally and the reproduction characteristics were good.

In the above explanation, we used a non-magnetic crystal substrate with a similar thermal expansion coefficient and thermal conductivity to the actual head substrate as a dummy substrate. If the film formation process is performed on the north side of the formed substrate and the dummy substrate is used for testing after film formation is completed and before separation, it is effective to reduce film formation errors. If the actual head substrate is made of non-magnetic material, it can be used as is as a housing dummy substrate.

(f) Effects of the Invention As described in detail, according to the method for manufacturing a magnetic head according to the present invention, it is possible to determine whether the reproduction characteristics of the MR head are good or bad after all film-forming processes are completed. Variations in the characteristics of the MR head can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional mutual bias type MR head, in which ta) is a sectional view of the main part, and FIG. 1(b) is a perspective view and block diagram. Figure 2 shows the conventional shunt bias method MR.
FIG. 2 is an explanatory diagram of the head, in which (a) is a cross-sectional view of the main part, and (b)
shows a perspective view and block diagram. FIG. 8 is an explanatory diagram of the manufacturing process of a multi-element MR head for magnetic tape, FIG. 4 shows dummy element test data of the shunt bias method, and FIG. 5 shows dummy element test data of the mutual bias method. In the figure, 1 is a magnetic substrate, 2 and 2 are magnetoresistive elements, 3 is a nonmagnetic insulating layer, 4 is a high magnetic permeability member, 5 is a cover plate, 6 is a magnetic recording medium, 7, 7', and 10
and 10 are power supplies, 8 is a differential amplifier, 9 is titanium, 9vi extraction layer, 181d shunt bias type dummy element, 1
Reference numeral 4 indicates a dummy element of mutual bias type. 2 To Ofi Figure 3 Figure 5

Claims (1)

[Claims] A magnetoresistive element thin film having the required thickness of one layer is to be manufactured on a non-magnetic substrate having the same or similar coefficient of thermal expansion and thermal conductivity as the substrate of the magnetoresistive head to be manufactured. A dummy head is formed in the same process at the same time as the magnetoresistive element thin film, and the characteristic curve showing the relationship between resistivity and magnetic field strength is determined using the current flowing through the magnetoresistive element thin film of the dummy head as a parameter. . A method of manufacturing a magnetic head, characterized in that the quality of the magnetoresistive element thin film is judged from a one-degree change in the operating portion of the curve, and the magnetic head is processed.