JPH0556561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film magnetic head used in magnetic disk devices and the like. This thin-film magnetic head has excellent frequency characteristics, and because it uses a manufacturing process based on semiconductor technology, it is possible to produce highly accurate magnetic heads at low cost, and is expected to become the mainstream of magnetic heads in the future. .

FIG. 1 shows a schematic cross-sectional view of such a thin film magnetic head. Here, a lower magnetic layer 13 is formed on the substrate 11 via an insulating layer 12,
After that, the insulating layer 14 which becomes a gap, the coil 1
5. A coil step elimination layer 16 is formed, and then an upper magnetic layer 17 and an overcoat layer 18 are formed.

By the way, in the thin film magnetic head having the above-mentioned structure, the upper and lower magnetic layers 17 and 13 are conventionally formed of the same soft magnetic material, and the upper magnetic layer 17 is indicated by the arrow in FIG. A shown
Since the upper magnetic layer 1 experiences a step difference in the
7, that is, the coercive force Hc and magnetic permeability μ are deteriorated compared to the lower magnetic layer 13, and in addition, the A part,
It has been pointed out that since the thickness of the A' portion is small, magnetic saturation occurs in the upper magnetic layer 17, resulting in a significant drop in writing/reading efficiency.

Therefore, conventionally, the thickness T' of the upper magnetic layer 17 is at least 30 mm compared to the thickness T of the lower magnetic layer 13.
A thin film magnetic head has been used which is made thicker by ~40% to minimize the influence of deterioration of the magnetic properties of the above-mentioned upper magnetic layer 17 in the A section or A' section. However, in such a thin film magnetic head,
In the case of a manufacturing method in which a soft magnetic material constituting the upper magnetic layer 17 is formed by a sputtering method or the like, and then a dry etching method is used to form the upper magnetic layer 17 in a predetermined shape, the film thickness is large. Therefore, a large amount of time is required for film formation and etching, which has the drawback of significantly impairing the workability and low cost of the thin film magnetic head. Furthermore, since the etching time is long, the thickness of the photoresist pattern must be increased, making it essential to form a photoresist pattern with a high aspect ratio, which poses a major problem in the process. In addition, the effect of the regression phenomenon of the photoresist pattern has become noticeable, and in particular, in thin-film magnetic heads for high recording density with narrow track widths, it has become difficult to realize a predetermined track width with high precision, resulting in major drawbacks in the process. was.

On the other hand, the upper magnetic layer 1 is
7, the height of the photoresist pattern serving as the plating frame must be increased, and even with this method, how to form a photoresist pattern with a high aspect ratio is a big problem in the process. Ta. In addition, the time required for plating is long, which has the disadvantage of impairing workability. Furthermore, a long plating time also means that there is a greater possibility of compositional deviation during plating, which necessitates stricter composition control during plating, which places a greater burden on the manufacturing process. It had the following drawback.

As mentioned above, it is extremely important in the manufacturing process to suppress the influence of deterioration of the magnetic properties of the upper magnetic layer 17 at the stepped portion by increasing the thickness of the upper magnetic layer 17. This was a major problem from the viewpoint of process workability, reproducibility, etc., or from the viewpoint of production costs.

In view of the above points, the present invention solves the various problems in the manufacturing process described above, and provides a thin film magnetic head that is inexpensive and has excellent write/read efficiency.

The present invention provides a thin film magnetic head comprising a coil made of a conductor sandwiched between a lower magnetic layer made of a soft magnetic material and an upper magnetic layer, in which a coercive force Hc of a first soft magnetic material forming the lower magnetic material layer is provided. , the magnetic permeability μ and the saturation magnetic flux density B, and the second magnetic layer forming the upper magnetic layer.
The coercive force H′c, magnetic permeability μ′ and saturation magnetic flux density B′ of the soft magnetic material have the following relationships: Hc≧H′c, μ<μ′ and B<B′ This is a thin film magnetic head, and by adopting this configuration, a thin film magnetic head that is easy to manufacture and has excellent write/read efficiency can be obtained.

The present invention will be explained below with reference to FIG. In FIG. 2, a lower magnetic layer 23 of a thickness T made of a first soft magnetic material is formed on a substrate 21 via an insulating layer 22 using a photo-etching technique or the like, and then an insulating layer 24 that becomes a gap is formed. , a coil 25 made of a conductor, or a step elimination layer 2 of the coil
6, the film thickness of the second soft magnetic material is
An upper magnetic layer 27 of T′ (T′≦T) is formed,
After that, an overcoat layer 28 is formed.
Here, the upper magnetic layer 27 has a coercive force Hc′,
Magnetic permeability μ′ and saturation magnetic flux density B′ are Hc′≦Hc, μ′>
It is composed of a second soft magnetic material having the relationship μ, B′>B.

In such a thin film magnetic head, the coercive force H'c of the second soft magnetic material forming the upper magnetic layer 27 and the magnetic permeability μ' are the coercive force of the first soft magnetic material forming the lower magnetic layer 23. H′c≦Hc, μ′＞ for Hc, magnetic permeability μ
Since the relationship is μ, the magnetic properties deteriorate due to the step at the stepped portion B or B′ shown by the arrow in Fig. 2, but the magnetic properties at the flat portion of the second soft magnetic material forming the upper magnetic material layer deteriorate. By adopting the configuration of the present invention in which the magnetic property values (values of coercive force and magnetic permeability) are superior to the magnetic property values of the first soft magnetic material forming the lower magnetic material layer, deterioration at the stepped portion is prevented. Even if such deterioration occurs, it is possible to maintain the magnetic property value after deterioration to be equal to or higher than the magnetic property value of the first soft magnetic body, and the influence of property deterioration becomes relatively small. Also, the saturation magnetic flux density is
Since there is a relationship B'>B, the thickness T' of the upper magnetic layer 27 is relative to the thickness T of the lower magnetic layer 23.
Even when T'≦T, magnetic saturation is unlikely to occur, and excellent writing/reading efficiency can be achieved. Moreover, as mentioned above, the upper magnetic layer 27
Since there is no need to increase the film thickness, the manufacturing process disadvantages of the conventional example described above, such as the long time required for film formation or etching, and the formation of a high aspect ratio photoresist pattern, are avoided. problems such as the difficulty of
This is considered to be extremely significant in the manufacturing process of thin-film magnetic heads.

In one embodiment of the present invention, the first soft magnetic material is, for example, a NiFe alloy film (coercive force Hc
0.5o¨e, magnetic permeability μ2000 at 10MHz, saturation magnetic flux density B10000 Gauss), coercive force Hc0.05o¨e, magnetic permeability μ3000 at 10MHz, and saturation magnetic flux density B14000Gauss.
It is conceivable to use a Co ₉₀ Zr ₁₀ (wt%) film as the second soft magnetic material.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a conventional example;
The figure is a schematic sectional view for explaining an embodiment of the present invention. 11, 21...Substrate, 12, 14, 22, 24
... Insulating layer, 13, 23 ... Lower magnetic layer, 1
5, 25... Coil, 16, 26... Step elimination layer, 17, 27... Upper magnetic layer, 18, 28...
...Overcoat layer.

Claims (1)

[Claims] 1. In a thin film magnetic head in which a coil made of a conductor is sandwiched between a lower magnetic layer and an upper magnetic layer made of a soft magnetic material, the coercive force Hc of the first soft magnetic material forming the lower magnetic material layer; Magnetic permeability μ and saturation magnetic flux density B, coercive force H′c of the second soft magnetic material forming the upper magnetic layer, magnetic permeability μ′ and saturation magnetic flux density B′ are such that Hc≧H′c, μ< A thin film magnetic head characterized in that it has a relationship of μ' and B<B'.