JPS6327768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a ferrite magnetic head that can be mounted on a magnetic disk, magnetic drum device, etc. to enable high-density recording.

In recent years, as recording density has increased, the track width of magnetic heads has tended to become narrower and narrower.
Conventionally, the track portion of a ferrite magnetic head has been processed mainly by so-called machining methods such as grinding or polishing, but when machining a track width of 30 μm or less using this method, chipping or chipping due to the brittleness of ferrite may occur. , the influence of the process-affected layer cannot be ignored, and the manufacturing yield and performance of the head are inevitably reduced significantly. Therefore, as an alternative method, a method has been proposed in which the track width processing is performed using an ion etching method that has high processing accuracy and is less affected by the processing.

FIG. 1 shows an example of the processing steps for forming the track portion and slider portion of a monolithic ferrite head using this method. That is, in this method, (1) gap 1 and coil winding window 2
(2) depositing a masking Cr film 4 on the surface facing the medium; (3) shaping this by photo-etching to form a mask 5 in the portions that are to become tracks and sliders. , (4) Form the track portion 6 and slider portion 7 by etching the medium facing surface not covered with the mask using the sputter etching method. (5) Remove the remaining Cr mask and remove the medium of the core block. A track portion and a slider portion are formed through the step of exposing the opposing surfaces.

By the way, when attempting to actually employ such a processing method, the first problem is the selective etching properties between the ferrite and the metal mask material. This is because, in order to produce a head with electromagnetic characteristics equivalent to those of a conventional machined head, it is necessary to sputter-etch the medium facing surface not covered by a mask by at least 4 μm, whereas the track width machining accuracy is This is because, considering the difficulty of film fabrication, etc., the amount of sputter etching of the Cr mask must be 1 μm or less. This corresponds to the fact that the etching rate ratio of ferrite and Cr must be 4 or more, and the conventional method, that is, using argon gas as the sputtering gas,
It is already well known that such selective etching cannot be achieved by sputter etching at a gas pressure of approximately 5×10 ^-3 Torr.

The present invention was developed as a result of taking these matters into consideration, and its feature is that when processing the track width of a ferrite head using the sputter etching method, a Cr mask and a sputter gas mainly composed of argon are used. , and this gas pressure is Ni−
0.8×10 ^-2 to 5× for Zn ferrite head
10 ^-2 Torr, for Mn-Zn ferrite head
The point is to set it at 1.5×10 ^-2 to 3×10 ^-2 Torr.
It was found that by adopting this method, the selective etching properties of ferrite and Cr can be greatly improved, making narrow track processing easier and more accurate than before.

The contents of the present invention will be explained in detail below based on Examples.

Example In FIG. 2, the solid line shows the results of investigating the sputter gas pressure dependence of the sputter etching rate for ferrite and Cr using argon as the sputter gas and fixing the power density to 3 W/cm ² .
From the same figure, (1) the etching speed of ferrite is 2
Maximum at gas pressure near ×10 ^-2 Torr, (2) Ni−Zn ferrite and Mn− at this pressure
The etching rate ratios of Zn ferrite and Cr are about 11 and about 7, respectively, indicating that the above-mentioned conditions regarding selective etching properties are fully satisfied.

Therefore, when we sputter-etched the surfaces of Ni-Zn and Mn-Zn ferrite core blocks on which a 1.5-μm thick Cr mask had been formed by about 4 μm under this pressure, we found that narrow track width processing was possible with an accuracy of 10 ± 0.5 μm. I understand. In addition, such a sputter etch head can be manufactured using methods well known in this technical field (for example, IEICE Study Group Materials, MR77-1
(1977)) by grooving to reduce the flying height and laser-assisted machining to eliminate the effects of unnecessary side gaps, it is possible to have electromagnetic conversion characteristics equivalent to conventional machining heads. This was confirmed.

Next, with the power density fixed at the above value, the effect of sputter gas pressure on the finish of the sputter etch head was investigated. As a result, in the case of Ni-Zn ferrite, the gas pressure was increased to 5×10 ^-2 Torr
or more, or less than 0.8×10 ^-2 Torr, (1)
It takes more than 4 hours to sputter etch ferrite to about 4 μm, which not only worsens work efficiency but also tends to cause fluctuations in the finished track width. (2)
If the film thickness of the Cr mask is not 1.5 μm or more, defects will easily occur on the surfaces of the track section 6 and slider section 7. (3) If the film thickness of the Cr mask is made thick to prevent the above defects, track width processing will be difficult. It was found that not only the accuracy decreased, but also the film was more likely to peel off. In addition, the above defects are likely to occur in the voids existing on the surface of the ferrite core block, and in order to eliminate the influence of these voids, the allowable Cr film thickness mentioned in (2) must be It was confirmed that this corresponds to the need to leave a mask of 0.5 μm or more. From these experimental results, when processing the track width of a Ni-Zn ferrite head using the sputter etching method, the argon gas pressure should be set at 0.8×10 ^-2 to 5×
Obviously, a setting of 10 ^-2 Torr is desirable.

On the other hand, for Mn-Zn ferrite, the above allowable gas pressure range is even narrower, from 1.5×10 ^-2 to
It was confirmed that it was 3×10 ^-2 Torr.

Although the case where only argon was used as the sputtering gas was described above, it was found that the same thing could be said when a small amount of hydrogen was added to argon. For example, when about 2% hydrogen is added to argon, the etching rate of Cr decreases as shown by the dotted line in Figure 2, but the etching rate of ferrite is hardly affected, so the selective etching of ferrite and Cr decreases. was further increased than in the case of using only argon. Therefore, the film thickness
Using a 1.5μm Cr mask, 0.8×10 ^-2 ~5×
Sputter etching of Ni--Zn ferrite headblocks in the 10 ^-2 Torr pressure range reduced the defect rate by about 30% compared to the argon alone method described above.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the process of processing a monolithic ferrite magnetic head using the sputter etching method, and FIG. 2 is a graph showing the relationship between argon gas pressure and sputter etching speed. Also, 1 is a gap, 2 is a coil winding window, 3 is a core block, 4 is a Cr film for a mask, 5 is a mask,
6 is a track section, and 7 is a slider section.

Claims (1)

[Claims] 1. When processing the track width of a ferrite head using the sputter etching method, a Cr mask and a sputter gas containing argon as a main component are used, and
A method for manufacturing a magnetic head, characterized in that the gas pressure is set to 0.8×10 ^-2 to 5×10 ^-2 Torr in the case of a Ni-Zn ferrite head. 2. When processing the track width of the ferrite head using the sputter etching method, use a Cr mask and sputter gas containing argon as the main component, and
A method for manufacturing a magnetic head, characterized in that the gas pressure is set to 1.5×10 ^-2 to 3×10 ^-2 Torr in the case of a Mn-Zn ferrite head.