JPH087228A - Method for working surface of alumina - Google Patents

Abstract

PURPOSE:To obtain a method by which burrs are inhibited from being generated at the periphery of the unengraved projecting part at the time of selectively performing engraving work of a surface of alumina with ion milling. CONSTITUTION:In this method, the resist film 3 is provided on the surface of the alumina film 2 so as to form a pattern and thereafter, the uncovered part of the surface of the alumina film 2 with the resist film 3 is subjected to engraving work with ion milling. At this time, the initial thickness of the resist film 3 is set so as to provide a <=3000Angstrom residual thickness of the resist film 3 at the point when the ion milling is completed through engraving the uncovered part of the surface of the alumina film 2 to a set depth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing an alumina surface, and more specifically to an improvement in a method for forming a predetermined recess on the surface by digging the alumina surface with an ion mill.

[0002]

2. Description of the Related Art As is well known, the manufacturing process of a thin film magnetic head includes the following steps. First, Fig. 3
As shown in (A), a substrate 1 having an alumina film 2 having a thickness of about 13 μm formed on the entire surface is prepared. Next, as shown in FIG. 3B, the entire surface of the alumina film 2 has a thickness of about 6 μm.
After forming the resist film 3 having a thickness of 1, the predetermined portion of the resist film 3 (the portion where the concave portion is formed on the surface of the alumina film 2) is removed by photoetching to form a predetermined pattern as shown in FIG. To do.

Then, as shown in FIG. 4A, ion milling is performed using the patterned resist film 3 as a mask, and the exposed surface of the alumina film 2 not covered with the resist film 3 is dug to a predetermined depth. . After that, by removing the resist film 3, as shown in FIG.
A predetermined recess 2b is formed on the surface of the alumina film 2.

[0004]

However, in the conventional processing process described above, as shown in FIG.
There was a problem that burrs 4b were generated at the corners of the protrusions 2a of the alumina film 2 that were not dug by the ion mill (the dug portions are recesses 2b).

The present inventor has determined that the burr 4b is generated by the following mechanism. That is, the shavings of the alumina film 2 generated with the progress of the ion milling process adhere to the side surface of the resist film 3 and solidify as shown in FIG. 4 (A). After that, a resist removal process is performed,
Since the alumina is not removed, the solidified scrap 4
That is, a remains as the burr 4b after the step of removing the resist film 3. Since such a large burr 4b remains, conventionally, it has been necessary to remove the burr 4b, for example, by scrubbing with a solvent such as acetone. Therefore, not only the productivity is lowered, but also the uneven pattern formed on the surface of the alumina film 2 is damaged by scrubbing and the dimensional accuracy is lowered.

The mechanism of burr formation will be described in detail.
About 13 μm in the manufacturing process of thin film magnetic head
The surface of the alumina film 2 having a thickness of 1 is selectively dug by a depth of about 2800 angstroms by ion milling. During this ion milling, the initial film thickness is 6 μm.
Although the resist film 3 is scraped off by about 7,000 angstroms, it is 5 μm even when the ion mill processing is completed.
The resist film 3 having the above thickness remains. Since a large amount of shavings 4a adhere to the side surface of the sufficiently thick resist film 3, the burr 4b after removing the resist film also becomes very large.

The present invention has been made in view of the above background, and an object of the present invention is to solve the above problems and to prevent harmful burrs when selectively digging an alumina surface by an ion mill. It is an object of the present invention to provide a method for processing an alumina surface that prevents the occurrence of

[0008]

In order to achieve the above object, in the method for processing an alumina surface according to the present invention, after a resist film is patterned on the surface of the alumina film, the resist film is coated with the resist film by an ion mill. In the method of digging the alumina surface of a non-existing portion, when the ion mill is finished by digging the alumina surface by a set depth, the residual film thickness of the resist film is more than 0 and 3000 angstroms or less. The initial film thickness of the resist film was set so that

As described above, the upper limit of the resist residual film is set to 30.
The reason why the thickness is set to 00 angstroms is that if the thickness is thicker than that, it is possible to recognize that the shavings of alumina have adhered to the side surface of the resist as burrs, which causes a practical problem. On the other hand, if no residual resist film remains, the alumina surface covered with the resist film may be slightly ion-milled. Therefore, the range of the thickness of the residual film is set to be larger than 0 and 3
The range was smaller than 000 angstrom.

[0010]

When the residual film thickness of the resist film is 3000 angstroms or less at the stage of digging the alumina surface by the set depth and finishing the ion mill, the scraps that are the source of the burr are generated as described above. Since there is almost no place to adhere (the side surface of the resist film), there is substantially no burr that causes a problem. Also, with the ion mill,
Since the resist film is simultaneously etched when the alumina surface is subjected to the engraving process, the thickness of the resist film applied to the alumina surface is determined in consideration of the amount to be removed.

[0011]

The preferred embodiments of the method for processing the surface of alumina according to the present invention will be described in detail below with reference to the accompanying drawings. 1 and 2 show an embodiment of the present invention and show an example applied to the formation of an auto-alignment marker which is a part of the manufacturing process of a thin film magnetic head similar to the conventional example. That is, in the case of a thin film magnetic head, a plurality of head elements are manufactured by laminating layers of a predetermined shape on a single wafer using a semiconductor process, and then appropriately cut and polished. Then, in order to determine the cutting position when performing the cutting process or as a reference for alignment when performing the photolithography, an uneven mark at a predetermined position around the wafer (alumina surface), that is, a bright field Various processes are performed by forming a concave pattern for dark field and a convex pattern for dark field and detecting and confirming the concave or convex pattern with a microscope or the like. Then, in the present embodiment, each of these patterns is formed.

Specifically, first, as shown in FIG. 1A, a substrate 1 having an alumina film 2 with a thickness of about 13 μm formed on the entire surface is prepared. Next, a very thin resist film 3 having a thickness of about 8000 angstrom is formed on the entire surface of the alumina film 2 as shown in FIG. This is the feature of the present invention.

That is, when the ion mill in the subsequent step is performed,
The exposed alumina surface is dug, but at the same time, the resist surface is also shaved. If the rate at which alumina is removed by the ion mill is 100 Å / min (depending on the power, etc.), the rate at which resist is removed under the same conditions is about 200 Å / min, which is about twice as fast. To be

On the other hand, in order to function as a pattern for the bright field and the dark field, about 2800 from the surface of alumina.
Angstrom needs to be dug. In the present invention, since the thickness of the resist residual film after ion milling needs to be suppressed to 3000 angstroms or less, the resist thickness can be obtained by substituting each predetermined value into the following formula.

[0015]

## EQU1 ## From the above calculation results, the thickness of the resist initially applied is 5600 to 8600 angstroms, which is 7000 angstroms with a margin of ±.

Next, the resist film 3 is partially removed by photoetching to form a predetermined pattern (a pattern in which the concave portion forming portion of the alumina surface is opened and exposed) as shown in FIG. . Ion milling is performed using the resist film 3 thus patterned as a mask, and the surface of the alumina film 2 that is not covered with the resist film 3 is dug by a depth of about 2800 angstroms. At this time, the resist 3 is also removed at the same time (see FIG. 2).
(A)).

Thereafter, the remaining resist film 3 is removed by performing O ₂ plasma cleaning and acetone cleaning a predetermined number of times. Then, as shown in FIG. 3B, each pattern of the concave portion 2b formed by being dug into the surface of the alumina film 2 and the portion (the convex portion 2a) covered with the resist is formed.
As the material of the resist film, a material mainly composed of a typical novolac resin is used, and the ion mill performs argon ion at an incident angle of zero.

By the way, the surface of the alumina film 2 is about 280
The ion mill process is completed by digging a depth of 0 angstrom, and the resist film 3 is also about 5600 in the meantime.
It is reduced by about angstrom (the cutting speed is about twice), and the residual film thickness at the end of processing is about 1400 angstrom. Since the residual film thickness of the resist film 3 is extremely small as described above, there is almost no place where shavings adhere during ion milling, so that the shavings adhere to the side surface of the resist film and solidify, and after removing the resist film. However, the remaining burr hardly occurs. Further, microscopically, the scraped alumina dust may adhere to the extremely thin side surface, but since the magnification of the microscope used when performing the above-mentioned auto-alignment is about 1000 times, it will be a burr. It cannot be recognized and there is no practical problem.

It should be noted that the thicknesses and dimensions in the above-mentioned embodiments are merely examples, and the predetermined conditions are satisfied depending on the amount of alumina dug, the speed at which the resist or the like used is scraped, and the thickness of the resist residual film. It goes without saying that an appropriate combination can be used within the range.

[0020]

As described above, in the alumina surface processing method according to the present invention, since the residual film thickness of the resist film at the end of the ion mill is extremely small (since there is almost no), the etching treatment (drilling processing) is performed. The place where the alumina scraps in the inside adhere (the side surface of the resist) finally disappears, so that the scraps adhere to the side surface of the resist film and solidify, and the burr remaining after the removal of the resist film hardly occurs. That is, the present invention is very effective in simplifying the manufacturing process of the thin film magnetic head and improving the accuracy of the product.

[Brief description of drawings]

FIG. 1 is a process drawing showing a processing method according to an embodiment of the present invention.

FIG. 2 is a process drawing showing a processing method according to an embodiment of the present invention.

FIG. 3 is a process drawing showing a conventional processing method.

FIG. 4 is a process diagram showing a conventional processing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Alumina film 2a Alumina film convex portion 2b Alumina film concave portion 3 Resist film 4a Shavings attached to the side surface of the convex portion 4b Burr

[Table 1]

Claims (1)

[Claims] 1. A processing method of patterning a resist film on the surface of an alumina film, and then engraving the alumina surface in a portion not covered with the resist film by an ion mill, wherein the alumina surface is set to a set depth. The alumina film surface is characterized in that the initial film thickness of the resist film is set such that the residual film thickness of the resist film is more than 0 and not more than 3000 angstroms after the ion milling is completed and the ion mill is finished. Processing method.