JPS5839009A - Forming method for permanent magnet film pattern - Google Patents

Abstract

PURPOSE:To obtain a magnetic film pattern virtually free of superficial unevenness consisting of Fe3O4 and gamma-Fe2O3 on a base substrate by utilizing the difference of magnetic behavior between different Fe oxides. CONSTITUTION:An alpha-Fe2O3 film 6 is formed by reactive sputtering in an Ar plasma and O2 atmosphere on the surface of a ceramic substrate 5, which is followed by the formation of a Cr film, on said film 6, to be photo-etched into a mask pattern 7. The entirety is then accommodated in a reducing furnace containing H2 where it is heated for about 1 hour, whereby the alpha-Fe2O3 film 6 not covered by the mask pattern 7 is reduced into an Fe3O4 film 8. The mask pattern 7 is removed by using an alkaline water solution of potassium ferricyanide. Thus, a permanent magnet film pattern is formed composed of an Fe3O4 film 8 in the alpha-Fe2O3 film 6. Heating follows at approximately 350 deg.C for 1 hour in the air for the oxidation of the Fe3O4 film 8 into a gamma-Fe2O3 film 9, for the realization of a permanent magnet film pattern, with its surface virtually free of unevenness, wherein a gamma-Fe2O3 film 9 is interwoven with an alpha-Fe2O3 film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a permanent magnet film pattern. More specifically, the present invention provides 7e304 or 1-I on a substrate.
This invention relates to a method of forming a permanent magnet film pattern made of F.203 and having no unevenness on the pattern surface.

Thin-film functional elements with fine patterns are used in integrated circuits, and thin-film functional elements with permanent magnet film patterns are used to apply bias magnetic fields in flux-responsive magnetoresistive heads that utilize the magnetoresistive effect of ferromagnetic thin films. It is used in fields such as bias films.

The conventional method of forming a permanent magnet film pattern is shown in Figure 1, which shows a schematic diagram of a partial cross section of the base material for each step.
This will be explained according to the diagram. That is, (1) base material (1)
(ii) Form a pattern of resist (8) on the surface of the permanent magnet film according to the desired pattern, (ifl ) Remove the permanent magnet film in the portions not masked by the resist (8) using various etching methods, and then (1v) remove the resist (3) by immersing it in a stripping solution or the like to form the desired permanent magnet. Since the conventional method for forming a permanent magnet film pattern is based on an expensive method, it has the following drawbacks.

One example of this is the occurrence of unevenness due to differences. In particular, recent thin film functional devices tend to be multi-layered, and when an element consisting of a permanent magnetic film pattern with such irregularities is used as a lower layer, it is necessary to keep the thin film elements laminated on the upper layer flat. I won't be able to do that. A second drawback is that if the permanent magnet film is an oxide magnet, etching is not easy.

The present invention was made in view of such conventional drawbacks,
It is an object of the present invention to provide a method for forming a permanent magnet film pattern that does not cause unevenness on the pattern surface and does not require etching of the permanent magnet film itself, using a method that is quite different from conventional permanent magnet film pattern forming methods. .

That is, the present invention includes (a) a step of forming α-ν·20311 on the surface of the group s;
←) Step of forming a mask pattern made of a material that does not react with hydrogen on the surface of the TOHA GO3 film, (c) A- of the part not masked by the mask pattern.
It consists of a step of reducing the ν.gos film to a 304 film of 1, and a) a step of removing the mask pattern, or in addition to the above steps ←) Fe
The present invention relates to a method for forming a permanent magnet film pattern comprising a step of oxidizing 504MI4 to an f-Fe203 film.

Although a-IPs203 is a nonmagnetic material, 1.304 obtained by reducing it and γ-1.203 obtained by oxidizing Fe304 are permanent magnets. The present invention takes advantage of the differences in magnetic properties due to the different types of iron oxide.

Methods for forming the a-Fe203 film on the surface of the substrate in step (a) include a method of forming by sputtering using α-IFe'203 as a target, a method of forming 1e by reactive sputtering in Ar+02 with target binding, and 1e. Although conventional methods such as a method of vapor depositing and culturing on a substrate can be mentioned, a method using reactive sputtering is particularly preferred.

The material that does not react with hydrogen in step (b) is not particularly limited, but chrome or aluminum is preferable in consideration of ease of forming a mask pattern, subsequent removal process, and the like. In the case of chrome or aluminum, the mask pattern is easily formed by photoetching.

For example, the reduction in the Aki process (c) is performed by reducing the base material to about 270~! This is done by heating at 120'o. If the temperature is lower than 270°, the reduction will not proceed, and if it is higher than 320°0, the reduction will be excessive and metallic iron (1.) will be formed, which is not preferable. The reduction time is appropriately determined in consideration of the thickness of the a-1.203 film and the reduction temperature.

The removal of the mask pattern in the above step) differs depending on the type of mask material, for example, chrome or Al1=
If it is, add 30g of red blood salt and KOH to 100p of water.
This is done by immersing it in an etching solution in which 5P is dissolved.

Said engineer! (to) to) a-? on the surface of the base material.
A permanent magnet film pattern consisting of 1·504 II & can be formed in the 5203 film, but according to the present invention, in addition to these steps, the 1·304 film is
By subjecting the OS film to the step (e) of oxidizing it, a permanent magnet film pattern consisting of the y-y.203 film can be formed within the a-y.203 film.

The oxidation in step (e) is carried out, for example, in air at a temperature of about 600 to
This can be easily done by heating at 550 ao. The oxidation time is appropriately determined in consideration of the thickness of the Fe3Q4 film, temperature, etc.

Next, an embodiment of the method for forming a permanent magnet film pattern of the present invention will be described with reference to FIG. 2, which shows a schematic partial cross-section of the base material in each step.

First, an a-'Pe203 film (6) with a film thickness of 0.2 to 0.5 μm was formed on the surface of the ceramic substrate (6) by active sputtering using iron as a target in an argon, plasma, or sulfur atmosphere (step (stomach)). Next, a chrome film was formed on the α-IPe203 film, and a mask pattern (7) was further formed by photoetching (step (b)). Next, this material was heated in a hydrogen reduction furnace width of about 600°O, which can be heated while hydrogen was flowing in, for about 1 hour. Thus a
A permanent magnet film pattern consisting of the 7e304 film (8) could be suspended within the -11m203 film (6).

This material was further heated in the atmosphere at about 650°a for 1 hour to oxidize the Fe3Q4 film (8) to an r-νe203 film (9), and a y-y203 film was formed in the tl-Fe2Q5 film (6). A permanent magnet film pattern consisting of (9) was obtained (step (e)).
).

The permanent magnet film pattern obtained in this way is 10.0
When the surface of the pattern was observed using a stylus film thickness meter with a magnification of 0.00 times, almost no irregularities were observed on the surface.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a partial cross section of the base material for each step in the conventional method for forming a permanent magnet film pattern. Figure 2 is a partial cross-sectional view of the base material for each step in the method for forming a permanent magnet film pattern according to the present invention. It is a schematic diagram of a cross section. (Main symbols in the drawing) (6): (1-IF@R03 film (γ): mask pattern (8): 'Fe3O4 film (9): γ-7a203 film agent Shin Kuzuno (and 1 other person)

Claims (1)

[Claims] (1) (a) A step of forming an a-7s203 film on the surface of the base material, (b) A step of forming a mask pattern made of a material that does not react with hydrogen on the surface of the α-IFe203 film, ( C) α− of the part not masked by the mask pattern
A step of reducing the IFe203 film to a 10304 film, and a) a step of removing the mask pattern, or in addition to the above steps) 1.3
A method for forming a permanent magnet film pattern comprising a step of oxidizing a 04 film to an rr203 film. (2) The method according to claim 1, wherein the formation of the a-'I.203 film in step (a) is performed by reactive sputtering. (8) The method according to claim 1 or 2, wherein the material that does not react with hydrogen in step (b) is chromium or aluminum. (4) Said engineering! Formation of (b) mask pattern is 7
The method according to claim S, which is carried out by the etching method. (5) The reduction in step (c) is performed in a hydrogen atmosphere at approximately 270%
Claims 1, 2, and 3 are carried out by heating at ~620°O for about 0.5 to 1.5 hours.
or the method described in paragraph 4. (6) The removal of the mask pattern in the step) is performed by etching.
The method described in section. (γ) The oxidation in the step (e) is about 600 to 65% in air.
Claims 1, 2, 3, 4, and 5 which are carried out by heating at 0°0 for about 1 to 5 hours.
or the method described in paragraph 6.